Background: Toxic stress (TS), resiliency-promoting factors (RPFs) and their interactions were investigated in relationship to incident dementia in a nationally representative sample (n = 6516) of American adults ≥50 years enrolled in the Health and Retirement Study between 2006 and 2016.
Methods: TS included experiences of everyday discrimination and RPF included personal mastery. Race/ethnicity was self-reported as African American, Caucasian, or Other. Multivariable Cox proportional hazards regression models estimated TS-, RPF- and race-associated hazard ratios (HR) for dementia diagnosis and 95% confidence intervals (CIs) with adjustment for comorbidity, lifestyle, and socio-demographic confounders.
Results: Discrimination-associated risk of dementia diagnosis on average increased with education level [discrimination x education, p = 0.032; HR = 1.75 (95% CI: 1.01-3.03) if < high school, HR = 5.67 (95% CI: 2.94-10.94) if high school completed and HR = 2.48 (95% CI: 1.53-4.00) if ≥some college education]. Likewise, African American vs. Caucasian race disparity in new-onset dementia was evident (HR = 2.12, 95% CI: 1.42-3.17) among adults with high-mastery while absent (HR = 1.35, 95% CI: 0.75-2.41) among adults with low mastery (Mastery x Race, p = 0.01).
Conclusions: TS is a contextual driver of incident dementia that seemingly operates in a race and RPF-dependent fashion among American adults. Association pattern suggests that TS may overwhelm the cognitive reserve benefit of RPF particularly in status-inconsistent contexts including persons subjected to discrimination despite high education and persons of African American descent despite high mastery. Policies that reduce discrimination and promote equitable treatment by race/ethnicity may support cognitive resiliency and reduce the risk of dementia diagnosis in adult Americans.
Keywords: everyday discrimination; incident dementia; older Americans; resilience-promoting factors; toxic stress.