What causes baldness

The effects of male hormones on genetically susceptible hair follicles cause androgenetic alopecia. Male hormones blamed to cause hair loss are also called androgens, hence the name “androgenetic alopecia”. There are three important factors involved in the hair loss process caused by androgenetic alopecia. These factors are closely related to each other.

Hair loss due to androgenetic alopecia occurs only if a person has a specific genetic code in his or her chromosomes. This code responsible for baldness is carried by a single gene or a group of genes and may be inherited from either mother or father.

A popular explanation for the inheritance of androgenetic alopecia is that a gene that is supplied by the mother and expressed in the sons who carry it. Genetic analyses of the chromosomes of patients with androgenetic hair loss have revealed that this belief was false in two respects: First, androgenetic hair loss is inherited in an autosomal dominant manner, that is, the gene responsible for hair loss can be inherited from either parent. Second, this genetic code can be expressed in both males and females; that is, both sons and daughters may have androgenetic alopecia in their future.

Another important point to note is that not everyone who carries the gene(s) responsible for androgenetic hair loss will develop baldness. To be active, the gene for baldness has to be “expressed” in the individual. The expression of a particular gene or genes depends on several factors such as hormones, age, stress level and so on. Thus, if a person does not develop male pattern baldness, the reason can be either the absence of this gene or lack of its expression.

A specific gene (or genes) responsible for androgenetic hair loss has not yet been identified. But scientists are sure that this gene (or genes) is involved in the synthesis of male hormones, the enzyme 5-alpha reductase and androgen receptors located on the hair follicles. These are found to be the three main actors involved in the process of male pattern baldness. 5-alpha reductase is the enzyme that converts testosterone (a male hormone) to a more active form, dihydrotestosterone (DHT), which binds in turn, to the androgen receptors found on hair follicles.

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.

Hair loss causes

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.

Male hair loss

Two types of androgens are involved in the mechanism of male pattern hair loss. These are testosterone and dihydrotestosterone (DHT). Dihydrotestosterone is a derivative of testosterone. The enzyme called 5-alpha reductase converts the relatively inactive testosterone to a more potent form, dihydrotestosterone. Thus, the key enzyme involved in androgenetic hair loss is 5-alpha reductase, which is also found in and around the hair follicle, especially in the dermal papilla. Once formed, this potent male hormone, DHT gains ability to bind any androgen receptor on the hair follicles. Plain testosterone can also act on the follicles, but its effect of causing hair loss is weaker.

By the interaction of these two hormones and their receptors on the follicle, hairs covering the scalp undergo some changes ending with hair loss. Over time, the growth cycles of the terminal hair follicles on the scalp get progressively shorter, with reduced anagen (growing) phase. Catagen (intermediate) and telogen (shedding or resting) phases of hairs remain the same, thus, yielding a net result of increased number of resting hair follicles. So, the usual proportion of telogen follicles (10%) increases up to 20% of total. That is, more hairs enter the resting stage and the number of hairs that shed increases.The affected follicles decrease both in length and diameter, growing thinner, shorter and more brittle hairs with weaker shafts.

Hormonal hair loss

One may ask why do some people develop male pattern baldness while others do not, although all men and women have these hormones causing hair loss and their receptors in their bodies? There is not a satisfactory answer to this question. There are some speculations however, of which the most important ones are mentioned below:

  • In the balding areas of the scalp of patients with androgenetic hair loss the number of androgen receptors in a single hair follicle is higher than normal. So that with the same level of androgens in the bloodstream, a more pronounced effect of androgens (that is, hair loss) is observed, as if their levels were higher than normal.
  • In balding persons’ hair follicles sensitivity of receptors to androgens is higher than normal, thus, resulting again in a more pronounced effect of androgens (that is, hair loss) in normal levels.
  • The activity of the enzyme 5-alpha reductase is higher in the balding area, thus, converting more testosterone to dihydrotestosterone. The higher the proportion of DHT to testosterone; the faster is the hair loss process.

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 ageing 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.