Depression link to chronic disease goes both ways

Washington -- Which comes first: chronic disease or depression? The question is being asked more frequently as the tangled relationship is examined.

While it is well-known that depression can be triggered by a chronic disease, new evidence is pointing to depression as a possible marker for a whole range of other conditions, too.

During the past decade, depression has been linked prospectively to hypertension, stroke, heart disease, diabetes, obesity and asthma, said Bruce Jonas, PhD, an epidemiologist with the Centers for Disease Control and Prevention's National Center for Health Statistics. While stopping short of identifying depression as a chronic disease risk factor, he noted it is a possibility.

Dr. Jonas was among researchers at a February CDC conference in Washington D.C., to provide evidence that diagnosing and treating depression as well as chronic disease is necessary for patient health.

The connection was also noted by Women's Health Initiative researchers, who reported in the Feb. 9 Archives of Internal Medicine that subclinical depression, often unrecognized by doctors, may pose increased risk of cardiovascular disease among women ages 50 to 79. In that study, women's increased chance of heart disease existed independently of such risk factors as smoking or obesity.

Meanwhile, a 1998 study of about 1,200 Johns Hopkins Medical School students found that those with a history of clinical depression were twice as likely to develop coronary artery disease. The study followed the participants for 40 years.

Overall, the reasons for the link could stem from the debilitating nature of untreated depression that can lead to such health-averse behaviors as smoking, obesity and failure to exercise or comply with medical advice, said Dr. Jonas.

There is also some research showing that depression is biologically connected to certain chronic diseases, he said. And this relationship is evident among people who have both low levels of depression as well as those significantly depressed.

This connection means that depression screening should not be overlooked among patients with chronic disorders, said family physician David Price, MD, director of education at the Colorado Permanente Medical Group in Denver.

Using criteria for major depression listed in DSM-IV, Dr. Price said that depressed mood, loss of interest in activities and guilt can more often be attributed to depression alone, while such symptoms as sleep disturbances, psychomotor retardation and agitation, appetite change, concentration difficulty, decreased energy and suicidal thinking can be attributed to a chronic disease as well as depression.

Adding more evidence to the need to screen, Dr. Price noted that the U.S. Preventive Services Task Force recommended in 2002 that all adults be screened for depression if there are adequate services available for treatment. Screening for depression is worthwhile for primary care physicians, said Dr. Price, and can yield results similar to those for mammography or cholesterol screening.

While there are several well-validated screening instruments available, Dr. Price recommended a quick, two-question tool as an effective way to garner results. The questions are:

• During the past month, have you often been bothered by feeling down, depressed or hopeless?
• During the past month, have you often been bothered by little interest or pleasure in doing things?

Research has also shown that treatment for depression is effective in patients with breast cancer, those who have had a heart attack and those with a history of major depressive disorder, said Dr. Price.

Treatment has also been found to be effective among elderly patients, who often attribute depression to "just getting old," said Dr. Price. "You may want to dig a little bit" to determine whether elderly patients with chronic diseases are also depressed.

Among the effective methods are nurse follow-up calls to patients that can build on established relationships between patients and primary care physicians, said Dr. Price. Weekly or monthly phone calls to patients showed reduction in symptoms of depression after six months.

Primary care physicians should consider referring patients to psychiatrists if their symptoms have not improved within 12 weeks, or if they have had depression all their lives or are exhibiting psychotic symptoms, he said.