Assessing the impact of prenatal exposure to air pollution on neonatal brain development using air pollution modelling and structural and diffusion MRI

Abstract

Prenatal exposure to air pollution has been shown to disrupt neurodevelopment in animals as well as in children. The impact on childhood neurodevelopment was previously investigated using cognitive and behavioural testing, with few studies using magnetic resonance imaging. To date, no research has been conducted on the impacts of prenatal exposure to air pollution on neonatal neurodevelopment. To assess whether prenatal exposure to air pollution affects neonatal neurodevelopment, I used modelled ambient exposures to investigate two previously imaged cohorts. The first cohort consisted of healthy, term-born infants who underwent structural and diffusion imaging in the neonatal period (n = 469), utilising a novel biophysical model to process the diffusion imaging data. The second cohort consisted of infants born extremely preterm (n = 249). Ambient air pollution exposures were modelled at residence. Associations between prenatal air pollution exposure and neonatal neuroimaging metrics were assessed using canonical correlation analysis (CCA), which is capable of incorporating multiple correlated variables and robust significance testing. I found that increased prenatal exposure to PM10 and decreased exposure to NO2 but not PM2.5 is associated with multiple structural measures of the brain in healthy neonates. When investigating diffusion tensor imaging as well as neurite orientation dispersion and density imaging, I found no associations in the same cohort between prenatal exposure to PM2.5, PM10, and NO2 and neonatal white matter microstructure metrics. Infants born preterm are at risk of adverse neurodevelopment. When investigating this vulnerable cohort, prenatal exposure to PM2.5, PM10, and NO2 was not related to any metric of neonatal brain morphology or white matter microstructure. Pregnant women may be vulnerable to the effects of air pollution exposure; however, no guidance for personal exposure reduction is available. Specific personal exposure reduction interventions were suggested and classified based on their scale, cost, and evidence of an effect.