androgens and pattern baldness
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Androgens and pattern baldness

In a world where personal appearance is constantly gaining importance, hair loss can be a very serious condition for both men and women. In order to regulate the growth of hair in certain areas of the body, a solid understanding about what causes hair loss can be extremely helpful. This research has been initiated by a team of scientists who have recently discovered some very interesting facts about hair loss.

Scientists have determined that one of the most important elements in the growth process of hair is the activity of androgens in the body. Androgens are male sex hormones that promote the development and maintenance of male sex characteristics in the body. One of these characteristics is hair growth. The major androgen in the body is known as "testosterone" but another important androgen is also known as "dihydrotestosterone" or DHT. DHT is made from testosterone by enzymes called 5 alpha reductase.

Scientists have recently discovered that, our body hair is dependant, at least in part, upon the presence of androgens. For most body hair follicles, androgens stimulate their growth activity and make small vellus hair follicles into larger terminal hair follicles that produce bigger hair fiber. In contrast, hair follicles on our scalp do not need androgens to grow into large terminal scalp hair follicles. Some scalp hair follicles have no significant response to androgens (mostly those follicles at the back of our scalps), but other scalp hair follicles (mostly limited to hair follicles on the top of our scalps) may actually start to miniaturize and even disappear when certain androgens become active! Body hair will grow when there are androgens in the body but scalp hair sometimes won't! This is a paradoxical fact about androgens that has had scientists "scratching their heads" for answers. Why should body hair follicles increase their growth while scalp hair follicles reduce their growth in response to the exact same androgen hormones?

It is common knowledge to most people that women almost always have a low level of testosterone in their bodies. Men, however, generally have a lot more testosterone than women. Since scalp hair does not need androgens to be present for hair growth to occur, women usually have just as much hair on their heads as men and often more! Scalp hair, it seems, will grow regardless of the presence of androgens in the body. Certain androgen activity, however, may also contribute to male pattern baldness.

This paradoxical fact about androgens was examined more closely through a controlled study of both men and women. This test was done through the introduction of a drug called Finasteride into the body. It was administered to both men and women and the results were astounding. When Finasteride was given to men who had suffered from scalp hair loss, the men showed a marked improvement in the growth of their scalp hair. When Finasteride was given to women with scalp hair loss, there was no improvement. From these results, scientists concluded that male pattern hair loss and female pattern hair loss were completely different conditions and they were based on completely different circumstances.

Of course, many people already know that male pattern baldness is different from female pattern baldness just from the typical age at which the sexes seem to acquire the condition. Men seem to go bald at an earlier age than women, usually in their 30's and 40's. Women, however, usually don't start to show signs of baldness until they are in their 50's. Men also tend to go completely bald whereas women usually show just a marked thinning of their hair. These obvious differences were made a lot clearer, however, through scientific studies.

The truth about androgens was studied in even more detail after the discovery was made that Finasteride could positively affect male pattern baldness but not affect female pattern baldness. Scientists wanted to know "What's going on here?" In the test, Finasteride was also referred to as a "type 2 5 alpha Reductase inhibitor". Finasteride was an "inhibitor" because it actually slowed down the production of the enzyme known as "type 2 5 alpha Reductase". This is one form of the enzyme that converts testosterone into DHT. By examining the effects of this slow down on enzyme activity, more conclusions were drawn.

By slowing down the production of the "type 2 5 alpha Reductase" enzyme in the body, Finasteride slowed down another process that normally took place in the body. This drug Finasteride was really having quite an effect! The process that was slowed by Finasteride was the process of testosterone being converted into DHT. Remember testosterone is the primary androgen in the body and DHT is another important androgen that comes about when testosterone is converted. Scientists thought that the conversion of testosterone into DHT was what eventually leads to Male pattern baldness. They found that they could stop the baldness from happening by inhibiting the "type two 5 alpha Reductase" enzyme and thereby stopping the DHT from forming in the body. This conclusion turned out to be true.

The problem is a bit more complicated than just having too much DHT in the body, but scientists were certainly well on their way to a new treatment for male pattern baldness. It still had to be explained by scientists that men who acquired male pattern baldness also had a genetic predisposition that contributed to the condition. In fact, the presence of DHT had to occur in combination with another factor; that of having hair follicles that were oversensitive to androgen activity. If the men had a genetic predisposition to be oversensitive to androgen activity, then the DHT would always adversely affect their hair growth.

One molecule of DHT actually has five times the androgen activity in the body as one molecule of testosterone. Androgen activity has a positive affect on body hair, but a negative effect on scalp hair in many men with the genetic disposition to androgen oversensitivity. As long as testosterone is being converted into DHT, this increase in androgen activity will come about and those with the genetic disposition to male baldness will start to lose their hair. This DHT formation is helped along by the presence of the enzyme "type 2 5 alpha Reductase" so, as scientists had originally theorized, the "type 2 5 alpha Reductase" enzyme had to be stopped!

Men have been lucky in that the treatment of Male pattern baldness has been extremely successful through the use of the "type 2 5 alpha Reductase inhibitor" Finasteride. Women have not been as lucky as men. Scientists have still not been able to clearly determine what causes female pattern baldness. These two conditions are very different and female pattern baldness will need more study in order to determine a successful treatment.


Androgens and pattern baldness references

  • Kaufman KD. Androgens and alopecia. Mol Cell Endocrinol. 2002 Dec 30;198(1-2):89-95. PMID: 12573818
  • Shapiro J, Kaufman KD. Use of finasteride in the treatment of men with androgenetic alopecia (male pattern hair loss). J Investig Dermatol Symp Proc. 2003 Jun;8(1):20-3. PMID: 12894990
  • Kaufman KD, Dawber RP. Finasteride, a Type 2 5alpha-reductase inhibitor, in the treatment of men with androgenetic alopecia. Expert Opin Investig Drugs. 1999 Apr;8(4):403-15. PMID: 15992088
  • Kaufman KD. Androgen metabolism as it affects hair growth in androgenetic alopecia. Dermatol Clin. 1996 Oct;14(4):697-711. PMID: 9238328
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