Association between allostatic load and incident dementia, and race/ethnic disparities in the association in the U.S. health and retirement study

Objective Allostatic load (AL), the cumulative physiological burden of chronic stress, is a significant health issue and has been linked with adverse health outcomes, including cognitive decline. We examined the association between AL and incident dementia in the United States. Method We used data from the United States Health and Retirement Study (HRS) cohort (2016–2020) and the 2016 Venous Blood Study (VBS) to examine the association between AL quartile and incident dementia among participants who were aged 56 and older at baseline. Dementia status was determined by cognitive performance of immediate and delayed word recall, serial 7’s, backward count, as well as self-report of dementia and Alzheimer’s disease. A composite score of biomarkers from neuroendocrine, immune, metabolic, and cardiovascular systems was used to create AL quartiles. The Cox regression model was used to examine the association between AL quartile and incident dementia. Results Of the 6806 non-Hispanic White, non-Hispanic Black, and Hispanic participants, 331 (4.9 %) developed dementia by the end of 5 years, with an incident rate of 12.8 per 1000 person-years. In the age and sex adjusted model, incident dementia was higher in the highest AL quartile than the lowest AL quartile (HR = 1.96, 95 % CI [1.37, 2.80], p < .001). The association was attenuated (HR = 1.59, 95 % CI [1.08, 1.10], p < .05) after adjusting for sociodemographic and health behaviors. Race/ethnicity did not modify the association between AL and incident dementia despite higher incident dementia among minorities. Discussion The findings highlight the relationship between AL and incident dementia. Further studies of the context of social determinants of health with longer follow-up are needed. Findings may inform the need for interventions to reduce stress stimuli and regular monitoring of biomarkers, thereby delaying the onset of dementia.