Abstract 036: The Association between Mid-Life Cardiorespiratory Fitness and Dementia in Later Life

Abstract

Introduction: Prior literature suggests that higher levels of physical activity are associated with a lower risk for Alzheimer disease and related dementias (ADRD). However, the association between cardiorespiratory fitness (CRF) in healthy, middle aged adults and ADRD decades later in older age has not been studied. Methods: We included 20,195 participants (21.0% female, mean age 49.8 years, and free of vascular disease at baseline) enrolled in the Cooper Center Longitudinal Study (CCLS) between 1970 and 2009. CRF was measured by modified Balke protocol and treadmill time was used to estimate metabolic equivalents (METs) and to stratify CRF into low-, intermediate-, and high-fit categories. Baseline data from the CCLS were matched with Medicare administrative claims data from the Center for Medicare and Medicaid Services (CMS). The primary outcome variable was the diagnosis of ADRD as defined by CMS validated algorithms. We used a Cox proportional hazard model to estimate the association between midlife fitness and the development of ADRD in later life. All models were multivariable-adjusted for age, BMI, hypertension, diabetes, hyperlipidemia, and smoking. Results: After more than 120,000 person-years of Medicare exposure, there were 1964 ADRD cases. As expected, we observed marked differences in the age-related prevalence of ADRD (age 70 1.19% vs. age 90 15.68%). In both men and women, higher midlife fitness was associated with a lower risk (per MET) for ADRD decades later [HR 95% CI: 0.96 (0.93–0.99) in men; 0.91 (0.86–0.98) in women]. Findings were similar when fitness was examined according to categories (high vs. low) but with wider confidence intervals in women [0.81 (0.70–0.95) in men; 0.76 (0.57–1.03) in women]. The figure illustrates dementia-free survival by fitness level for men and women. Conclusions: Higher mid-life CRF was associated with a lower risk of developing ADRD decades later in older age.