Using the same cortical-pattern matching method of comparing cortical thickness measurement as Luder et al, a cross-sectional study in 176 subjects who ranged from 7 to 87 years of age reported females to have thicker cortices in the right inferior parietal and posterior temporal regions (Sowell et al., 2007). In this study, the authors accounted for scaling issues related to differences in total brain size by creating a subsample of 36 adult subjects (18 males and 18 females) who had been individually matched on total brain volume and age. They found that even when overall brain volume and GM volumes were identical, females had thicker cortex in the right lateral frontal, temporal, and parietal cortices. These were in similar regions as found when using the entire sample, except even more statistically robust, despite the smaller sample size. While there were also significant changes in cortical thickness with age, these were not in the same regions as where sex differences were identified, leading the authors to suggest that these sex differences may exist prior to the age of the youngest participants in their study, which was age 7.
