Feelings of depression could be one reason patients fail to follow their doctors’ orders on exercising and eventually become less physically active, a new research review finds.

Although past research shows that exercise improves chronic health conditions, such as heart disease and diabetes, it also shows that patients with these conditions often suffer from depression.

The new analysis evaluated 11 studies comprising some 20,000 patients. Eight studies reported that having symptoms of depression after a coronary event, such as heart attack, was a significant risk factor for developing a sedentary lifestyle or a poor adherence to an exercise regimen recommended by the patients’ doctor.

The review appears in the July/August issue of the journal General Hospital Psychiatry.

One study, for example, investigated the role of depression and anxiety in 224 heart attack survivors, at three months and 12 months after their hospitalization. Of those with anxiety and depression during hospitalization, 59 percent had a significant decrease in exercise after three months, compared with 31 percent of those who were not depressed. A year later the gap widened, with 51 percent of depressed patients exercising less compared with 26 percent of non-depressed patients.

The studies used different methods to measure depression and physical activity and there was a great difference in how they compared factors such as the patients’ health, physical activity and depression.

There are many suggested theories to explain why depression leads to a decline in activity. Babak Roshanaei-Moghaddam, M.D. of the department of psychiatry and behavioral sciences at University of Washington in Seattle and lead author of the study offered one theory.

“We have hypothesized that there are both behavioral habits associated with depression, such as smoking and obesity, which may then limit exercise motivation and enjoyment, as well as biologic factors that can cause obesity and decrease energy level, exercise tolerance and pain threshold,” he said.

Evette Joy Ludman, Ph.D., of Seattle-based Group Health Cooperative, who had no affiliation with the study, agreed.

“Depression can indeed make people have less motivation and energy to exercise,” Ludman said. “The sad part about this is that physical activity is not only important for preventing and managing many chronic conditions; it can be very helpful for improving mood and other symptoms of depression.”

General Hospital Psychiatry is a peer-reviewed research journal published bimonthly by Elsevier Science. For information about the journal, contact Wayne Katon, M.D., at (206) 543-7177.

Roshanaei-Moghaddam B, Katon WJ, Russo J. The longitudinal effects of depression on physical activity. Gen Hosp Psychiatry 31(4), 2009.

Source: Health Behavior News Service