October 31, 2008

Depression’s toll on heart patients studied

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Michael Vollman, Ph.D., R.N., left, talks with patient Robert Hanvey. (photo by Susan Urmy)

Depression’s toll on heart patients studied

Can depression actually affect physical health in patients with heart failure?

This is one of several questions Michael Vollman, Ph.D., R.N., is hoping to answer as he finishes up his National Institutes of Health study targeting depression in patients diagnosed with heart failure.

“We've known for a number of years that patients who are diagnosed with heart failure have a disproportionately higher level of depression compared to the general population and to people who have other forms of chronic medical illness, including other forms of heart disease,” said Vollman, assistant professor in the Vanderbilt School of Nursing, and the departments of Medicine (Division of Cardiovascular Medicine) and Psychiatry.

The incidence of depressive symptoms in patients with heart failure can range from 15 percent to 60 percent compared to approximately 10 percent in the general population. Depressive symptoms may include fatigue, sleep disturbance, weight fluctuations and disturbed cognition. Accurately assessing these symptoms in patients with heart failure can be tricky because they mirror physical symptoms often associated with the disease.

Heart failure occurs when the heart is unable to pump enough blood around the body to deliver the oxygen and nutrients that our metabolism requires. In some people with heart failure, the heart is keeping up with demands, but only operating under high 'filling pressures' such that there is a back up of blood into the lungs or other tissues.

“It is a common condition that is associated with disabling symptoms and mortality,” said Doug Sawyer, M.D., Ph.D., interim chief of Cardiology and a physician in the Vanderbilt Heart & Vascular Institute's heart failure program.

Sawyer said he has observed depressive symptoms in his patients, particularly those who are newly diagnosed and those living with chronic physical impairment.

“Heart failure is a debilitating condition to many people, limiting what they can do physically. It is also a condition that people learn is ‘deadly,’ so the message they might hear is 'I'm going to die.' “

There are many treatments for heart failure, and most patients with this diagnosis will see improvement in how they feel when they are fully treated. For those whose symptoms do not improve or for whom transplantation is not an option, life can be filled with what Vollman calls “serial losses.”

“The clinical trajectory of heart failure is one of serial losses over time — loss of physical function, role identity, social integration and financial resources due to forced disability. We know from the literature that loss, or perception of loss, is one of the main reasons why these patients experience depression.”

Once patients with heart failure develop a clinically significant level of depression, their clinical course becomes more problematic, Vollman said.

For one thing, people who have depression may experience levels of psychological distress that can actually change how they view their situation and how they react to it. Secondly, depression also may negatively affect biological mechanisms.

The six-month prospective study looks at a number of psychosocial factors associated with depression, such as coping behaviors, cognitive adaptation, the amount of social support patients believe they have, and whether they feel they have any control over their illness and care.

“We look to see how changes in those variables are associated with changes in depressive symptoms,” Vollman said.

Vollman's research also takes a fairly innovative look at the relationship among those psychosocial factors and key biological symptoms.

“My basic assumption is this: Thoughts and beliefs affect biological mechanisms,” he said.

Patients who have more depressive symptoms often have increased sympathetic nervous system activation, increased production of plasma norepinephrine and decreased heart rate variability. Depressed patients also may have increased production of pro-inflammatory cytokines.

“This study is looking at whether or not the effects of psychosocial factors are potent enough stimuli to affect these biological mechanisms. We have reason to assume they do, but this hasn't been fully explained in patients with heart failure,” Vollman said.