By Jeffrey Kopman
Coughing, wheezing, and trouble breathing are common symptoms of chronic obstructive pulmonary disease (COPD), but two other symptoms - depression and inflammation - might be linked in some patients, according to a study presented at the American Thoracic Society 2013 International Conference in Philadelphia.

Using depression and respiratory symptom questionnaires, researchers at the University of Pittsburgh surveyed 450 patients and found that 37 men and 49 women reported being depressed. The depressed patients were more likely to have high levels of a biomarker that can cause inflammation and pain throughout the body, the researchers found, and these levels were unrelated to the severity of COPD, but were linked to depression.

Systemic inflammation like the depressed COPD patients had can cause pain and worsen COPD symptoms. Researchers believe that the pain associated with this inflammation causes depression, more than having just COPD or other symptoms.

"Depression has been linked with a number of symptoms and comorbidities [when patients have more than one condition at the same time] in COPD patients," said Hilary Strollo, M.S., a graduate of the University of Pittsburgh School of Health and Rehabilitation Sciences, in a press release. "Our findings add evidence of a strong relationship between depression and one of the hallmarks of COPD, systemic inflammation, independent of the severity of disease."

trollo believes these findings should encourage doctors to assess and treat depression in people with COPD - potentially relieving some of their COPD symptoms.

COPD affects approximately 10 percent of people worldwide, including about 13 million U.S. adults. Almost half of COPD patients are believed to have depression or other psychiatric disorders.