Patients with depression frequently talk to their physicians about symptoms such as headache, back or muscle pain, stomach ache and dizziness instead of symptoms more commonly associated with depression such as fatigue, lack of motivation and moodiness, says Kurt Kroenke, M.D., professor of medicine in the Division of General Internal Medicine and Geriatrics at IU and a research scientist at the Regenstrief Institute, Inc.

"Depression is a risk factor for symptoms of pain," he said. "The most reports of pain – such as muscle pain, headaches, leg pain – are two or three times more common in people with depression."

Physical symptoms also may serve as a barometer for physicians to gauge the effectiveness of common antidepressant treatments, he said.

"Physical symptoms may not respond to common antidepressant treatment as much as the emotional symptoms," says Dr. Kroenke. "Even though the physical symptoms may be related to or aggravated by the depression, they can linger longer than the emotional symptoms."

In his article "The Outcome of Physical Symptoms with Treatment of Depression," Dr. Kroenke cautions it is important to monitor physical symptoms when assessing patients with depression. If the physical symptoms persist, additional medical assessments may be needed.

The study examined the prevalence, impact on quality of life and outcome of physical symptoms in patients with depression during nine months of antidepressant therapy. A total of 573 depressed primary care patients at 37 clinic settings were assessed at one, three, six and nine months.

In more than a third of the patients, the physical symptoms persisted longer than the depression symptoms.

"While physical symptoms showed, on average, some improvement with antidepressant treatment, the improvement was typically less than was reported for emotional symptoms," he said. "Most of the improvement for the physical symptoms occurred within the first month of treatment, while the emotional symptoms continued to improve over a nine-month period."

A related study by Dr. Kroenke also revealed a correlation between the severity of pain as reported by the patient and the success of treatment for depression. The more severe the pain at the beginning of treatment, the less responsive depression is to antidepressant medication.