Impact of air pollution on Neurite Orientation Dispersion and Density metrics (NODDI) in 10-13-year-old children with and without ADHD diagnosis

Air pollution is a significant risk factor for adverse neurodevelopmental outcomes in children. While studies have linked pollutants to changes in brain structure, specific effects on white matter microstructure remain inconclusive. Neurite Orientation Dispersion and Density Imaging (NODDI) provide two nuanced, separate white matter measures that serve as proxies for neurite density and cell-body organization. We used NODDI to examine potential associations between prenatal, early life and current exposure to nitrogen dioxide (NO2) and particulate matter with diameter < 10 micrometers (PM10) and white matter microstructure in school-aged children. We also explored whether ADHD diagnosis moderated these associations. We observed several negative associations between both NO2 and PM10 exposure and neurite density across various white-matter fibers and exposure windows, but none of the associations were statistically significant after correcting for multiple comparisons. In this analysis, we did not find any statistically significant associations between long-term exposure to PM10 and NO2 and white matter microstructural integrity as measured by NODDI. Our results highlight the challenge of detecting modest environmental impacts on the brain and underscore the need for larger, more targeted studies to confirm these preliminary trends.