Sex differences in the brain are not reduced to differences in body size

Abstract

In their comprehensive review of sex differences in the brain, Eliot et al. (2021) conclude that (1) men and women significantly differ in global brain size, but this “mostly parallels the divergence of male/female body size during development” and that (2) “once we account for individual differences in brain size, there is almost no difference in the volume of specific cortical or subcortical structures between men and women”. In sum, almost all brain differences would directly or indirectly follow from differences in body size. In a recent study that does not have the same limitations as most studies reviewed by Eliot et al., we find that sex differences in total brain volume are not accounted for by sex differences in height and weight, and that once global brain size is taken into account, there remain numerous regional sex differences in both directions (Williams et al., 2021).