New evidence for link between depression and heart disease

In his most recent study, Angelos Halaris, MD, PhD, and colleagues found that an inflammatory biomarker, interleukin-6, was significantly higher in the blood of 48 patients diagnosed with major depression than it was in 20 healthy controls.

Interleukin-6 has been associated with cardiovascular disease. Halaris presented his findings at a joint congress of the World Psychiatric Association and International Neuropsychiatric Association in Athens, Greece. At the congress, Halaris formally proposed creation of a new Psychocardiology subspecialty.

Forty to 60 percent of heart disease patients suffer clinical depression and 30 to 50 percent of patients who suffer clinical depression are at risk of developing cardiovascular disease, Halaris said.

Stress is the key to understanding the association between depression and heart disease. Stress can lead to depression, and depression, in turn, can become stressful. The body's immune system fights stress as it would fight a disease or infection. In response to stress, the immune system produces proteins called cytokines, including interleukin-6. Initially, this inflammatory response protects against stress. But over time, a chronic inflammatory response can lead to arteriosclerosis (hardening of the arteries) and cardiovascular disease.

It's a vicious cycle: depression triggers a chronic inflammation, which leads to heart disease, which causes depression, which leads to more heart disease. Clinical depression typically begins in young adults. "Treating depression expertly and vigorously in young age can help prevent cardiovascular disease later on," Halaris said.

Physicians often work in isolation, with psychiatrists treating depression and cardiologists treating cardiovascular disease. Halaris is proposing that psychiatrists and cardiologists work together in a multidisciplinary Psychocardiology subspecialty.

A Psychocardiology subspecialty would raise awareness among physicians and the public. It would forge closer working relationships between psychiatrists and cardiologists. It would formalize multidisciplinary teams with the requisite training and expertise to enable early detection of cardiovascular disease risk in psychiatric patients and psychiatric problems in heart disease patients. And it would provide continuing education to physicians in the safe and correct use of medications in cardiac patients who have psychiatric disorders.

"It is only through the cohesive interaction of such multidisciplinary teams that we can succeed in unraveling the complex relationships among mental stress, inflammation, immune responses and depression, cardiovascular disease and stroke," Halaris said.

Halaris is medical director of Adult Psychiatry and a professor in the Department of Psychiatry and Behavioral Neurosciences at Loyola University Chicago Stritch School of Medicine.