Longitudinal associations between air pollution and adolescent gray matter development: Insights from the ABCD study

Air pollution, fueled by industrialization, vehicular emissions, and wildfires, poses a global public health challenge with significant effects on physical and neurological health. Fine particulate matter (PM₂.₅), nitrogen dioxide (NO₂), and ozone (O₃) have been implicated in systemic inflammation, oxidative stress, and compromised blood-brain barrier integrity. Adolescents, undergoing critical periods of brain maturation involving synaptic pruning and myelination, may be especially vulnerable to such exposures. While prior studies have primarily examined cross-sectional associations between air pollution and brain structure in adults, longitudinal data in adolescents remain limited. This study utilized data from 10,947 participants in the Adolescent Brain Cognitive Development (ABCD) Study, the largest U.S. adolescent neurodevelopmental cohort, to investigate associations between combined exposure to PM₂.₅, NO₂, and O₃ and cortical thickness over time. Exposure estimates were derived from geocoded residential addresses linked to regulatory air monitoring data. Structural MRI data were collected across two to three waves. Linear mixed-effects models were used to evaluate associations between pollutant exposure and cortical thickness, adjusting for demographic and socioeconomic confounders. Greater exposure to PM₂.₅ and NO₂ was associated with accelerated cortical thinning in frontal and temporal regions, areas important for executive function and socioemotional processing. O₃ showed minimal association with cortical morphology. These findings suggest that air pollution may alter neurodevelopmental trajectories in adolescence, with potential implications for cognitive and emotional outcomes. Policy efforts aimed at reducing air pollution could be critical for promoting healthy brain development. Future research should extend follow-up and incorporate cognitive and functional assessments to elucidate long-term consequences.