Reificating Disorders Into Natural Kinds

PDF document: N.K. Gervais – Reification of Disorders

In psychological science, what counts as a disorder undergoes constant reexamination. Scholars are frequently bringing modifications to diagnostic manuals based on their latest experimental results. Yet, the way disorders are constructed and updated is sporadically investigated, especially in contrast with the amount of research within the framework of a disorder. As such, the investigation of how scientific facts are constructed is often left to outsiders and historians (Danziger, 1994; Latour & Woolgar, 1979), which bear little influence on common practice. As a result, psychological science is vulnerable to certain fallacies that go unchallenged within the field. This conundrum is of particular magnitude when psychological experts need to define normality in order to inform medical or legal practice. As neuroscience and pharmacology gain more importance in psychiatry, the spotlight has quickly turned to the biological aspect of mental illness. This has led scientists to make ambitious claims about the neurological basis of mental illness, that go far beyond reasonable inferences. As a result, psychological disorders are increasingly and erroneously portrayed as natural kinds. In other terms, mental illness is portrayed as conceptualizing categories created independently from human judgment. In the midst of rapidly evolving technology and research, scientists and the public alike appear to lack a clear understanding of the social construction of disorders.

What is a disorder?

The DSM-5 defines psychological disorder as “a clinically significant disturbance in an individual’s cognition, emotion regulation, or behavior that reflects a dysfunction in the psychological, biological, or developmental processes underlying mental functioning” (APA, 2013). Without an exception, psychiatric diagnoses were initially introduced as recurrent problematic behaviors. It is critical to acknowledge that psychological disorders are categories based on behavioral symptoms, and that biological measures used in academic research are only exploratory. In fact, if used in psychiatric practice, biological measures are taken to rule out any physical anomaly. Despite this, a dysfunctional neurobiology is often assumed to cause psychological disorders, through the process of reification.


Reification is the fallacy of treating an abstraction as if it were a concrete real event or physical entity. Constructs are examples of reification. A construct is a hypothetical explanatory variable that is not directly observable. Since the field of psychology investigates unobservable mental processes, its use of constructs is extensive, in order to mediate access to reality. For example, the concept of agreeableness in psychology is a construct: it is not directly observable, but is retroactively attributed a causal role based on aggregated behavioral samples. Complications can arise from such hypothetical thinking, however, by inadvertently suggesting that constructs refer to a discernible reality, which is called reification. After extensive data collection to support the measurability of a certain phenomenon, its “realness” is established in the scientific world. As a consequence, it is assumed that this categorization embodies a natural distinction, independent of human judgment—referred to as a natural kind. In social sciences, reification seems unavoidable, and this fallacious thinking can be traced back to centuries ago. John Stuart Mill (1806-1873) said that “the tendency was always strong to believe that whatever received a name must be an entity or being, having an independent existence of its own” (Robson, 1989). This common misconception mirrors an objectivist perspective, which assumes that all of reality consists of entities with fixed properties, and that a given property is necessary and sufficient to form categories.

Disorders are ‘kind of’ natural kinds?

            Natural kinds typically refer to categories that are homogeneous and have boundaries that do not rely on human judgment. In Plato’s words, it “carves nature at its joints”. The individual members of a natural kind must share some underlying structure or property that characterizes the kind in all possible cultures, historical periods and worlds in which it could exist (Dupré, 1981). In contrast, human kinds are constructed by humans and have properties that can be affected by human activity.

With the advent of neuroscience and pharmacology, psychological science has been illustrating the brain as the key to understanding individual differences in behavior. For instance, George Bush, then president of the United States, inaugurated the Decade of the Brain (1990-1999), stimulating research for a better understanding of the human brain and behavior (Bush, 1990). In a similar vein, the “chemical imbalance” theory of mental illness is widespread in society, even though it is unfounded (Leo & Lacasse, 2007). Naturally, all planned behavior originates from the brain, which explains the title of this section. However, it is commonly theorized that identifiable categories of brain anomalies or dysfunctions cause the problematic behavior. In turn, the disorder becomes gradually defined by its (undefined) neurological essence rather than behavioral presentation. Neurorealism, the idea that brains can offer “proof” of the existence of a phenomenon, is a widespread misconception in media coverage of scientific endeavor (Racine, Waldman, Rosenberg, & Illes, 2010). In sum, psychological disorders are commonly framed as natural kinds, defined by neurological categories.

The issue with disorders as ‘natural kinds’

No matter how appealing it is for certain grant-seeking scientists, the portrayal of disorders as natural kinds is improper. Verhoeff (2012) describes this issue in two parts. While it was done in the context of autism, it applies to psychological disorders in general. To begin with, there is hardly a distinct unifying essence in psychological disorders, which Verhoeff refers to as the issue of heterogeneity. Despite the widespread contrary assumption, psychiatric diagnoses are not separated by natural boundaries (Kendell & Jablensky, 2003). Neuroscientific research has not successfully “carved nature at its joints” (Hyman, 2007, p. 729), and we remain unable to diagnose psychiatric disorders using brain scans, including neurodevelopmental disorders. Psychiatric disorders do not represent categories based on biological criteria.

Some might say that those afflicted with mental illness share symptoms, for instance social deficiencies in the case of autism. Yet, the essence of most disorders in still hotly debated. In the case of autism, the nature of empathetic deficiencies is still a matter of debate, whether it is cognitive (Baron-Cohen, 2000), or affective (Chevallier, Kohls, Troiani, Brodkin, & Schultz, 2012). This blurs the notion of autism’s core symptomatology or essence. A feature that is rarely mentioned in autism, but always present, is sensitivity to environmental stimuli. Sensory sensitivity does lead to social impairment (Richard, French, Nash, Hadwin, & Donnelly, 2007). Thus, even with identical observations, two or more distinct conclusions can be argued, an issue typically referred to as the Rashomon effect (Heider, 1988). Furthermore, the diagnostic tools used have been very diverse, which changes the diagnostic criteria (which is in turn the essence) at every alteration. Recently, the construct of autism transitioned into a spectrum, a path that increasingly more disorders will probably follow, which altered the nature of autism. Even then, these diagnostic tools rely on constructs, arbitrary cutoff points, and clinical judgment. As such, the essence of psychiatric categories is not set in stone and is heterogeneous, and the factors leading to an individual’s inclusion in a certain category relies heavily on human judgment. This disputes the assertion that psychiatric diagnoses are natural kinds.

The second argument of Verhoeff’s (2012) position is that people classified within certain categories of disorders interact with the classification, which is a feature of human kinds. Hacking (1995) introduced the “looping effect”, or how categorization interacts with the targets they aim to describe (Hacking, 2007). As such, psychological accounts are “making up people”, kinds of people who did not exist before, due to the investigation interacting with them. For instance, the framing of substance addiction as a disorder might reduce the likelihood of the categorized to take action against their maladaptive behavior. Thus, mere categorization has altered the target. This has been extensively discussed within categories, but classification also interacts with the non-categorized, and with cultural conceptions of normality. For instance, consider the concept of gender in the social sciences. Social scientists have devised a construct that refers to the non-biological aspect of sexually dimorphic behavior. Slowly, the concept of gender has become reified into a reality, having an existence of its own. In present times, most are convinced that gender refers to something beyond a lexical object: a tangible entity that causally affects cognition and identity. In turn, this creates people that see gender variance as a way to be a person, or as a way to understand the world, which represents a new kind of people. This effect of looping is increasing as social movements gain traction, which strengthens the influence of institutions on the categorized.

Despite these pitfalls, behavioral sciences insist on framing disorders as natural kinds. Below are examples of misconceptions frequent in public and academic discourse, that reveal an underlying assumption of disorders as natural kinds.

Common misconceptions

            The politically correct nomenclature for those afflicted with mental illness is “people with” a certain disorder, in order to avoid reducing them to their impairment. Labeling individuals with a disorder implies that there is, somewhere, a true and intact person without mental illness and its associated features. Or, that this person’s behavior and tastes are part of the framework of mental illness. Had he been born without autism, the socially impaired programmer would have been interested in talk shows and team sports. Not only it is not any less stigmatizing, but it is logically incorrect. It implies that mental illness is an entity that one can have, or not have. “Having” a certain behavior, for example autism, is either a misnomer, or a concealed assumption of an underlying natural kind. Correct nomenclature would be “autistic people” or “people with autistic symptomatology”, which denotes a tendency to behave in certain ways, rather than a natural entity.

There are persistent debates about whether disorders are “real”. In the International Consensus Statement on ADHD, 52 prominent authors state that “The notion that ADHD does not exist is simply wrong. All of the major medical associations […] recognize ADHD as a genuine disorder because the scientific evidence indicating it is so is overwhelming” (Barkley et al., 2002). The realness of ADHD is undebatable. Its inclusion in diagnostic manuals is what makes it a real disorder. However, the consensus seems to imply that certain behaviors or experimental findings can support the existence of a disorder, suggesting that these provide evidence for a palpable but unobservable reality. On the contrary, natural criteria cannot dictate what counts as a disorder. This indicates that the authors believe that having a name, a measurement, and correlates grants ADHD the status of natural kind. In fact, psychiatric disorders are constructed, and embody all features of a human kind.

            The reification of mental illness into natural kinds is such that certain disorders are argued to apply to those who do not correspond to the usual criteria. A salient example is the creation of alternative criteria for men and women, assuming that an inner, natural property is shared but expressed differently. Tony Attwood, a prominent scholar on autism, states that “We understand far too little about girls with autism spectrum disorders because we diagnose autism based on a male conceptualization of the condition. We need a complete paradigm shift” (Attwood, 2009). Attwood makes the claim that something other than the conceptualisation of autism conceptualizes autism. That makes very little sense, unless you perceive psychiatric categories through the lens of natural kinds. Some even claim that autism can be “camouflaged” in girls with a normal social and academic life (Dean, Harwood, & Kasari, 2017). In a similar vein, Quinn (2005) argues that women with ADHD are underdiagnosed, because their ADHD is often expressed as daydreaming and looking out the window, instead of hyperactivity. As such, their excessive motor behavior, which defines ADHD, is not expressed in the form of excessive motor behavior. If a behavioral pattern does not correspond to a certain description, then it logically cannot obtain the label of this description. In short, assumptions of natural kinds are frequent in the scientific literature on mental illness.


The classification of psychological disorders seems to unavoidably reify them into real, essential physical entities. In turn, it easily transforms them into natural kinds, allegedly based in neurological categories that are inferred, rather than observed. This process is without a doubt facilitated by pharmacology and neuroscience, which focus on the biological aspect of mental illness, and benefit from extensive funding and media coverage. However, portraying disorders as natural kinds is erroneous. The lack of unifying essence and the interactive effect of classification represent features of man-made human kinds. Yet, the assumption that disorders are natural kinds prevails both in popular media and academia. Hopefully, there can be a gradual convergence of philosophers of science and scientists, that would shed light on this easily rectifiable misunderstanding. For instance, Steven E. Hyman, former director of the National Institute of Mental Health (NIMH), affirmed that “cautionary statements within the DSM-IV, if read at all, provide little protection among many communities of users against reification of the disorders listed within” (Hyman, 2010, p. 158). The acknowledgement of the issue is the silver lining to this conundrum.


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Attwood, T. (2009). Doctors are ‘failing to spot Asperger’s in girls’. Retrieved from

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Dean, M., Harwood, R., & Kasari, C. (2017). The art of camouflage: Gender differences in the social behaviors of girls and boys with autism spectrum disorder. Autism, 21(6), 678-689.

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Hacking, I. (1995). The looping effects of human kinds. In D. Sperber, D. Premack, & A.J. Premack (Eds.), Causal cognition: A multidisciplinary debate (pp. 351–383). Oxford: Clarendon.

Hacking, I. (2007). Kinds of people: Moving targets. Proceedings of the British Academy, 151(1), 285–318.

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Quinn, P. O. (2005). Treating adolescent girls and women with ADHD: Gender‐Specific issues. Journal of Clinical Psychology61(5), 579-587.

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Richards, A., French, C. C., Nash, G., Hadwin, J. A., & Donnelly, N. (2007). A comparison of selective attention and facial processing biases in typically developing children who are high and low in self-reported trait anxiety. Development and Psychopathology19(2), 481-495.

Robson, J. M. (1989). The collected works of John Stuart Mill, Vol. XXXI: Miscellaneous writings. Toronto, Ontario: University of Toronto Press.

Verhoeff, B. (2012). What is this thing called autism? A critical analysis of the tenacious search for autism’s essence. BioSocieties7(4), 410-432.


ADHD, Autism, and Psychopathy as Life Strategies: The Role of Risk Tolerance on Evolutionary Fitness

Here is a copy in PDF format.


This literature review suggests that autism spectrum disorders (ASD), attention deficit and hyperactivity disorder (ADHD), and antisocial personality disorder/psychopathy (ASPD) represent masculine life strategies. The diagnostic criteria of ADHD overlap with ASD and ASPD, both of which are often diagnosed alongside of ADHD. Additionally, all three are mostly diagnosed in males and related to brain masculinity. Those with masculinized brains would distinguish between themselves by their optimal stimulation level (or risk tolerance), which results in different competitive outcomes. Individuals with the highest optimal stimulation levels reach increased fitness.

Keywords: ADHD, psychopathy, autism, conduct disorder, testosterone, cortisol

ADHD, Autism, and Psychopathy as Life Strategies

Attention deficit and hyperactivity disorder (ADHD), autism spectrum disorders (ASD) and antisocial personality disorder/psychopathy (ASPD) are strongly related in terms of symptomatology, epidemiology, and comorbidity. The symptoms and comorbidities of ADHD diverge in two different directions. The symptoms of ADHD, especially ADHD-i (the inattentive subtype), overlap to a high degree with those of ASD. On the other hand, symptoms of ADHD, especially ADHD-c and ADHD-h (the combined and the hyperactive subtypes), overlap with those of antisocial disorders (conduct disorder, oppositional defiant disorder, and antisocial personality disorder). Moreover, the symptoms of ADHD that are shared with ASD correlate negatively with the symptoms shared with ASPD, suggesting that autism and ASPD are two ends of a spectrum. The current essay will argue that all three represent masculine life strategies to maximize evolutionary fitness, and are distinguished by their relative competitive success, as illustrated by their optimal stimulation level (Zentall & Zentall, 1983) and sexual behaviors. Importantly, all conditions mentioned are highly male-biased, and are often linked to the extreme masculinization of the brain. The present review would be the first to organize all these male-biased conditions along a single dimension: a vertical hierarchy of intra-sexual competitive strategies.

Attention Deficit and Hyperactivity Disorder

The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) defines the attention deficit and hyperactivity disorder (ADHD) as a persistent pattern of inattention and/or hyperactivity that impairs daily functioning, particularly in school and work settings. Three subtypes have been identified; the inattentive subtype, the hyperactive subtype, and the combined type. Most features associated with ADHD seem to converge two directions. The symptoms of ADHD-i resemble a milder form of autism, including poorer cognitive empathy, and a lower optimal stimulation level. On the other hand, the symptoms of ADHD-c and ADHD-h resemble the under-stimulated aspect of psychopathy, along with its absence of severe cognitive empathy impairment.

Common features of ASPD and ADHD-c/ADHD-h

Antisocial disorders resemble the symptoms of ADHD in many ways (e.g., Herpertz et al, 2001). Many are diagnosed with both ADHD and antisocial disorders—oppositional defiant disorder (ODD), conduct disorder (CD), or ASPD, or progress from one to another (Barkley, 1997; Campbell, Shaw, & Gilliom, 2000; Loeber, Burke, & Pardini, 2009; Salisbury, 2013). Hyperactive individuals are seven times more likely to develop antisocial disorders than controls (Mannuzza, Klein, Bessler, Malloy, & LaPadula, 1993).

Antisocial disorders and ADHD show similar patterns in interpersonal relationships. As a general rule, people with ADHD and antisocial disorders show stronger affective empathy deficits (problems with appropriate emotional response to others) relative to lesser cognitive empathy problems (problems with perspective taking). Some children with ADHD may prioritize personal goals such as sensation seeking and fun rather than complying with rules and equity (Melnick & Hinshaw, 1996). Children and adolescents with ADHD are often perpetrators of bullying in school (Bacchini, Affuso, & Trotta, 2008), are particularly reactive to provocation from peers (King et al., 2009), and tend to lack appropriate social skills, such as sharing, cooperation, and turn taking (Cordier, Bundy, Hocking, & Einfeld, 2010; Wehmeier, Schacht, & Barkley, 2010). Likewise, psychopaths and children with psychopathic tendencies have an intact Theory of Mind (Blair, 1999; Blair, 2007), but severely ignore the well-being of their peers. Children with CD, as opposed to those with ASD, show amygdala hypo-reaction in empathy tests. In children with both ASD and CD this results in lack of attention to the eyes (Bons et al., 2013). This propensity of those with ADHD to be impulsive, bullying, hostile and unable to form relationships based on the needs of both parties are a milder form of the interpersonal traits defining psychopathy, namely their instrumentality and manipulativeness, which denotes unidirectional benefits in interpersonal relationships. Indeed, people with ADHD show psychopathic personality traits but are not within the range of clinical psychopathy (Fowler et al., 2009; Piatigorsky & Hinshaw, 2004). While people with ADHD and psychopaths can be sociable and make new friendships, but have little motivation to do so, and show little concern about the well-being of others.

People with ADHD and antisocial disorders share a general tendency to use approach mechanisms, especially marked in the hyperactive/impulsive and combined subtypes. People using approach mechanism have an increased sensitivity to rewards, and decreased sensitivity to punishment (Keltner, Anderson, & Gruenfeld, 2003). As such, their sensory feedback is somewhat attenuated. Using the Sensitivity to Punishment and Sensitivity to Reward Questionnaire for children (SPSRQ-C), Luman, van Meel, Oosterlaan, and Geurts (2012) found that all their ADHD groups had higher reward sensitivity than controls. Additionally, those with a comorbid diagnosis of autism showed the most punishment sensitivity compared to other experimental groups. Becker and colleagues (2013) found that those with sluggish cognitive tempo (SCT), a cluster of symptoms that is not very different from ADHD-i, had an increased sensitivity to punishment, fear and shyness, compared to those with undifferentiated ADHD, who had an increased sensitivity to rewards and had traits of impulsivity. In conclusion, the closer the symptoms of ADHD are to psychopathy, the higher the sensitivity to rewards, and the least sensitivity to punishment. Increased reward sensitivity has been studied quite extensively in psychopaths (Wallace, Malterer, & Newman, 2009).

ADHD has many symptoms related to under-arousal, often resulting is excessive sensation-seeking tendencies. Examples include: dangerous driving behavior (Barkley, Murphy, Dupaul, & Bush, 2002) resulting in increased number of traffic accidents (Swensen et al., 2004), criminality (Mannuzza, Klein, Abikoff, & Moulton III, 2004), higher probability of physical injury, substance and alcohol abuse (Lee, Humphreys, Flory, Liu, & Glass, 2011; Rooney, Chronis-Tuscano, & Yoon, 2012) as well as risky sexual behaviors (Flory, Molina, Pelham, Gnagy, & Smith, 2006).

Psychological traits characterizing the symptoms of psychopathy and ADHD are highly overlapping, namely in regards to attention. In vigilance tasks, in which subjects must endure long periods of low stimuli, people with ASPD become quickly under-aroused. They become bored when they are unable to seek stimulation and they have difficulties paying attention (Orris, 1969). Moreover, just like individuals with ADHD, they are constantly seeking excitement from dangerous experiences and engage in more impulsive sensation seeking than controls (Ruch & Zuckerman, 2001). In a meta-analysis of 38 studies, Gao and Raine (2009) found that psychopaths have reduced P3 amplitudes on encephalographs, which are a measure of brain activity and an indicator of the extent to which the brain is engaged. These results have been replicated with participants with ADHD (Szuromi, Czobor, Komlosi, & Bitter, 2011). This indicates that the hyperkinetic tendencies of people with ADHD might originate in the traits that they share with psychopaths: a high need for stimulation and excitement.

Common features of ASD and ADHD-i

Children with ADHD-c/ADHD-h tend to be more aggressive and disinhibited, whereas ADHD-i children tend to be more passive and shy (Hodgens et al., 2000), similarly to children with ASD. ASD and ADHD, especially the inattentive subtype, share numerous symptoms (Rommelse, Geurts, Franke, Buitelaar, & Hartman, 2011; Salisbury, 2013; Taurines et al., 2012; Taylor, Charman, & Ronald, 2015). The first striking resemblance between ADHD-i and autism is the similarity of their classroom behaviors. They are often distracted, unorganized, do not seem to listen when spoken to and have trouble following instructions. For autism, these symptoms are typically believed to be the result of their narrow interests and difficulties attending to social stimuli. In the case of ADHD-i, the causes remain unclear. People with ADHD-i also have narrow interests and difficulties with communication, which indicates that the source of their difficulties might be the same than the difficulties of those with autism.

Those with ADHD, similar to those with ASD, have persistent deficits in social interaction. They both have a weak Theory of Mind (ADHD: Uekermann et al., 2010; ASD: Baron-Cohen, Leslie, & Frith, 1985). Enduring symptoms include difficulties with understanding others, knowing implicit social norms and having conversations made of reciprocal turn taking. Individuals with either condition drift off during conversation and pay little to no attention to social cues. People with ADHD have trouble understanding a social situation from someone else’s perspective (Marton, Wiener, Rogers, Moore, & Tannock, 2009). These difficulties frequently result in poor peer relationships and few friendships for both individuals with ADHD and ASD. While people with autism are less often rejected, they are more likely to be ignored. The rejection patterns of those with the inattentive subtype of ADHD resemble those of autism; being neglected rather than rejected (Hodgens, Cole, & Boldizar, 2000). Miller, Hanford, Fassbender, Duke, and Schweitzer (2011) found that emotion recognition was poorer in the inattentive subtype than in the combined subtype of ADHD, indicating that ADHD-i more closely resembles social cognition deficits of ASD than ADHD-c. Social anxiety is prevalent in both conditions (Bejerot, Eriksson, & Mörtberg, 2014; Matson & Nebel-Schwalm, 2007). Some researchers have explored autistic traits in people with ADHD specifically. Reiersen, Constantino, Volk, and Todd (2007) found that those with ADHD had more severe communication impairment than controls. People with the inattentive subtype of ADHD are two to five times more likely than their ADHD-c counterparts to be referred for speech and language problems (Weiss, Worling, & Wasdell, 2003). The communication and social impairments in ADHD suggest that the inattention problems in ADHD, especially ADHD-i, might partly stem from their little interest for social cues, which is similar to autism.

Narrow interests, one of the two core components of autism (APA, 2013), are often observed in people with ADHD, although often overlooked. Recent theories have suggested that inattentive symptoms are a result of poor motivation (e.g., Sonuga-Barke, 2003) rather than a generalized inability to concentrate. People with ADHD-i maybe be dreamy, bored and distracted in class, but they do not spend their leisure time stationary and daydreaming. They are very capable of pursuing hobbies, which happen to be different than the school curriculum. Accordingly, people with a diagnosis of ADHD show good concentration for activities they find interesting (Walitza, Drechsler, & Ball, 2012). For instance, video game use is often linked to autism and ADHD (Gentile, Swing, Lim, & Khoo, 2012), most pronounced in autism and the inattentive portion of ADHD (Mazurek & Engelhardt, 2013). The fact that “inattentive” people can play video games for long intervals challenges the assumption that they are unable to pay attention, and suggests that people with ADHD show a certain selectivity in their interests. Their lack of motivation in school settings might be partly explained by narrow interests, one of the two core components of autism.

ADHD and ASD are highly comorbid, have high co-heritability rates and have similar patterns of comorbidity. The comorbidity rates are between 14% and 78% (Gargaro, Rinehart, Bradshaw, Tonge, & Sheppard, 2011). ADHD is the second most common comorbid disorder in people with autism (Simonoff et al., 2008). One could argue that ADHD deserves the first place, which is currently held by social anxiety, as it is somewhat redundant since autism is defined by severe social communication impairments. ADHD and ASD have similar comorbidities. Within those diagnosed with Tourette’s syndrome, 60% are also diagnosed with ADHD (Barkley, 1993). Of all those with ADHD, 20% will be diagnosed with a tic disorder (Leckman, 2002). Similarly, among individuals with ASD, 22% had tic disorders (Canitano & Vivanti, 2007). Moreover, ASD and ADHD are highly heritable, ASD often being considered as the most heritable mental disorder. Lichtenstein, Carlström, Råstam, Gillberg, and Anckarsäter (2010) found that genetic effects accounted for 80% of the variation in ASD and 79% in ADHD. It has been suggested that this indicates a common genetic or environmental cause (Taylor et al., 2015). This hypothesis has been tested multiple times, resulting in reports of moderate degrees of genetic overlap in middle childhood to adulthood (Lichtenstein et al., 2010; Lundström et al., 2011; Reiersen, Constantino, Grimmer, Martin, & Todd, 2008; Ronald, Simonoff, Kuntsi, Asherson, & Plomin, 2008; Taylor et al., 2013).

In short, ADHD also includes symptoms that seem related to ASD, namely in terms of poor Theory of Mind and lower optimal stimulation levels. For instance, they have a weak Theory of Mind (Farrant, Fletcher, & Maybery, 2014), drift off in conversation, lack social skills, are impulsive in interpersonal relationships, have ODD and CD comorbidities (McBurnett & Pfiffner, 2009), have difficulties with friendships (Coleman, 2008), have delayed language acquirement (Bellani, Moretti, Perlini, & Brambilla, 2011) and have problems following instructions.

Autism Spectrum Disorders

Many who are diagnosed with ADHD fit the criteria for autism. The DSM-5 defines autism in terms of two patterns of behavior. The first is persistent deficits in social communication, such as a lack of reciprocity, poor verbal and nonverbal interaction and deficits in developing, maintaining and understanding relationships. Individuals with autism typically have abnormal eye-contact patterns, difficulties using gestures, a lack of facial expressions and fail to respond appropriately to social interactions. It is generally said that autism is characterized by a weakened Theory of Mind (ToM; Baron-Cohen et al., 1985). ToM is the ability to attribute emotional states, motivations and intentions to others and to understand that others have inner states that differ from one’s own. The second pattern is stereotyped and repetitive behaviors, interests and activities. People with ASD commonly have extremely narrow interests, abnormal in their intensity and focus, such as fixating on a specific part of an object, fictional character or subject. They insist on sameness, have specific routines and show considerable distress when routines need to be changed. Approximately 90% of individuals diagnosed with ASD have an auditory hypersensitivity (Gomes, Pedroso, & Wagner, 2008). There are fields in which people with autism excel. There is a higher rate of autism in families of people talented in physics, engineering and mathematics (Baron-Cohen et al., 1998), and people with autism are disproportionately present in science, technology, engineering, and mathematics (STEM; Wei, Yu, Shattuck, McCracken, & Blackorby, 2013). To put it more concisely, autism is defined by selectivity in interests, low tolerance for stress originating from environmental stimuli and difficulties with social cognition, but are interestingly disproportionately present in the hard sciences.

Antisocial Personality Disorder

ADHD is often comorbid with or precursor of antisocial behavior. Antisocial personality disorder (ASPD) is defined as impairments in personality functioning and pathological personality traits. ASPD was one of the first disorders ever identified, commonly known under the name psychopathy. These terms will be used interchangeably. Impaired personality functioning in psychopathy is characterized by a long-term pattern of manipulating, exploiting and violating the rights of others. Individuals with ASPD have a diminished capacity to feel remorse and empathy, and use deceit, coercion as well as dominance to control others. Pathological personality traits in the category of antagonism are manipulativeness, deceitfulness, callousness, and hostility. In the case of disinhibition: irresponsibility, impulsivity, and risk taking (APA, 2013). Robert D. Hare, author of the Hare Psychopathy Checklist, believes that psychopaths are especially present in the corporate culture, as their manipulative and fearless tendencies might be adaptive in these settings (Hare & Babiak, 2006). Conduct disorder (CD) is characterized by behavior that violates either the rights of others or major societal norms and is normally diagnosed before adulthood. Symptoms include provoking others, lying, bullying, destructing property, deceiving, and violating rules. The DSM-5 defines oppositional defiant disorder (ODD) as a pattern of angry/irritable mood, argumentative/defiant behavior, or vindictiveness lasting at least six months (APA, 2013). Typical symptoms include arguing with adults, blaming others for one’s own actions, being irritable and losing one’s temper, and deliberately provoking others. Only children and adolescents are eligible for an ODD diagnosis. Although the DSM-IV forbade a dual diagnosis, clinical studies have demonstrated that 60 to 95% of CD cases have a comorbid ODD diagnosis (Rowe, Costello, Angold, Copeland, & Maughan, 2010). This exclusion criterion has been removed in the DSM-5.

Diagnoses of ASD, ADHD, and ASPD in Females

Even though this review concerns the expression of disorders in males, it needs to be addressed that there is a substantial number of girls diagnosed with the highlighted disorders. The existing literature demonstrates that girls diagnosed with either of them rarely meet the specified criteria, and suggests that they are clusters of symptoms almost exclusively seen in males.

ASD, as it is currently defined, is virtually non-existent in females. The male to female ratio in Asperger’s Syndrome (high functioning autism) is greater than 10:1 (Baron-Cohen, 2002). Although there is an overall male to female ratio of 4:1 or 5:1 in ASD (Shin Kim et al., 2011), females with autism do not show the typical autism phenotype. Females with autism have repeatedly scored lower than males on restricted interests and behaviors (Van Wijngaarden-Cremers et al., 2014), which constitute one of the two families of symptoms of autism. The behavioral profile of girls with autism is not consistent with the widely accepted model of autism as an extremely low social motivation, as introduced by Chevallier, Kohls, Troiani, Brodkin, and Schultz (2012). Severe deficits in pretend play, compared to mild deficits in non-pretence play, is oftentimes considered to be the earliest behavioral manifestation in boys with autism, and girls with autism do not show this tendency (Knickmeyer, Wheelwright, & Baron-Cohen, 2008). This finding is especially meaningful as pretend play requires the inference of mental states to others, to understand the implicit rules that guide imaginative play in groups. Girls with autism show more interest in social relations, and have even been reported to be misdiagnosed as borderline personality disorder, which is characterized by an extreme sensitivity in interpersonal relationships (Attwood, 2007). The social impairment of females with autism, although substantial compared to normal females, is still lesser than that of normal males (Head, McGillivray, & Stokes, 2014). Intellectual disability occurs twice more often in females diagnosed with autism (Mandy et al., 2012), which indicates that the cause of their impairments might stem from their intellectual disability rather than other specified causes. Furthermore, narrow interests and repetitive behaviors are often seen in those with intellectual disability, which might increase their occurrence in girls with autism, even though they are seldom observed (Van Wijngaarden-Cremers et al., 2014). For these reasons, many studies exclude autistic females altogether, resulting in an average ratio of 15:1 for fMRI studies on autism (Philip et al., 2012). It seems that the traditional phenotype of autism is seen in males only. Psychological categorization is always subject to change, and impaired social cognition in some females deserves consideration (or not, since autistic females score higher than normal males on friendship measures); however, females do not appear to experience autism as is presently described. Autism will be referred to as a male-only condition.

Females do not seem to embody the ADHD criteria often. An astonishing 92% of girls are diagnosed with the inattentive subtype (Weiler, Bellinger, Marmor, Rancier, & Waber, 1999). To put it more boldly, 92% of girls diagnosed with ADHD do not fit the behavioral criteria of ADHD. Girls with ADHD have increased internalizing problems, although externalizing problems is one of the defining characteristic of ADHD (Rucklidge, 2010). When actual symptoms need to be observed, such as in clinical studies, boys have outnumbered females up to 10:1 (Biederman et al., 2002). When ADHD is pervasive, ratios go up to 16:1 (Rutter, Caspi, & Moffitt, 2003). Females are rarely diagnosed with the combined subtype, and their impulsivity symptoms rarely reach conduct disorder. Females are outnumbered from 10 to 15 times in the persistent type of conduct disorder (Moffitt, 2006). The difficulties of girls with ADHD might originate from elsewhere than those of boys with ADHD. In a meta-analytic review, Gaub and Carlson (1997) compared individual variables in boys and girls with ADHD, and found statistically significant medium effect sizes disfavoring girls in terms of three different intelligence measures. These results were replicated by Gershon (2002). Their classroom difficulties might also originate from eating disorders (Biederman et al., 2007).In short, females do not embody what the academia has communally termed “ADHD”, and their difficulties in the classroom might not have the same causes than males. Since girls diagnosed with ADHD have a fundamentally different behavioral profile than their male counterparts, the burden of proof is in the hands of those who claim that the male and female presentation are based on a common causal mechanism. As we are not even remotely close to establish objective distinguishing characteristics between people with and without ADHD, phenotypic expression is the only diagnostic tool, and it differs fundamentally between boys and girls with ADHD. Henceforth, ADHD will be described as a behavioral pattern that is seen in males only.

Females do not appear to reach the clinical criteria for psychopathy, which was mostly specified based on males. This is because males and females differ in their expression of psychopathy (Wynn, Hoiseth, & Pettersen, 2012). Male psychopaths tend to be aggressive, engage in criminal behavior and substance abuse. Female psychopaths tend to flirt, manipulate and exhibit self-injury (Forouzan & Cooke, 2005), which fit more accurately in the criteria of histrionic and borderline personality disorder, which tend to be diagnosed alongside of ASPD in women (Warren et al., 2003). There is only a slight sex difference in the prevalence of ODD, but there is a major one in the case of CD (Loeber et al., 2009), a better predictor of adulthood psychopathy. Boys are 10 to 15 times more likely than girls to develop the life-course-persistent type of conduct disorder. Accordingly, Moffitt (2006) argues that it is an exclusively male phenomenon. This sex difference is one of the most stable finding in all of antisocial behavior research (Rutter et al., 2003). Regardless of diagnoses, the large sex gap is seen is violent juvenile crime and physical aggression (Eme, 2007).

Theoretical Accounts for the Male Bias

There is a major sex bias in favor of males in disorders that are characterized by a deficient empathy and the disregard for the rights of others. In this way, cognitive and affective empathy impairments define male-biased disorders. A lack of empathy as the extreme form of a male brain has been investigated by Baron-Cohen.

The Extreme Male Brain Theory of Autism

In 2002, Baron-Cohen introduced the extreme male brain (EMB) theory of autism. The rationale behind this theory is that people with ASD behave in ways that are congruent with normal sex differences, but to an abnormal extent. Males generally outperform females in systemizing measures. By systemizing, Baron-Cohen means:

Anything that takes inputs and deliver outputs. When you systemise, you use ‘if–then’ (correlation) rules. The brain focuses in on a detail or parameter of the system, and observes how this varies. That is, it treats a feature as a variable. Or a person actively manipulates this variable (hence the English word, systematically). They note the effect(s) of this one input elsewhere in the system (i.e. the output). ‘If I do x, then y happens’ (Baron-Cohen, 2002, p.248).

Males outperform females on systemizing tests, such as tests of intuitive physics or map reading. As a result, fields that comprise the most inflexible manipulation of systems are almost entirely composed of males, such as chess players, symphony composers, physicists, and computer programmers. On the other hand, females outperform males on empathy measures, such as Reading the Mind in the Eyes test or emotion recognition tests, and people with autism score significantly lower than normal males. The most promising evidence brought forward by Baron-Cohen is that people with autism carry the biological marker of pronounced brain masculinization, which is prenatal testosterone (Auyeung et al., 2012).

There are numerous shortcomings to the Extreme Male Brain theory. The most fundamental flaw is that the reasoning that led to autism being the extreme male brain, could be used to nominate other disorders as the extreme male brain. Namely, a few other conditions have been linked to similar high prenatal testosterone levels, but their phenotypes are different. ADHD is an example. Based on 2D:4D ratios, de Bruin, Verheij, Wiegman, and Ferdinand (2006) found no significant differences between the autism group and the ADHD group, indicating that a more pronounced brain masculinization in autism, compared to ADHD, could not be empirically demonstrated.

Most importantly, many behaviors that are stereotypically masculine are not shown by those with ASD, such as spatial abilities, athletic abilities (see Hönekopp & Schuster, 2010 for a review), aggression and sensation seeking, which are all correlates of prenatal testosterone, an indicator of brain masculinity (Liu, Portnoy, & Raine, 2012). This indicates that autism is a form of the extreme male brain, but that it only represents one type of expression.

The EMB theory does not account for many findings about ASD, such as that 90% of those diagnosed with ASD have an auditory hypersensitivity (Gomes et al., 2008), or that people with ASD have poor motor coordination (Gowen & Hamilton, 2012), which do not fall under the criteria of repetitive behaviors and lack of responsivity to social cues. This suggests that the clinical definition of hypermasculinity should include disorders characterized by aggression and stimulus seeking, in addition to a lack of sociability.

Zentall and Zentall’s Optimal Stimulation Theory

In 1983, Zentall and Zentall theorized that hyperactivity was a homeostatic mechanism to regulate activity level. Healthy individuals, when experiencing a sensory overload, usually tend to avoid stimuli. They become disorganized and withdraw socially. Repetitive movements, such as tics, are found in normal individuals when over-aroused. Furthermore, stimulus overload shrinks the focus of attention (see Hockey, 1970 for a review). This shrinking of the focus of attention contrasts with the wide attentional focus of people with ADHD, who are often said to be unable to focus without attending to other surrounding distracting stimuli. Low levels of arousal decrease discrimination of inutile peripheral stimuli (Callaway & Stone, 1960), as if the mind was seeking arousing stimuli. When normal individuals are deprived of their senses, they typically seek stimuli. When healthy subjects were not allowed to move in an experiment, they experienced reduced intellectual ability and inability to concentrate. Similar results have been found in rats and monkeys in sensory deprivation studies. In this way, it appears that the difference between hyperactive individuals and the neurotypical population is that hyperactive individuals have a greater need for stimulation, which results in a faster boredom of non-exciting stimuli. For high stimuli settings, such as a film or game, no difference was found between hyperactive and non-hyperactive individuals.

Zentall and Zentall’s Optimal Stimulation Level theory is interesting because it suggests that the difference between someone with autism and someone with antisocial disorders is caused by the same underlying mechanism. Different individuals have different level of risk tolerance or stimulation needs, and this shapes their personality permanently.

The main weakness of this model is that it does not account for the impaired social cognition that is a central aspect of autism. A weak Theory of Mind, however, is unlikely to be a result of the male brain. Fetal testosterone levels, indicator of the brain’s masculinity, do not differ significantly between those with autism and ADHD (de Bruin et al., 2006), and Theory of Mind of people with ADHD is much less impaired. The male to female ratio for autism has been shown to converge towards 2:1, and impaired social cognition is arguably the only autistic trait that is the basis for autism diagnoses in females. Most importantly, girls with borderline personality disorder are the current candidate for the extreme female brain (Larson et al., 2015), and they are impaired in all three aspects of social cognition: executive functioning, Theory of Mind and emotion recognition (Baez et al., 2015). Deficits in ToM are neither always permanent nor exclusive to people with autism. It is impaired in many conditions that involve anxiety and distress. For instance, those who are depressed or psychotic have a weaker Theory of Mind (Wang, Wang, Chen, Zhu, and Wang, 2008; Zobel et al., 2010). This means that an impaired Theory of Mind is not exclusive to neither autism nor the male brain, but is better explained by distress. As a matter of fact, over-arousal decreases cognitive performance (Zentall & Zentall, 1983). Cognitive empathy deficits in autism might be better explained by the combination of a typically masculine disinterest in social relationships, and over-arousal (Bal et al., 2010; Hirstein, Iversen, & Ramachandran, 2001), which impedes social skills (Richard, French, Nash, Hadwin, & Donnelly, 2007).

Autistic people, compared to those with ADHD or ASPD, have a lower stress tolerance level. Hypersensitivity is an intricate part of the ASD clinical presentation (Kern et al., 2007), such as auditory hypersensitivity (Gomes et al., 2008). There is a high correlation between all forms of hypersensitivity and autism severity in children. In fact, physical clumsiness increases with autistic symptoms (Hilton et al., 2007). Next, we have ADHD-i, which has lower rates of injury compared to controls, ADHD-c and ADHD-h groups (Lahey et al., 1998). People with an ADHD diagnosis score significantly higher than controls on measures of risk-taking, resulting in dangerous driving behavior (Barkley et al., 2002), more traffic accidents (Swensen et al., 2004), criminality (Mannuzza et al., 2004), increased substance abuse (Rooney et al., 2012) and risky sexual behavior (Flory et al., 2006). The combined subtype is more strongly linked to risky, impulsive behaviors, notably drug use (Wilens, Faraone, & Biederman, 2004). The combined subtype of ADHD is also more strongly correlated with ODD (66%), CD (47%; Freitag & Retz, 2010) and externalizing disorders (Acosta et al., 2008). Lastly, antisocial personality disorder, commonly known as psychopathy, is by distal definition extreme risk taking. Psychopaths need extreme stimulation, which they receive through drug use, alcohol consumption, risky sexual behaviors, and multiple sexual partners. Furthermore, they are responsible for about half of the violent crimes (Hare & Babiak, 2006). Importantly, psychopathic traits in people with ADHD correlate negatively with autistic traits. Farrant and colleagues (2014) have found that deficits in social cognition were inversely correlated with hyperactivity in a typically developing sample. This indicates that autism spectrum disorders and psychopathy represent two ends of a spectrum.

This increase in risky behaviors from autism to ADHD, and then psychopathy indicates that their risk tolerance inclines them to different patterns of behavior and activities. The idea that people differ in regards to excitement seeking needs has been investigated before. Zentall and Zentall (1983) have suggested that humans differ fundamentally in regards to their optimal stimulation levels, and put ASD, ADHD and psychopathy in this framework.

Hence, if masculinity is the common component in autism, ADHD and psychopathy, we would expect biomarkers to support this reasoning. Likewise, if they are distinguished by their sensation seeking needs, we would expect them to have hormonal profiles corroborating this theory. If autistic individuals, people with ADHD and psychopaths are chronically above or below their threshold of excitement, their stress hormone levels and their approach hormone levels should reflect their behavioral tendencies.

Testosterone and Cortisol

Testosterone influences behavior in two major ways throughout a male’s life. First, testosterone has organizational effects on the brain. Organizational effects influence childhood play behavior, sexual orientation and identity and other differences between men and women in the normal population. Studies of amniotic fluids have suggested that prenatal testosterone levels determine the extent to which a brain is masculinized. Prenatal testosterone levels are often based on measuring the length of the second digit (“pointing finger”) compared to the fourth digit (“ring finger”). Individuals exposed to higher level of prenatal androgens have lower ratios, and men and women have been repeatedly found to have contrasting ratios. 2D:4D ratios are the preferred biological marker to measure prenatal testosterone (see Manning, Kilduff, Cook, Crewther, & Fink, 2014 for a review). ADHD, ASD, and ASPD were suggested to be a result of highly masculinized brains. We would therefore expect them to be linked to lower 2D:4D ratios, indicating hyper masculinization.

Second, testosterone affects reproductive behavior postnatally. Testosterone facilitates competitive behavior and reproductive behavior, and is produced in higher quantities posterior to successful encounters (Archer, 2006). On the other hand, those who “lose” the interaction have a decrease in their testosterone levels, triggering inhibition tendencies. In this way, testosterone is the “reward” that successful males receive, that will encourage subsequent competitive behaviors. These results are not found in chance-based competition. Conversely, a decrease in testosterone levels will discourage further competitiveness. The higher the stakes are, the higher the testosterone surge will be, such as physical vs non-physical competition (there is no data comparing physical confrontation and psychopath-like competitive behavior). Therefore, we should expect autistic individuals to show low testosterone levels, as they are extremely risk averse relative to their environmental expectations. In the case of psychopaths and people with ADHD, we would expect high levels.

Cortisol is a steroid hormone produced in the adrenal cortex. Often called the hormone of stress, cortisol regulates changes in the body in response to stress. Cortisol levels are commonly used to operationalize stress levels. The risk tolerance is the dimension on which autism spectrum disorders, hyperactive disorders and antisocial disorders vary. One would then expect higher cortisol levels in people with autism and lower levels in those with antisocial disorders.

What kind of prenatal hormonal profiles do people with autism, ADHD and psychopathy show? People with autism had lower (more masculine) finger length ratios than controls (Al-Zaid, Alhader, & Al-Ayadhi, 2015; Auyeung et al., 2012; Manning, Baron-Cohen, Wheelwright, & Sanders, 2001).

People with ADHD have been consistently shown to have lower 2D:4D ratios, indicating a masculinized brain (de Bruin et al., 2006; Martel, Gobrogge, Breedlove, & Nigg, 2008; Martel, 2009; McFadden, Westhafer, Pasanen, Carlson, & Tucker, 2005; Stevenson et al., 2007). Indeed, 2D:4D ratios are inversely correlated to ADHD symptoms (Romero-Martinez, Polderman, Gonzalez-Bono, & Moya-Albiol, 2013).

Portnoy, Raine, Seigerman, and Gao (2011) found that 2D:4D ratios were inversely correlated to the fearlessness, impulsive nonconformity and cold-heartedness subscales of psychopathy. Liu and colleagues (2012) have found increased aggression (and attention) problems in children with lower finger length ratio. When comparing offenders and non-offenders, the former has significantly more masculinized ratios (Hanoch, Gummerum, & Rolison, 2012). Moreover, impulsivity (not 2D:4D ratios) significantly predicts low educational achievement, which strongly predicts criminal behavior. In this way, these results suggest that 2D:4D ratios lead to criminality only if it is paired with impulsivity. The bottom line is that psychopaths (as illustrated by offenders) have a masculinized brain, but those with a masculinized brain do not necessarily become psychopaths.

In short, studies of prenatal androgen exposure converge towards the conclusion that 2D:4D ratios spawn different types of behavioral patterns. As hypothesized, psychopathy, ADHD, and autism have masculinized finger length ratios, indicating a masculine brain.

What kind of postnatal hormonal profiles do people with autism, ADHD and psychopathy show? Auyeung and colleagues (2012) did not find a link between Quantitative Checklist for Autism in Toddlers scores and postnatal testosterone. Takagishi and colleagues (2010) did not find a significant relationship between Autism Quotient and salivary testosterone. Furthermore, Croonenberghs and colleagues (2010) found lower testosterone levels in individuals with autism. In low functioning autism, cortisol was found to be higher than in controls and in those with Asperger’s (Putnam, Lopata, Thomeer, Volker, & Rodgers, 2015). Likewise, individuals with autism show a significantly higher increase in cortisol when stressed, compared to controls (Spratt et al., 2012).

Testosterone levels predict sensation seeking behavior in adolescents with ADHD (Martin et. al, 2006). People with ADHD have lower cortisol levels relative to controls, especially the hyperactive/impulsive type (Blomqvist et al., 2007). Maldonado, Trianes, Cortés, Moreno, and Escobar (2009) found decreasing cortisol levels from controls, to ADHD-i to ADHD-h. Ma, Chen, Chen, Liu, and Wang (2011) found the same pattern in plasma cortisol levels.

Terburg, Morgan, and van Honk (2009) identify low cortisol and high testosterone as the hormonal marker for psychopathic tendencies and violent social aggression, which has been supported empirically by Glenn, Raine, Schug, Gao, and Granger (2011).

The 2D:4D ratios are lower than controls in all male-biased disorders, indicating that they are indeed varying expressions of the male brain. The decreasing levels of cortisol and increasing levels of testosterone from autism to ADHD, and then psychopathy indicate that individuals are less and less stressed and more and more successfully competitive as they approach psychopathic tendencies. This is consistent with Zentall and Zentall’s reasoning, which suggested that people with autism, ADHD and psychopathy have an optimal stimulation level that does not match their environment (Zentall & Zentall, 1983).

Different Behavioral Profiles and Intra-Sexual Competition

A fundamental assumption in evolutionary reasoning is that all forms of life compete with their conspecifics to transmit their genes. In humans, it has been generally accepted that males compete more fiercely, and are therefore wired for competition. Archer (2006) showed that intra-sexual competition had bidirectional relationship with hormonal levels. When an individual successfully defeats an opponent, the former has a surge in testosterone, while the latter has a decrease in testosterone levels. An increase promotes further competitive and approach behaviors, such as disinhibition and mating efforts. In contrast, diminished testosterone levels discourage competitive behavior, or the sought for safer forms of competition. The testosterone surge is more pronounced in physical confrontations. In this way, successful confrontation promotes psychopathic traits, and unsuccessful confrontation promotes autistic traits.

As males strive to reach higher tiers of competition, we would expect success in riskier systems to represent a more attractive outcome, namely in regards to reproductive fitness. Accordingly, psychopathy and impulsivity conditions are therefore expressions of relative fitness. Psychopathy has been argued to represent a life strategy rather than a disorder (Krupp, Sewall, Lalumière, Sheriff, & Harris, 2013). For instance, facial symmetry is often considered as the best predictor of physical attraction, as it indicates healthy development (Penton-Voak et al., 2001). People with autism have pronounced facial asymmetry compared to controls (Hammond et al., 2008), in contrast to psychopathic offenders, who have better facial symmetry compared to both non-psychopathic male offenders and non-offenders (Lalumière, Harris, & Rice, 2001). People with ADHD have earlier sexual experiences, more casual sex, and more short term sexual partners (Flory et al., 2006). Similarly, multiple short-term sexual encounters are one of the main behavioral symptom of psychopathy. Ellis and Walsh (2007) have reviewed 51 studies, 50 of which reported a positive association between number of sexual partners and antisocial behavior. Anecdotally, in a large forensic hospital, among psychopathic patients who were acquitted due to (malingered) insanity, 39% had a consensual sexual relationship with female staff members (Gacono, Meloy, Sheppard, Speth, & Roske, 1995). More generally, positive correlations between sensation-seeking and sexual success has been extensively studied (Bogaert & Fisher, 1995; Cyders, Dzemidzic, Eiler, & Kareken, 2016; Eisenberg, Campbell, MacKillop, Lum, & Wilson, 2007; Lalasz Weigel, 2011; Victor, Sansosti, Bowman, & Hariri, 2015; Webster & Crysel, 2012). In contrast, people with autism have shown to be intrusive, stalking, persisting for months and to engage in inappropriate courting behavior towards ex-partners, celebrities and colleagues (Stokes, Newton, & Kaur, 2007), representing desperate strategies. To conclude, psychopaths and people with ADHD represent the evolutionary successful version of the male brain.


The present review aimed to demonstrate that attention deficit hyperactivity disorder shares traits with ASD and ASPD. These conditions represent the male brain, as they are all highly male-biased, linked to brain masculinization, and they all share a characteristic: a lack of empathy, which is the defining element of the female brain (Baron-Cohen, 2002). There are differences in how this lack of empathy is expressed. Autistic individuals tend to avoid social interactions, people with attention deficits can be somewhat rude and misunderstand others, and those with antisocial disorders may provoke and aggress others repeatedly. The increase of risky social behavior shows a parallel with overall tendencies of those diagnosed with male-biased disorders. Individuals with autism are especially sensitive to sounds and changes of routines, and people with impulsive disorders show increasingly dangerous behavior as the severity of their psychopathic traits increases. This is illustrated by lower levels of stress hormones and higher levels of testosterone in psychopaths, and the opposite pattern in autistic individuals.

Different patterns of behavior indicate how the environment shapes one’s behavior and personality in a permanent fashion. Autistic symptoms are the behavioral patterns of chronically overstimulated males, and psychopathy is how a male acts when consistently under-aroused. When over-aroused, males withdraw and seek safer forms of competition, and when under-aroused, seek higher, riskier forms of competition and use approach mechanisms. As people with autism, ADHD and psychopathy are overrepresented in systems, sports and criminal activities respectively, they all engage in intra-sexual competition based on their optimal level of stimulation. Males who engage in the highest tiers of intra-sexual competition have increased evolutionary fitness.


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Social Motivation as The Extreme Female Brain: Borderline, Dependent, and Histrionic Personality Disorders

This is a paper I wrote in my free time as a second year psychology
bachelor student. It wasn't published anywhere. 
Here's a PDF copy in APA style:
The Extreme Female Brain - Nicolas Kilsdonk-Gervais.

Cite as: Kilsdonk-Gervais, N. (2017). Social Motivation as The Extreme Female Brain: Borderline, Dependent, and Histrionic Personality Disorders. Unpublished manuscript. 


Baron-Cohen’s Extreme Male Brain theory of autism has generated a novel perspective of psychological disorders: the depiction of clinical behavioral patterns as extreme expressions of normal sex differences. Consistent with this view, this review suggests that histrionic, borderline, and dependent personality disorders are the best candidates to represent the extreme female brain, as they are all characterized by excessive social or empathizing needs, and are related to feminization.

Keywords: borderline personality disorder, histrionic personality disorder, dependent personality disorder, autism spectrum disorders, extreme male brain theory

The Extreme Female Brain

From the moment species have evolved as sexual, females and males have gone through differential selection processes, in response to different roles involved in the continuation of the species (Buss & Schmitt, 1993). In humans, as in most species, males provide a group with resources vital to group functioning, while females bear and nurture children. As such, their respective physiology and psychology are designed to fulfill this purpose (Trivers, 1972). Women are highly dependent on others’ input and collaboration to get the necessary material to ensure the survival of both themselves and their children, since their evolutionary purpose is the upbringing of children. As evolutionary processes retain those who have a spontaneous drive to accomplish what is beneficial for them, this dependence on social ties must result in considerable gratification when fulfilled, and considerable distress when unfulfilled. As a result, socialization would entail greater gratification for women when successful, and greater distress when unsuccessful. The basic and ultimate need of women is to socialize, or empathize (Baron-Cohen, 2002), and they would then compete with each other on socialization processes. Different behavioral presentations represent different strategies to fulfill a social need, with differential outcomes and tactics. This review will suggest that some psychological disorders might be extreme forms of what defines a feminine psychology.

Theoretical Background

Baron-Cohen (2002) provided the first spectrum to account for psychological sex differences. The empathizing/systemizing theory suggests that males have a higher spontaneous drive to construct systems, and women have a higher drive to empathize. This model is the reasoning behind the Extreme Male Brain theory of autism (Baron-Cohen, 1997), based on a suggestion of Hans Asperger in 1944. People with autism spectrum disorders, theorized to be an extreme form of the male brain, have an unusually high drive to construct systems, and have an extremely low ability to understand others and create and maintain interpersonal relationships. They are considered to be mind-blind. On the other hand, the female brain would be characterized by a lesser drive to construct systems, but would be highly motivated to create and maintain social bonds. In this way, the extreme female brain would be extremely empathetic, but unstimulated by system construction. This model postulates that an extreme female brain would be system-blind, but extremely skilled at creating social bonds.

There are important shortcomings to Baron-Cohen’s theory. First, there is an underlying assumption that an extreme brain necessarily results in functional impairment, and in only one behavioral pattern. Some people with an extreme male brain score quite low on autistic symptoms (Auyeung et al., 2009). This introduces the second point; many other behavioral presentations are seen within those with a hyper-masculinized brain, such as individuals with attention deficit and hyperactivity disorder and psychopathy (Hanoch, Gummerum, & Rolison, 2012). While they do not share the cognitive empathy impairments (Charman, Caroll, & Sturge, 2001; Meffert, Gazzola, den Boer, Bartels, & Keysers, 2013; Richell et al., 2003), they show the same low drive for socialization in itself, and often prefer status gains over well-functioning (Melnick & Hinshaw, 1996) and use instrumental interpersonal strategies respectively (APA, 2013). In this way, there is not a single extreme male brain presentation, and other presentations do not necessarily have cognitive empathy deficits, although there seems to be a generalized asocial tendency, or a low social motivation. Psychological theorists have previously suggested that autism is defined by a decreased social motivation (Chevallier, Kohls, Troiani, Brodkin, & Schultz, 2012). Another weakness of Baron-Cohen’s theory was uncovered when it was found that individuals with an extreme female brain (girls with a borderline diagnosis) had poor empathetic skills. Lastly, Baron-Cohen’s suggestion assumes that there is only one type of social drive. This no doubt led to the ambiguity that supposedly socially unmotivated autistic women are as social as non-autistic males (Head, McGillivray, & Stokes, 2014), and are even clingy inasmuch as they can be misdiagnosed with borderline personality disorder (Attwood, 2007). Even females who are thought to have a non-empathic brain have the clinginess that is here suggested to be a feminine trait. Consequently, it could be argued that systemizing and empathizing are needs rather than skills. In this way, the extreme female brain would be defined by an extreme social need, and may have multiple presentations, rooted in different strategies to fulfill a social dependency need.

Candidates of the Extreme Female Brain

Behavioral presentations that involve an excessive social need will be explored. Psychological disorders are useful in this regard, because clinical categorization classifies individuals into stable, pervasive, and delimited behavioral patterns, for which empirical data has been gathered extensively. In contrast, correlating femininity, life strategies, and pathology would be a colossal endeavor, based on statistical approximations. The prevalence of males in the described disorders does not mean that it is not a predominantly female behavior, as individuals act out on a need, but assuming that men and women live in roughly the same environment, more often this environment will be perceived as socially unstimulating.

Numerous personality disorders appear to be rooted in an excessive social motivation. Dependent personality disorder, borderline personality disorder, and histrionic personality disorder are all characterized by an excessive sensitivity to the social world. All have historically been linked to women. Among clinically-naïve participants reading the diagnostic criteria, histrionic and dependent personality disorders were seen as female disorders (Rienzi & Scrams, 1991). Importantly, the epidemiology and definition of these disorders are biased towards women.

Borderline Personality Disorder

Borderline personality disorder is perhaps the most interesting candidate for the extreme female brain. It is defined in the DSM-5 as a “pervasive pattern of instability in interpersonal relationships, self-image, and affects, and marked impulsivity, beginning by early adulthood and present in a variety of contexts” (APA, 2013, p. 663). People with borderline personality disorder typically make frantic efforts to avoid real or imagined abandonment, their interpersonal relationships tend to be intense and characterized by an alternation between extremes of idealization and devaluation, they feel empty and have a self-image that depends on others, People with borderline personality disorder have high rates of compulsive buying (Maraz, Urbán, & Demetrovics, 2016), and use Facebook excessively (Delfour, Moreau, Laconi, Goutaudier, & Chabrol, 2015). Some theorists have suggested that people with borderline personality disorder are socially insatiable, in the sense that they expect extreme inclusion from others (De Panfilis, Riva, Preti, Cabrino, & Marchesi, 2015). Interestingly, borderline symptoms correlate positively with the number of piercings and tattoos (D’Ambrosio, Casillo, & Martini, 2014), and anecdotally, with hair dying frequency.

The hypothesis stating that females with borderline personality disorder represent an extreme form of female typical behavior has been informally suggested following Baron-Cohen’s Extreme Male Brain theory of autism. A recommendation for research was also expressed by Larson and colleagues, including Baron-Cohen (2015). Recently, the hypothesis was experimentally tested by Dinsdale, Mokkonen, and Crespi (2016). Using the results of the Reading the Mind in the Eyes Test (RMET), they concluded that the extreme female brain may be what is known as borderline personality disorder and subclinical depression. Further evidence shows that borderline traits are linked to hormonal femininity, and are magnified by oral contraception use. DeSoto, Geary, Hoard, Sheldon, and Cooper (2003) found that borderline traits were linked to fluctuations in estrogen levels, by conducting three studies. First, borderline symptoms were most common in the period of the menstrual cycle in which estrogen is at its highest, and in women using oral contraceptives. Second, across a menstrual cycle, the presence of borderline traits was predicted by estrogen levels, even when a generalized increase in negative mood was statistically controlled for. In a sample of forty women, estrogen and progesterone influenced borderline traits (Eisenlohr-Moul, DeWall, Girdler, & Segerstrom, 2015). Lastly, for women with pre-existing borderline traits, use of oral contraceptive exacerbates the symptoms of the disorder. Additional indirect evidence for hormonal influence on borderline symptoms comes from premenstrual dysphoric disorder (PMDD). PMDD occurs when estrogen levels are increasing before ovulation. The symptoms of PMDD are nearly identical to the borderline behavioral profile. The DSM-5 provides the following symptoms to illustrate PMDD:

markedly depressed mood, feelings of hopelessness, or self-deprecating thoughts; marked anxiety, tension, feelings of being “keyed up” or “on edge”; marked affective lability (e.g., feeling suddenly sad or tearful or experiencing increased sensitivity to rejection); persistent and marked anger or irritability or increased interpersonal conflicts (APA, 2013, p. 171).

Thus, fluctuating levels of estrogen play a role in borderline traits. Similarly, fluctuations in estrogen trigger depressive episodes in women (Payne, 2003), and women with PMDD tend to have high estradiol levels during the follicular phase (Redei & Freeman, 1995).

Borderline traits are also related to brain femininity. 2D:4D finger length ratios, the preferred biomarker for the evaluation of brain masculinity/femininity, is positively correlated to emotional instability (Lindová, Hrušková, Pivoňková, Kuběna, & Flegr, 2008). This means that the most feminized a brain is, the most emotionally unstable a person is. 2D:4D ratios correlate positively with neuroticism scores (Austin, Manning, McInroy, & Mathews, 2002; Fink, Manning, & Neave, 2004). Neuroticism is the trait of the Big Five on which men and women differ the most globally (Schmitt, Voracek, Realo, & Allik, 2008), and unsurprisingly, girls with borderline are acutely neurotic. 2D:4D ratios correlate with borderline characteristics: estrogen, neuroticism, and correlates negatively with autistic symptoms (which is the diametrical opposite of borderline interpersonal tendencies; extreme unresponsiveness to social stimuli; Putz, Gaulin, Sporter, & McBurney, 2004). 2D:4D ratios significantly predicted overall borderline traits, and the affective component of the borderline presentation more specifically (Evardone, Alexander, & Morey, 2008). In short, converging methods have provided evidence that borderline personality disorder is related to a pronounced femininity.

A large body of psychoanalytic literature suggests that borderline traits are caused by sexual, physical, or psychological abuse during childhood. In the academic literature, questioning participants on their abuse is an ongoing ethical debate. The cost-benefit analysis of asking about child abuse is often ignored, and researchers are often left with important research decisions that are ultimately based on individual beliefs on prevalence and effects of child abuse. The costs of not asking about abuse may actually be more significant than not asking (Becker-Blease & Freyd, 2006). Some have insisted for borderline personality to be relabeled as PTSD, as they can be confused for each other (McLean & Gallop, 2003). There is, however, a meaningful absence of confirmed reports in regards to the post-traumatic model. The hypothesis that borderline traits result from abuse is based on self-reports of people with the diagnosis, who are known to lie compulsively (Snyder, 1986), and to be exactly the type of people who would benefit from the nurturing and professional care that would ensue. Paris (1998) found that most victims of childhood trauma are resilient, personality is heritable, and traumatic childhood experiences do not consistently lead to psychopathology. Moreover, women are more resilient to childhood traumatic events than men (McGloin & Widom, 2001). Bierer and colleagues (2003) did not find childhood sexual abuse to be a predictor of borderline in adulthood. The only significant predictor was emotional abuse, but was only significant in men. Girls with borderline have been identified for being at risk for false rape accusations (O’Donohue & Bowers, 2006). Bailey and Schriver (1999) questioned experienced psychiatrists and found that “patients with borderline personality disorder were rated as especially likely to misinterpret or misremember social interactions, to lie manipulatively and convincingly, and to have voluntarily entered destructive sexual relationships, possibly even at young ages” (p. 45). The validity of the childhood trauma is at best anecdotical, and one should remain cautious towards any claim of victimization from people with borderline personality disorder. If anything, this literature could be interpreted as a strategy to evoke nurturance.

Borderline personality disorder is diagnosed three times more often in women. Yet, it was originally related to the concept of female hysteria, which was believed to originate in the womb. However, psychiatry as a whole does not seem to condemn major tweaks to psychiatric diagnostic criteria to equalize gender statistics, as is the case with ADHD and autism. It is then debatable if this ratio can be interpreted rationally. Regardless of the sex ratio, the diagnosis of men with borderline is based on the widespread faulty assumption that characteristics of one sex can be equally applicable to the other (Cahill, 2006). Although the female-to-male ratio is 3:1, there is a range of phenomena that apply mostly to women, for which borderline traits are the norm. The following section will explore that assertion.

The Ramifications of Borderline Personality Disorder

Regardless of the clinical ratio, borderline traits are often seen in other phenomena that are predominantly seen in women, which certainly undermines the true ratio. Furthermore, these phenomena often have little to no supporting objective evidence, and can be suspected that people with a borderline personality disorder diagnosis simply malinger nurturance. In terms of cost/benefit analysis, it is undeniable that many of these strategies represent opportunities to garner attention for little cost. That does not necessarily mean, however, that people with a borderline personality are aware of the motivations behind these actions.

Females with a borderline personality disorder diagnosis, like those with histrionic personality disorder, have been identified as being more prone to press false rape charges (O’Donohue & Bowers, 2006). False rape charges offer interesting opportunities to obtain nurturance from others, as they are often accepted at face value, at least in psychiatry. While people that were sexually abused are indistinguishable from controls on measures of depression, post-traumatic stress, fantasy proneness, and dissociation; patients with repressed memories recovered through psychoanalytic hypnosis scored higher (McNally, Clancy, Schacter, & Pitman, 2000). Hence, those with rape experiences recovered through flimflamming techniques often have borderline traits. Those with presumably legitimate memories of the abuse do not.

Factitious disorder is a condition that is typically seen in women. In a sample of 88 borderline patients, Links, Steiner, and Mitton (1989) found that 13% had factitious psychotic symptoms. Factitious disorders are usually thought to be motivated by regressive needs, fear of abandonment, need for caring, and nurturing. Feldman (cited by Adams, 2008) found borderline traits in patient with factitious symptoms: self-destructiveness, itinerancy, problems developing and maintaining relationships, hostility, and pseudologia fantastica. Goldstein (1998) found that borderline traits are commonly found in patients with factitious disorders. Undiagnosed borderline traits, such as insecure attachment, are the norm behind factitious presentations. Noyes and colleagues (2003) found that hypochondriasis is associated with insecure attachment that in adults gives rise to abnormal care-seeking behavior. Hypochondriacal and somatic symptoms were positively correlated with all of the insecure attachment styles, especially the fearful style. These same symptoms were positively correlated with self-reported interpersonal problems and negatively correlated with patient ratings of satisfaction with, and reassurance from, medical care. Hypochondriacal and somatic symptoms were also positively correlated with neuroticism. When under stress as adults, somatizers use physical complaints to elicit care (Stuart & Noyes, 1999). Poor self-esteem and poorly defined self-concepts are other characteristics common to both factitious disorders and borderline personality disorder (Hamilton & Janata, 1997). Phillips, Ward, and Ries (1983) found that their sample with factitious bereavement presented with depression and suicidal ideation secondary to reported multiple dramatic deaths for which there was no available verification, and many had histories of factitious physical symptoms, manipulative suicide attempts, substance abuse, and sociopathy. Factitious symptoms can better be understood as one form of dysfunctional care-eliciting behavior.

Pseudologia fantastica is often seen in people with borderline (Snyder, 1986). This pathological need for lying is used to garner attention and caring.

People with borderline are at great risk of self-harming, insofar that it is part of the diagnostic criteria. One of the motivation for self-harm is expressing distress to obtain nurturance (Linehan, 1993; Paris, 2005).

Munchausen Syndrome by Proxy (MSBP) is a type of factitious disorder in which the mother secretly inflicts harm to her child to obtain medical care. This phenomenon is especially likely when the surroundings offer nurturance and praise in response to the brave mother of a sick child. Moreover, it is widely believed that perpetrator mothers use the child to pursue a relationship with charismatic and care providing physicians (Cramer, Gershberg, & Stern, 1971). Borderline features are often seen in MSBP, to the extent that MSBP has been suggested to be a subtype of borderline pathology (Nadelson, 1979). Ehlers and Plassmann (1994) found that half of their sample of 18 MSBP patients had borderline personality disorder, and that one third had narcissistic personality disorder, which has comorbidity rates of 32.2% with borderline (Grant et al., 2008). Adshead and Bluglass (2005) found that 82% of their sample of 67 MSBP mothers had insecure childhood attachments, and 60% had unresolved trauma or loss reactions. Gray and Bentovim (1996), based on a sample of 37 families, found that all the perpetrator mothers had suffered at least one of the following: privation, child abuse, psychiatric illness, or significant loss or bereavement, and that 40% had serious marital problems.

Conversion disorders are by definition any unfounded neurological symptom. Reported childhood abuse, neglect, dissociative symptoms, abuse, self-harm, and suicide attempts—which are typical of people with borderline—are frequently seen in those with conversion disorders (Şar, Akyüz, Kundakçı, Kızıltan, & Doğan, 2004).

As for many phenomena associated with borderline, multiple personalities (now dissociative identity disorder; DID) is highly controversial, as it has very weak and inconsistent support in terms of validity. Two thirds of DID cases also fit the borderline personality criteria (Horewitz & Braun, 1984). The association is so strong that Benner and Joscelyne (1984) have argued that it should be classified as a borderline personality disorder. The existence of “multiple personalities” is highly questionable (Giesbrecht, Lynn, Lilienfeld, & Merckelbach, 2008; Lynn, Lilienfeld, Merckelbach, Giesbrecht, & van der Kloet, 2012), as its core assumptions are violated (e.g., Huntjens, Verschuere, & McNally, 2012). There is no study to this date that used verified claims of trauma from a representative sample of the population. Hence, the legitimizing factor will be disregarded in favor of the effect, i.e., nurturing possibilities originating from a social need.

In short, borderline traits are found in a myriad of unexplained phenomena that appear to be strategies to obtain nurturance and contact with reassuring, father-like, providing figures. Moreover, some of these strategies are exclusively employed by women, which may undermine the 3:1 woman to man ratio. For instance, factitious disorder by proxy is conducted by the biological mother in 98% of cases. Factitious presentation is also a phenomenon that is predominantly seen in women.

Corrections to Baron-Cohen’s Empathize/Systemize Dichotomy

            Although people with borderline constitute a promising venue for understanding the extreme female brain, they do not represent exactly what would be expected from Baron-Cohen’s theory. Putting aside their psychopathic traits (Sprague, Javdani, Sadeh, Newman, & Verona, 2012), they do not have a superior empathy, capability of deciphering social cues, or an unusually efficient theory of mind (see Lazarus, Cheavens, Festa, & Rosenthal, 2014, for a review). Although they are hyper-mentalizing (Sharp et al., 2011), people with borderline have been shown to be deficient in emotion recognition (Baez et al., 2015) and theory of mind (Baez et al., 2015; Preißler, Dziobek, Ritter, Heekeren, & Roepke, 2010), although some have found no difference in cognitive empathy compared to controls (Dinsdale et al., 2016; Vaskinn et al., 2015). A revealing study by Franzen and colleagues (2011), provided a more comprehensive view of the psychology of people with borderline, that includes the motivational component of socialization that lacks in cognitive empathy tests. In a fairness game, controls and borderline patients were equally accurate at emotion recognition, but the latter was more dependent on others’ emotions to judge their own fairness. These results parallel the findings of Levine, Marziali, and Hood (1997). In short, people with borderline are more socially dependent than socially skilled. Again, the empathizing/systemizing dichotomy needs to be regarded as a need rather than a skill, and defined by their underlying motivation, as borderlines cannot be considered socially skilled, or empathetic in the broader sense of the word.

Genetics and Borderline Personality Disorder

Disorders linked to excessive masculinity are usually highly heritable. Namely, ADHD and autism spectrum disorders have repeatedly been linked to low 2D:4D ratios (e.g., Auyeung et al., 2012; de Bruin, Verheij, Wiegman, & Ferdinand, 2006). Both are highly heritable and co-heritable. Lichtenstein, Carlström, Råstam, Gillberg, and Anckarsäter (2010) found that genetic effects accounted for 80% of the variation in ASD and 79% in ADHD. In regards to co-heritability, among monozygotic twins of children with autism, the probability of having a diagnosis of ADHD was 44%, compared to 15% among dizygotic twins (Lichtenstein et al., 2010). Importantly, 2D:4D ratios in girls are 66% heritable (Paul, Kato, Cherkas, Andrew, & Spector, 2006). If borderline is truly linked to hyper-femininity, this pattern should also be observed. Evidence suggests that it is. Amad, Ramoz, Thomas, Jardri, and Gorwood (2014) estimate the heritability of borderline to be 40%. Like other conditions related to a pronounced sexual expression, borderline personality disorder is highly heritable.

Although the present framework suggests that borderline personality disorder is a good candidate of the extreme female brain, it needs to be addressed that one third of the diagnoses are made in men. However, many findings suggest that the true ratio might be more biased towards women than previously assumed. First, there are a vast range of other pathologies that share the neurotic presentation seen in borderline, that are exclusively seen in women. People with Munchausen Syndrome by Proxy are all women, and most have borderline features. Ratios which demonstrate similar base rates of borderline in men and women are often based on community samples (e.g., Grant et al., 2008), with no regard to confounding variables or referrals. Substance abuse, impulsivity, social anxiety, and sexual promiscuity are strongly linked to ADHD, but ADHD is not borderline (APA, 2013; Davids & Gastpar, 2005; Lampe et al., 2007; Nigg, Silk, Stavro, & Miller, 2005; Xenaki, & Pehlivanidis, 2015). Similarly, behaviors that are similar between men and women are often erroneously considered having the same motivation (Cahill, 2006). For instance, sexual promiscuity is the optimal evolutionary success for males of almost all species. In contrast, sexuality is the female resource (Baumeister & Vohs, 2004), and indiscriminate promiscuity is what women are evolutionarily wired to avoid. Promiscuous sexuality in females is linked to emotional distress (Ethier et al., 2006), physical unattractiveness (Walsh, 1993), borderline personality disorder (APA, 2013), susceptibility to sexual victimization (Perilloux, Duntley, & Buss, 2011), and attachment problems. As a thought-provoking example, depression is linked to females with many sexual partners, in contrast to men, in which it is unusually present in those with few partners (Weisfeld & Woodward, 2004). Hence, borderline personality might differ in motivation and expression, notably in the case of promiscuity. Most importantly, if both brain and hormonal femininity promote borderline traits, their occurrence in men requires clarification.

Histrionic Personality Disorder

The DSM-5 defines histrionic personality disorder as “a pervasive pattern of excessive emotionality and attention seeking, beginning by early adulthood and present in a variety of contexts” (APA, 2013, p. 667). Symptoms include: being uncomfortable in situations in which he or she is not the center of attention, inappropriate sexually seductive or provocative behavior, shallow expression of emotions, using physical appearance to draw attention to self, using an excessively impressionistic style of speech, self-dramatizing, theatricality, exaggerating expression of emotion, being suggestible, and considering relationships to be more intimate than they actually are.

There is not much to say about histrionics, as they are clearly incredibly successful social agents, as can be seen by their number of Facebook friends (Rosen, Whaling, Rab, Carrier, & Cheever, 2013), or their interpersonal style more broadly. They are always up to the latest fads, and familiar with everyone. As a symptom of autism is the unwillingness to share intentions and group movements (Tomasello, Carpenter, Call, Behne, & Moll, 2005), histrionic personality disorder is the opposite of this social behavior.

Histrionic personality disorder was argued to be the female phenotype of antisocial personality disorder by Cale and Lilienfeld (2002). Their empirical results were weak and inconsistent, but their methodology was questionable, as they tested histrionics on Newman’s (1987) response modulation hypothesis of psychopathy. This assumes that men and women have a common pathway to psychopathy, as psychopathy scales are tailored for men specifically. As our conspecifics are the key to evolutionary success or failure, elevated interpersonal power suggest a success at negotiating interpersonal power and influence. Fitness is achieved differently in men and women. As a striking example, men and women use different aggression strategies. Women use more relational aggression, such as excluding someone from a social network (see Wynn, Høiseth, & Pettersen, 2012 for an overview of psychopathy in women). Indeed, histrionic women have been identified as being at risk of making false rape charges (O’Donohue & Bowers, 2006). Kanin (1994) identified three main motivations behind false accusations: obtaining sympathy and attention, getting revenge, and providing an alibi. Likewise, McNamara, McDonald, and Lawrence (2012) found that 50% of their sample was motivated by attention-seeking and sympathy. It could be argued to be a form of fraud, for which male psychopaths are known for. Psychopathy in women might be achieved by interpersonal skill and power, resulting in lowered social fear, as opposed to psychopathic men, who might express psychopathic traits due to a lack of physical fear (Hosker-Field, Gauthier, & Book, 2016). Differential fear mechanisms would be based on differential evolutionary competitive aggressive patterns, namely indirect aggression, relational aggression, and social aggression for women (Archer & Coyne, 2005), and physical aggression for men (e.g., Archer, 2004). Since intra-sexual competitive encounters usually involve a form of competition that establishes the fittest individual based on an evolutionarily adaptive trait, it is not surprising that men and women differ in aggression patterns. While a woman attempts to rob another woman from her social bonds, a man attempts to show himself as the most capable to generate and protect resources with physical capability.

Substantial support for the hyper-femininity perspective of histrionic personality disorder came from the measurement of finger length ratios of female psychopaths (Blanchard & Lyons, 2010). The results gave a statistically significant positive correlation of 0.45 between 2D:4D ratios and psychopathy in women.

Histrionic personality disorder is mostly diagnosed in women, although the exact sex ratio is unknown. Researchers and the DSM-5 are generally unwilling to divulgate the sex ratio, as it is repeatedly quoted that “the sex ratio is not significantly different than the sex ratio of females within the respective clinical setting” (APA, 2013, p. 668). There is a range of diagnostic features that do not really apply to men, such as “consistently use physical appearance to draw attention to themselves”, which is quite revealing as histrionic women are the only subgroup of “disordered” women linked to physical attractiveness (Bornstein, 1999). This higher physical attractiveness is not seen in men, so it remains to be clarified how unattractive men use their physical appearance to draw attention (excluding paraphilias, such as exhibitionism). “[Histrionics] may “fish for compliments” regarding appearance and be easily and excessively upset by a critical comment about how they look or by a photograph that they regard as unflattering” (APA, 2013, p. 668). Most social media users might confirm that this behavior is seldom seen in men, and applies to more than the 2–3% prevalence that the DSM-5 suggests. The DSM-5 expresses that “[histrionics] often act out a role (e.g., “victim” or “princess”)” (APA, 2013, p. 668), which, once again, does not seem to apply to non-paraphilic male behavior. The existence of histrionic personality disorder stems from hysteria, which was linked to women, the female genitalia, and femininity since Ancient Egypt. In short, it seems like unwillingness to divulge sex ratios in clinical psychology stems from a general unwillingness to accept the reality of sex differences (Cahill, 2006). Clinically naïve participants associate histrionic personality to women five times more than to men (Rienzi & Scrams, 1991).

Histrionic personality disorder is highly linked to borderline personality disorder. Among histrionic females, 36% are also borderline. Among those with borderline, 10.3% are histrionic (Grant et al., 2008).

Dependent Personality Disorder

Dependent personality disorder also represents an interesting candidate for a behavioral expression of the extreme female brain. If the female brain is more responsive, gratified, and motivated to pursue and maintain social bonds, it might be expressed as excessive investment and dependence in social relationships on a small scale, without a severely neurotic or theatrical component. Dependent personality is defined by the DSM-5 as “a pervasive and excessive need to be taken care of that leads to submissive and clinging behavior and fears of separation, beginning by early adulthood and present in a variety of contexts”. Symptoms include having needing others to assume responsibility for most major areas of his or her life, having difficulty expressing disagreement with others because of fear of loss of support or approval, having difficulty initiating projects or doing things on his or her own, going to excessive lengths to obtain nurturance and support from others, feeling uncomfortable or helpless when alone, and urgently seeking another relationship as a source of care and support when a close relationship ends (APA, 2013, p. 675).

While it seems intuitive to nominate disorders with an extremely neurotic presentation as the extreme female brain, girls with borderline who ameliorate their outcome most likely still attach importance to interpersonal bonds. The presentation of borderline without its acute neurotic features would resemble dependent personality disorder—frantic efforts to avoid real or imagined abandonment and a pattern of intense relationships. Perhaps dependent women share the brain femininity with those who have borderline personality disorder, without the behavioral tendencies originating from elevated estrogen levels. Unfortunately, very little research is done on dependent personality disorder.

Like borderline, dependent personality is highly heritable. Heritability rates are estimated to be from 55% to 72% (Gjerde et al., 2012). People with dependent personality disorder have a non-dominant, submissive interpersonal style, like those with borderline (Russell, Moskowitz, Zuroff, Sookman, & Paris, 2007). Kaplan (1983) argued that dependent personality disorder is nothing more than a woman conforming to society’s idea of a woman, and that behaving in a feminine stereotyped manner alone is sufficient to get a DSM-III diagnosis. Oddly the author remains silent over the fact that this is also true for males, but combined with a neurological justification and a psychoactive solution. Klonsky, Jane, Turkheimer, and Oltmanns (2002) found that in a sample of 665 college students, dependent personality traits were related to higher femininity and lower masculinity in men and women. As indicated by their absent initiative and risk-taking, people with dependent personality disorder have an external locus of control, which is negatively correlated to masculinity (Richards, Stewart-Williams, & Reed, 2015). Their appeasing interpersonal style is sacrificing autonomy to maintain social bonds. For instance, avoiding negotiating, arguing, or discussing. It is an extreme form of the principle of least interest, that explains that people hold more power in relationships in which they have the least interest (Sprecher, Schmeeckle, & Felmlee, 2006). In essence, dependent personality disorder is a life strategy motivated by strong social dependence needs.

Bridging Candidates of the Extreme Female Brain as Evolutionary Strategies

Individuals with the covered personality disorders represent a critical and revealing insight into evolutionary-based motivation. Mating strategies differ greatly between men and women (Schmitt, 2015), and are rarely placed in a context-dependent framework. Different mating strategies co-vary with behavioral (or clinical) profiles, which might reveal underlying motivations. It is known that women have a social need. It is also known that women have a need to regulate their sexual value (Baumeister & Vohs, 2004). Both can be seen as intertwined variables to manage for an optimal evolutionary success.

Dependent, borderline, and histrionic personality disorders are three disorders primarily defined by an interpersonal component. Dependent and histrionic personality disorders have been argued to be strongly linked to dependent personality disorder, as both are inflexible, exaggerated dependency needs (Bornstein & Malka, 2009), and the borderline personality certainly fits under this description as well. Dependent and histrionic personality disorders are believed to have emerged from hysterical personality in the DSM-II (Disney, 2013).

A major distinguishing factor between them is their relative success at fulfilling their social need. While all three involve a certain social dependency, it differs on the scale and type of dependence. This is consistent with the hypothesis that the female brain is highly motivated to be active in the social world. Reproductive success in women does not solely depend on their social success. Having the greatest investment in offspring, women need to carefully choose their sexual partners (Schmitt, 2015). As a matter of fact, sexual promiscuity in females is linked to high-scores on measures of depression (Grello, Welsh, & Harper, 2006; Weisfeld & Woodward, 2004), emotional distress (Ethier et al., 2006), and psychological distress (Fielder & Carey, 2010; Glenn & Marquardt, 2001), which is the opposite pattern than that of men’s. The sexual tendencies of the three personality disorders covered reveals different mating selection and retention strategies.

Borderline personality disorder is a neurotic form of dependent personality disorder. They crave their partner’s commitment and sometimes engage in frantic and irrational acts to avoid abandonment, such as accusing others of rape and violence, or having children for mate-retention purposes. They are extremely dependent on a single relationship, until this relationship suddenly loses all interest and another one is more inviting. People with borderline are always dependent on someone, but the target of this dependency is rapidly changing. Thus, they sacrifice sexual value to retain social relationships, as they are usually quite sexually promiscuous (Hurlbert, Apt, & White, 1992; Mangassarian, Sumner, & O’Callaghan, 2015). In essence, they obtain masculine investment at an extremely high cost, which also depletes extremely fast. They are usually overweight (Sansone, Wiederman, & Monteith, 2001). Borderline scores correlate 0.44 with body mass index. Similar to histrionics, they use sexuality to obtain men’s attention, but “engage” in the sex that histrionics tease with. Women with borderline have more sexual assertiveness and erotophilic attitudes, meaning that they are more willing to give the sex to obtain what they want (Hurlbert et al., 1992). As such, they spend the sexual currency (Baumeister & Vohs, 2004) that they possess to obtain male investment, which histrionics are known to withhold.

Histrionics are extremely dependent on the social world, but unlike the other two personality profiles mentioned, they are dependent on a large number of people. In essence, histrionics correspond more or less of what a typical feminine woman would dream to embody, if the feminine psychology was indeed defined by a drive for socialization. Physical attractiveness, committed and obsessive providing partner, and an extremely large social circle. In regards to sexual attitudes, histrionic women have lower sexual assertiveness and have erotophobic attitudes, demonstrating a lower willingness to have sex per se, but show more sexual preoccupation, lower sexual desire, more marital dissatisfaction, more sexual boredom, more orgasmic dysfunction, higher sexual self-esteem, and greater likelihood to have an extramarital affair (Apt & Hurlbert, 1994). This suggests that they have more sexual potential, and apply it discriminately. They are more likely to cheat, which suggests that monogamous relationships limit their perceived potential gains. People with histrionic personality disorder are more physically attractive than other personality disorders or no personality disorders (Bornstein, 1999). If achievable and maintainable, a histrionic presentation is the most evolutionarily attractive, as it entails ultra-socialization, and also selective—but high in value—sexuality. Histrionics are also known to tease men by appearing sexually interested, but are also known to refuse actual contact (APA, 2013). As such, they successfully bargain interactions with men without using their sexual currency. Teasing can be conceptualized as an unwillingness to reciprocate a man’s investment. Their life strategy seems effective from an evolutionary standpoint, as the bored histrionic vs. obsessive husband was once the most encountered case in marital therapists (Martin & Waldo Bird, 1959). Although it seems like an adaptive strategy, it also entails great social risks. Being loud and sexually provocative provides many opportunities for “bitching”. As in psychopathy in men, it could be argued that histrionics play the evolutionary game with the highest stakes.

Dependent personality disorder is a small scale dependence pattern, usually on a central romantic figure that defines their lifestyle, tastes, activities, and values. In short, they are defined by a single relationship in which they are deeply invested. As dependent girls usually have few to no friendships, they can use their sexual value to satisfy this social urge in a romantic relationship. Their social life is usually limited to one idealized partner. People with a dependent personality seek relationships rapidly after one has ended, and become “indiscriminately attached to another individual” (APA, 2013, p. 676). This involves collateral damage, however, as they exert little discrimination in their mate choice. In this way, superordinate goals (quality of the genetic material) are sacrificed for basic socializing needs. In sum, both social success and sexual success are low in people with dependent personality disorder, as they have few social bonds, and an indiscriminate mating pattern. However, it offers stability.


It seems accurate that the extreme female brain is defined by social hyper-sensitivity, as the three mentioned disorders, characterized by an excessive social motivation, are all more prevalent in women. All of the presented disorders are linked to excessive fear of abandonment and reassurance (APA, 2013). This parallels the finding that 2D:4D ratios are positively correlated to an external locus of control, i.e., the perception of effectively affecting outcomes (Richards et al., 2015). It suggests that the female brain is expressed by an accentuated social dependency, relative to the male brain.

This essay investigated the concept of an extreme female brain, originally based on Baron-Cohen’s Extreme Male Brain (1997, 2002, 2009) and Theory of Mind (Baron-Cohen, Leslie, & Frith, 1985) theories of autism. The empathizing/systemizing theory proposes that the extreme female brain would be characterized by superior mentalizing, but deficient systemizing. Hence, the current review has argued that borderline, dependent, and histrionic personality disorders are the best candidates to portray the extreme female brain, as they are all defined by a strong social, empathizing need, and their epidemiology is strongly biased towards women. Their success at being a social agent varies greatly. Whereas histrionics are clearly highly functioning socially, the same cannot be said about borderlines, who have average (Dinsdale et al., 2016) to poor social skills (Baez et al., 2015; Bouchard, Lussier, Sabourin, & Villeneuve, 2009; Franzen et al., 2011; Levine et al., 1997), although they are indeed hyper-mentalizing (Sharp et al., 2011). This reiterates the relevance of the position that the empathizing/systemizing drives are needs that do not necessarily translate into superior skills. In aggregate, the hypothesis that the extreme female brain is characterized by a strong empathizing drive is more than plausible, and gaining materiality.


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Atheism, autism and naivety.

”Politically or in other ways, [people with Asperger’s] views are often held very strongly, and are black on white. They are typically convinced by the rightness of their beliefs, and given the chance will spend hours relentlessly trying to convince the other person to change their view. They feel their beliefs are not beliefs in the sense of being ”just one point of view”, a matter of subjectivity. Rather, they believe their own beliefs are a true reflection of the world, and as such, correct. Coming up against a different person’s belief therefore can mean trying to persuade you that they are right and you are wrong” (Baron-Cohen, 2005, p.23).

Atheism has long been linked to autism in popular culture, as both share many behavioral similarities. Indeed, some accuse atheism of neglecting the social value of organized religion, paralleling the low interest in the social world that defines autism. Moreover, impairments in imaginative thinking are some of the earliest behavioral manifestations of autism (Charman & Baron-Cohen, 1997), and have been theorized to promote religious disbelief. Lastly, some believe that the rational and systematic cognitive style of people with autism leads to atheism.

Recently, the relationship was investigated by psychological research. The hypothesis that people with autism have a higher likelihood to be atheist was empirically verified. Yet, it remains unclear how autism hinders religiosity. The current academic view holds that difficulties understanding the mental states of others renders the conceptualizing of a God troublesome. Consequently, people with autism, having an impaired social cognition, would not be able to contemplate the existence of a deity with its own mental states. On the other hand, popular culture believes that the rational and objective thinking style of people with autism is the source of their atheism. Putting these hypotheses aside, I suggest that the key to understanding atheism in autistic people might rather originate in processes that are not exclusively religious, but in the transmission of cultural knowledge. In this way, the lack of responsivity  towards the social world leads to religious disbelief via a disinterest towards cultural norms. Hence, low social motivation promotes religious disbelief, not objective and rational thinking.

What does the research say?

Caldwell-Harris, Murphy, Velazquez, and McNamara (2011) conducted two studies to investigate the religious beliefs of people with autism. The first study used 192 posters from the forum, where people with autism can safely discuss among each other. The results indicated that people with autism were much more likely to identify as atheist. Furthermore, they were also more likely to be agnostic and to construct their own religious beliefs. In their second study, 61 respondents with autism filled a survey about their religious preferences. Similar to the results from the first study, people with atheism were less likely to belong to an organized religion.

Norenzayan, Gervais, and  Trzesniewski (2012) have conducted four studies that provided similar results, while providing additional details. Using a sample of adolescents, a sample of Canadians and two samples of Americans, they concluded that autism decreases the belief in God. The magnitude of the relationship between autism and atheism was mediated by mentalizing deficits, that is, the ability to infer mental states to oneself and others. Atheist identification increased with increased mentalizing problems. It is often assumed that people with autism do not follow organized religion due to their logical and rational thinking, but the findings did not support that hypothesis. Indeed, systemizing failed as a mediator of the relationship. The inability to understand others’ mental states explained atheist beliefs, not rational thinking. Most interestingly, the results have given empirical support to explain the sex gap in religious beliefs. Women have long been shown to hold more religious beliefs than men. As autism has often been seen as an extreme male brain (Baron-Cohen, 2002), it is no surprise that people with autism even less religious beliefs than neurotypical men.

Explanations (or lack thereof) from researchers

A handful of possible explanations have been brought forward by Norenzayan and his colleagues to account for the relationship between atheism and mentalizing. First, they suggested that adversity causes people with autism to attend less religious services, and consequently decrease their beliefs. This proposition was not supported by their data. Second, they suggested that religious attendance causes more mentalizing. This suggestion was also discarded on empirical grounds. Third, they suggest that an innate interest for the hard sciences discourages religiosity in people with autism. Once again, this hypothesis did not hold, as systemizing failed as a mediator. Last, individual differences in conscientiousness, agreeableness and intelligence were often linked to religious beliefs, have been believed to play a role in religious disbelief in people with autism. None have shown to mediate the relationship between autism and atheism. The pathway from mentalizing deficits to religious disbelief is at best very ambiguous. The papers mentioned mention it in just a few vague, evasive words. In the case of Caldwell-Harris and colleagues, they simply assert that ”individual differences in cognitive styles is an important predictor of human belief systems, including religious belief”(p.3366). Norenzayan and colleagues explain it as such: ”mentally representing supernatural beings (and their mental states) requires mentalizing capacities. This in turn implies that mentalizing deficits would constrain intuitive support for belief in God”(p.1). In short, they believe that mentalizing deficits directly impede the conceptualization of supernatural beings.

Do religious beliefs originate from a belief in God? No

By claiming that mentalizing deficits hinder the belief in God, and consequently decrease religiosity, Norenzayan and colleagues implicitly suggest that religiosity originates from a personal connection with God. That would suggest that religious beliefs are intrinsically motivated and individually developed. In a similar vein, it implies that the belief in God is the ultimate cause of religiosity, and is necessary to identify as religious. As the belief in God is neither the end purpose, nor is it necessary to identify as religious, the proposition that religious disbelief is solely caused by an inability to infer mental states and motivation to others, resulting in an ability to connect with fictional entities, is unlikely. The answer must reside elsewhere.

First, only 79% of Roman Catholics and 48% of Jews believe in God (Harris Interactive, 2003). Believing in God is apparently not necessary to practice religion. Regardless, God is a minor aspect of organized religions, in terms of religious practice. Most religious people rarely attend religious services, and even if this was the case, religious services mostly do not require coercive (subjective) contact with God. The absence of belief in God does not prevent attending church, accepting religious values, etc. If it does, it does only via decreased motivation.

Second, many people with autism have pronounced interests towards fictional characters. In fact, in popular culture, autism is often linked to massive multiplayer online role-playing games (MMORPGs), cartoons, fiction, role-playing, anime, cosplaying, which are all characterized by fantasy worlds and imaginary entities. It seems that the autistic mind is absolutely capable of connecting with fictional characters, despite being aware that they are fictive. Moreover, people with these hobbies are often extremely dedicated to these interests. The reason that autistic people are mostly atheist does not reside in an inability to connect to an imaginary character.

The hypothesis that deficits in social cognition lead to the inability to conceptualize spiritual entities has no direct empirical support. Meanwhile, some general tendencies of people with autism offer explanations that are more rigorous.

Unwillingness to socialize as the basis of religious disbelief

Some experts perceive autism as an extreme case of diminished social motivation (Chevallier, Kohls, Troiani, Brodkin, & Schultz, 2012). People with autism  show a decrease in the attentional weight assigned to social information. People with autism do not show emotional spontaneity, do not make efforts to maintain interpersonal relationships, do not show interest in social stimuli or attempt to make friends. Importantly, people with autism show little interest for social rewards (Demurie, Roeyers,  Baeyens, & Sonuga-Barke, 2011).

Consequently, people with autism have little interest to conform to social norms, and show little response to social expectations. In order to be an active member in a social group, one has to demonstrate interest towards the implicit norms that guide behavior, and behave accordingly. In this way, active socialization is sometimes costly and consuming. Those who do not need socialization will evade unnecessary investment. In the case of autism, their atheism might originate from the fact that religious belief is reinforced and transmitted socially, and they care little about the social world and its potential rewards. Now that scientific progress is challenging organized religion, the social forces propagating religion are weaker than ever. The incentives to theism being at an all time low, those with a low sensitivity to social rewards are the firsts to reject social expectations, often on the basis of scientific reasoning. Although scientific findings often justify atheism, they predict atheism less than a poor social motivation. In contrast, religiosity is linked to extraversion and agreeableness (i.e socialization; Saroglou, 2002). Since systemizing failed as a predictor of religious disbelief, as opposed to mentalizing deficits, autists’ atheism does not emerge from a rational thinking, but mainly from social impairment.

What does this mean at a bigger scale?

The fact that people with autism are less naive and vulnerable to socially constructed ”truths” goes further than atheism. Indeed, it has been repeatedly noted that people with autism can be extremely offensive, as they do not consider the social value of their opinions. Their unresponsivity to social influences can result in the endorsement of values that are incongruent with their social environment. Importantly, the ongoing politically correct forces that guide the neurotypical mind discourages many ideas that are deemed unacceptable, regardless of objective validity. Accordingly, many opinions could be defended based on empirical support, but are discouraged due to cultural sensitivities, or random cultural fluctuations. In this way, the validity of statements are appraised by two criteria: their social value and their factual validity. Hence, in the neurotypical population, both the factual validity and social value of ideas are considered. In the case of autism, however, the social value is given no weight.

Examples of insensitivity to the social value of a certain element in autism are diverse. First, ”narrow interests” is one of the two core components of autism according to the diagnostic criteria. These narrow interests are often odd and unusual, even inappropriate in some instances. For example, Japanese cartoons are popular among the autistic population, although socialized individuals might arguably see them as childish and socially undesirable. Second, unusual political stances have been documented in people with autism (Baron-Cohen, 2005), such as ”Green Fascism” (shooting those who damage nature). This political model, although somewhat appealing, would not be judged appropriate by the commoners. Lastly, anonymous communities based on unsocialized interests (to say the least) – the infamous image boards, contain the most politically incorrect and unsocialized material known to mankind. Although these micro subcultures evade scientific scrutiny, they are often informally linked to autism in popular culture.

Unsocialized interests indicate that people with autism grant little weight to what is considered socially appropriate. Constantly, cultural forces encourage us to (selectively) consider the social value or objective reality of our environment, and people with autism mostly ignore the former.

Final words

Autism and religious disbelief have shown to be strongly related. The current assumption in psychological research is that deficits in mentalizing impairs the ability to conceive an mental image of an entity with their own motivations and mental states. Disregarding this proposition, I suggest that people with autism show little responsivity to the mode of transmission of religiosity. As a matter of fact, there are many examples that indicate that the autistic mind does not respond to dynamic cultural influences. In this way, mentalizing deficits lead to atheism not by a decreased belief in God, but a lesser responsivity to socialization processes that transmit religiosity. Consequently, the social value is outweighed by the factual value. Autism leads to atheism through a lack of weight granted to what others believe they should accept as true.

The most prevalent theory of autism claims that people vary on a continuum of a need to interact with others. Males, on average, have a lesser socialization drive, and autism is the extreme form of it (Baron-Cohen, 2002). That is why people with autism do not process social information thoroughly, and mostly consider the objective reality as the only source of knowledge. As a result, they are impermeable to social engineering and socially constructed truths like organized religion or other culturally established ”truths”. On the other side of the spectrum, there are those who have a pronounced social motivation. Hopefully, socialized people do not process reality only by social conditioning.

Regardless, whatever motivates family and community involvement matters little. One of the earliest symptom of autism is difficulty in imaginative and pretend play in childhood (Charman & Baron-Cohen, 1997), forcing them into isolation. Refusing to conform to unifying ideologies on the basis of the scientific unlikelihood of Noah’s Ark is a provocative parallel. As the need to belong is one of our most powerful drive and main evolutionary strategy (Baumeister & Leary, 1995), using imaginative and pretending skills to stimulate socialization is as scientific as it gets. Relatives offering their prayers never cured cancer directly, but perceived social support is a major variable in well-being (Sheldon & Wills, 1985) or even physical recovery (Bucholz et al., 2014). Rational thinking can hardly motivate religious disbelief, in contrast to a decreased interest in socializing.


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[ Are some psychological disorders extremes of sex-specific traits? ]

Nicolas Kilsdonk-Gervais

A shortened, edited version of this essay appeared on Honours Review, a student
journal for Honours students of the University of Groningen.

In the past decades, sex differences have garnered increasing scrutiny from psychological researchers. Despite this enthusiasm, sex differences are often erroneously assumed to be unimportant, small and unreliable (1). Yet, some psychological and behavioral phenomena show stable biases towards one sex that cannot be satisfactorily explained by differences in upbringing and socialization. The sex differences in psychopathology are striking, and can be utilized to understand sex-differential inclinations in neurotypical populations.

Many behavioral disorders are characterized by extreme forms of behaviors that are otherwise considered normal and can shed light on the drives that define the human mind. Psychopathology and developmental disorders differ greatly between males and females, as men and women are born with universal and stable predispositions that prepare them for different evolutionary purposes. The magnitude of the sex specific traits fluctuate on a continuum, not an all or none basis, and can therefore result in extreme, maladaptive expressions of sex typical tendencies. This differential prevalence of psychological conditions can offer us crucial insights into sex-specific tendencies and functionalities that might be decisive for forming certain disorders. This essay will compare the epidemiology of mental illnesses in both sexes, and suggest that many mental conditions are extreme expressions of sex specific inclinations that are present in nonclinical populations.

‘’it’s pretty difficult to find any single factor that’s more predictive for (psychiatric) disorders than gender’’ (2).

– Thomas Insel, head of the National Institute of Mental Health

[ the Extreme Male Brain Theory of Autism ]

In 1997, Simon Baron-Cohen introduced the extreme male brain theory of autism. This theory stipulates that the symptoms of autism embody extreme male traits (3). It introduced the proposition that some disorders are a result of brains that are too masculine. Autism spectrum disorder (ASD) is characterized by impaired social interaction, the inability to understand others, a weak theory of mind (ToM), narrow interests, and stereotyped, repetitive behaviors. People diagnosed with autism oftentimes excel in their narrow interests. Accordingly, individuals with Asperger’s syndrome, a high-functioning form of autism, were often called ‘’little professors’’ by Hans Asperger (4), due to their ability to memorize large amounts of information about a particular subject. A high interest in understanding systems is a striking feature of autism spectrum disorders.

The rationale behind the extreme male brain theory is that autistic individuals show an extreme form of sex differences seen in the nonclinical population. Neurotypical males are slightly impaired in empathizing compared to neurotypical females, but are usually better at systemizing (5). Baron-Cohen defines empathizing as the drive to identify another person’s emotions and thoughts, and to respond to these with an appropriate emotion. On the other hand, systemizing is the understanding of input/output relationships, such as understanding the rules of music, mechanics or computer programming (5). People with autism are severely impaired in regards to empathy but have an unusual ability to understand systems. A powerful tenet of this theory is that males and people with autism are over-represented in fields guided by systems, such as physics or music. Consequently, Baron-Cohen introduced the empathize/systemize dichotomy to define the female brain and the male brain. These sex differences are based on averages, and the theory concurs that autism can also be present in females. ASD is four times more prevalent in males than in females (6). In high-functioning autism, the male to female ratio is higher than 10:1 (5). Autism spectrum conditions constitute the phenotype of excessive brain masculinization, according to Baron-Cohen.

The functional aspect of narrow interests are often overlooked.

The functional aspect of narrow interests is often overlooked.

[ the extreme female brain ]

Baron-Cohen claims that excessive systemizing and insufficient empathizing characterize autism. But, what about people who have a low interest for systems, but have an unusually high drive to empathize? Logically, we would expect excess empathizing and inadequate systemizing to be undesirable as well. This would lead us to the female end of the spectrum. There are indeed disorders characterized by an excessive sensitivity to social relationships, which are primarily seen in females. For example, borderline personality disorder (BPD) and histrionic personality disorder (HPD) are both characterized by an abnormal drive for socialization. BPD is defined by instability of behaviors, interpersonal relationships, and self-image (7). Symptoms include sensitivity to rejection, fear of abandonment, self-harm, suicidal tendencies, quickly changing between idealizing and devaluating others, uncertainty concerning one’s own identity, intense sensitivity in relationships with others, and severe dissociation (8). People with BPD engage in potentially dangerous behaviors, such as substance abuse, promiscuous sexual behavior, hair coloring, tattooing, and piercing (9). BPD patients show weak autobiographical memory (8), constantly feel empty, have no self-concept outside of their relationships, experience imaginary victimization (10), and often do not know what they personally like, believe, value or prefer (11). Interestingly, although it is not part of the diagnostic criteria, BPD patients frequently lie and manipulate others, often to trick people into expressing sympathy for them. The female-to-male ratio in BPD is 3:1. By simple definition, BPD is a maladaptive pattern of behavior to fulfill an intense social need, often expressed by manipulative strategies to obtain nurturing attention.

A similar disorder is dissociative identity disorder (DID), mostly known under the name of multiple personality disorder. It is characterized by enduring distinct identities or dissociative states. Approximately half of those diagnosed with DID fit the criteria for BPD, as their diagnostic criteria overlap considerably (12). Lack of social support, reported childhood trauma, and disorganized attachment (both hating and adoring someone at the same time) are necessary components for a diagnosis of DID. Self-harm is a widespread occurrence in the DID population (13). Many people diagnosed with DID claim that child abuse marked the onset of their symptoms, but there is no evidence to support that claim (14). DID is nine times more prevalent in adult females than adult males (15).

Borderline personality disorder.

A famous case of borderline personality disorder.

An excessive sensitivity to interpersonal relations is not always as pervasive as in BPD, and can be seen in people that are less distressed, such as people with histrionic personality disorder (HPD). HPD is characterized by excessive attention seeking behaviors and a strong need for approval from others. People with HPD are loud, behave inappropriately, have an unstable personality, exaggerate their behaviors and emotions, are flirtatious, crave stimulation, and are easily influenced by others. People with HPD are usually promiscuous, parasitic, and manipulative. They are generally well-functioning and have good social skills, and frequently use them to be the center of attention, for instance by exaggerating symptoms of physical illness, dramatizing, behaving in sexually inappropriate ways, and exaggerating their difficulties. HPD is closely related to BPD, as both emerged from the discontinued diagnosis of hysteria. Some criteria for HPD have been removed from the DSM-III as it could not distinguish between HPD and BPD, such as craving for activity, irrationality, and manipulative suicidal attempts. Furthermore, both are overly dependent on the social environment, leading to naivety and suggestibility as defining characteristics. HPD affects women four times more than men (16). People with HPD usually do not struggle as much as people with BPD, but its female bias is nonetheless consistent with the view that females are overrepresented in conditions of immoderate need to empathize.

BPD and HPD can be seen as the extreme of the normal female profile, as it shows extreme forms of the higher need for empathizing in females (5). In addition, individuals with either condition have acute neuroticism (17), and neuroticism is the trait of the Big 5 Personality Traits that distinguishes best between men and women (18). Their intense social needs lead them to use harmful strategies to achieve their goals. This inflexible tendency to seek nurturing attention is best illustrated with their higher likelihood to use strategies to obtain comforting, such as factitious symptoms, false rape allegations, factitious claims of child abuse, conversion disorder, accusations based on repressed memories, and a myriad of other disabling phenomena for which there is no scientific evidence (including DID). BPD and HPD are certainly under-diagnosed in favor of these conditions. In an article published in June 2015, Baron-Cohen expressed a recommendation to continue considering people with BPD as having extreme female brain (19). The empirical test of this theory will most likely follow shortly, but the female preponderance in BPD and HPD is highly suggestive.

[ other candidates for the phenotypic expression of the extreme male brain ]

Earlier, I explored Baron-Cohen’s suggestion that autism was a result of extreme brain masculinization. There are, however, a number of disorders that are primarily seen in males which are strongly related to other masculine traits. This suggests that the Extreme Male Brain theory might not encompass all the possible phenotypes of the male brain, and that this shortcoming requires clarification. Here are additional disorders that are often linked to excess masculinity.

Antisocial personality disorder (ASPD), commonly known as psychopathy, is defined by enduring antisocial behavior, reduced empathy, bold behavior, and fearlessness. One quarter of the male prison population fits these criteria. Robert D. Hare, who developed the Hare Psychopathy Checklist, believes that psychopaths are relatively successful in the workplace, as psychopathic traits are common in higher positions of corporate organizations. Their boldness and propensity for risk-taking may be adaptive in executive functions, and even organized crime. The traditional phenotype of psychopathy, characterized by grandiose self-image and instrumental violence, is almost exclusively seen in males (20). Females diagnosed with antisocial personality disorder (psychopathy) show symptoms that are more accurately described by HPD and BPD, which are often diagnosed alongside of ASPD in females (20). Other than being highly male biased, psychopathy is strongly linked to correlates of hyper masculinity, such as aggression, sensation seeking, criminality, and testosterone. This suggests that autism might not encompass the whole range of the extreme male brain.

ADHD is a neurodevelopmental disorder characterized by hyperactivity, not listening when spoken to, struggling with instructions, frequently interrupting others, acting without considering the consequences, having difficulties waiting for their turn, having difficulties sitting still, squirming and fidgeting, and having impairments in social interactions and friendships. ADHD has three subtypes: inattentive, hyperactive/impulsive and combined. ADHD is often linked to hyper-masculinity, as it is often seen in traits and behavioral patterns that are often typically defined as masculine, such as drug and alcohol abuse, high spatial ability, conduct disorder, risk-taking activities, and physical injury. Interestingly, people with ADHD are overly represented in sports, as it has been theorized that 25% of athletes have hyperactivity disorder. ADHD is diagnosed three times more often in males than females, and males are treated nine times more than females, and in severe ADHD, the ratio is 16:1. The higher numbers of males with ADHD and its correlations to masculine traits challenges the Extreme Male Brain theory of autism.


ADHD and the dangerous lifestyle.

ADHD and the dangerous lifestyle.

Many have studied the link between ADHD and psychopathy and autism. Indeed, ADHD is often comorbid with either and its subtypes diverge in symptoms of psychopathy and autism. Specifically, the symptoms of the inattentive subtype resemble those of autism, and those of the hyperactive and combined subtype resemble

psychopathy. ADHD and autism both share the symptoms of low attentiveness to social cues, communication problems and narrow interests. Indeed, language delays, difficulty in listening when spoken to, missing social cues, difficulty processing nonverbal and verbal language, and the inability to concentrate on material that is not personally interesting are all symptoms shared by sufferers of ADHD and autism. ADHD is also linked to a weak theory of mind (21) and repetitive behaviors (22) which are the core components of ASD. Furthermore, ADHD is, like autism, highly comorbid with Tourette’s syndrome. ADHD and psychopathy are both characterized by the persistent breaking and defying of social norms, impulsivity, impatience, acting without regard to the consequences, impulsive behavior, substance abuse, and proneness to boredom. Some have argued that people with ADHD have psychopathic traits, but to a subclinical extent (23). Additionally, the inattentive symptoms correlate negatively with the hyperactive symptoms, indicating the psychopathic traits and autistic traits correlate negatively in those with ADHD, indicating that psychopathy and autism represent two ends of a spectrum. In short, people with ADHD show symptoms of autism, notably in their narrow interests and social deficits, and also have mild psychopathic traits, as seen in their impulsive and sensation-seeking tendencies. Does the continuum from autism, to ADHD, to psychopathy represent the male end of excess masculinization?

It appears not, according to current assumptions about the male brain. It is unlikely that psychopaths have an extreme male brain, as they are usually reasonably well functioning socially. As a matter of fact, psychopaths have an intact theory of mind (24) and decent emotion recognition skills for most emotions, unlike individuals with autism. Even though psychopathy is strikingly sex biased and it might seem like an indicator of an extreme male brain, psychopathy has been linked to elevated intrapersonal power, and men and women use this power differently. In a similar vein, people with ADHD experience a decrease in their symptoms over time and about 40% will have no enduring symptoms in adulthood, even though their social cognition is mildly impaired. These conditions show sex-specific behaviors and their epidemiology is biased towards males, but they do not have the burdensome symptoms that individuals with autism have. Therefore, if the extreme male brain is characterized by the absence of a theory of mind, autism spectrum disorders represent the extreme expression of sex specific traits more accurately. Yet, ADHD and psychopathy can be considered as excessively masculinized behavioral tendencies.

[ what defines both extremities of the spectrum? ]

Females are vastly over-represented in adolescent-onset emotional disorders involving shallow self-concepts, extreme neuroticism, dissociation and excessive social needs (25). Such social need often expresses itself in manipulative strategies to evoke nurturance, by self-harm, imagined victimization or factitious symptoms (26). Yet, it is unclear how dissociation and empathic needs relate to each other. Females consider others as representing a larger part of their identity, compared to males (27). Accordingly, those with an extremely female brain might have a self-concept that is almost entirely characterized by their relationships with others, at the cost of not having a stable, durable identity, and personal interests. This might lead to a point where their fragile sense of self makes them vulnerable to dissociation due to a complete abandonment of one’s identity. Empathy would come at a cost that would contrast with the narrow interests and autonomy that people with autism have. To determine the validity of this theory, further consideration is needed. A possible first step would be to explore the empathizing/systemizing scores of individuals with dissociative disorders to establish if they score lower on systemizing than average females. That would indicate that they have an extremely female brain. If this is the case, the term empathy would seriously need reconsideration, as both histrionic and borderline personality disorders have been argued to constitute the female phenotype of psychopathy (28, 29).

Multiple personalities.

Multiple personalities.

Males make up the large majority of those diagnosed with early-onset neuropsychiatric disorders that involve a lack of conformity to social norms and antisocial behavior (25). These disorders are all strongly linked to impairments in socialization. Consequently, lack of empathy does appear to define the male brain. More specifically, if a deficient ToM represents an extreme form of a lack of empathy, autism would be the phenotype of an extreme male brain. Yet, some ambiguity remains. For instance, there has been a recent increase in autism diagnoses in females. While they do not show the typical phenotype of autism, their impairments in social cognition are substantial. Most notably, people with borderline personality disorder, who have been theorized to have an extreme female brain, have impaired emotion recognition, which is characteristic of a deficient theory of mind. This suggests that the deficient theory of mind is not exclusive to the male brain, and it would be premature to exclude ADHD and psychopathy as potential expressions of excess masculinity on the basis of their functional theory of mind. Another point that needs to be addressed is that many correlates of the male brain do not appear to be linked to autism. In spite of the strong relationship between masculinity and spatial abilities, athletic abilities, aggression and sensation seeking, people with autism show none of these inclinations. In contrast, psychopaths and hyperactive people show these tendencies. As a result, people with ADHD and psychopathy are over-represented in sports and executive positions, respectively. One might argue that the definition of systems should be extended to include physical and professional fields, which are systems vastly dominated by males. In this way, the reasoning that was used to nominate autism as an extreme form of male traits could be extended to ADHD and psychopathy. Consequently, the hypothesis that autism, ADHD and psychopathy are all different phenotypes of the extreme male brain deserves empirical evaluation.

[ conclusion ]

The differential prevalence of mental conditions suggests that we are all on a continuum from poorly socialized to overly socialized. As psychological disorders represent maladaptive strategies to fulfill a need, they can offer us tools to determine the nature of the needs that define us. Females are over-represented in disorders characterized by an excessive social need, and males make up the majority of those with disorders characterized by poor socialization and a need to manipulate systems. To this day, the best candidates for the phenotypical expression of the extreme male brain are autism spectrum disorders, attention deficit and hyperactivity disorder and psychopathy, and borderline personality disorder (and its ramifications) and histrionic personality disorder for the extreme female brain. These sex-differential inclinations offer an unprecedented parallel with different evolutionary purposes in men and women, which are generating material and social capital respectively. A certain flexibility in systemizing needs and sociability is a healthy compromise, as people with an excessive social need, just like those who are overly antisocial, experience (and cause) considerable distress. These disorders represent extreme and inflexible forms of normal tendencies, and should not be marginalized, as they help us understand the proclivities that define all of us.

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