PROSPECTIVE-STUDY OF THE PREVALENCE OF ALZHEIMER-TYPE DEMENTIA IN INSTITUTIONALIZED INDIVIDUALS WITH DOWN-SYNDROME

Institutionalized patients with Down syndrome (n=307) were monitored f or 5 to 10 years prospectively to determine prevalence of Alzheimer-ty pe dementia. Clinical signs, cognitive functioning, and EEGs were asse ssed. When possible, postmortem neuropathological examinations were co nducted. Progressive mental and physical deterioration was found for 5 6 of the residents. Mean age at onset of dementia was 56 years. Preval ence increased from 11% between ages 40 and 49 to 77% between 60 and 6 9. All patients 70 and over had dementia. Neuropathological findings w ere consistent with clinical diagnosis. Use of a dementia checklist, c ognitive skills inventory, and EEG reliably detected Alzheimer-type de mentia at an early stage.