Structural MRI Studies in Down Syndrome

Consistent with prior imaging studies, subjects with Down's syndrome had smaller overall brain volumes, with disproportionately smaller cerebellar volumes and relatively larger subcortical gray matter volumes. In subjects with Down syndrome, there was a relative preservation of parietal lobe gray and temporal lobe white matter. The results largely confirm findings of previous studies with respect to overall patterns of brain volumes in Down's syndrome and also provide new evidence for abnormal volumes of specific regional tissue components. The presence of these abnormalities from an early age suggests that fetal or early postnatal developmental differences may underlie the observed pattern of neuroanatomic abnormalities and contribute to the specific cognitive and developmental deficits seen in individuals with Down's syndrome.

Further, our structural MRI analyses indicated that hippocampal volumes were significantly smaller in the Down syndrome group compared with age-matched normal controls, which may be primarily due to early developmental differences rather than neurodegenerative changes. In this study, amygdala volumes were not significantly different in subjects with Down syndrome.