MONDAY, Feb. 9, 2004 (HealthDayNews) -- Postmenopausal women suffering from mild depression have a higher risk for developing or dying from heart disease than women who aren't depressed, a new study says.
These findings from the Women's Health Initiative (WHI), the largest study of American women's health ever undertaken, appear in the Feb. 9 issue of the Archives of Internal Medicine.
Although previous research has found links between depression and heart disease, the new study differs from its predecessors in a number of ways. Most notably, this trial is the largest of its kind and it looked at women aged 50 to 79, whereas other studies focused on younger women, says study author Sylvia Wassertheil-Smoller, a professor of epidemiology and population health at the Albert Einstein College of Medicine in New York City.
Also, the women in the new study were healthy when it began, meaning they had no prior history of heart disease, adds Wassertheil-Smoller.
This last point is significant because the previous research had focused on people with overt heart disease.
"With serious heart disease, depression seems to have a devastating effect," says Dr. Alexander Glassman, head of clinical psychopharmacology at the New York State Psychiatric Institute in New York City. "If you ask the question -- 'Is depression related to heart disease?' -- the answer from the data before is, the more severe the depression baseline, the more clearly it will lead to coronary artery disease in the future."
Glassman was the principal investigator on another trial that looked at the effect of antidepressants on people who had already had heart attacks.
"Is hers [Wassertheil-Smoller's] a useful article?" Glassman asks. "Yes. It cements an area where the data was weaker."
Wassertheil-Smoller and her colleagues followed 93,676 postmenopausal women at 40 medical centers throughout the United States for an average of 4.1 years. Women with major depression were excluded from the study.
Overall, about 16 percent of the women showed depressive symptoms, and these women had a 50 percent greater risk of developing or dying from heart disease than their counterparts who were not depressed.
The risk of dying from any cause was about 30 percent higher for the depressed women.
What's more, the chance of heart disease for the depressed women existed independently of other risk factors, such as smoking or obesity. That was particularly true for those women with no prior history of cardiovascular disease.
At the same time, depression didn't seem to influence other health problems. "It didn't predict the incidence of cancer. So it isn't just that, if you're more depressed, everything goes wrong," Wassertheil-Smoller says. "It seems to be more specific."
The big question, of course, is why the depression-and-heart-disease link? A number of hypotheses have been put forth, none of them proven.
"It could be that people really have some kind of subclinical disease [and] maybe the first place it manifests itself is in the depressed mood," Wassertheil-Smoller says. "Another possibility is that the depressed mood itself influences certain other things that then lead to disease. We just don't know."
Another important question is whether treating depression can reduce the risk for heart disease and stroke. Glassman and others are arguing for a definitive trial on this subject.
"People in the medical profession don't pay attention to depression," Glassman says. "But if it was proven that reducing depression reduces mortality, they'd have to learn how to diagnose it... It's not just mood and motivation. It [depression] affects the heart and blood vessels and bones. There's evidence that it affects insulin resistance, which probably affects vulnerability to diabetes. Depression is a bad illness. It tends to be chronic and it has lots of effects on health."