Sex differences in neurological and psychiatric disorders

摘要

Sexual dimorphisms in structure and physiology are widespread in the animal kingdom, including humans. Extreme examples of dimorphic secondary sexual characteristics arise from sexual selection where they are used as indicators of fitness of potential mates (e.g. tail feathers in peacocks and birds of paradise). Some sexual dimorphisms arise from intrasexual competition for resources, such as territory and mates, and include increased body size and weaponry (e.g. antlers) in males of many species. Other sexual dimorphisms are necessitated by sex differ- , ences in reproductive physiology, including genitalia, and mammary glands. Accompanying these obvious sexually dimorphic features, sex differences in the brain ensure the expression of male- or female-typical behaviors to maximize the fitness of each sex. The vast majority of sex differences in neuroanatomy, neuro-chemistry and neuronal structure and connectivity are established by the organizational influences of gonadal sex steroids or genes found on sex chromosomes. Sex differences in adult steroid hormone secretion also contribute to sex differences in the brain. Sex differences in the brain are likely more pervasive than many appreciate. A recent study reported that up to 2.5% of genes are differentially expressed or spliced in the brains of men and women (Trabzuni et al., 2013). Despite these sex differences, most biomed-ical research is carried out in only one sex, typically males, and therefore fails to identify many of the consequences of sex differences in brain in relation to disease (Beery and Zucker, 2011; McCarthy et al., 2012).