In a double blow, bald men may be at higher risk of coronary heart disease, said a study Wednesday, but only if the hair is lost at the crown.
Men who bald from the front appear to carry no significant added risk for the clogged artery disease that can cause heart attacks, said a report in the online journal BMJ Open.
Researchers from the University of Tokyo's Department of Diabetes and Metabolic Diseases analysed six studies on male pattern baldness and coronary heart disease conducted between 1993 and 2008 with nearly 40,000 participants in the United States and Europe.
They showed that men who had lost most of their hair were more than a third more likely to develop coronary artery disease than those with hair.
The severity of baldness influenced the degree of risk, but again, only if the balding was at the crown, or vertex.
"These findings suggest that vertex baldness is more closely associated with systemic atherosclerosis (coronary heart disease) than with frontal baldness," said the study.
"Thus, cardiovascular risk factors should be reviewed carefully in men with vertex baldness, especially younger men, and they probably should be encouraged to improve their cardiovascular risk profile."
They also urged further studies to confirm the findings.
The study said about 30 to 40 percent of adult men suffer from male-pattern baldness -- and up to 80 percent by the age of 80.
The reasons for the association were unclear, but the authors pointed to previous links drawn between baldness and insulin resistance, diabetes, chronic inflammation or sensitivity to testosterone -- all of which may lead to cardiovascular disease.