Hidden stress underlies heart attacks

Main Category: Public Health
Article Date: 11 Nov 2003 - 0:00 PST


Increase in blood pressure often undetected, study finds

Stress you didn't even know you had could kill you, U.S. researchers reported on Tuesday. They found people whose blood pressure rose during "mental stress" were six times more likely to have a heart attack or other severe heart event within six years than people who handled the stress more calmly.

AND IT WAS not stress that people knew they were feeling - pulse was not affected and volunteers usually had no idea their blood pressure was spiking, the researchers told a meeting of the American Heart Association in Orlando.

"How do you learn to manage something when you don't know you have it?" asked Diane Becker of Johns Hopkins University in Baltimore, who led the study.

The mental stress reaction trumped everything else. Other risk factors such as smoking, having high cholesterol, diabetes or being a man paled in comparison, the researchers found.

"People with hyper-reactive blood pressure to mental stress were more than six times as likely to have a coronary heart disease event," they said.

They tested 295 siblings who were under 60 but already had some signs of coronary artery disease. They tested this with an angiograph, which measures the thickness of an artery.

Many had not known they had early signs of heart disease.

They gave them a stress test during which they measured pulse and blood pressure, and then watched them for six years.

An "event" was defined as a heart attack, severe chest pain known as angina or a 50 percent or more blockage of an artery.

Hyper-reactive people were those in the upper 25 percent of reaction, as defined by how much their blood pressure went up. The "hot" responders saw, on average, a 20 point rise in blood pressure during the stress test.

TEST THAT ANNOYS EVERYONE

The test was one that stresses most people, at least consciously, said Becker.

Words such as "red," "green" or "blue" are displayed on a computer screen. The background is in one color, the letters themselves are written in another, often a color not matching the word, and sometimes other distracting colors are thrown on the screen.

The colors and words change. "You are told to identify the color in the written word," Becker said. "It is very confusing. If you don't get it correct, it sends you a message that says 'wrong'," she added.

"The more you get right, the faster it goes, so you can never master it."

Becker said she could hear hear volunteers swearing at the screen as they took the test. Their pulse and blood pressure was monitored continuously.

Afterward, the volunteers rated how much stress they felt.

"There was no relationship between people's perception of stress and their actual mental stress," Becker said.

She believes the effect has to do with the sympathetic nervous system, which controls blood pressure and other nonconscious bodily functions. A hormone called catecholamine, which is related to adrenaline, may be the direct cause although she says more study is needed.

Becker hopes to identify the gene or genes responsible. Perhaps a blood test could be developed to warn those most at risk.

And while some studies have strongly linked hostility with heart disease, others have had mixed results.

Becker believes conscious stress and biological stress may be two different things.

"People's capacity to tell you that they are stressed is worth about nothing," she said. "We would see people with hideous responses who say they are fine."

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