Androgenic Alopecia: What You Need to Know (Part 1)

Male pattern baldness. Menopausal hair loss. Age-related baldness. No matter what name you know it by, androgenic alopecia (sometimes called androgenic alopecia) is extremely common, affecting about 50 million men and 30 million women in the U.S. - that’s about a quarter of the entire population. or more than a third of American adults. As baby boomers and gen Xers age, the number of people suffering from androgenic alopecia is only expected to rise, leaving healthcare providers scrambling to offer treatments that offer real results for their patients.

The good news: While a standard one-size-fits-all cure for androgenic alopecia remains elusive, there are a handful of solutions that can offer reliable results for many patients. These formulations work by addressing the root causes of androgenic alopecia, essentially helping hair follicles turn back the clock so patients can enjoy restored hair growth, along with increased feelings of confidence and satisfaction.

The precise pathogenesis of androgenic alopecia isn’t known, but researchers believe both genetic and environmental factors likely contribute to the condition. What they DO know is that androgen hormones - or more specifically, the hormone dihydrotestosterone or DHT - play a central role in the way hair follicles act. Interestingly, although androgens can cause hair loss as we age, they actually work to spur pubic and underarm hair growth during puberty in both sexes, and a little later, facial hair growth in males. This dichotomy - the promotion of both hair growth and hair loss - is sometimes referred to as “androgen paradox.”

While the androgen testosterone is synthesized primarily in the adrenal glands and the sex glands (the testes and ovaries), DHT is produced from testosterone by the 5-alpha reductase enzyme in the skin and other peripheral tissues. Researchers believe androgens act on hair growth by interacting with paracrine factors that control signaling among the hair follicles and the dermal papillae. These interactions control not only the actual growth of hair, but also the thickness and coarseness of the hair as well. Plus, androgens can control the length of time an individual hair can grow before it falls out during the natural hair growth cycle, and they can also prolong the time between the time a hair is shed and a new hair grows in to take its place.

The hair growth changes that occur during puberty are a good example of all these interactions, demonstrating the significant effect androgen hormones have on follicle function and hair growth. Prior to puberty, axillary (underarm) hair and pubic hair are very fine and virtually invisible, indistinguishable from the soft, light-colored hairs on the arms, legs, and torso during childhood. These hairs are called vellus hairs.

But as androgen production ramps up during puberty, these hormones act on the hair follicles, changing them from vellus follicles to terminal follicles. Afterward, the affected follicles produce terminal hair, which is thicker, coarser and darker hair than vellus hair. Terminal hair also tends to be longer and sometimes curlier than vellus hair.

However, in androgenic alopecia, there is a progressive decrease in the density of terminal hair, and a concurrent increase in the density of vellus hairs, the opposite of what happens during puberty. In effect, terminal hairs are turned off and are transformed into vellus hairs, and this effect is due to the hair follicle miniaturization, which is associated with a substantial reduction in hair diameter. Androgen receptors embedded in hair follicles also play a role in hair growth and follicle activity. These receptors and their related coactivators act together to increase or decrease an individual follicle’s sensitivity to the effects of androgen. The number of receptors contained on a person’s follicles is one factor that may be determined by genes. In one recent large-scale European study, researchers identified seven chromosomes involved in androgenic alopecia, confirming that the condition is not only genetic, but also highly heritable. Men and women with these genetic differences have follicles that are “pre-programmed” to be more receptive, or more sensitive, to androgen hormones, making them more susceptible to developing androgenic alopecia.

While androgens are an important actor in androgenic alopecia, other recent studies indicate there are other contributing factors, including oxidative stress, which has also been implicated in other age-related disorders and diseases, as well as in the aging process itself. In a nutshell, oxidative stress is simply the body’s inability to ward off or neutralize damaging free radicals through antioxidant activity. Chronic stress, diet, aging, and disease can all hamper the body’s ability to neutralize damaging free radicals, which are present in many forms, including environmental pollutants, smoke even UV radiation.

In androgenic alopecia, oxidative stress acts to damage the follicles as well as the surrounding skin cells at the cellular level. Free radical damage may also trigger microinflammation and fibrosis inside the follicles, providing another potential trigger for pattern baldness. And finally, skin conditions like psoriasis and seborrhea can also cause or contribute to inflammation in and around the hair follicles, which means they may also have an effect on the ability of the follicles to function normally, especially over time.

In men, androgenic alopecia affects the follicles initially at the temples and at the vertex of the scalp - the point near the back of the top of the scalp, where the horizontal surface of the scalp begins to descend down the back of the head. Over time, the condition can spread until only a wreath of hair is left. In women, pattern baldness is more diffuse, with thinning occurring across the scalp but without the receding hairline (in most cases). In both men and women, androgenic alopecia rarely progresses to complete baldness. Although initially, researchers believed affected hair follicles were no longer able to produce hair, today studies indicate these follicles may be dormant, suggesting therapies designed to wake up dormant follicles may be effective in promoting new hair growth. The patterns associated with androgenic alopecia differ markedly from alopecia areata, a less-common cause of hair loss that’s caused by an immune disorder. Alopecia areata causes hair loss to occur in circular “patches” rather than the standard patterns associated with male and female androgenic alopecia.

Androgenic alopecia is increasingly common among men as they age. Many men find it a distressing and unwelcome event and increasing numbers are seeking treatment to prevent further hair loss and reverse the process. The changes in the hair follicles that lead to baldness have caught the interest of stem cell scientists, geneticists, developmental biologists and immunologists, and hair biology has become an increasingly fruitful field of scientific endeavor. A number of therapeutic options are now available for these men with favorable cosmetic outcomes possible in the majority of cases. Learn more about these options in the second edition of this series, “Androgenic Alopecia: Treatment Options (Part 2).”