People who report feeling high levels of stress in their daily lives are more likely to develop heart disease than those who don't experience as much stress, according to a new review of earlier studies.
While the finding isn't surprising, the review gives a clearer picture of the relevant research to date.
"Everybody knows that stress is bad for your heart but the evidence has been scattered out over the years," said researcher Dr Donald Edmundson of Columbia University Medical Center in New York City.
Starting with a large British study from the 1960s that found an increased heart disease risk among poor people, researchers have linked stress to poor heart health.
How the research was done
For their new meta-analysis, published online in the American Journal of Cardiology, Dr Edmundson and his colleagues pooled data from six large studies on the topic involving nearly 118 000 people.
Some studies asked participants to rate the severity or frequency of their stress, while others used a simple yes or no response to the question of whether someone had felt stressed.
At the beginning of the studies, none of the participants had been diagnosed with heart disease.
Over follow-up periods ranging from three to 21 years, people who felt stressed were 27% more likely later to be diagnosed with coronary heart disease, be hospitalised with the condition, or die from it.
Dr Edmundson said the rise in heart disease risk related to stress is equivalent to smoking five cigarettes a day. However, there is no ironclad proof that stress is to blame for the heart problems.
One possible explanation is that stress raises the blood levels of hormones that can be take a toll on the heart.
In addition, people who are stressed might behave in ways that are less healthy, "like smoking, unhealthy dietary choices, physical inactivity etc. These mechanisms usually interact, making the situation much more complicated," said Dr Demosthenes Panagiotakos, a professor at Harokopio University of Athens, who was not involved in the study.
Dr Panagiotakos said Dr Edmundson's review supports the link between stress and heart disease, "however, this is based only on six relevant studies, a fact that makes the causal inference very difficult."
Dr Edmundson said people can take steps to reduce their stress, such as exercise, yoga and meditation.
"Good old-fashioned exercise, good old-fashioned stress reduction techniques, are probably - the study hasn't been done yet - but are probably going to be good for healthy people to offset their risk of heart disease going forward," he said.
(Reuters Health, September 2012)
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