Stress, depression raise stroke risk

NEW YORK (Reuters Health) - People who suffer from high levels of stress, hostility and depression may be more likely to have strokes, suggests a new study.

The increased stroke risk doesn't appear to result from other well-known physical risk factors like high blood pressure or smoking, according to the researchers writing in the journal Stroke.

"The reason the findings are of interest and importance for the general audience is that it really documents that these emotional characteristics and stress have an influence on brain health," said the study's lead author Susan Everson-Rose, from the University of Minnesota in Minneapolis.

Over 795,000 people in the U.S. have strokes every year, according to the Centers for Disease Control and Prevention (CDC). About one in every 19 deaths in the U.S. is attributable to stroke.

So-called ischemic strokes are the most common type, says the CDC. During ischemic strokes, the flow of oxygenated blood to the brain is blocked - usually by a blood clot. The other type of stroke occurs when a blood vessel in the brain leaks or ruptures. Both types can kill brain tissue, leaving the victim seriously disabled, or can be lethal.

Everson-Rose and her colleagues write that stress and negative emotions are known to affect heart disease risk. And while heart disease and stroke share many risk factors, less is known about the influence of emotions on strokes.

For the new study, the researchers analyzed data on 6,749 U.S. adults between ages 45 and 84 years old. The participants did not have cardiovascular disease when they entered the study between July 2000 and August 2002.

The researchers used questionnaires to assess the participants' stress, depressive symptoms, anger and hostility at the beginning of the study period, then tracked people for an average of 8.5 years.

Overall, there were 147 strokes and 48 transient ischemic attacks (TIA) - a milder episode that produces stroke-like symptoms for anywhere from a few hours up to a day - during that period.

The researchers found that stress, hostility and depressive symptoms were all tied to an increased risk of stroke or TIA. Anger, however, was not.

After accounting for the participants' ages, demographic backgrounds and other health details, the researchers found that those who had the highest depression scores were 86 percent more likely than those with the lowest scores to have stroke events.

People with the highest stress scores were 59 percent more likely to have stroke events, compared to those with the lowest scores. And people with the highest hostility scores were over two times more likely to have strokes, compared to those with the lowest scores.

The results held even after the researchers adjusted for the participants' traditional stroke risk factors such as blood pressure, alcohol use, smoking and exercise, as well as inflammation, which has been linked to stroke risk in other research.

"We had hypothesized that we'd see these associations, but I was surprised they were so robust even after we considered some of the classic risk factors," Everson-Rose said.

She and her colleagues can't say why people with higher levels of stress, hostility and depression are more likely to have strokes.

Neither inflammation nor lifestyle differences with regard to smoking, exercise and other coping mechanisms associated with stress, seemed to influence stroke risk, the authors note.

It's possible, they write, that stress increases levels of chemicals involved in the fight-or-flight response that affect blood vessel function and platelets, which help form clots, but the study did not investigate those factors.

More research is needed to determine the mechanism behind the increased risk and whether certain ethnicities or races are more susceptible to this risk than others, the researchers conclude.

Dr. Carolyn Brockington, who was not involved in the new study, said another question that needs to be answered is whether something has to be done for people experiencing chronic stress to potentially reduce their risk of stroke.

"We know the traditional risk factors for strokes . . . but that chronic stress, depression etc. has never been discussed as something modifiable," said Brockington, director of the stroke center at Mount Sinai St. Luke's Roosevelt in New York City.

She said prevention is key and it is worth it for patients and doctors to discuss chronic stress or other negative emotions.

"People should also realize despite the prevention strategies, people do have strokes," Brockington said, adding that people should seek help immediately if they believe they're having a stroke.