Theories about male pattern baldness
An old theory about the cause of male pattern baldness, proposed by Dr. Lars Engstrand of Sweden, was the tight scalp or more properly the tight galea theory. The galea is the flat, thin, fibrous membrane covering the crown of the head. It's about forty square inches in area. According to Dr. Engstrand, after males reach puberty, the galea tends to become thick and inelastic because of the influence of the male hormone testosterone.
Supposedly a thick and inelastic galea constricts the blood vessels that nourish the hair follicles. When this happens the follicles shrink and cease to produce a healthy hair. Engstrand performed a chilling surgical procedure to ease scalp and galea tension. A similar procedure is still being performed in Europe today.
There are some weaknesses in the tight scalp theory--in fact, many weaknesses. But there is also some plausibility because a positive correlation exists between a tight scalp and hair loss. But correlation does not necessarily mean causation. For example, there does seem to be a positive correlation between the length of a man's marriage and the loss of his hair. The problem is that one doesn't necessarily cause the other. Or then again maybe it does.
The current theory about the cause of male pattern baldness is complex but it is also credible. It holds that in males who are genetically predisposed to baldness, certain areas of scalp tissue start to produce an enzyme. The enzyme is called 5-alpha reductase. This enzyme converts the male hormone testosterone circulating in the bloodstream into dihydrotestosterone or just simply DHT.
Let me restate this because it is a complex theory. In men who are prone to baldness, areas of scalp tissue (and these are the areas that become characteristically bald) start to produce 5-alpha reductase which grabs testosterone from the bloodstream and converts it into the potent metabolite DHT.
DHT is the culprit. DHT has an adverse affect on the hair follicles. Here's a simplistic statement on how it works. High concentrations of DHT in the follicles cause them to spend less time in the growing stage and perhaps more time in the resting stage of the hair cycle. I now want to discuss in some detail the hair cycle because this is an important concept if one is to understand male pattern baldness - androgenetic alopecia.
The three stages of the hair cycle
The first is the growing stage or anagen. This stage lasts from two to five years. At any one time about ninety percent of the hair follicles are in this stage. During this stage certain cells at the base of the follicle in an area called the matrix produce the tough protein keratin of which the hair is composed. (See the drawing.) When these cells (the keratinocytes) are working properly, they produce a hair thick in diameter. This is called a terminal hair. But when these cells are not working at their full capacity they produce a hair thin in diameter. This is called a vellus hair. It's the kind of peach fuzz you see on the scalps of men who are going bald. When the follicles spend less than the normal amount of time in the growing stage because of the influence of DHT, they tend to produce vellus hair.
The second stage of the hair cycle is catagen - this is a transitional stage. It lasts just a week or two. At any one time only one or two percent of the hair follicles are in this stage. During this stage there is a rapid wrinkling and contraction of the lower part of the follicle. Keratin and melanin production cease during this stage. (Melanin is the molecule that gives color to the hair.)
The third stage of the hair cycle is the resting stage or telogen. This stage lasts between three and five months. At any one time about ten percent of the hair follicles are in this stage. During this stage the old telogen hairs just rest in the now fully contracted follicle bulbs. Late in this stage these old hairs gradually start to fall out, so it is not unusual for a man or a woman to lose between thirty and fifty of these hairs daily. But with healthy hair follicles, these old telogen hairs are replaced by new anagen hairs in the next growing stage of the hair cycle.
The hair follicle is the factory where the hair and the hair coloring are produced. The activity of each follicle is independent of the others (a mosaic pattern). Each follicle has its own rhythm going through the various stages of the hair cycle perhaps twenty-five times in a person's lifetime. Enlargement or miniaturization of the follicles takes place only during the early growing stage.
The hair matrix is where the action takes place. Here specialized cells produce the keratin of which the hair is made and the melanin which stains the keratin giving the hair its color. This action takes place during the growing stage of the hair cycle. Hair synthesis and melanin production occur deep in the follicle's core. Superficial cures for baldness like shampoos to "unclog" the follicles or tonics with "active ingredients" to stimulate hair growth don't work.
You can see in the drawing that the follicle is nourished by a network of capillaries. These capillaries are the delivery system bringing nutrients to the base of the follicle. The amount of blood available to the scalp and therefore to the follicles is determined by the health of the capillaries in the scalp and of the arteries in the neck and temples.
Most dermatologists tend to be highly skeptical of any approach or treatment that is not in accord with their biochemical theory. (See the last section on this page for an in-depth treatment of the biochemical theory.) They have a right to be skeptical. The biochemical theory is strong. These dermatologists believe that hair loss is not related to things like clogged follicles, improper diet, toxins in the blood, lack of blood circulation to the follicles, and emotional trauma. They believe that certain people are genetically predisposed to baldness, and that very little can be done to slow down, stop, or reverse the inevitable.
They believed this until recently. Most dermatologists these days are recommending either Rogaine or Propecia or a combination of both. The fact that many hair follicles tend to regrow during the use of Rogaine and Propecia has cast doubt on the old irreversibility theory of male pattern baldness.
A clear statement of the biochemical theory
From everything I've read about the biochemical theory of male pattern baldness, I've extracted the following--and I want to give this the clearest expression I can without cluttering it up with too much detail.
The male hormone testosterone circulating throughout the body has receptor sites to which an enzyme attaches itself. The specific enzyme is called 5-alpha reductase. It is formed in scalp tissue and in the sebaceous glands which are adjacent to each follicle and in other parts of the body too. When this enzyme attaches itself to the testosterone, it triggers the conversion of this hormone into DHT (dihydrotestosterone).
Certain cells that comprise the hair follicles in turn have receptors to which this DHT attaches itself. The number of these receptors and their sensitivity varies depending on where the hair follicles are on the scalp. Follicles in areas of the scalp that become characteristically bald probably have more receptor sites and these receptor sites tend to be more sensitive to DHT.
DHT once it becomes attached to the hair follicles has an adverse effect on these follicles in several ways:
- It shortens the growing (anagen) stage of the follicles and possibly lengthens the resting (telogen) stage.
- It causes a shrinking (miniaturization) of the follicles so that they can no longer produce a hair thick in diameter.
- It may cause a constriction of the capillaries that nourish the follicles.
The understanding of all this is certainly not necessary for my approach to work. In fact, the full understanding of the biochemical process will probably make my approach seem foolish if not downright fraudulent. I hope these mixed signals do not discourage anyone from at least trying my approach. There is nothing fraudulent about it. Another reason, though, for my writing about the biochemical theory of male pattern baldness is to inoculate people against the truly fraudulent material out there especially on the Internet. A thorough understanding of the subject will give readers a healthy skepticism about all promises of cure.
Continue to - Female Hair Loss
Isoenzymes are chemically distinct forms of an enzyme (iso means equal). Even though they are chemically distinct, they catalyze the same physiological reaction. DHT is produced from testosterone by two 5-alpha reductase isoenzymes called type I and type II. The conversion takes place in scalp tissue close hair follicles susceptible to androgenetic alopecia (AGA). DHT is unstable - it breaks down quickly. It has to be created close to the hair follicles for it to have its negative effect.
"Because a hair follicle probably has only a limited number of cycles in it - a good guess is 25 - the shorter the cycle, the sooner it will stop producing hair. That's what happens in most bald men. "Their follicles live fast and die young." I don't know who wrote this, but it's a depressing statement.
Change in hair diameter
The diameter of the hair changes only with the emergence of the new anagen follicle. Before the hair follicle gets either larger or smaller, it has to enter the telogen resting stage first. As it enters the new anagen stage, the hair follicle redevelops but does not always stay the same size as it was in the previous cycle. Sometimes it gets smaller (miniaturizes); sometimes it gets larger and therefore produces a thicker hair. Often it takes several cycles for the hair follicle and therefore the hair shaft to make a significant change in size.
"Will my hair thicken in diameter?"
If the hair shaft gets thicker in diameter it will do so only in the early anagen stage of the hair cycle. In other words, the hair shaft does not get thicker in the later periods of the long growing stage. It may get thicker only in the early stage of anagen when the new hair shaft emerges from the hair canal after the old telogen hair falls out or, less likely, is pushed out. This depressing narrative of the hair cycle explains why it takes such a long time for progress to be made. Young people, especially, tend to be impatient. I can understand why they don't like the idea of waiting perhaps a year to see a better image of themselves in the mirror. I was impatient too so I understand this. But biology cannot be altered by wishful thinking.