The study, led by the Barcelona Institute for Global Health (ISGlobal), included data on nearly 30,000 children from seven European countries. Recent studies have concluded that prenatal exposure to air pollution could affect brain development in children, but the evidence on the effects of air pollution on ADHD symptoms is limited.
The study estimated exposures to nitrogen oxides (NOx) and particulate matter (PM10 and PM2.5) throughout pregnancy at each participant's home address. ADHD symptoms were assessed using various questionnaires completed by parents and/or teachers.
Joan Forns, lead author of the study, commented, "Our findings show no association between exposure to air pollution during pregnancy and increased risk of ADHD symptoms."
"Given the conclusions of this study and the inconsistent findings of previous studies, we hypothesise that exposure to air pollution might not increase the risk of ADHD in children in the general population," explained ISGlobal researcher Monica Guxens, who coordinated the study. "However, we believe that exposure to air pollution could have harmful effects on neuropsychological development, especially in genetically susceptible children."
It has been shown that ADHD is the result of complex interactions between genetic background (heritability is approximately 75 percent), environmental factors and social determinants. "We will continue to study the role of air pollution in order to rule out its association with childhood ADHD and improve our understanding of what causes this disorder," said Guxens.
The study appears in the journal Epidemiology.