Study links asthma and mental health

Study links asthma and mental health
(June 2009 Issue)

By Pamela Berard

People who rate their mental health as poor had an increased occurrence of asthma compared to those who report their mental health as good, according to a recent study by Brown University researchers.

Lead researcher Thomas Chun, M.D., an assistant professor of emergency medicine, says that although they can't prove that the two are causally related, it may be important to treat both conditions. Improving one may improve the other, he says.

The study, published in the December issue of Chest, analyzed data that Chun's team collected on 318,151 non-institutionalized adults in the U.S. who participated in the Behavioral Risk Factor Surveillance System survey.

The study does not prove that asthma causes poor mental health or vice versa. "That's the core question - which is the chicken and which is the egg?" Chun says. "You can hypothesize; we talk about some possible mechanisms. Stress unto itself affects the body's immune system and the body's inflammatory response and all those things may trigger an asthma attack," he says. But on the flip side, having asthma could negatively impact quality of life and affect mental health.

The study shows that respondents who report any degree of mental health impairment were at increased risk of reporting current asthma. Those reporting less than one week of poor mental health had a 1.38 times greater chance for having asthma than those who reported no days of poor mental health. The relative risk ratio for those reporting one to two weeks of poor mental health went up to 1.49; two to three weeks of reported poor mental health rated 1.67, while the ratio for more than three weeks of poor mental health was 2.75.

It also shows a dose-response relationship. For each one-week increment of poor mental health that a participant reported, there was a corresponding increase in current asthma risk. That is important, Chun says. "You can't prove causality, but when you are trying to draw a link, one of the things that lends credence is that the more you take something, the better you get or the more you are exposed to something, the worse you are," he explains. "It's just one of the underpinnings of when you are trying to show causality that this might be a plausible thing."

To be classified as currently having asthma, subjects would need to have answered yes to having been told by a doctor or healthcare provider that they had asthma and also still have it. The reports says the BRFSS also asks subjects: "Now thinking about your mental health, which includes stress, depression and problems with emotions, for how many days during the past 30 days was your mental health not good?" The subjects were not necessarily diagnosed as having a mental health disorder. They were asked to rate themselves on how many days they would report their mental health as not good. In this study, subjects were put in five categories: those with 0 days of poor mental health reported; those with one to seven days; eight to 14 days; 15 to 21 days and 22 to 30 days.

The rate of current asthma was 6.2 for those who reported no poor mental health days; 8.7 for those who reported one to seven days of poor mental health; 10 for those who reported eight to 14 days; 12.8 for those who reported 15-21 days; and 21.6 for those who reported 22 days or more.