Depression puts middle-aged and older women at significant risk of suffering potentially debilitating strokes, according to a study published today. Depressed women who reported taking such popular antidepressants as Prozac, Zoloft and Celexa were "perhaps at even higher risk," the study's senior author said.
"There is something about being depressed that increases your risk of stroke," said Dr. Kathryn Rexrode, an internist at Brigham and Women's Hospital in Boston. However, she took pains to say that women taking antidepressants should not interpret the findings as a signal that "stopping SSRIs is going to make your risk of stroke go down. There is no data about that." (SSRIs, or selective serotonin reuptake inhibitors, are the most commonly prescribed antidepressants.)
"I don't think the medications themselves are the primary cause of the risk," Rexrode said. Instead, she suggested that women who medicate their depression might suffer from more severe symptoms than those who don't opt for the pills.
The bottom line, she said, was that regardless of the mechanism, doctors need to be made aware of the relationship between depression and strokes. "We ought to intensify efforts to reduce that risk through the usual risk factors for stroke, and we ought to test and research interventions we can to do help modify that risk."
Strokes constitute the nation's third-leading cause of death. Strokes that don't kill often leave sufferers with trouble speaking, thinking and with limited use of their limbs. As a result, strokes are a leading cause of permanent disability.
The findings, which appear in Stroke: Journal of the American Heart Association, were drawn from the landmark Nurses' Health Study, which began in 1976 and has followed more than 120,000 women for numerous health conditions. Researchers studying stroke risk followed 80,574 of them, predominantly white, female RNs, with an average age of 66, without any stroke history.
Study participants underwent periodic evaluations for depression, and were asked every couple of years if they'd taken antidepressants or had been diagnosed with depression by a doctor. At the beginning of the study, 22.3 percent of the women were depressed, meaning that they scored high for symptoms of depression, had taken antidepressants or had a formal diagnosis of depression.
During six years of follow-up, researchers documented 1,033 strokes. They calculated that depression increased a woman's risk of stroke by 29 percent, compared with women who never reported being depressed. Among depressed women taking any of the SSRIs, stroke risk was 39 percent higher than among women who never reported being depressed or taking antidepressants.
Rexrode said that the 10 percent difference between those two figures "was not statistically significant." One of the study weaknesses was the inability to determine whether women took antidepressants for depression or for other problems, such as anxiety or nerve-related pain.
"Stroke risk appeared higher among currently depressed women than among women who [had a history of] depression," Rexrode said. Also, depressed women were more likely to be single, younger (the group spans ages 54 to 79) and have such cardiovascular risk factors as being overweight, a smoker or sedentary. Depressed women also were more likely to suffer from high blood pressure, diabetes and heart disease.
Rexrode said that depression might interfere with a woman's ability to control such risk factors as diabetes and hypertension through medication, or by making important lifestyle changes.
Rexrode and her co-authors could not explain the mechanism linking depression and strokes, but suggested that depression might increase inflammation, which is known to damage blood vessels in the heart and brain. Depression also can alter neurological functions and the body's response to stress, and may make blood more likely to clot.
"These findings confirm our own findings in the Women's Health Initiative which showed that depression is a risk factor for subsequent stroke," said Sylvia Wassertheil-Smoller, a co-author of a large 2009 study in Archives of Internal Medicine that found older women taking antidepressants had a small, but statistically significant increase in stroke risk.
Wassertheil-Smoller, a professor of epidemiology and public health at Albert Einstein College of Medicine in the Bronx, N.Y., agreed with the current study authors about the need to inform doctors about the risks and to conduct additional research. "Since mild or moderate depression is not usually screened for, or even given much attention by primary care physicians, it is important that they be alerted to this finding," she said. "The interesting question is whether depression is a subclinical manifestation of impending stroke or whether there is some causal pathway."