Detection of an Alzheimer disease pattern of cerebral metabolism in Down syndrome.

Correlational analysis of cerebral metabolic (rCMRglc) data obtained with positron emission tomography (PET) assesses group differences and has demonstrated reduced frontal-parietal rCMRglc interdependencies in Alzheimer's disease (AD). A multivariate analysis of rCMRglc data assesses individual differences. We recently identified discriminant functions, reflecting frontal-parietal rCMRglc interdependencies, that separated AD from control subjects. To test if the functions would identify an AD rCMRglc pattern in older Down syndrome (DS) adults with (DS DAT+) or without (DS DAT-) dementia, we applied the functions to longitudinal rCMRglc data in: young DS (n = 15), DS DAT- (n = 10), DS DAT+ (n = 4), and young controls (n = 15). All DS DAT+ and some of the later DS DAT- scans were classified as AD. The results provide additional validation of the functions and suggest their utility for the early detection of AD.