Long-term Air Pollution and Noise Exposures and Structural Parameters of the Default Mode Network in the 1000BRAINS Study

Abstract

Background/Aim: While evidence suggests that long-term air pollution (AP) and noise may have negative effects on brain health and cognition, little is known about structural and functional changes in the brain networks that may underlie these associations. We investigated the association between AP and traffic noise exposures and structural parameters, including cortical thickness and the local gyrification index (lGI), of the Default Mode Network (DMN) in the brain, as it is important for resting-state brain function. Like what is seen in the DMN with aging, we hypothesized AP and noise exposures to be associated with decreased cortical thickness and more local atrophy (i.e., lower lGI). Methods: We used data from 559 participants of the 1000BRAINS study in Germany. Residential mean AP exposures (particulate matter [PM] 10, PM2.5, NO2, and accumulation mode particulate number concentration [PNAM]) were modeled for the years 2006-2008 using the validated EURAD chemistry transport model on a 1 km2 scale. Long-term traffic noise was modeled at participants’ homes according to European standards. Cortical thickness and lGI values in the left and right medial prefrontal cortex, posterior cingulate cortex, and inferior parietal lobule of the DMN were calculated from T1-weighted structural brain images collected between 2011 and 2015. Associations between environmental exposures and brain parameters were estimated using linear regression models, adjusting for demographic and lifestyle characteristics. Results: Exposure to PM10, PM2.5 and PNAM was weakly associated with decreased cortical thickness in the left prefrontal cortex (e.g., -0.02 [95% Confidence-Interval: -0.03, 0.00] mm per 3.65 µg/m3 increase in PM10). No associations were observed for AP and lGI or between traffic noise exposure and either DMN parameter. Conclusion: Weak associations between AP and structural parameters of the DMN in the brain were observed, but further studies are needed to validate this result.