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Depression tied to stroke risk: What explains link?

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(CBS) Scientists just gave depressed people another reason to feel sad.

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Depression significantly increases the risks of having a stroke, and dying from it, according to a new study published in the September 21 issue of the Journal of the American Medical Association.

For the study, researchers reviewed 30 studies of nearly 320,000 patients, and found that depression was associated with a 45 percent increased risk for stroke. The study also found depression was associated with a 55 percent increased risk for dying from a stroke.

"Stroke is a leading cause of death and permanent disability," study author Dr. An Pan, professor at the Harvard School of Public Health, said in a written statement. "Given the high prevalence and incidence of depression and stroke in the general population, the observed association between depression and stroke has clinical and public health importance."

How might depression lead to stroke?

The authors of the study aren't exactly sure. They say depression causes inflammation of the nervous and immune systems which may somehow increase stroke risk. Also, they add, depression ups risk for diabetes and high blood pressure, which in turn raise the risk for stroke.

Unhealthy habits associated with depression may also play a role, like smoking, eating poorly, and being sedentary. Even antidepressant medications may contribute to stroke risk, by altering chemical pathways in the brain.

But, "There is a lot of information we don't know, so we don't want to send the wrong message to patients or doctors that they should stop their anti-depressant medications," Dr. Pan told Time.

This study may give depressed people another reason to see a doctor.

"Depression is prevalent and is probably under-detected and under-treated," Dr. Ralph Sacco, chair of the neurology department at the University of Miami, who was not involved in the study, told WebMD. "So this is another reason to think about monitoring people for depression and getting them the proper treatment."

Stroke is the third leading cause of death in the U.S. each year, killing nearly 144,000 people. About 795,000 people suffer a stroke, with risk doubling each decade after age 55. Nearly 19 million Americans have depression.

WebMD has more on depression.

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