Apolipoprotein E and Change in Episodic Memory in Blacks and Whites

Background: Apolipoprotein E (APOE) epsilon 4 is related to faster decline in episodic memory in Whites, but the relation is unknown in Blacks. The purpose of this study was to determine whether epsilon 4 has a selective effect on decline in episodic memory in Blacks. Methods: Data are from two cohort studies with similar design. The sample consisted of 1,211 participants [28.4% Blacks, mean age = 78.6 years (SD = 7.4), education = 14.7 years (SD = 3.1)] without dementia at baseline, who underwent annual clinical evaluations for up to 6 years. Summary measures of 5 cognitive abilities were derived from 18 neuropsychological tests. Results: In mixed models that controlled for age, sex, education, and race, possession of epsilon 4 (present in 32.9% of Blacks and 21.0% of Whites, p < 0.001) was related to faster decline in episodic memory and 4 other cognitive abilities (all p values < 0.01). In separate models that examined the interaction of race and epsilon 4 on decline, there was no significant difference between Blacks and Whites in the effect of epsilon 4 on decline in episodic memory, perceptual speed, or visuospatial ability. By contrast, the effect of epsilon 4 differed for semantic memory and working memory. Results were similar after adjusting for vascular conditions. Conclusions: The results suggest that APOE epsilon 4 is related to a faster rate of decline in episodic memory in Blacks similar to Whites. In addition, there were racial differences in the effect of epsilon 4 in other cognitive abilities such that the epsilon 4 allele was related to faster decline in semantic memory and working memory for Whites but not for Blacks. Copyright (c) 2013 S. Karger AG, Basel