September 21, 2011
Stroke Risk Increased With Depression
Researchers have compiled data from multiple studies and found that people with depression are more likely to have a stroke than those who are mentally healthy, and their strokes are also more likely to be fatal.
The researchers noted that depression is a relatively minor risk factor for stroke compared to high blood pressure and other health conditions that damage blood vessels. Still, the analysis suggests that as many as 4 percent of the estimated 795,000 strokes that occur in the US each year can be attributed to depression.
“Stroke is a leading cause of death and permanent disability, with significant economic losses due to functional impairments. Depression is highly prevalent in the general population, and it is estimated that 5.8 percent of men and 9.5 percent of women will experience a depressive episode in a 12-month period. The lifetime incidence of depression has been estimated at more than 16 percent in the general population,” according to background information in the research article.
But whether depression increases the risk of stroke has been unclear.
“If you have depression but no other health issues, you probably don't have to pay too much attention to stroke risk,” said An Pan, PhD, of the Harvard School of Public Health and lead author of the analysis. “But if you are depressed and are also obese, or have hypertension or...unhealthy lifestyle factors, your risk is going to increase dramatically.”
The studies involved in the analysis date back to the mid-1990s and include 318,000 people overall. About 2.7 percent of the participants had a stroke during the studies, which ranged in length from 2 to 29 years.
The team found that people who received a diagnosis of depression from a doctor or who reported feeling depressed were 45 percent more likely to have a stroke and 55 percent more likely to die from a stroke, compared to those who showed no signs of depression.
They also discovered that depression raised the risk of ischemic stroke (when a blood vessel becomes blocked), but did not considerably increase the risk of hemorrhagic stroke (when a blood vessel leaks or bursts).
This is the latest study in a long line of research linking depression to chronic disease and serious physical health problems.
“We knew that depression raises a person's risk of developing diabetes, obesity, hypertension, and cardiovascular disease,” said Pan. “We also knew that depression can occur after patients suffer a stroke. We just didn't have strong enough evidence to know if the reverse was true, or what really comes first.”
Researchers have already established that depression increases the risk of heart attacks, so it makes sense that depression would also increase the risk of stroke, Norman Rosenthal, MD, clinical professor of psychiatry at the Georgetown University School of Medicine, in Washington, D.C, told CNN.com.
“Strokes and heart attacks both represent blood vessels becoming blocked and blood being withheld from a vital organ, whether it's the heart or the brain,” said Rosenthal. “They're essentially the same disease.”
Depression´s role in increasing stroke risk could play out in many ways, said Pan. People suffering from depression are more likely to smoke or drink heavily, to follow unhealthy diets, and to neglect personal health. The data from the studies suggest that at least some of the stroke risk in depressed people can be contributed to an unhealthy lifestyle.
There are also other ways depression can lead to higher chances of stroke. Depression can increase the production of stress hormones in the body, and can trigger dangerous inflammation in the blood vessels.
“Little things, like keeping up good dental hygiene or socializing with friends, all affect inflammation levels -- and these are things that a depressed person is less likely to do,” said Rosenthal.
Depression may also cause people to stop using their medications needed to control other stroke-related conditions, such as diabetes and high blood pressure. But also, some medications prescribed to treat depression have been shown to cause weight gain and obesity, a known risk factor for stroke.
Pan noted more research is needed to determine whether depression drugs contribute to stroke risk. Doctors should always monitor patients´ weight and blood pressure while using depression medications, but Pan said there is no reason for patients to stop using these drugs. “For now, physicians should prescribe medication if they think it is necessary, or if non-drug treatments haven't worked,” he said.
Although depression isn´t the most important risk factor for stroke, the researchers say it likely has a noticeable impact on the stroke rate. They estimate that depression is responsible for an additional 106 strokes per 100,000 people in the United States each year.
“In conclusion, this meta-analysis provides strong evidence that depression is a significant risk factor for stroke. 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,” the research team wrote.
“More studies are needed to explore the underlying mechanisms and elucidate the causal pathways that link depression and stroke,” they add.
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