Hair Loss Canada > Hair Loss Information

Hair Loss Causes

Androgenetic alopecia accounts for 95 percent of men's hair loss. It is caused by heredity, hormones, and age. Scientific research has proven that the gene for hair loss comes from either or both sides of the family, and contrary to popular belief, is not traced only to the mother's side. The best indicator you have is your immediate family - if your family members are experiencing hair loss, you may also be at risk.

The rate of hair shedding in androgenic alopecia is speeded up by three forces: advancing age, an inherited tendency to bald early, and an over-abundance of the male hormone dihydrotestosterone (DHT) within the hair follicle.

The conversion from testosterone to DHT is driven by an enzyme called 5-alpha reductase, which is produced in the prostate, various adrenal glands, and the scalp. Over time, the action of DHT causes the hair follicle to degrade and shortens the anagen phase. Thought the follicle is technically still alive and connected to a good blood supply--it can successfully nurture a transplanted follicle which is immune to the effects of DHT--it will grow smaller and smaller. Some follicles will gradually die, but most will simply shrink to the size they were when you were born which produce weaker hairs. With a steadily shorter anagen growing cycle, more hairs are shed, the hairs becoming thinner and thinner until they are too fine to survive daily wear and tear. Balding hair gradually changes from long, thick, coarse, pigmented hair into fine, unpigmented vellus sprouts.

However, the sebaceous gland attached to it remains the same size. As the hair shafts become smaller, the gland continues to pump out about the same amount of oil. So as your hair thins, you will notice that your hair becomes flatter and oilier.

But the hormonal link in balding is complex. Eunuchs, who produce no testosterone, never go bald -- even if carrying a baldness gene. However, if castrated men with a family history of baldness are given testosterone, they lose hair in the classic horseshoe-shaped pattern.

Studies show that while balding men don't have higher than average circulating testosterone levels, they do possess above-average amounts of a powerful testosterone derivative, dihydrotestosterone in the scalp follicles. In male balding, genetically primed follicles convert circulating testosterone to dihydrotestosterone, which successively diminishes or miniaturizes follicle size, producing ever weaker hairs. With a steadily shorter anagen growing cycle, more hairs are shed, the hairs becoming thinner and thinner until they are too fine to survive daily wear and tear. Balding hair gradually changes from long, thick, coarse, pigmented hair into fine, depigmented vellus sprouts.

The amount of sebum in the scale has been linked to hair loss. Sebum contains a high amount of DHT, and clogs pores in the scalp, both of which cause the malnutrition of the hair root. The amount of sebum in balding hair is related to the amount of oil in the hair, and most doctors agree that frequent shampooing is advised in hair loss cases with oily scalps.

Other physiological factors might cause hair loss. Recently, a group of Japanese researcher reported a correlation between excessive sebum in the scalp and hair loss. Excessive sebum often accompanying thinning hair is attributed to an enlargement of the sebaceous gland. They believed excessive sebum causes an high level of 5-alpha reductase and pore clogging, thus malnutrition of the hair root.

Although this condition could be hereditary, they believe diet is a more prominent cause. The researchers note that Japanese hair was thick and healthy, with a small gland and little scalp oil, until the occidental habit of consuming animal fat crept into their diet after World War II. This change has led to a significant height increase in the Japanese population, but it has also resulted in more Japanese men losing hair. To some extent, their observation makes sense since problems with greasy hair have often been noted as much as six months to a year prior to when thinning hair becomes noticeable, but this might be just one of the symptoms, not underlying cause, more research is needed. Most doctors agree that if you have a oily scalp with thinning hair, frequent shampooing is advised. shampooing can reduce surface sebum, which contains high levels of testosterone and DHT that may reenter the skin and affect the hair follicle.

"The major reason for hair loss is genetic, but that is a black box," said Dr. Howard Baden, a dermatologist at Massachusetts General Hospital.

Medical researchers in Asia believe that hair loss is caused mainly by insufficient blood  supply to the scalp and poor circulation. The other possibility is excessive sebum in the scalp which causes pore clogging and malnutrition in the hair root, making it impossible for new hair to grow.

And so far, maybe that we simply don't know enough about the science of hair loss, there is still not an ideal cure for hair loss.

back to Hair Loss Information