Baron-Cohen's ‛extreme male brain’ theory postulates that autism involves exaggerated male-typical psychology, with reduced empathizing (considered here as social–emotional interest, motivation and abilities) and increased systemizing (non-social, physical-world and rule-based interest, motivation and abilities), in association with its male-biased sex ratio. The concept of an ‘extreme female brain’, involving some combination of increased empathizing and reduced systemizing, and its possible role in psychiatric conditions, has been considerably less well investigated. Female-biased sex ratios have been described in two conditions, depression and borderline personality disorder (BPD), that also show evidence of increases in aspects of empathy in some studies. We evaluated the hypothesis that BPD and depression can be conceptualized in the context of the ‘extreme female brain’ by: (1) describing previous conceptualizations of the extreme female brain model, (2) reviewing evidence of female-biased sex ratios in BPD and depression, (3) conducting meta-analyses of performance on the Reading the Mind in the Eyes test (RMET) among individuals with BPD, clinical or sub-clinical depression, and other psychiatric conditions involving altered social cognition and mood (schizophrenia, bipolar disorder, eating disorders, and autism), in relation to disorder sex ratios, and (4) evaluating previous evidence of increased empathic performance in these, and related, psychiatric conditions, and (5) synthesizing these lines of evidence into models for causes and effects of an ‘extreme female brain’. Our primary empirical results are that RMET performance is enhanced in sub-clinical depression, preserved in borderline personality disorder, and reduced in other disorders (by meta-analyses), and that across disorders, more male-biased patient sex ratios are strongly associated with worse RMET performance of patients relative to controls. Our findings, in conjunction with previous work, suggest that increased cognitive empathizing mediates risk and expression of some psychiatric conditions with evidence of female biases, especially sub-clinical depression and borderline personality disorder, in association with increased attention to social stimuli, higher levels of social and emotional sensitivity, negative emotion biases, and over-developed mentalist thought. These results link evolved human sex differences with psychiatric vulnerabilities and symptoms, and lead to specific suggestions for future work.
- Female brain;
- Borderline personality
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