Pathways explaining racial/ethnic disparities in incident all-cause dementia among middle-aged US adults

INTRODUCTIONRacial disparities in dementia incidence exist, but less is known about their presence and drivers among middle-aged adults. METHODSWe used time-to-event analysis among a sample of 4378 respondents (age 40-59 years at baseline) drawn from the third National Health and Nutrition Examination Surveys (NHANES III) with administrative linkage-spanning the years 1988-2014-to evaluate potential mediating pathways through socioeconomic status (SES), lifestyle, and health-related characteristics. RESULTSCompared with Non-Hispanic White (NHW) adults, Non-White adults had a higher incidence of AD-specific (hazard ratio [HR] = 2.05, 95% confidence interval [CI]: 1.21, 3.49) and all-cause dementia (HR = 2.01, 95% CI: 1.36, 2.98). Diet, smoking, and physical activity were among characteristics on the pathway between race/ethnicity, SES, and dementia, with health-mediating effects of smoking and physical activity on dementia risk. DISCUSSIONWe identified several pathways that may generate racial disparities in incident all-cause dementia among middle-aged adults. No direct effect of race was observed. More studies are needed to corroborate our findings in comparable populations.

Automated summary

There are racial disparities in dementia incidence among middle-aged adults, which are influenced by socioeconomic status (SES), lifestyle, and health-related characteristics. Non-White adults have a higher risk of AD-specific (HR=2.05) and all-cause dementia (HR=2.01) compared to Non-Hispanic White adults. Diet, smoking, and physical activity mediate the relationship between race/ethnicity, SES, and dementia, with smoking and physical activity having health-mediating effects on dementia risk.