Male pattern baldness (also known as androgenic alopecia) is the most common type of hair loss in men affecting ~50% of men over 40 years of age and caused by the interaction of genetics, hormones, and lifestyle factors including smoking, alcohol and stress from a hormonal perspective. The primary contributor, dihydrotestosterone (DHT), results from metabolized testosterone and changes gene expression, leading hair follicles to shorten their growth phase and to miniaturize.
Androgens are hormones accountable for male features and reproduction. Testosterone, the most potent androgen, is responsible for the deep voice, increased muscle mass, strong bones that characterize the gender, and also stimulates the production of red blood cells by the bone marrow. Although testosterone works directly on many tissues, some of its least desirable effects do not occur until converted into another androgen, dihydrotestosterone (DHT). DHT acts on both skin and hair follicles, putting hair on the chest but often taking it off the scalp. Male-pattern baldness is one thing, but studies have shown testosterone and androgenic alopecia have an association with cardiovascular disease, prostate cancer, and colon cancer. In the interest of taking care of the whole patient it is important be aware of these possible diseases linked to male pattern baldness.
Male pattern baldness could provide a possible visual clue to identify the people who are at greatest risk of coronary heart disease and who will benefit most from preventative measures. Researchers have been investigating a link between androgenic alopecia and cardiovascular disease or risk factors for cardiovascular disease. These studies have looked at different facets of AGA as it relates to CAD, including studies that have identified elevated rates of cardiovascular disease in patients with vertex hair loss, vertex and frontal hair loss, early onset of hair loss, and rapidly progressive hair loss.
We know testosterone acts on the liver, and while normal amounts are harmless, high doses can cause liver disease and boost the production of LDL ("bad") cholesterol while lowering the amount of HDL ("good") cholesterol. Also potentially present are increased risks for hypertension, excess weight, abnormal lipids, insulin resistance, carotid atheromatosis, and death from diabetes or heart disease. While these studies have yielded conflicting findings, nevertheless, there is a growing body of evidence showing abnormal lipid profiles in patients with androgenic alopecia. Thus ensuring these patients have their blood pressure, cholesterol and HgbA1C followed is very necessary.
An association between male pattern hair loss and development of prostate cancer has been reported, and since DHT stimulates both hair loss and the growth of prostate cells, do men with androgenic alopecia have a heightened risk of prostate cancer? Perhaps, however, the strength of the association remains to be clarified. Studies revealed that patients with prostate cancer were twice as likely to have androgenic alopecia at age 20, but the pattern of hair loss was not an imminent factor for the development of cancer. Also, there was no association between early-onset alopecia and an earlier diagnosis of prostate cancer or with the development of more aggressive tumors. Therefore, whether this population can benefit from routine prostate cancer screening or regular use of 5-alpha reductase inhibitors as primary prevention is to be determined.
A possible association between male pattern balding and other cancers has been explored. A new first-of-its-kind 18-year prospective study including over 30,000 male participants has found a modest link in certain types of male pattern baldness and increased risk of colorectal polyps, which can be the predecessors to colorectal cancer. In men with frontal baldness (a receding hairline) and with frontal-plus-mild-vertex baldness (receding hairline plus slight baldness on the crown of the head), researchers discovered an approximately 30% increased risk of colon cancer, relative to men with no baldness. However, further studies are needed to confirm this association.