March 4 (HealthDay News) -- The notion that stress can help bring on a stroke may have merit, British researchers say.

"If you divide the population into five different groups according to how severe their stress is, someone in the highest stress group, reporting the greatest stress, has a 40 percent increased risk of stroke than someone in the lowest group," said Paul G. Surtees, a psychologist at the University of Cambridge. "That is quite a difference."

On the other hand, his team found no association between depression and stroke risk.

Reporting in the March 4 issue of Neurology, Surtees' group followed more than 20,000 British men and women, aged 41 to 80, for an average of 8.5 years. The participants answered questions on their levels of stress and depression, using standard measures of mental health.

A total of 595 participants experienced a stroke during the study period, 167 of them fatal.

The risk of stroke rose steadily with the amount of stress reported, the researchers said, and the relationship was not changed when other stroke risk factors -- such as smoking, blood pressure, obesity, diabetes and family history -- were factored in.

The risk of stroke was not increased for participants who reported experiencing major depression at any time in their lives or who had had an episode of major depression in the past year.

According to Surtees, the study was not designed to determine how stress might increase stroke risk. "We have thought about this, and we have concluded that the mechanism is linked to the ability to adapt to psychological stress," he said. "People differ considerably in the way they deal with stressful circumstances. The increase is probably due to that, but we need to follow it up."

The relationship might have a simple explanation, said Dr. Mark Goldberg, professor of neurology at Washington University in St. Louis. "People who are under a great deal of stress may not take medications that are prescribed for them," he speculated.

Those medications would be aimed at conditions known to increase the risk of stroke -- high blood pressure, high blood cholesterol, diabetes and the like, Goldberg said. But the newly reported study does not mean that stress should be ranked among those leading risk factors, he said.

The increased risk due to stress "is nothing compared to the relative risk of high blood pressure or smoking or all the other known risk factors," Goldberg said.

"I don't think this should change our understanding of how we should deal with the risk of stroke," he said. Stress is associated with a number of conditions, Goldberg noted. "It increases the risk of infection, cancer and mental health problems," he said.

"Ours was not a treatment study, so we are not free to comment on how the risk might be reduced," Surtees said. "If I were speculating, I would say that if people learn to deal with stresses in life more effectively, it might contribute to reducing their risk."

SOURCES: Paul G. Surtees, Ph.D., psychologist, University of Cambridge, England; Mark Goldberg, M.D., professor, neurology, Washington University in St. Louis; March 4, 2008, Neurology