A meta-analysis of sex differences in human brain structure

tThe prevalence, age of onset, and symptomatology of many neuropsychiatric conditions differ betweenmales and females. To understand the causes and consequences of sex differences it is important to estab-lish where they occur in the human brain. We report the first meta-analysis of typical sex differences onglobal brain volume, a descriptive account of the breakdown of studies of each compartmental volumeby six age categories, and whole-brain voxel-wise meta-analyses on brain volume and density. Gaussian-process regression coordinate-based meta-analysis was used to examine sex differences in voxel-basedregional volume and density. On average, males have larger total brain volumes than females. Exami-nation of the breakdown of studies providing total volumes by age categories indicated a bias towardsthe 18–59 year-old category. Regional sex differences in volume and tissue density include the amyg-dala, hippocampus and insula, areas known to be implicated in sex-biased neuropsychiatric conditions.Together, these results suggest candidate regions for investigating the asymmetric effect that sex has onthe developing brain, and for understanding sex-biased neurological and psychiatric conditions