FRIDAY, Jan. 11, 2013 (HealthDay News) -- People who develop depression after surviving a stroke may die sooner than those without the mental health disorder, a new study suggests.
Researchers found that of more than 10,000 Americans followed for two decades, those who developed depression after suffering a stroke were about three times more likely to die of any cause during the study period, versus people without either condition.
Stroke survivors without depression also faced a heightened death risk, but it was less pronounced: They were 80 percent more likely to die during the study period than people with no history of stroke or depression, the investigators found.
The findings are being released by the American Academy of Neurology, ahead of its annual meeting in San Diego in March. A similar link has been seen for heart attack survivors with depression, the study authors noted in an academy news release.
The reasons for the findings are not completely clear. The researchers were able to account for some factors, such as age, race and income. But they didn't have information on the severity of people's strokes, and whether they suffered any disabilities afterward, said lead researcher Dr. Amytis Towfighi, chair of neurology at the Rancho Los Amigos National Rehabilitation Center in Downey, Calif.
That's important because more severe strokes may leave people more vulnerable to depression.
It's also possible, though, that depression could have some direct effect on long-term survival after a stroke, according to Towfighi.
"There are both behavioral and physiological reasons postulated," she said.
On the behavior side, depression might hinder people from taking their medications properly, eating right or getting exercise. On the biological side, some researchers suspect that depression affects the functioning of blood cells involved in clot formation; blood clots are the cause of most strokes, and can also lead to heart attacks.
The study is a "worthy addition" to the research on stroke and depression, said Dr. Robert Robinson, a professor of psychiatry at the University of Iowa in Iowa City whose own work has found a link between post-stroke depression and mortality.
Depression is believed to be common after stroke -- affecting up to one-third of stroke sufferers. And there are probably multiple reasons, Robinson said.
Brain damage from the stroke may leave people vulnerable to depression. And research suggests that depression risk is linked to the severity of a person's post-stroke disabilities -- particularly problems with routine daily tasks, Robinson said.
He added, though, that studies suggest that depression can worsen those impairments; so it's not necessarily clear which comes first.
The current findings are based on 10,550 Americans aged 25 to 74 who enrolled in a national health study in the early 1970s. They reported on their history of stroke and were screened for depression; 48 people with a history of stroke had depression symptoms, while another 73 had survived a stroke but were not depressed.
Compared with people with neither condition, stroke sufferers had a higher death rate over two decades -- not surprisingly. But those with depression were at relatively greater risk.
Despite the high rate of post-stroke depression, there is no routine screening for the disorder.
"Most patients are not screened for depression and are missed by their doctors," Robinson said.
Towfighi suggested that stroke survivors and their loved ones be aware of potential depression symptoms, and talk with their doctor if they are concerned. She said those symptoms can include feeling down or hopeless, sleep problems, poor appetite or overeating, and having little interest in doing the things you once enjoyed.
Experts note that studies presented at meetings are generally considered preliminary until they are published in a peer-reviewed journal.
Learn more about post-stroke depression from the U.S. National Institute of Mental Health.