Sex differences in cortical and subcortical human brain anatomy

Abstract

Previous research has reported many sex differences in cortical and subcortical anatomy, but only a subset of findings is consistent across studies. Here, we used improved Freesurfer-based automated methods to analyze the properties of the cortex and seven subcortical structures in young, right-handed subjects (69 male and 69 female), carefully matched in age and education. Significant sex differences were observed. Females had greater gyral complexity (i.e., greater bending energy). In contrast, males had greater unadjusted cortical surface area (+10.3%), but area differences were reduced (to +2.8%) when area was adjusted for total intracranial volume (ICV). There were no significant omnibus sex differences in cortical thickness. Males showed larger unadjusted subcortical gray matter structural volumes, as well as larger ICV-adjusted volumes in the amygdala. These results help to resolve some of the inconsistencies in previous studies of sex differences in brain anatomy.