Asthma associated with environmental triggers (such as high levels of traffic-related pollution and tobacco smoke) seems more of a possibility to children of stressed out parents.
The study, led by researchers at the Keck School of Medicine of the University of Southern California (USC), appears this week in the Online Early Edition of the Proceedings of the National Academy of Sciences.
The study found that the risk of asthma associated with traffic-related pollution was significantly higher for children of parents reporting high levels of stress. Stress, as well as low parental education, was also associated with larger effects of exposure to tobacco smoke during pregnancy.
The study drew upon data from the USC Children's Health Study, a longitudinal study of respiratory health among children in 13 southern California communities.
Researchers followed 2,497 children with no history of respiratory problems over three years, tracking whether they developed asthma starting in kindergarten or first grade.
hey also measured parental stress and parental education-as an indicator of socioeconomic status-using a questionnaire, and collected information on exposure to traffic-related pollution and whether the children had been exposed to tobacco smoke in utero.
The results showed that parental stress alone did not increase the risk that children would develop asthma. However, when children had a combination of parents with stressful lives and also lived near high levels of traffic-related pollution, their risk of asthma increased compared with children only exposed to pollution.
"Air pollution can promote inflammatory responses in the airways of the lung, which is a central feature of asthma," McConnell says.
"Stress may also have pro-inflammatory effects and this may help explain why the two exposures together were important," the expert added.
Children whose parents perceived their lives as unpredictable, uncontrollable, or overwhelming were susceptible to the effects of pollution, the authors noted.