Root Causes of the Great Hair Migration

Don’t worry, men: You are not really losing the hair on your head; it’s merely migrating to your back – or so it may seem.
As we age, body hair performs an undignified switcheroo. It thins on the top of the head while proliferating on the back, the chest, in our nostrils and just about everywhere else.

“Basically, you get hair where you don’t want it and lose it where you do want it,” said Dr. Alfred Hernandez, a Sarasota dermatologist.
This problem also afflicts women, but to a milder degree. That lustrous head of hair they sported in their youth starts to thin; meanwhile, hairs appear on the lip, chin, around the nipples, on the chest, abdomen and buttocks.

The culprit in both sexes is testosterone.
“Body hair – particularly sexual hair, which is hair under the arms and pubic hair – is very sensitive to testosterone levels in both men and women,” said Dr. Adrian Dobs, a professor of medicine at Johns Hopkins University School of Medicine. “Testosterone binds to the testosterone receptor in the hair follicles and stimulates hair growth.”

Testosterone doesn’t create hair on the body; it merely stimulates the follicles to transform short, fine vellus hairs, which are barely visible, into longer and darker terminal hairs.

Because both sexes produce testosterone, both have terminal hair on the arms, legs and other parts of the body, but because men produce about 10 to 20 times as much testosterone as women, they tend to have more conspicuous body hair.

For some women, unwanted hair may be the result of an endocrine problem known as polycystic ovarian syndrome. PCOS occurs when tiny ovarian cysts disrupt hormone production, resulting in irregular periods, acne and excessive body hair. But in most cases, the amount of unwanted hair is determined by the number of hair follicles on the body and the sensitivity of those follicles to testosterone.

Women of Mediterranean background, for example, tend to inherit many more hair follicles than Asian women, and when sensitized by testosterone at puberty, those follicles are more likely to produce longer, darker hairs.

Because hormones steadily decrease after peaking in a person’s late teens and early 20s, one might expect body hair to diminish, but hair follicles, once stimulated by testosterone, remain stimulated.

“Hair follicles respond to how long the testosterone has been around rather than to the absolute blood level of the hormone,” said Dr. Geoffrey Redmond, an endocrinologist in New York who specializes in hormonal hair and skin problems. “Even if testosterone levels drop, a person won’t go back to looking like a child with no facial or body hair.”

In contrast, hair follicles on the top of the head tend to respond to testosterone by shutting down.
“Baldness and back hair are both due to testosterone, but the hair follicles have the opposite response to testosterone,” Redmond said. “Testosterone inhibits the hair follicles on the scalp but stimulates them elsewhere on the body. They’re all responding to the hormone, but something different happens on the scalp when the hormone reaches the cell.”

Eradicating body hair can be just as difficult as growing hair. A prescription cream called Vaniqa inhibits the growth of facial hair on women somewhat, and a drug called spironolactone, developed as a diuretic for people with congestive heart failure, seems to inhibit the growth of hair all over the body.

Vaniqa and spironolactone (sold under the name Aldactone) are prescribed primarily for women who have long battled unwanted hair on their face and elsewhere.
Michael Boroughs, a research assistant at the University of South Florida in Tampa, has noticed that men have started trimming and removing body hair too, so he launched a study based on interviews with 132 men between 18 and 35. He found that 64 percent of them trimmed or removed hair below their neck.

“Some have been doing it for 10 to 15 years,” Boroughs said. “And even though you see lots of ads for laser hair removal, that was at the bottom of the list. Most use razor and shaving cream.”

Some men remove body hair to show off the muscles they’ve cultivated in the gym. “Removing body hair makes the muscles look more defined,” Boroughs said.
“But when we asked them why they shaved, we found an interesting contradiction. The highest percentage – 73.8 percent – said they did it for cleanliness. They said hair on their bodies felt unclean. They gave other reasons: 70.2 percent said they did it to increase their sex appeal, but only 40.5 percent said they did it for muscle definition.”

Only two techniques eliminate body hair permanently –

electrolysis and laser treatment. Redmond thinks the two treatments are equally effective, but each has a drawback. Because electrolysis involves inserting a fine needle into a hair follicle and administering a small jolt of electricity, it is very time-consuming and slightly painful. “Electrolysis is fine if it’s a limited area,” Redmond said.

To remove hair from the back, the chest or other large areas, laser treatment is quicker, but it costs thousands of dollars and can be dangerous for people with dark skin.

“The pigment is what absorbs the energy,” Redmond said. “When the hair is black and the skin is very white, the laser heat will be transmitted only to the hair. When a person has black hair and dark skin, however, the laser heat will be transmitted not only to the hair but to the surrounding skin as well, which may cause depigmentation.”