Abstract
UNICEF estimates that over 100 million infants and 300 million children are exposed to levels of pollution that exceed WHO recommended limits, and around 95% of the world’s population lives in regions with unhealthy levels of air pollution, with low- and middle-income countries experiencing the highest levels of exposure. There is growing concern regarding the effect of exposure during gestation as exposure to PM2.5 is associated with low birth weight, preterm birth, still birth and congenital abnormalities.
There is a growing body of evidence linking exposure to air pollution and adverse neurologic consequences in children highlighting that air pollution should be considered a developmental neurotoxicant [1]. In animal studies, prenatal exposure to pollution is associated with altered microglial development [2] disrupted cortical development [3] reduced myelination [4] impaired memory and learning ability, and increased anxiety and persistent behavioural deficits, particularly in male offspring [5]. Human studies show that prenatal and childhood exposure to air pollutants have adverse effects on intelligence, memory, behaviour and mental health in childhood and adolescence [6-8].
Brain magnetic resonance imaging (MRI) studies have reported that in utero and childhood exposure to air pollution is associated with altered microstructural, morphological and functional brain development in childhood. MRI studies in children (imaged between 6 and 12 years) exposed to high levels of ambient pollution in utero demonstrated reduced brain volume, impaired myelination, diminished cortical gyrification and altered functional connectivity [7, 9, 10]. However, research examining the relationship between prenatal exposure to air pollution and fetal or neonatal brain development is limited. The only study to date to assess the relationship between prenatal exposure to air pollution and neonatal brain morphology investigated brain volumes from 469 healthy infants recruited in London, UK to the developing human connectome project (http://www.developingconnectome.org/). Higher gestational exposure to PM10 and lower exposure to NO2 was associated with larger relative ventricular and cerebellar volume, along with modest associations with smaller relative cortical grey matter, amygdala and hippocampus volumes, and larger relative volumes of brainstem and extracerebral CSF [11].
This presentation will discuss studies assessing the relationship between exposure to air pollution and (i) brain MRI findings and (ii) neurodevelopment.