Cardiorespiratory Fitness, BMI, and Dementia risk: Findings from The Cooper Center Longitudinal Study

Abstract

AbstractBackgroundCardiorespiratory fitness (CRF) and body mass index (BMI) are each independently related to premature mortality. Previous research indicates that high fitness is protective against premature mortality even among those who are overweight or obese. We aimed to explore the independent and joint associations of CRF and BMI with incident dementia among middle‐aged adults.MethodData on CRF, BMI and covariates were derived from the Cooper Center Longitudinal Study (CCLS). The sample included 6,458 middle‐aged adults (mean age 50.9±7.6 years; 85% men; mean CRF 11.6±2.3 METs and BMI 25.3±3.2 kg/m2), who attended the Cooper Clinic (Dallas, TX) for preventive medical exams twice between 1970‐1999 (mean time between exams 2.5±2.1 years), and had fee‐for‐service Medicare coverage after age 65 at any time between 1999 and 2009. Maximal metabolic equivalents (MET) levels of CRF were computed based on the final speed and grade on treadmills. BMI was calculated based on measurements of weight and height (kg/m2). The primary independent variables consisted of average CRF and BMI from the two exams and the change between exams. The chronic condition warehouse definition of Alzheimer’s disease and related dementias was based on the International Classification of Diseases, 9th Revision. Proportional hazards models were applied to investigate the independent and joint associations of midlife CRF and BMI and their change over time with dementia diagnosis adjusted for age, sex, education, systolic blood pressure and fasting glucose and cholesterol levels.ResultOver 40,975 person‐years of Medicare surveillance (average 6.3±3.6), 637 cases of dementia were identified. Average CRF and BMI were each related to incident dementia (HR = 0.95 per MET 95% CI 0.91‐0.99 and HR = 1.03 per kg/m2 95% CI 1.00‐1.06, respectively), but not the interaction. Change in CRF or BMI between exams did not predict incident dementia.ConclusionIn line with studies exploring the link of CRF and BMI with mortality, our findings suggest that baseline fitness is related to dementia incidence independently of body mass and that significant joint effects were not observed.