Association of Air Pollution and Physical Activity With Brain Volumes.

8,600 participants were included, with an average age of 55.55 (sd=7.46). After correcting for multiple testing, in overall models VigPA was positively associated with grey matter (GMV) and negatively associated with white matter hyperintensity volumes (WMHV), while NO2, PM2.5absorbance, and PM2.5 were negatively associated with GMV. NO2 and PM2.5absorbance interacted with VigPA on WMHV (FDR-corrected interaction p-values=0.037). Associations between these air pollutants and WMHVs were stronger among participants with high VigPA. Similarly, VigPA was negatively associated with WMHV for those in areas of low NO2 and PM2.5absorbance, but was null among those living in areas of high NO2 and PM2.5absorbance. CONCLUSIONS: Physical activity is associated with beneficial brain outcomes, while AP is associated with detrimental brain outcomes. Vigorous physical activity may exacerbate associations of AP with white matter hyperintensity lesions, and AP may attenuate the beneficial associations of physical activity with these lesions.