Depression may dampen some of the benefits of exercise and other healthy behaviors, a new study suggests.

In the research, people who were physically active generally had lower levels ofC-reactive protein (CRP), a marker of inflammation in the body. But this link was not found in people with symptoms of depression — exercise did not affect their CRP levels. Previous studies have shown that high CRP levels are a risk factor for heart disease.

In addition, drinking less alcohol also lowered CRP levels, but only among men who weren't depressed.

“Our findings suggest depression not only directly affects an individual's mental and physical health, it might also diminish the health benefits of physical activities and moderate alcohol consumption,” said study researcher Edward Suarez, associate professor of psychiatry and behavioral sciences at Duke University Medical Center in Durham, N.C.

If future research confirms the findings, doctors could consider depression treatments as an additional method of reducing heart disease risk, along with traditional recommendations such as exercise and healthy eating, Suarez said. Early intervention is important, because any episode of depression, if left untreated, can last months to years, the researchers said.

However, the study found only an association, and not a cause-effect link. It's possible CRP levels may change in depressed people over time, but lag behind those who aren't depressed.

The researchers noted that other markers of heart disease, such as levels of fat in the blood and levels of “good” cholesterol, did show improvements in participants who exercised, regardless of whether they were depressed. Additionally, depression in the study was assessed only with a questionnaire, rather than clinically diagnosed, Saurez said.

The researchers did not evaluate whether study participants had heart disease or follow them over time to see if those with depression developed heart disease at a higher rate. However, previous studies have found that people who are depressed are at increased risk for heart disease and, vice versa, people who have heart disease are at increased risk of depression.

The new study is published today (March 26) in the journal Brain, Behavior, and Immunity.

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