When found in your tresses, high cortisol levels may predict a heart attack about to strike, according to research published in the journal Stress and reported by Agence France-Presse.

Cortisol is a hormone the body produces in response to stress, including stress related to jobs, money, relationships and so on. Scientists have known that stress is related to cardiovascular disease, but until this research involving cortisol levels in hair, researchers didn’t have a biological marker to measure chronic stress and predict heart attacks.

For the study, scientists at the University of Western Ontario looked at hair samples from 56 male heart attack patients at Israel’s Meir Medical Centre and compared them with hair samples from 56 other men hospitalized for non-cardiovascular issues.

Researchers found that heart attack patients had higher cortisol levels in their hair. Moreover, the levels of cortisol in hair remained the strongest predictor of a heart attack even after scientists accounted for risk factors such as diabetes, hypertension, smoking and family history of coronary artery disease.

Traditionally, cortisol is measured in serum, urine and saliva. But these measurements don’t reflect the body’s stress response over prolonged periods of time, said study authors Stan Van Uum and Gideon Koren.

On average, hair grows a half to one inch per month, and cortisol accumulates in the hair shaft during the process. By examining about two and a half inches of hair, scientists can study several months of stress levels.

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