Mental health–asthma link heightened by obesity

Sep 10 2013

Data from Norway suggest that anxiety and depression interact with obesity to increase the risk for adult-onset asthma.

The findings, which came from the Nord–Trøndelag Health Study, show that individuals with anxiety or depression on the Hospital Anxiety and Depression Scale were a significant 39% more likely to develop incident asthma than those without over a mean follow-up of 11 years, after accounting for confounders.

But in obese individuals with anxiety or depression the odds were increased 2.93-fold compared with those who had none of these conditions. By comparison, those who were obese but not anxious or depressed had a 1.47-fold increased odds and those who were anxious or depressed but not obese had a 1.20-fold increased odds for incident asthma.

And the authors found evidence that the interaction between obesity and anxiety or depression was not just additive, being associated with a 1.26 relative excess risk.

Their analyses included 23,246 participants aged 19 to 55 years at baseline, of whom 15.0% and 7.8% had anxiety and depression symptoms, respectively; 3.8% developed asthma during follow-up.

The team, led by Ben Brumpton (Norwegian University of Science and Technology, Trondheim), says that their findings add to previous reports of separate associations of anxiety, depression, and obesity with asthma, and indicate that they share a common pathway.

Noting that both obesity and psychologic distress result in pro-inflammatory states, they suggest: “The further complication of obesity in anxious or depressed participants may worsen a common inflammatory pathway and, at least in part, explain the joint association that we observed.”

Writing in the International Journal of Epidemiology, Brumpton and colleagues say their study indicates that “identifying people with anxiety or depression symptoms and obesity may make asthma prevention more effective.”

They conclude, however, that “the study findings and their mechanistic implications merit further investigation.”

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