Air pollution does not increase the risk of attention deficit hyperactivity disorder (ADHD) symptoms in children aged three to ten years, a new study from the Barcelona Institute for Global Health (ISGlobal), Spain, has found.
Attention deficit hyperactivity disorder is the most common childhood behavioural disorder, with a worldwide prevalence of 5%. The condition is characterised by a pattern of inattention, hyperactivity and/or impulsivity that is atypical for the child’s age.
ADHD can interfere with a child’s development and has been associated with academic problems at school-level children, as well as increasing the risk of addiction problems or risky behaviours.
Studying pollution’s impact on brain development
Recent studies have concluded that exposure to air pollution during pregnancy could affect brain development in children; however, evidence on its effects on ADHD symptoms has been scarce.
This new study, published in the journal Epidemiology, included 30,000 children between the ages of three and ten years from eight birth cohorts in:
- Germany;
- Denmark;
- France;
- Italy;
- The Netherlands;
- Sweden; and
- Spain.
It 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.”
Can air pollution affect brain development?
ISGlobal researcher Monica Guxens, co-ordinator of the study, added: “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.
“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%), environmental factors and social determinants.
Guxens concluded: “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.”
