Leisure-time physical activity mitigated the cognitive effect of PM_2.5 and PM_2.5 components exposure: Evidence from a...

Exposure to fine particulate matter (PM_2.5) impairs cognition, while physical activity (PA) improves cognitive function. However, whether taking PA with PM_2.5 exposure is still beneficial to cognition remains unknown.

We utilized national representative longitudinal data from the China Family Panel Study (CFPS), comprising a total sample of 108,099 from 2010 to 2018 in three waves. Cognitive performance and leisure-time PA were measured using the standard cognitive module and Godin-Shephard Leisure-Time Physical Activity Questionnaire. Gridded overall PM_2.5 and major chemical components of PM_2.5 were estimated using a two-stage machine learning model and matched to each participant based on their residential location. Mixed-effect models and difference-in-difference models were employed to investigate the individual and joint effects of total PM_2.5, PM_2.5 components, and leisure-time PA on cognition.

Every 1 μg/m³ increase in PM_2.5 was associated with a -0.035 (95% confidence interval [CI] = -0.052, -0.018) point change in cognitive score. All PM_2.5 components exhibited negative associations with cognitive change, with black carbon (BC) contributing the most significant cognitive decline (β = -1.025, 95% CI = -1.367, -0.683). Every one-time (or one-hour) increase in leisure-time PA frequency (or PA time) per week was associated with an increase in cognitive score by 0.576 (0.270) points (PA frequency: 95% CI = 0.544, 0.608, PA time: 95% CI = 0.248, 0.293). PA frequency (β = -0.005, 95% CI = -0.006, -0.003) and PA time (β = -0.002, 95% CI = -0.003, -0.001) exhibited interactive effects with PM_2.5. Increased PA frequency and time were more beneficial to cognitive function in the low PM_2.5 exposure group compared to those exposed to high PM_2.5 levels. Moreover, relative to lower PM_2.5 exposure, the cognitive benefits of physically active individuals with higher PM_2.5 exposure were attenuated but still improved cognition when compared to those with no PA.

Engaging in leisure-time PA provides cognitive benefits even under PM_2.5 exposure, although PM_2.5 exposure attenuates these benefits. Among all PM_2.5 components, BC demonstrated the most significant cognitive hazard and interaction with leisure-time PA. Promoting PA as a preventive measure may offer a cost-effective and convenient strategy to mitigate the negative impact of PM_2.5 exposure on cognition. There is no excuse to avoid PA under PM_2.5 exposure, as its cognitive benefits persist even in polluted environments.