Depression in older women is strongly linked with a higher risk of dying from heart disease, according to research on more than 90,000 women.
While previous research has shown that depressed men and women run an increased risk of developing heart disease, a recent, smaller study found a link with heart-related death only in men.
The new study is one of the largest yet to examine the issue and found that depressed but otherwise healthy postmenopausal women faced a 50 percent higher risk of dying from heart disease during four years of follow-up than women who were not depressed.
An independent risk factor
“What is most striking about our findings is that depression was found to be an independent risk factor for subsequent cardiovascular death, particularly in those who had no prior history of cardiovascular disease,” said lead researcher Sylvia Wassertheil-Smoller, a professor of medicine at Albert Einstein College of Medicine in New York.
The study appears in Monday’s Archives of Internal Medicine.
The researchers examined data on 93,676 women 50 and older who were taking part in a government study on women’s health and followed for an average of about four years.
Nearly 16 percent had strong symptoms of depression, based on questionnaires women completed at the outset.
None of the women had severe, debilitating mental illness. While researchers lacked data on whether any participants had actually been diagnosed with depression, about 8 percent were taking anti-depressant medication.
During the follow-up, there were 159 heart-related deaths among the 20,130 depressed women, or 0.8 percent. That compared with 372 heart-related deaths among the 71,546 women who were not depressed, or 0.5 percent.
The 50 percent difference remained even when the researchers took into account other factors that affect the risk of heart disease, including age, weight and cholesterol.
Biological explanation unknown
Smoller said it is unclear how depression might cause heart problems, but previous research has shown that stress hormones that might be activated in depression can constrict blood vessels and might lead to artery blockages.
Some studies also have shown that depression and associated inactivity might cause blood levels of inflammatory proteins to rise, which also can increase heart disease risk, said Dr. Albert Chan, a cardiologist with the Ochsner Clinic Foundation in New Orleans.
Chan said the study presents among the strongest evidence yet of a link between depression and heart risks in women. Still, he said that it does not prove that depression causes future heart problems, and that there might be some unidentified factors that would explain the association.
“Right now we still don’t have a biological explanation,” Chan said.