Dose-Response Association Between Physical Activity and Cognitive Function in a National Sample of Older Adults

Purpose: Previous research demonstrates a favorable effect of physical activity on cognitive function among older adults. The potential dose-response relationship between physical activity and cognitive function in this population is less understood, which was the purpose of this study. Setting: Data from the 1999 to 2002 National Health and Nutrition Examination Survey were employed. Participants: A total of 2157 older adults aged 60 to 85 years. Measures: Cognitive function was assessed from the Digit Symbol Substitution Test. Moderate-to-vigorous physical activity (MVPA), expressed as metabolic equivalent of task (MET)-min-month (MET-min-month = days x duration x MET level), was assessed via self-report, with 5 MVPA categories evaluated: (1) <2000 MVPA MET-min-month, (2) 2000 to 3999 MVPA MET-min-month, (3) 4000 to 5999 MVPA MET-min-month, (4) 6000 to 7999 MVPA MET-min-month, and (5) 8000+ MVPA MET-min-month. Analysis: Weighted multivariable linear regression. Results: An inverted U-shaped relationship was observed. Consistent across several adjusted models, those who engaged in 6000 to 7999 MVPA MET-min-month had the highest cognitive function score. Conclusion: The results suggest an optimal amount of physical activity to prevent the cognitive decline associated with aging.