Healthy Lifestyles and the Risk of Alzheimer’s Disease and Related Dementias among Low-Income Black and White Americans

Abstract

ObjectivesWhile the importance of healthy lifestyles for preventing Alzheimer's disease and related dementias (ADRD) has been recognized, epidemiologic evidence remains limited from non-White or low-income populations who bear disproportionate burdens of ADRD. We examined the associations of major lifestyle factors, individually and together, with incident ADRD in a prospective cohort of primarily low-income Black and White Americans.MethodsIn the Southern Community Cohort Study, incident ADRD were identified using claims data among participants enrolled in Medicare for at least 12 consecutive months after age 65. Five lifestyle factors: tobacco smoking, alcohol consumption, leisure-time physical activity (LTPA), sleep hours, and diet quality, were each scored 0 (unhealthy), 1 (intermediate), or 2 (healthy) based on health guidelines. A composite lifestyle score was created by summing all scores. Cox regression was used to estimate hazard ratios (HRs) and 95% CIs, treating death as a competing risk and adjusting for potential confounders.ResultsOf 17,209 participants, 1,694 incident ADRD were identified during a median 4-year follow-up in claims data; the mean age at ADRD diagnosis was 74.0 years. Healthy lifestyles were individually associated with 11%–25% reduced risk of ADRD: multivariable-adjusted HR (95% CI) was 0.87 (0.76–0.99) for never vs. current smoking, 0.81 (0.72–0.92) for low-to-moderate vs. no alcohol consumption, 0.89 (0.77–1.03) for ≥150 minutes of moderate or ≥75 minutes of vigorous LTPA per week vs. none, 0.75 (0.64–0.87) for 7–9 hours vs. >9 hours of sleep, and 0.85 (0.75–0.96) for the highest vs. lowest tertiles of Healthy Eating Index. The composite lifestyle score showed a dose-response association with up to 36% reduced risk of ADRD: HRs (95% CIs) across quartiles were 1 (ref), 0.88 (0.77–0.99), 0.79 (0.70–0.90), and 0.64 (0.55–0.74); p-trend < 0.001. The beneficial associations were observed regardless of participants’ sociodemographics (e.g., race/ethnicity, education, and income) and health conditions (e.g., history of cardiometabolic diseases and depression).ConclusionsOur findings support the importance of healthy lifestyles for ADRD prevention among socioeconomically disadvantaged Americans to reduce the growing burden and disparities posted by ADRD.Funding SourcesThe National Institutes of Health.