Quantitative CT analysis of brain morphometry in adult Down's syndrome at different ages.

Quantitative CT demonstrated that healthy adults with Down's syndrome (DS) have smaller brains and smaller intracranial volumes than controls. Normalized volumes of CSF, ventricles, and brain parenchyma did not differ in patients and controls. Both DS subjects and controls showed similar significant age-related increments in volumes of CSF and ventricles. Of seven older DS subjects, one was demented, whereas the group as a whole showed reductions in cognitive test scores as compared with younger DS subjects. The results demonstrate cognitive decline in older DS subjects, but no brain atrophy other than that expected with aging.