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. DHT is a highly active form of testosterone, which influences many aspects of manly behavior, from sex drive to aggression.
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 (figure 3). 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 become 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 fleece 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 become 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 fleece sprouts.
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 a 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 the underlying cause, more research is needed. Most doctors agree that if you have an 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.
With advances in genetic engineering and genetic medicine, it will not take long for scientists to identify the specific gene (or genes) exclusively responsible for male pattern baldness. This will help us not only treat androgenetic hair loss, but also give us the ability to predict future hair loss in a newborn baby.
2- Hormonal hair loss
The hormones involved in the mechanism of androgenetic hair loss are male hormones, which are called androgens. The answer to the question “How androgens cause baldness?” is not straightforward. Androgens have profound influences on several biological mechanisms. They exert their actions by interacting with specific receptors found on cell membranes or inside cells, as all other hormones do. Several types of androgens can affect a single hair follicle and different types of hair follicles in different regions of the skin respond to the same androgen in different ways. For example, hairs located on the armpit respond to androgens by growing, whereas hairs in the scalp fall out in response to them.
There are several types of hair loss, some are more severe than others and some require more medical attention than others. Telogen Effluvium is one of the most common types but it is no less unwelcome to those who suffer from it. The condition is stress related and is not permanent. Rather than simply falling out, the hair first stops growing. It can then lie dormant for as long as 3 months before actually falling out. Unlike more severe types of hair loss, the hair will start to grow back during the following 6 to 9 months.
Another stress-related type of hair loss is Alopecia Areata. This occurs when white blood cells attack hair follicles. This then leads to rapid hair loss. The loss often occurs in patches but within the space of a few weeks, the entire scalp can be affected. In extreme cases, body hair can also fall out. The hair often grows back in time, but not always; in some cases treatment is required.
The most common type of stress-induced hair loss is telogen effluvium. In this type of hair loss, the hair stops growing and lies dormant, only to fall out 2 or 3 months later. Then it grows back within 6 to 9 months.
If you are experiencing hair thinning or baldness and you think there may be a problem then it is advisable to consult a doctor. It may be the body’s natural aging process but if you are still young; in your teens or early twenties, or if the loss seems irregular or uneven then there could be a problem.
In many cases of hair loss, the root of the problem is stress. Stress has always been with us, it’s not a new phenomenon, but due to increased awareness through medical advances and the way that the condition is reported in the media, we now have a better understanding of the debilitating effect it can have on people. The demands of modern life certainly don’t help and if you are concerned that stress may be the cause of your hair loss it is worth taking a good look at your lifestyle to see if there is anything you can do to manage your stress levels. (Scroll down for additional resources) Lifestyle plays a large part in our wellbeing and our hair is not impervious to this.
It should be kept in mind that even the presence of both, necessary genes and hormones, is not sufficient to cause androgenetic hair loss. The hair loss process also needs time, during which susceptible hair follicles will be exposed to male hormones. The time required for this kind of hair loss to take place varies from one individual to another. The development of male pattern baldness is dependent on a person’s genetic expression and the level of androgens in his or her blood.
Moreover, even when there is no predisposition to androgenetic hair loss, as people get older, some hairs randomly begin to shrink both in length and diameter. This process is called miniaturization. As a result, miniaturized hairs will be shed and actual follicular units decrease in number.