Long-Term Exposure to Traffic-Related Air Pollution and Noise and Dynamic Brain Connectivity across Adolescence.

Background: Traffic-related exposures, such as air pollution and noise, show long-term associations with brain alterations in children and adolescents. The associations with functional connectivity have been studied using static approaches of resting-state functional magnetic resonance imaging (rs-fMRI) (i.e., average connectivity between regions across the scanning session).

Objectives: Our aim was to investigate the long-term association of traffic air pollution and noise during pregnancy and childhood with functional connectivity across adolescence using a dynamic approach, which captures different connectivity patterns across the scanning session.

Methods: We used data from the Generation R population-based birth cohort. We estimated levels of 14 air pollutants and traffic noise at home addresses during pregnancy and childhood. We acquired rs-fMRI data at the age-10 y and age-14 y visits. We included participants with rs-fMRI data in at least one visit and either air pollution data ($n=\mathrm{3,588}$) or noise data ($n=\mathrm{2,642}$). We used k-means clustering to identify five connectivity patterns, called "states," that reoccur over time and across subjects and visits. We calculated the mean time spent in each state for each participant and visit. We performed multi- and single-pollutant mixed effects models adjusted for socioeconomic and lifestyle variables, including the individual as random effect to test the associations between the exposures and the mean time spent in each state.

Results: Exposure to nitrogen oxides, particulate matter (PM), and road-traffic noise was related to differences in the time spent in the connectivity states, both in the multi- and single-pollutant models. For instance, higher levels of exposure to PM with aerodynamic diameter between $2.5\mu m$ and $10\mu m$ (${\mathrm{PM}}_{\text{COARSE}}$) during pregnancy and higher noise exposure during childhood were associated with more time spent in a state in which the default-mode network, related to self-referential processes and mind-wandering, shows high connectivity.

Discussion: Traffic-related exposures might be related to long-term alterations in brain functional network organization in adolescents. Further research should explore the potential impact of these differences on cognition and psychopathology. https://doi.org/10.1289/EHP14525.