Exposure to tobacco smoke can lead to high degrees of hyperactivity, aggression, and depression in boys with asthma, according to research conducted at Cincinnati Children’s Hospital Medical Center.

The researchers found that behavioral problems increase as exposure levels rise increasing about two-fold with each doubling in tobacco smoke exposure. Additionally, the tobacco smoke exposure did not lead to an increase in behavioral problems among girls in the study, even though they were exposed to higher levels of tobacco smoke than were the boys.

“The largest increase we observed was in overall behavioral problems, but it was interesting that in addition to externalizing behaviors—like hyperactivity and aggression—we also saw an increase in internalizing behaviors, such as depression,” says lead author Kimberly Yolton, PhD, a researcher at Cincinnati Children’s.

“These findings should encourage us to make stronger efforts to prevent childhood exposure to tobacco smoke, especially among higher risk populations, such as children with asthma,” says Yolton.

The study is published in the Journal of Developmental and Behavioral Pediatrics.