Sept. 3, 2010 -- While financial woes, on-the-job-stress, and relationship troubles build up over time and may cause ongoing stress, there was no direct evidence supporting the link between such chronic stress and heart disease -- until now. New research shows that increased levels of the stress hormone cortisol in the hair shaft -- a marker for chronic stress -- raise the risk of heart attack.

The findings appear online in the journal Stress.

Levels of cortisol have previously been measured in blood, urine, and saliva, but these measurements only provide a snapshot of stress at the moment. Hair cortisol, however, can provide a longer-term assessment of stress levels. Hair grows about 1 centimeter a month, so a 3-centimeter hair sample, for example, is a marker for stress over three months.

"We felt that stress was a minor factor compared to the other known risk factors for heart disease, but we didn't think it would be the strongest of them all," says study researcher Stan VanUum, MD, PhD, an associate professor of medicine at the Schulich School of Medicine & Dentistry at the University of Western Ontario in London, Canada.

Our body's fight-and-flight response is designed to help us out when we are in peril. Sudden spikes of cortisol can do just that, but when our increase of cortisol is chronic, it can have negative effects on our health.

"Over the long term, elevated cortisol can cause increases in blood pressure, blood sugar, body fat, and blood clotting -- all of which are known risk factors for heart attack," says VanUum.

Hair Cortisol Levels and Heart Risk

In the new study, researchers compared 3-centimeter hair strands from 56 men who were hospitalized after a heart attack to hair strands from men who were hospitalized for conditions other than a heart attack.

The men who had heart attacks showed higher levels of cortisol in their hair shafts than men who did not have heart attacks, the study shows. The new findings held even after researchers controlled for other known risk factors for heart disease.

Both groups had similar rates of certain heart disease risk factors such as diabetes, high blood pressure, smoking, and family history of heart disease, but the men who had heart attacks did have higher blood levels of low density lipoprotein or "bad" cholesterol levels, and higher body mass indexes (BMI), than their counterparts who did not have a heart attack. In addition, men who had heart attacks also had lower levels of high density lipoprotein or "good" cholesterol levels.

Can Stress Be Lowered?

Some heart disease risk factors can be modified such as blood pressure and cholesterol, while others like age and gender can't, he explains. "We don't know if cortisol is one that we can change," he says. "If we can reduce it with stress-reduction measures, that is great, but if we can't, it could point us toward a high-risk group who will benefit from more aggressive management of other modifiable risk factors."

The new hair test is not ready for prime time, VanUum says.

"It is still fairly labor intensive," he says. "The next steps are to look at hair cortisol in women, and to see if there is any intervention to reduce cortisol levels in hair, such as behavioral therapy," he says.

Is Hair Cortisol the New Cholesterol? Maybe

"Not only did hair cortisol levels differ among men in each group, but they were also the strongest predictor of who would have a heart attack," says Redford Williams, MD, director of the Behavioral Medicine Research Center at Duke University Medical Center in Durham, N.C. Williams has been calling attention to the stress-heart disease connection for years.

"This is yet another nail in the coffin of those who believe that stress is not a risk factor for heart attack," he says of the new study.

Is routinely measuring hair cortisol -- and intervening if it is elevated -- an option?

Maybe one day, he says. "More research is needed before we get to the point that we routinely measure cortisol in the hair, but we are getting there," he tells WebMD.

Williams would like to see a study that looks at how, or if, stress management techniques such as cognitive behavioral therapy affect hair cortisol levels.

"If we could show that they go down, that would a powerful demonstration that it is possible to train people to manage stress in ways that reduce basic levels of cortisol production and secretion in their blood," he tells WebMD.

Until then, William suggests that everyone takes steps to keep their stress to a minimum.

"Work hard to change things that you can change and need changing, but really let go of anger, stress, and frustration that you can't change," he suggests.