Stress, race, and APOE: understanding the interplay of risk factors for changes in cognitive functioning

Biological and environmental factors are thought to contribute to the development of cognitive decline (CD). The Apolipoprotein E (APOE) ϵ4 allele is the greatest known genetic risk factor. The current study focused on the extent to which environmental factors, specifically stress, influence the relationship between the APOE allele and cognitive functioning and whether this relationship is stronger for African-Americans compared to Caucasians.

Participants consisted of community-dwelling older adults from the Duke Established Populations for Epidemiologic Studies of the Elderly (N = 4,162). Data were drawn from two waves, which were three years apart. Cognitive functioning was assessed at both waves using the Short Portable Mental Status (SPMSQ).

Whereas there was no main effect of stress, there was a significant interaction between APOE status and stressful life events, such that increased stress in individuals with an ϵ4 allele lead to more errors on the SPMSQ than individuals with no allele. Inconsistent with predictions, there was a significant interaction between stress and race such that increased stressful events predicted CD in Caucasians but not African-Americans.

Recent stressful late-life events have a greater impact on the cognitive status of individuals with an ϵ4 allele. While Caucasians appear to be less vulnerable to cognitive losses at lower levels of stress, as the number of stressful life events increases that advantage disappears for Caucasians.