Memory complaints and APOE-ε4 accelerate cognitive decline in cognitively normal elderly

Objective: To investigate to what extent subjective memory complaints and APOE-epsilon4 allele carriage predict future cognitive decline in cognitively intact elderly persons, by evaluating both their separate and combined effects. Methods: We selected 1,168 subjects from the population-based Longitudinal Aging Study Amsterdam who were 62 to 85 years of age and had no obvious cognitive impairment at baseline (Mini-Mental State Examination [MMSE] score, greater than or equal to 27). Memory complaints and APOE phenotypes were assessed at baseline. MMSE, the Auditory Verbal Learning Test (memory: immediate recall and delayed recall), and the Alphabet Coding Task-15 (information processing speed) were used to study cognitive decline. Follow-up data were collected after 3 and 6 years. Data were analyzed with generalized estimating equations, adjusted for age, sex, education, and depression. Results: Baseline memory complaints were reported by 25.5% of the cognitively intact elderly persons. Overall, 25.3% of the subjects were carriers of at least one APOE-epsilon4 allele. Memory complaints were associated with a greater rate of decline in all cognitive measures, except immediate recall. In addition, APOE-epsilon4 allele carriers had a greater rate of cognitive decline shown by MMSE scores and slower information processing speeds after 6 years. The effects of both memory complaints and APOE-epsilon4 allele carriage were additive: subjects with both factors had a two times higher cognitive decline than did subjects without both factors. Conclusions: Both memory complaints and APOE-epsilon4 allele carriage predict cognitive decline at an early stage. This finding highlights the importance of subjective memory complaints, which are important even at an early stage when objective tests are still unable to detect cognitive deficits and are especially important for elderly carriers of the APOE-epsilon4 allele because they have an additional risk.