CINCINNATI, Ohio -- December 5, 2008 -- Boys with asthma who are exposed to environmental tobacco smoke have higher degrees of hyperactivity, aggression, depression, and other behavioural problems, according to a study published early online and appearing in an upcoming issue of the Journal of Developmental and Behavioral Pediatrics.
The researchers said behavioural problems increase along with higher exposure levels, but they added even low levels of tobacco smoke may be detrimental to behaviour.
"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," said lead author Kimberly Yolton, PhD, Children's Environmental Health Center, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.
Interestingly, although girls in the study were on average exposed to higher levels of tobacco smoke than boys, the exposure did not lead to an increase in behavioural problems among them. In boys, however, behavioural problems increased about 2 fold with each doubling in their tobacco smoke exposure, said Dr. Yolton.
The study included 220 boys and girls aged 6 to 12 years. According to estimates provided by parents, children were exposed to an average of 13 cigarettes a day. Investigators also measured the cotinine levels in the children's blood to more accurately measure tobacco smoke exposure.
The researchers compared cotinine levels to behavioural patterns observed in the children during the previous 2 weeks. Behavioural patterns were reported by parents using the Behavioral Assessment System for Children (BASC).
Researchers also accounted for other factors that might affect a child's behaviour such as socioeconomics, parent mental health, asthma severity, and medications used. They assessed physical and nurturing qualities of the home by the Home Observation for Measurement of Environment (HOME). Investigators also included whether mothers smoked during pregnancy.
"The largest increase we observed was in overall behavioural problems, but it was interesting that in addition to externalising behaviours -- like hyperactivity and aggression -- we also saw an increase in internalising behaviours, such as depression," explained Dr. Yolton. "Few studies have found a link between tobacco smoke and depression in children."
SOURCE: Cincinnati Children's Hospital Medical Center
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