IMPACT OF HEALTHY LIFESTYLE FACTORS ON THE RISK OF ALZHEIMER'S DEMENTIA: FINDINGS FROM TWO PROSPECTIVE COHORT STUDIES

Abstract

Epidemiological studies have identified various healthy lifestyle factors that individually contribute to a lower risk of Alzheimer's dementia. The extent to which the combination of those lifestyle factors reduces the risk of Alzheimer's dementia deserves investigation. Using data from the prospective cohort studies, the Chicago Health and Aging Project (CHAP n=1,431) and the Rush Memory and Aging Project (MAP n=920), we defined a low-risk (healthy) lifestyle score on the basis of never smoker, >=150 min/week moderate/vigorous leisure physical activity, light-to-moderate alcohol consumption (1-15g/day in women and 1-30g/day in men), high quality MIND diet (upper 40% of score distribution), and engagement in late-life cognitive activities (upper 40%), giving an overall score ranging 0 to 5. After adjusting for age, sex, race, education, APOE e4, and history of cardiovascular disease, a sample weight adjusted Cox proportional hazard models were used for each cohort to estimate the hazard ratio (HR) and 95% confidence interval (95%CI) of the low-risk lifestyle score with Alzheimer's dementia. A random effect meta-analysis was used to pool the findings. During a median follow-up of 9.1 years in CHAP and 6.0 in MAP, 293 (20.5%) and 229 (24.9%) participants had incident Alzheimer's dementia, respectively. In multivariable-adjusted models, the pooled HR (95%CI) of Alzheimer's dementia across two cohorts was 0.78 (95%CI 0.71-0.86) per each additional low-risk lifestyle factor. Compared to participants with 0 or 1 low-risk lifestyle factor, the risk of incident Alzheimer's dementia was 39% lower (HR 0.61, 95%CI 0.48-0.78) in those with 2 or 3 low-risk lifestyle factors, and 59% lower (HR 0.41, 95%CI 0.28-0.58) in those with 4 or 5 low-risk lifestyle factors. These associations were largely similar across gender and race but were modified by APOE e4 status in CHAP. Although the risk of Alzheimer's dementia decreases with the adoption of each low-risk lifestyle factor, our study underscores the importance of adherence to all five low-risk lifestyle factors for maximum health benefit, and as an effective strategy for lowering the risk of Alzheimer's dementia.