ADHD linked to prenatal exposure to air pollution in study

Pregnant women exposed to air pollution are five times more likely to have children who develop behavior problems related to attention-deficit/hyperactivity disorder, or ADHD, a new study reports.

A child's risk of ADHD symptoms by age 9 appears to increase dramatically if they were exposed in the womb to high levels of air pollutants called polycyclic aromatic hydrocarbons (PAHs), researchers at Columbia University reported.

Compared with children with low PAH exposure, children exposed to high levels are more likely to have both an increased number of symptoms and more intense symptoms, said lead author Frederica Perera, a professor of environmental health sciences at Columbia's Mailman School of Public Health in New York City.

Pollutants and other environmental factors likely interact with an unborn child's genetics to increase their risk of ADHD later in life, said Stephen Faraone, a professor of psychiatry at SUNY Upstate Medical University in Syracuse, N.Y., who reviewed the study's findings.

"We think it means as the brain is developing, these toxins change something in the functional connectivity or structure of the brain that downstream leads to ADHD," Faraone said. He noted that studies like this prove an association but not a direct cause-and-effect link between air pollution and ADHD.