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February 1993

Cerebral Morphologic Distinctions Between Williams and Down Syndromes

Author Affiliations

From the San Diego (Calif) Veterans Affairs Medical Center (Dr Jernigan), Departments of Psychiatry (Dr Jernigan), Radiology (Drs Jernigan and Hesselink), and Neurosciences (Dr Hesselink), University of California, San Diego School of Medicine, Laboratory for Cognitive Neuroscience, The Salk Institute (Drs Bellugi and Doherty), La Jolla; and San Diego State University/University of California, San Diego, Joint Doctoral Program in Clinical Psychology (Ms Sowell).

Arch Neurol. 1993;50(2):186-191. doi:10.1001/archneur.1993.00540020062019

• Neurobehavioral studies of Williams syndrome (WS) and Down syndrome (DS) have revealed distinct profiles of cognitive strengths and weaknesses. In a previous report, we described several gross brain morphologic distinctions on magnetic resonance images between these two disorders. While the observed cerebral hypoplasia was of equal degree in the two groups, cerebellar size was entirely normal in the subjects with WS but dramatically reduced in subjects with DS. In WS, paleocerebellar vermal lobules subtended a smaller area on midsagittal sections, but neocerebellar lobules were actually larger. These results suggested important distinctions between WS and DS in terms of the action and anatomic targets of factors that alter brain development in these syndromes. The present study extends the earlier findings by focusing in detail on the morphologic features of the cerebral hemispheres, particularly cerebral gray matter. The results suggest that some frontal and temporal limbic structures are relatively preserved in WS, while some basal ganglia and diencephalic structures are relatively preserved in DS.