Young adults who keep a cool head under stress may be less likely to develop high blood pressure as they age, U.S. researchers said on Monday.

A study of 4,000 young adults showed that those who stressed out the least while playing a difficult video game and taking other tests were less likely to develop high blood pressure in their 40s.

“In general, the individuals who had larger blood-pressure responses to stress had a greater risk for developing high blood pressure,” Karen Matthews, a professor of psychiatry at the University of Pittsburgh who led the study, said in a statement.

“This risk was independent of other known risk factors such as race, gender, education, age, and body-mass index (a measure of obesity).”

Matthews and colleagues used information from a continuing study tracking the natural history of cardiovascular disease.

In 1985 researchers began studying 5,115 men and women, ages 18 to 30, and re-examined them at regular intervals.

At the second-year examination, 4,202 of the volunteers who had normal blood pressure of 140/90 or below took stress tests.

In one, they plunged a hand in ice-cold water and kept it submerged for 45 seconds. Another involved tracing an image. And one involved a video game - which at the time was fairly novel and still stressful for many to play.

“In general, participants who had the greatest blood-pressure increases during all three tasks had the highest risk for later high-blood pressure,” said Dr. Mary Whooley of the University of California San Francisco, who worked on the study. The study was published in the journal Circulation.

“The greater the blood-pressure changes in all three tasks, the earlier the onset of hypertension,” she said.

After 13 years of follow-up, 353 of the participants developed high blood pressure, they found.

“This study confirms previous work demonstrating an association between blood-pressure response to various stressors and the future development of hypertension,” said American Heart Association spokesman Dr. Daniel Jones.

“It is still unclear whether exposure to stress is a part of the cause of hypertension in some people or whether these tests measuring response to stress are simply good markers for the future development of hypertension.”

High blood pressure eventually affects up to 90 percent of Americans as they become elderly and is a leading cause of heart attack, stroke and heart failure.

SOURCE: Circulation, 2004.