28 Social Support, APOE Genotype, and Memory Associations in a Community-Based Sample of Older Adults in Texas

Objective:The apolipoprotein E (APOE) gene has been identified as a major risk factor for the development of Alzheimer’s disease in late life. Research has shown that APOE e4 allele carriers demonstrate poorer memory performance and accelerated cognitive decline relative to non-carriers, and there is a need to identify potential factors of resiliency against the negative effects of e4 on cognition. Social support may represent one potential mechanism given that higher levels of social support have been linked to better cognitive and functional outcomes in older adults. Thus, the current study sought to examine whether social support moderates the relationship between APOE e4 status and subjective and objective memory performance in a large community-based sample of Hispanic/Latino (H/L) and Non-Hispanic White (NHW) older adults residing in Texas.Participants and Methods:Participants included 1,564 (H/L = 808, NHW = 756) older adults (mean age = 66.36±8.68) without dementia that had enrolled in the Health and Aging Brain Study-Health Disparities. Participants completed study questionnaires and a comprehensive neuropsychological battery. Apolipoprotein e4 status (e4 carriers vs. non-carriers) was determined by possession of at least one e4 allele. Perceived social support was measured using the total score from the abbreviated 12-item version of the Interpersonal Support Evaluation List. Objective memory performance was assessed using a z-score composite of Story A and B from the Weschler Memory Scale (WMS)-III and immediate and delayed recall trials from the Spanish-English Verbal Learning Test. Subjective memory was assessed using the total score from the Subject Memory Complaints Questionnaire. Race stratified multiple linear regression models, controlling for age, sex, and years of education, examined APOE e4 positivity x social support interactions on subjective and objective memory performance.Results:There was a significant APOE e4 genotype x social support interaction on objective memory performance (ß = -1.10, p = 0.003) in H/Ls such that higher levels of social support were associated with better memory performance in non-e4 carriers (ß = 0.14, p < .001), but not in e4 carriers (ß = -0.13, p = 0.9). In contrast, no significant APOE e4 status x social support interaction was observed on subjective memory (ß = -0.39, p = 0.35) in H/Ls. Finally, results revealed no significant APOE e4 genotype x social support interactions on subjective memory (ß = 0.14 p = 0.77) or objective memory (ß = 0.67, p = 0.11) performance in NHWs. Conclusions: Findings revealed that social support did not mitigate against the negative effects of e4 on subjective and objective memory performance in H/Ls or NHWs. However, results demonstrate that higher levels of social support are associated with better objective, but not subjective memory performance in H/Ls without the e4 genotype. These findings suggest that social support may protect against cognitive decline and enhance cognitive reserve in non-e4 carriers. Future studies should explore other potential factors of resiliency (e.g., diet, exercise) and examine the association between genetic risk and social support on neural markers (e.g., cortical thinning, hippocampal atrophy).