Stress May Cause Asthma in Kids
Risk Exists When Environmental Triggers Are Also Present, Study Shows
July 21, 2009 -- Children living in high-stress homes may be more at risk for asthma associated with environmental triggers like traffic-related air pollution and exposure to cigarette smoke, new research shows.
Among children who had regular exposure to pollution from traffic exhaust, those living in households with the most stress were 50% more likely to develop asthma than those living in low-stress homes.
Stress did not have a big influence on asthma risk when the environmental trigger was not present, says study researcher Rob S. McConnell, MD, of the University of Southern California (USC) Keck School of Medicine.
“It is well known that pollution can cause inflammatory effects in the lungs, and inflammation is a cardinal feature of asthma,” he tells WebMD. “Stress can also have a pro-inflammatory effect, so it is certainly plausible that the impact of stress and air pollution together might be worse than either one by itself.”
Pollution, Stress, and Asthma
The study included about 2,500 children between the ages of 5 and 9 enrolled in a larger study examining the effect of air pollution on respiratory health.
None of the children had evidence of asthma or wheeze at enrollment, and all were followed for three years.
As a marker of childhood stress, which is not easy to measure directly, parents completed questionnaires examining their own stress levels. Researchers also collected other information, including smoking exposure, household characteristics, and parental education, which is an indicator of socioeconomic status.
During the three-year study, 120 children developed asthma
Although stress alone did not appear to increase asthma risk, McConnell and colleagues from USC and Toronto’s St. Michael’s Hospital found that the combination of living in a stressful home and living near high levels of traffic-related pollution was a bigger risk factor for asthma than living in a traffic-congested area alone.
Children whose mothers smoked during pregnancy were also more likely to develop asthma when their home environment was stressful.
“This research provides some new clues about what might be contributing to this complex disease that almost certainly has multiple causes,” McConnell says.