Ten of the 13 47,XXY males who had been identified as part of the Denver cohort were studied with MRI when they were between 24 and 32 years of age (mean age 27.3, SD 3.0 years) [Patwardhan et al., 2000]. In the Denver study, an unselected cohort of 40,000 consecutive newborns were screened for SCAs in Denver between 1964 and 1974 and followed from birth to adulthood [Bender et al., 1993b]. Full-scale IQ had been obtained on these subjects during childhood and found to be slightly below average (mean IQ 91.30, SD 13.86) [Bender et al., 1993a]. Subjects undergoing MRI were individually matched on age and sex with 10 healthy controls (mean age 26.81, SD 3.28 years). Half of the XXY males had been given testosterone supplementation (XXY + T) and half had not (XXY − T), allowing a post hoc comparison of the effects of testosterone on brain structure. Gray and white matter segmentation and measurement of lobar, subcortical, and ventricular volumes were performed using automated methods [Reiss, 1999], whereas manual tracing was used to delineate the volume of the superior temporal gyrus (STG). Measurements of cognitive function included IQ and verbal fluency.
