If you're a guy and going gray earlier than your friends, you may be at an increased risk of heart disease, says a new study which found that graying hair may indicate increased damage to arteries regardless of your age.

"Aging is an unavoidable coronary risk factor and is associated with dermatological signs that could signal increased risk," said Dr. Irini Samuel, a cardiologist at Cairo University, Egypt, who conducted a study to examine whether gray hair was an independent risk factor for heart disease.

Adult men with suspected coronary artery disease underwent multi-slice computed tomography (CT) coronary angiography, and were then divided into subgroups according to the presence or absence of coronary artery disease, and the amount of gray/white hair.

The amount of gray hair was graded using the hair whitening score: 1 = pure black hair, 2 = black more than white, 3 = black equals white, 4 = white more than black, and 5 = pure white. Each patients' grade was determined by two independent observers.

The researchers found that a high hair whitening score (grade 3 or more) was associated with increased risk of coronary artery disease independent of chronological age and established cardiovascular risk factors, including diabetes, smoking, hypertension, and family history.

Patients with coronary artery disease had a statistically significant higher hair whitening score and higher coronary artery calcification than those without coronary artery disease. Only age was an independent predictor of hair whitening.

"Atherosclerosis and hair graying occur through similar biological pathways and the incidence of both increases with age," said Samuel. The pathways include inflammation, hormonal changes, and reduced DNA repair.

"Our findings suggest that, irrespective of chronological age, hair graying indicates biological age and could be a warning sign of increased cardiovascular risk," she said.

"If our findings are confirmed, standardization of the scoring system for evaluation of hair graying could be used as a predictor for coronary artery disease," Samuel said.

The Egyptian study isn't the first to connect a physical characteristic with heart risk. A study published in the New England Journal of Medicine determined that shorter people have a higher risk of heart disease. They found that for every two-and-a-half inches a person is below average height, their risk of heart disease increased by about 14 percent.