WM volumes continued to increase in both males and females throughout the age range of the study. Consistent with a prior report from an independent cohort of 188 children and adolescents (De Bellis et al., 2001), WM in males grew more rapidly, resulting in increasingly larger volumes relative to females with age. After covarying for total brain volume, many of the regional size differences disappeared. Differences were still present in the frontal lobe, in which GM volume was proportionately larger in females, and which had sex differences in rates of growth for GM and WM. The lateral ventricles were larger in males, while the corpus callosum was relatively larger in females (Lenroot et al., 2007).
