Attention-deficit/hyperactivity disorder (ADHD) affects an estimated 5% of children worldwide, making it the most common cognitive and behavioral disorder among children. The cause of ADHD remains unknown; twin and adoption studies have found that the disease’s heritability is between 60% and 90%, but it is unclear how the genes connect with one another and how environmental and genetic factors interact. It is believed that particulate matter air pollution exposure increases the risk of autism spectrum disorders; recent research has also examined the correlation between exposure to particulate matter and ADHD. Researchers conducted a systematic review of epidemiological studies to investigate this relationship and identify any education gaps.
A search of PubMed and Embase was conducted in December 2018. Epidemiological studies examining particulate matter exposure and ADHD-related health outcomes in children of any age were included. The quality of the articles was determined using the Newcastle-Ottawa Scale, and the Office of Health Assessment and Translation approach was used to determine the risk of bias.
Among 774 results collected from the keyword search, 12 studies encompassing 181,144 total children were included: 10 prospective cohort studies and two cross-sectional studies. Nine of the total studies identified a positive association between particulate matter exposure to outdoor air pollution and attention-related behavioral problems. The studies designs presented a significant degree of heterogeneity. Nearly all of the studies (n=11) were believed to have a high bias risk in the exposure assessment.
The study authors concluded that there is a need for more high-quality studies to more definitively analyze the relationship between particulate matter air pollution exposure and ADHD.