Structural imaging measurement of brain volumes including total gray and white matter, lobar measures, caudate volume, cross-sectional area of the corpus callosum, and cortical thickness were obtained using an automated pipeline [Zijdenbos et al., 2002; Lerch and Evans, 2005]. Overall brain volume and regional volumes for both gray and white matter were significantly decreased in the 49,XXY group, with the exception of the parietal white matter. This was not different than controls, possibly in keeping with the relative sparing of nonverbal function. The area of the corpus callosum was also not affected. All brain volume differences survived covarying for IQ differences except for frontal white matter, which was no longer significant. The caudate was approximately 10% smaller in the 49,XXY group and was still significantly smaller after controlling for overall changes in brain volume. Measures of brain asymmetry were not reported.
