Male pattern baldness is associated with an increased risk of heart disease, but only if the baldness is on the crown of the head, a new meta-analysis of previous studies reports.
Among men with receding hairlines, no significant increase in risk was found.
Male pattern baldness is an inherited condition that affects about 30 to 40 percent of adult men — a proportion that jumps to 80 percent by age 80, according to background information presented in the meta-analysis.
Previous studies have associated baldness with an increased risk of heart disease, but the strength of the risk varied widely. The Japanese authors of this new meta-analysis, which was published Wednesday in the online journal BMJ Open, decided to take a closer look at all the earlier research to see if they could clarify the relationship between male hair loss and heart disease.
What they found was interesting, but not definitive.
Focusing on six studies
The researchers searched Medline and the Cochrane Library databases for studies published on the topic between 1950 and 2012. They found 850 possibilities, but only six studies, involving about 37,000 men living in the United States and Europe, met their strict criteria and were included in the meta-analysis. These studies had been published between 1993 and 2008.
Three of the studies were cohort studies: They tracked men for up to 11 years. An analysis of those studies revealed that men with severe baldness on the top (vertex) of their head had a 32 percent increased risk of developing heart disease compared to men who had retained their hair. Among younger men (those who had not yet reached their 61st birthday), the risk was slightly greater: 44 percent. The percentages were reached after adjusting for other heart-disease risk factors, such as smoking, high blood pressure and obesity.
The analysis also found that the more severe the baldness, the greater the risk.
The other three studies were case-control studies, which are generally considered less rigorous than cohort ones. They compared the incidence of heart disease among bald men and non-bald men. An analysis of those studies revealed that bald or balding men were 70 percent more likely to have heart disease. In younger age groups, the risk jumped to 84 percent.
A possible marker
The reasons for the association between baldness and heart disease are unclear, the meta-analysis authors point out. It may be, however, that top-of-the-head baldness is a marker for insulin resistance or chronic inflammation or some other factor that promotes heart disease.
“These findings suggest that vertex baldness is more closely associated with systemic atherosclerosis than with frontal baldness,” the authors conclude. “Thus, cardiovascular risk factors should be reviewed carefully in men with vertex baldness, especially young men, and they probably should be encouraged to improve their cardiovascular risk profile.”
Now, these findings come with all sorts of caveats. First of all, the findings reflect a relative, not an absolute, risk. Relative risk is much less meaningful, as British statistician Kevin McConway explains in a statement about the meta-analysis that he provided Wednesday to Britain’s Science Media Centre:
The study reports (in one place) that severely bald men in younger age groups have a 44 percent greater risk of coronary artery disease than their hairier counterparts, but it doesn’t answer the question ‘44 percent greater than what?’ To make sense of this we need to know the absolute risks — how likely is a 50-year-old man with a full head of hair to have a heart attack in the next 10 years? How likely is it for a 50-year-old bald man?
In addition, the confidence interval — the range of relative risk found in the meta-analysis — was very wide. Among men of all ages, the risk ranged from 8 percent to 63 percent, and among the younger age group the risk ranged from 11 percent to 86 percent.
Another major weakness: The meta-analysis included only a small number of studies.
‘Interesting,’ but not concerning
Bald men should, like all other men (and women), take steps to lower their risk of heart disease, but they shouldn’t get overly concerned about this study’s findings.
Here, again, is McConway:
The researchers describe what they found as a ‘potential relationship’ between baldness and heart disease, and suggest it should be investigated in further major studies to see if it can be confirmed. They do suggest that bald younger men should be encouraged to improve their heart risk profile, presumably by healthier eating, giving up smoking and so on, but that probably applies to all of us. And they specifically warn against screening men for signs of heart disease just because they are bald.
So yes, this is interesting, but I won’t be advising my bald friends to do anything different.
BMJ Open is an open-access journal. You can downloaded and read the study in full from the journal’s website.