Are the neurodevelopmental effects of gonadal hormones related to sex differences in psychiatric illnesses?

There are large sex differences in the incidence of many psychiatric diseases. The bases for these sex differences are probably complex and are likely to involve the interaction of both social and biological factors. Probable social factors include child rearing practices, personal expectations and lifestyles, and societal institutions. Biological factors would likely include genetic effects, hormonally mediated neurodevelopmental effects and hormonally mediated neuroregulatory effects. This paper focuses upon the developmental effects of gonadal hormones. The sex differences observed in the neuroanatomy and behavior of nonhuman mammals are reviewed. The instances in which developmental exposure to gonadal hormones has been demonstrated to be involved in establishing these sexual dichotomies are surveyed. The molecular mechanisms by which differences in prenatal and early postnatal levels of gonadal hormones may generate such sex differences are examined. Sex differences in human neuroanatomy and cognitive function are discussed. Finally, we speculate on ways in which similar hormonal mechanisms might act to influence psychiatric disorders.