The Role of Inflammation and Psycho-Behavioral Factors as Mediators Between Acculturation and Time to Incident Dementia Among Older Mexican Americans

Abstract

Background: The mechanisms through which acculturation influences the onset of cognitive impairment and dementia are not well understood, especially among older Hispanics. Objective: To investigate whether inflammation and psycho-behavioral factors mediate the relationship between acculturation and incident dementia among older Mexican Americans. Methods: We analyzed the Sacramento Area Latino Study on Aging (1998–2007, SALSA), a longitudinal study (N = 1,194) with 10 years of follow-up, and used g-computation for mediation analysis with pooled logistic regression to evaluate whether acculturation (assessed by the Revised Acculturation Rating Scale for Mexican Americans [ARSMA-II]) affected dementia or cognitive impairment but not dementia (CIND) through inflammation (i.e., interleukin 6 [IL-6], tumor necrosis factor-α (TNF-α), high-sensitivity C-reactive protein [hs-CRP]), smoking, alcohol consumption, and depressive symptoms. The potential mediators were assessed at baseline. Results: The 10-year average adjusted risk ratio (aRR) for the effect of high U.S. acculturation and dementia/CIND was 0.66, 95% CI (0.36, 1.30). The indirect effects were: IL-6 (aRR = 0.98, 95% CI (0.88, 1.05)); TNF-α (aRR:0.99, 95% CI (0.93, 1.05)); hs-CRP: (aRR = 1.21, 95% CI (0.84, 1.95)); current smoking: aRR = 0.97, 95% CI (0.84, 1.16); daily/weekly alcohol consumption (aRR = 1.00, 95% CI (0.96, 1.05)); and depressive symptom score (aRR = 1.03, 95% CI (0.95, 1.26)). Hs-CRP yielded a proportion mediated of -26%, suggesting that hs-CRP could suppress the potential effect of high U.S. acculturation. The other factors explored resulted in little to no mediation. Conclusions: The effect of acculturation on time to incident dementia/CIND varied over time. Our study suggests that inflammation could suppress the effect between high U.S. acculturation and dementia risk.