BRAIN COGNITION AND METABOLISM IN DOWN-SYNDROME ADULTS IN ASSOCIATIONWITH DEVELOPMENT OF DEMENTIA

To identify changes in brain functions associated with the development of dementia, brain metabolism and cognition were assessed repeatedly in 12 adults with Down syndrome (DS) using positron emission tomograph y and neuropsychological tests. Ten subjects remained non-demented (ND ) and showed no significant changes over time in cognitive measures or in cerebral metabolism. Two subjects developed dementia after 7 years . Brain functions were relatively stable prior to the onset of dementi a; after the onset of dementia, both cognitive function and glucose me tabolism in parietal and temporal brain regions known to be vulnerable to Alzheimer disease (AD) showed a rapid linear decline. These findin gs support the concept that brain functions are stable over time in ND individuals with DS and that decline of brain functions in DS subject s with dementia follows two distinct phases that correspond to the cli nical progression of AD. This may have implications for timing of new therapeutic strategies.