Cognition, Lifestyles, and Environments: Quantifying the Roles of Body Physiology and the Brain

Lifestyle and environmental factors such as diet, physical activity, residential greenspace exposure, alcohol consumption, and sleep are increasingly promoted as modifiable targets for maintaining cognitive health and mitigating age-related decline. Yet, it remains unclear how well they predict cognitive functioning and, importantly, to what extent their associations with cognition are reflected in brain and bodily health. Here, we applied machine learning to multimodal data from over 10,000 UK Biobank participants to evaluate the predictive value of twelve lifestyle and environment domains, spanning physical activity, diet, smoking and alcohol consumption, sleep, sexual behavior, electronic device use, and environmental exposures, for cognitive functioning - both individually and in combination - and performed commonality analysis to quantify the extent to which these associations are captured by body and brain markers. A model integrating all lifestyle and environment domains explained 23% of the variance in cognition at an out-of-sample r=0.48, comparable to models based on body and brain measures. Physical activity, together with diet, alcohol consumption, sun exposure, and local environmental characteristics, emerged as the strongest predictors of cognitive functioning. A composite brain marker integrating three neuroimaging modalities accounted for 57.7% of the lifestyle-cognition association, while a composite body marker spanning nine physiological systems accounted for 47.8%. Jointly, lifestyle, environment, body, and brain captured nearly all age-related variation in cognition (92.6%). Collectively, these results indicate that integrating lifestyle and environmental factors enables robust prediction of cognitive functioning and that a substantial portion of this association is reflected in brain and body health.