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Air pollution exposure and prefrontal connectivity in early adolescence

Principal Investigator: 

University of Southern California

This New Investigator Award study is evaluating how fine-particle exposure affects the development of prefrontal connections and emotional behaviors during the transition from childhood to adolescence and whether this, in turn, contributes to greater risk for neuropsychiatric disorders.

Funded under

Poster abstract for HEI Annual Conference 2022

Air Pollution Exposure and Prefrontal Connectivity and Emotional Outcomes in Early Adolescence

Megan M. Herting1, Elisabeth Burnor1, Hedyeh Ahmadi1, Sandrah P. Eckel1, Kiros Berhane2, Rob McConnell1, Joel Schwartz3, Wesley K. Thompson4, Chun Chan4, Jiu-Chiuan Chen1, William Gauderman, PhD1

1University of Southern California, Los Angeles, USA; 2Columbia University, New York City, USA; 3Harvard University, Cambridge, USA; 4University of California San Dieg, San Diego, USA

Background. We aim to investigate whether ambient PM2.5 and NO2 exposures at 9-10 years are associated with 1) prefrontal connectivity in youth ages 9-10 and 2) subsequent behavioral health problems and risk for neuropsychiatric disorders at ages 10-11 years.

Methods. The current study uses data from the nationwide Adolescent Brain Cognitive Development (ABCD) study℠ (N=11,873), with cross-sectional data on diffusion weighted imaging at 9-10 years and longitudinal data on emotional health outcomes at 9-10 and 11-12 years. Based on 2016 residential addresses at ages 9-10, novel hybrid spatiotemporal exposure models were applied to estimate the annual average ambient exposures to PM2.5 and NO2. Prefrontal connectivity was measured using diffusion tensor imaging (DTI) in white matter tracts that innervate the prefrontal cortex. Emotional behavioral measures were estimated using the caregiver-reported Child Behavioral Checklist (CBCL) scores for total, internalizing and externalizing problems, as well as five sub-scale scores. Mixed-effects models were fit with both PM2.5 and NO2 to adjust for study site and socio-demographics. For DTI outcomes, data were stratified by brain hemisphere and models were further adjusted for MRI manufacturer, mean frame displacement, and handedness. For emotional health outcomes, longitudinal models included interaction terms for pollutant-by-time for both pollutants. All results were corrected for multiple comparisons.

Results. The mean annual 2016 exposures to PM2.5 and NO2 across 21 study sites were 7.62 ug/m3 [1.72 – 15.90 ug/m3] and 18.7 ppb [0.73 – 37.9 ppb], respectively. Models investigating white matter microstructure revealed significant negative associations between PM2.5 and mean diffusivity (MD) in five white matter tracts in the left hemisphere and one tract in the right hemisphere (p < 0.05). Negative but nonsignificant associations between NO2 and MD were observed in all tracts. Estimated exposure effects on CBCL outcomes were small, although the PM2.5-by-time interactions were statistically significant for the sub-scale measuring anxious/depressed behavior (p = 0.02) and the overall internalizing score (p = 0.01). The estimated associations with most CBCL scores were non-remarkable, although the NO2-by-time interaction was borderline significant for the attention problems sub-score (p = 0.08).

Conclusions. Our analyses indicate that differences in white matter microstructure in adolescents may be associated with PM2.5 in a hemisphere-specific manner, while longitudinal associations of CBCL-measured outcomes with PM2.5 and NO2 are negligible. Our preliminary data therefore suggests that white matter microstructure, but not necessarily behavioral outcomes, at adolescence could be associated with air pollution at exposure levels largely below U.S. national ambient air quality standards. The ultimate findings from our study may provide important epidemiologic data on developmental neurotoxicity at low exposure levels to inform the continuing review and risk assessment for the National Ambient Air Quality Standard.