Hormone in Hair May Reveal Heart Risk
Study Shows High Levels of Cortisol in Hair Shaft May Raise the Risk of Heart Attack
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.
In the new study, hair cortisol levels were actually a more important predictor of heart attack risk than other known heart disease risk factors such as high blood pressure, smoking, and high cholesterol.
"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.