Prospective memory and apolipoprotein E in healthy aging and early stage Alzheimer's disease.

The present study examined whether prospective memory performance discriminates healthy aging from very mild dementia of the Alzheimer type (DAT) and individuals at risk for DAT because of the presence of the apolipoprotein E (ApoE) epsilon4 allele. Four groups (young subjects, young-old control subjects, old-old control subjects, and subjects with very mild DAT) engaged in an event-based prospective memory task wherein they responded to a specific word embedded in a general knowledge test. Results indicated that prospective memory performance was clearly impaired in the very mild DAT group relative to the healthy older control groups. Moreover, prospective memory performance appears to capture unique variance in discriminating these 2 groups above and beyond standard retrospective memory tests. However, prospective memory was not affected by ApoE status in the young-old control group and, contrary to predictions, the epsilon4+ old-old control subjects showed better performance than did the epsilon4- subjects. In contrast to the healthy individuals, in the very mild DAT group, epsilon4+ subjects showed deficits in performance relative to the epsilon4- subjects. Discussion focuses on prospective memory as a cognitive indicator of early stage DAT.