Can an ‘Extreme Female Brain’ be characterised in terms of psychosis?

Abstract

The empathising–systemising (E–S) theory proposes that many sex differences can be explained by females typically demonstrating greater empathising abilities (understanding of the social world) and males typically demonstrating greater systemising abilities (understanding of the non-social world). Autism is argued to represent an ‘Extreme Male Brain’, with impaired empathising alongside preserved or enhanced systemising producing a hypo-empathising profile. A recent account hypothesised that a hyper-empathising ‘Extreme Female Brain’ would be characterised in terms of psychosis. The present study tests this hypothesis by investigating the relationship between levels of empathising and systemising, as well as self-report measures of psychosis, depression and anxiety, in 70 healthy female undergraduates. Results showed a hyper-empathising profile was related to psychosis, and specifically paranoia and mania (positive symptoms). No relationship was found between hyper-empathising and either depression or anxiety, consistent with the idea that an ‘Extreme Female Brain’ is specifically associated with psychosis. In addition, empathising and systemising were found to negatively correlate with each other, suggesting they are separate but related components.

Introduction

Sex differences are of great interest to humans. One framework for investigating and understanding sex differences is the empathising–systemising (E–S) theory (Baron-Cohen, 2002, Baron-Cohen, 2003, Baron-Cohen, 2009). Empathising is the drive to identify another person’s emotions and thoughts, and to respond to these with an appropriate emotion. Empathising also allows one to predict a person’s behaviour, and to care about how others feel. Systemising is defined as the drive to analyse the variables in a system, to derive the underlying rules that govern the behaviour of a system. Systemising allows you to predict the behaviour of a system, and to control it (Baron-Cohen, 2002). The relationship between empathising and systemising is currently unclear. While some research has shown a negative correlation between empathising and systemising (Goldenfeld et al., 2005, Wheelwright et al., 2006), other findings have been inconsistent with this (Carroll and Chiew, 2006, Voracek and Dressler, 2006). Bowler, Briskman, Gurvidi, and Fornells-Ambrojo (2005) developed a mechanical (systemising) analogue to an empathising task and showed that performance upon the two tasks was significantly correlated. This raises the possibility a common mechanism may underlie systemising and empathising performance, which would predict a correlation between measures of these abilities within individuals.

A number of studies have shown that females do better on tests of empathising compared to males. For example, on the Reading the Mind in the Eyes test, which requires people to read the mental and emotional states of others from the eye regions, females score significantly higher than males (Baron-Cohen et al., 1997, Baron-Cohen et al., 2001). Research using the Empathising Quotient (EQ), which is a questionnaire designed to tap into empathising ability, has shown that females score higher than males (Auyeung et al., 2009, Baron-Cohen and Wheelwright, 2004, Wakabayashi et al., 2006). Together, these findings illustrate an advantage for females over males in terms of empathising ability.

On the other hand, males typically outperform females on tasks measuring systemising. In the intuitive physics task, where participants have to predict the outcome position of a series of pulleys and levers, males score higher than females (Carroll and Chiew, 2006, Lawson et al., 2004). This was found to be the case irrespective of whether their academic discipline was in science or humanities (see also Focquaert et al., 2007, Wheelwright et al., 2006). Males also score higher than females on the Systemising Quotient (SQ), a questionnaire designed to tap into systemising ability (Auyeung et al., 2009, Baron-Cohen et al., 2003, Wakabayashi et al., 2006).

Therefore, the male-typical profile involves systemising exceeding empathising abilities (S > E), while the female-typical profile has empathising exceeding systemising (E > S: see Fig. 1). In this model, a ‘Balanced’ brain type is represented by relatively equivalent levels of empathising and systemising ability (E = S). The Extreme Male Brain (EMB) occurs at one end of the continuum and is characterised by systemising abilities that are far better than empathising abilities (S » E). Conversely, the Extreme Female Brain (EFB) appears at the opposite end of the continuum and is characterised by empathising abilities that are much better than systemising abilities (E » S). In a study of 1761 students (Wheelwright et al., 2006), females were far more likely to register as EFB (E » S), while males were more likely to register as EMB (S » E). In addition, almost two-thirds of a sample with a diagnosis of autism or Asperger Syndrome, which are both Autism Spectrum Disorders (ASD), met an EMB profile of S » E (see also Baron-Cohen, 2002, Baron-Cohen et al., 2003, Baron-Cohen, 2009). ASD are characterised by deficits in social cognition and communication, alongside repetitive behaviour and restricted interests (APA, 2000).

Consistent with the Extreme Male Brain theory of autism (Baron-Cohen & Hammer, 1997), people with ASD perform worse than typical males and females on the Reading the Mind in the Eyes task (Baron-Cohen et al., 1997, Baron-Cohen et al., 2001). People with ASD also score significantly lower on the Empathising Quotient than both males and females (Baron-Cohen & Wheelwright, 2004). On the other hand, people with ASD score higher than both typical males and female controls on both the Systemising Quotient (Baron-Cohen et al., 2003), and in tests of intuitive physics (Baron-Cohen et al., 2001, Lawson et al., 2004).

Unfortunately, there has been a dearth of theories and research about the opposite end of the spectrum to the EMB, where empathising skills far exceed systemising skills. A recent model by Badcock and Crespi, 2006, Badcock and Crespi, 2008, Crespi and Badcock, 2008 specifically addresses the EFB and proposes it is associated with psychosis. More specifically, the autism-psychosis model by Badcock and Crespi (2008), proposes that hyper-empathising underpins paranoia, and represents the opposite pattern of behaviour to the hypo-empathising behaviours associated with autism. From this perspective, the gaze deficits seen in autism may be the exact opposite to paranoid delusions of being watched or spied upon. Further, the autistic inability to appreciate what goes on in groups can be seen as the antithesis to paranoid delusions of conspiracy, which involves imagining group activity everywhere. Therefore, Crespi and Badcock (2008) conceptualise ASD and psychosis at opposing ends of a social brain continuum.

A number of early studies on mentalising (empathising) in schizophrenia reported deficits compared to controls (e.g. Corcoran, Mercer, & Frith, 1995; see Frith, 1992/2003). Thus schizophrenia was characterised by impaired mentalising, similar to autism; deficits were more evident for those with negative schizophrenic symptoms, and less clear for those with predominantly paranoid symptoms (Langdon et al., 1997). Langdon and Brock (2008) argue that the same schizophrenic patient can demonstrate both hyper-mentalising and hypo-mentalising and the deficit is best characterised as impaired perspective taking. Montag, Heinz, Kunz, and Gallinat (2007) characterise impaired perspective taking as a deficit in ‘cognitive empathy’ in schizophrenia which is distinct from ‘affective empathy’. A study by McCabe and colleagues using clinical interviews with schizophrenic outpatients showed that the participants with schizophrenia had an understanding of the interviewer’s beliefs during the conversations, even when the beliefs differed from their own (McCabe, Leudar, & Antaki, 2004). These findings are consistent with more recent conceptualisations of mentalising in schizophrenia suggesting those who show predominantly positive symptoms have intact mentalising abilities, and may actually over-attribute beliefs to others (Abu-Akel & Bailey, 2000). Frith (2004) similarly associates separate mentalising difficulties to positive versus negative schizophrenia. A person with negative symptoms may have no awareness of, or take no account of, the beliefs and desires of others. However, a person with positive symptoms has no problem ascribing intentions to others. In fact, they may inappropriately and excessively ascribe intentions to others (e.g. ‘over-mentalising’). Evidence for over-mentalising in schizophrenia comes from patients attributing intentions to behaviour seen as random by control participants and people with affective disorders (Blakemore et al., 2003, Russell et al., 2006).

In the Crespi and Badcock model, psychosis is characterised as a triad of three main conditions: schizophrenia, bipolar depression and major depression. This idea fits in well with prevalence rates of major psychiatric conditions, as females have a higher prevalence compared to males for mood disorders such as depression and anxiety (Kessler et al., 1994, Kuehner, 2003, Pigott, 1999). While the evidence is less clear for schizophrenia, there is evidence to suggest some sex differences evident in timing and severity (see Crespi & Badcock, 2008 for an overview). To address the issue of why schizophrenia is not a female-dominated disorder, Crespi and Badcock argue that schizophrenia with positive symptoms is relatively more frequent in females, while schizophrenia with negative symptoms is more frequent in males. To date, however, there have been no published research reports testing the nature of the EFB profile. The present study aims to fill this gap with initial evidence characterising the EFB profile, by looking at associations between empathising and systemising ability and measures of psychosis, depression, and anxiety. According to Crespi and Badcock (2008) hyper-empathising should positively correlate with measures of psychosis, and particularly with paranoia.