Sex matters during adolescence: Testosterone-related cortical thickness maturation differs between boys and girls

Age-related changes in cortical thickness have been observed during adolescence, including thinning in frontal and parietal cortices, and thickening in the lateral temporal lobes. Studies have shown sex differences in hormone-related brain maturation when boys and girls are age-matched, however, because girls mature 1-2 years earlier than boys, these sex differences could be confounded by pubertal maturation. To address puberty effects directly, this study assessed sex differences in testosterone-related cortical maturation by studying 85 boys and girls in a narrow age range and matched on sexual maturity. We expected that testosterone-by-sex interactions on cortical thickness would be observed in brain regions known from the animal literature to be high in androgen receptors. We found sex differences in associations between circulating testosterone and thickness in left inferior parietal lobule, middle temporal gyrus, calcarine sulcus, and right lingual gyrus, all regions known to be high in androgen receptors. Visual areas increased with testosterone in boys, but decreased in girls. All other regions were more impacted by testosterone levels in girls than boys. The regional pattern of sex-by-testosterone interactions may have implications for understanding sex differences in behavior and adolescent-onset neuropsychiatric disorders. © 2012 Bramen et al

Results from correlating TES levels with thickness, independent of age in boys and girls.

<p>Top of figure shows results of analysis in boys. Bottom of figure shows results of analysis in girls. Left side of figure shows results from the left hemisphere. Green circles indicate regions that survive correction for multiple comparisons using false discovery rate (FDR). Regions surviving FDR correction in boys include the right lingual gyrus. Regions surviving FDR correction in girls include the left inferior parietal lobule, calcarine sulcus, right middle temporal gyrus and lingual gyrus.</p

Demographic characteristics of 85 normally developing adolescents, by sex.

<p>Demographics from 85 participating adolescent boys and girls. Demographics are tabulated for girls (TOP) and boys (MIDDLE) as data from each sex was analyzed separately in some statistical tests. Sex differences (BOTTOM) in key demographics of participating boys and girls are tabulated. A one-tailed, two-independent sample t-test was used to calculate sex differences in TS. Two-tailed, two-independent sample t-tests were used to calculate sex differences in age and circulating testosterone.</p>*<p>denotes significance (p<0.05).</p

Results from Sex x TES-Thickness interaction.

<p>Left side of the figure contains results from the left hemisphere. Green circles indicate regions that survived correction for multiple comparisons using false discovery rate (FDR). Scatterplots represent results extracted from center of significant portion in region indicated. Boys are plotted in blue. Girls are plotted in red. Regions plotted include the left dorsal lateral prefrontal cortex (L DLPFC), middle temporal gyrus (L MTG), inferior parietal lobule (L IPL), calcarine sulcus (L Calcarine), posterior cingulate gyrus (L Post Cingulate), right dorsal lateral prefrontal cortex (R DLPFC), posterior cingulate gyrus (R Post Cingulate), and lingual gyrus (R Lingual Gyrus). Regions surviving FDR include the left inferior parietal lobule, middle temporal gyrus, calcarine sulcus, and right lingual gyrus.</p