Long-Term Ambient Air Pollution Exposures and Brain Imaging Markers in Korean Adults: The Environmental Pollution-Induced Neurological EFfects (EPINEF) Study

BACKGROUND: Only a limited number of neuroimaging studies have explored the effects of ambient air pollution in adults. The prior studies have investigated only cortical volume, and they have reported mixed findings, particularly for gray matter. Furthermore, the association between nitrogen dioxide ([Formula: see text]) and neuroimaging markers has been little studied in adults. OBJECTIVES: We investigated the association between long-term exposure to air pollutants ([Formula: see text] , particulate matter (PM) with aerodynamic diameters of [Formula: see text] (PM10) and [Formula: see text] (PM2.5), and neuroimaging markers. METHODS: The study included 427 men and 530 women dwelling in four cities in the Republic of Korea. Long-term concentrations of PM10, [Formula: see text] , and PM2.5 at residential addresses were estimated. Neuroimaging markers (cortical thickness and subcortical volume) were obtained from brain magnetic resonance images. A generalized linear model was used, adjusting for potential confounders. RESULTS: A [Formula: see text] increase in PM10 was associated with reduced thicknesses in the frontal [[Formula: see text] (95% CI: [Formula: see text] , [Formula: see text])] and temporal lobes [[Formula: see text] (95% CI: [Formula: see text] , [Formula: see text])]. A [Formula: see text] increase in PM2.5 was associated with a thinner temporal cortex [[Formula: see text] (95% CI: [Formula: see text] , [Formula: see text])]. A 10-ppb increase in [Formula: see text] was associated with reduced thicknesses in the global [[Formula: see text] (95% CI: [Formula: see text] , 0.00)], frontal [[Formula: see text] (95% CI: [Formula: see text] , [Formula: see text])], parietal [[Formula: see text] (95% CI: [Formula: see text] , [Formula: see text])], temporal [[Formula: see text] (95% CI: [Formula: see text] , [Formula: see text])], and insular lobes [[Formula: see text] (95% CI: [Formula: see text] , 0.00)]. The air pollutants were also associated with increased thicknesses in the occipital and cingulate lobes. Subcortical structures associated with the air pollutants included the thalamus, caudate, pallidum, hippocampus, amygdala, and nucleus accumbens. DISCUSSION: The findings suggest that long-term exposure to high ambient air pollution may lead to cortical thinning and reduced subcortical volume in adults. https://doi.org/10.1289/EHP7133