A - 9 The Role of Ethnicity in Relationships among Depression, Chronic Stress, and Biomarkers of Alzheimer Disease

Abstract Objective The purpose was to determine relationships among psychosocial risk factors, ethnicity, and blood biomarkers of Alzheimer Disease (ad) using data from the Health and Again Brain Study-Health Disparities. Hypotheses included significant three-way interactions between ethnicity, chronic stress, and depression in predicting ad biomarkers. Method Participants were 2200 adults (62.5% female; age M = 65.4 [SD = 8.7]; education M = 13.1 [SD = 4.5]) from a community cohort study. 49.8% identified as non-Mexican American white; 50.2% identified as Mexican American. Clinical Dementia Rating (CDR) scores: 0 (76%), 0.5 (20%), 1 (3%), 2 (1%). Hierarchical regression analyses were performed; age, gender, education, and CDR were covariates. The Geriatric Depression Scale and Chronic Burden Scale measured depression and chronic stress. Outcome variables were tau and the beta amyloid (Aβ) 42/40 ratio in plasma. Results Chronic stress predicted tau (β = 0.07 [CI = 0.02–0.12], p = 0.004). The three-way interaction between chronic stress, depression, and ethnicity predicting tau was significant (β = 0.09 [CI = 0.01–0.18], p = 0.047). Chronic stress and ethnicity interacted to predict Aβ 42/40 (β = 0.11 [CI = 0.02–0.20], p = 0.019). Mexican American individuals had higher Aβ 42/40 at higher levels of chronic stress; White individuals had higher Aβ 42/40 at lower levels of chronic stress. Conclusions Overall, findings indicated that chronic stress was more predictive of ad plasma biomarkers for Mexican American individuals versus non-Mexican American white individuals in this sample. Further investigation into the role of ethnicity in relationships among risk factors and biomarkers of ad is warranted.