The Effects of APOE Alleles, Cognitive Activities, and Social Activities on Cognitive Decline in African Americans.

Objective: Older African Americans are among the fastest growing populations, yet are underrepresented in studies examining risk factors related to decline. The present study examines whether biological factors (APOE alleles) interact with behavioral factors including cognitive activities (e.g., reading, playing games) and social activities (e.g., participating in social groups) to predict cognitive decline in African Americans.

Methods: 734 African American adults from the Minority Aging Research Study (MARS), aged 65 and older (with no known dementia at the time of enrollment) underwent annual cognitive testing for up to 10 years. At baseline, APOE status was determined and participants reported their frequency of participation in social and cognitive activities. Structural equation modelling was used to examine the effects of APOE, cognitive activities, and social activities on cognitive decline, and their interaction effects over a ten-year period.

Results: The number of APOE alleles had an effect on cognitive decline, such that a greater number of APOE4 alleles was associated with greater cognitive decline, whereas a greater number of APOE2 alleles was associated with less cognitive decline. Cognitive and social activities did not interact with APOE count to predict cognitive decline, however, APOE4 and social activities had additive, independent effects on cognitive decline.

Discussion: Results replicate prior findings linking APOE4 to cognitive decline and highlight the importance of APOE2 and social activities in delaying cognitive decline in African Americans.