An Active Lifestyle Reinforces the Effect of a Healthy Diet on Cognitive Function: A Population-Based Longitudinal Study

The joint effect of diet and leisure activity on cognitive function remains unknown. We aimed to verify the hypothesis that an active lifestyle reinforces the effect of the Nordic Prudent Dietary Pattern (NPDP) on cognitive function. A total of 2223 dementia-free Swedish adults aged ≥60 with Mini-Mental State Examination (MMSE) scores ≥27 were followed for an average of 6 years. MMSE was tested during follow-ups. Diet was assessed by food frequency questionnaire. The NPDP index was calculated and tertiled (low, moderate, and high adherence). Participation in physical, mental and social activities was trichotomised (low, moderate, and intense). An active lifestyle was defined based on the participation in each activity. Data were analyzed using mixed-effects models. Moderate-to-high adherence to NPDP was associated with a reduced decline in the MMSE score (β: 0.19, 95% Confidence Interval (CI): 0.14–0.24). This association became stronger when combined with moderate-to-intense physical (β: 0.34, 95% CI: 0.2–0.45), mental (β: 0.29, 95% CI: 0.21–0.37), or social (β: 0.27, 95% CI: 0.19–0.34) activities. An active lifestyle strengthened the effect of NPDP on cognitive function by two times, and further lowered risk of MMSE decline by 30%. Thus, an active lifestyle reinforces the effect of a healthy diet on preserved cognitive function, and further decreases the risk of cognitive decline.