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For men, a huge increase in androgen production occurs during puberty. Testosterone circulates throughout the male body and starts causing a number of changes - the voice deepens, there's an increase in skeletal and muscular development, and pubic hair begins to grow. Facial hair also starts to emerge, and with it, a lifetime of shaving begins! (What I find really interesting here, is that testosterone, which has been cited as the hair loss cause, will also produce hair growth at puberty). So, how exactly is hair loss caused by testosterone? Most research suggests that it's dihydrotestosterone that provokes the hair loss caused by androgenetic alopecia. Dihydrotestosterone (DHT) is a biologically active metabolite (derivative) of testosterone. It's about 30 times more powerful than testosterone and currently thought to be the most potent androgen that affects human hair growth. It's formed in the testes (testicles), prostate gland, adrenal glands and hair follicles by an enzyme called 5-alpha reductase. Most hair loss professionals agree that the attachment of DHT to receptor sites in the follicles (that grow hair) is largely suspected as the hair loss cause. (A receptor is an arrangement of molecules that will bind to other molecules with a complimentary shape). This theory states that, when DHT binds to these receptors, it can force a follicle to shrink and enter the resting stage of the hair growth cycle. And, because this happens earlier than usual, it will also reduce the length of time subsequently spent in the growth stage. This results in the production of hair that becomes thinner and shorter with each successive growth cycle. Eventually, when the DHT has attached to a large number of receptors, the follicle shuts down - it becomes dormant and hair growth stops. Note:
telogen effluvium
is usually the type of hair loss caused by growth cycle deviations in this way. There has been much research and study of course, and suggestions made that DHT, 5-alpha reductase or the receptor sites are more abundant in those who lose hair (especially in the MPB region of the scalp). But, all these suggestions still fail to give the actual mechanism that would cause follicles to shrink and hair to fall. And, when a theory cannot give a full explanation, it casts serious doubt over its credibility - it follows that this theory is, in fact, wrong! The reason I know this is simply because this theory fails to answer the following very important questions concerning the hair loss process: 1. Testosterone and DHT will stimulate hair to grow in other parts of the body (especially during puberty as mentioned earlier). So, how can it be linked to both hair loss and growth? (This is the "fly in the ointment" that's been pestering trichologists and dermatologists for years - DHT should help scalp hair growth, not hinder it. This means that there must be something else that's causing the follicles to shrivel).
Find out more about skull expansion? Need convincing first? ![]() ![]() Just look at these two very famous faces. You can see, quite clearly, that the skull shape of each is different - Brad Pitt has a flat crown (and a full head of hair), whereas Bruce Willis has a more domed shape (and complete hair loss). (This skull shape difference appears in both side-on and face-on profiles).
Other hair loss professionals believe that DHT increases sebum production (this is the oil that lubricates your hair) which then clogs up the follicles, making them shrivel and so become the hair loss cause. This theory also offers another reason why fewer women suffer androgenetic alopecia than men. To find out more about this theory (and why it's wrong) |
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