By Megan Rauscher

NEW YORK (Reuters Health) - Patients with the chronic breathing disorder COPD appear to have a significantly higher risk of becoming clinically depressed than healthy individuals and patients with another common chronic condition - diabetes.

"The relationship between depression and COPD was described before, but what this study adds is that we found a temporal relationship. In other words, COPD did lead to a higher risk for a diagnosis of depression," said Lisette van den Bemt from Radboud University Nijmegen Medical Centre, The Netherlands.

"It seems that the increased risk of depression is not the result from having a chronic disease in general but is specific for COPD," she and her colleagues note in the current issue of the medical journal Chest.

COPD, or chronic obstructive pulmonary disease, is a progressive disease that makes it hard to breathe. COPD can cause coughing that produces large amounts of mucus, wheezing, shortness of breath, chest tightness, and other symptoms. Cigarette smoking is the leading cause of COPD.

In their study, van den Bemt's team compared the risk of an initial diagnosis of depression in 999 patients with COPD, 978 with diabetes, and 2494 matched control subjects without chronic health conditions.

In total, 5.5 percent of the overall population of patients with COPD or diabetes could not be included in the study because of an existing history of depression.

According to the investigators, the risk of a first diagnosis of depression was significantly higher in the COPD patients than in the control patients.

Co-existing illness, they note, "is a well-established phenomenon that was found in 85 percent of the patients with COPD in this study but did not result in higher risk for depression in patients with COPD compared to healthy control subjects and diabetes mellitus patients."

"Patients with COPD have a higher probability of a first episode of depression at any time...compared to patients with diabetes mellitus and control subjects," the researchers note.

Doctors, van den Bemt told Reuters Health, need to be aware of the higher risk of depression in patients with COPD. "Especially since there are treatment options for depression, and reduced mood and emotional functioning can enhance dyspnea (difficulty breathing) -- one of the key symptoms of COPD," she said.

SOURCE: Chest, January 2009.

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