The androgenetic alopecia, also kwown as “common baldness”, is the most spread cause of hair thinning. It shows in around the 70% of men and 40% of women.
The causes of the condition are indicated by the term itself. “Andro” indicates the action of the androgen hormones, “genetic” underlines the necessity of a genetic predisposition. Only with the right predisposition the hormones will attack the correct functioning of the life cycle of the hair follicles.
The type 2 5-alfa-reduttasi is the responsable for the transformation of the testosterone into diidrotestosterone (DHT). Only when there is a genetic predisposition, as we said, the DHT attacks the hair follicles causing a miniaturization of them and the following hair loss.
This happens because the growing phase of the hair, called anagen, reduces always more, bringing the follicle to the de-evolution phase, catagen, and eventually to the rest phase, telogen.
It happens both in man and women
The androgenetic alopecia shows in different ways in man and women. Generally, it affects the man in the front-temporal area and in the crown area. From there, it spreads to the front, the mid scalp and the vertex. In women, instead, the hairline is safe and only a spread thinning in the superior part of the scalp occurs.
For the last case we talk about “feminine andrigenetic alopecia”. However, it is important to underline that this hair thinning pattern shows, even if rarely, in men too.
Two scales to measure androgenetic alopecia exist. The Hamilton-Norwood scale measures it in men, and the Ludwig scale measures it in woman.
Which genes are involved?
The experts are not able to answer this question yet. Many studies have been carried out, but still they do not allow to identify the genes involved in the hair loss.
For this reason, androgenetic alopecia in defined as a poligenic pathology, which means that it is caused by several genes.
The receptor genes for the androgenes, for example, are identified in the X chromosome. It is inherited by the male child from the family of the mother. The experts found out other responsable genes and the researches in this field keep on being carried out.
Treatments to combat miniaturization
The Food and Drug administration (FDA), the american institution that deals with the regulation and the certification of pharmaceutical and food products, has recognised, until now, two effective drugs against hair loss: Minoxidil e Finasteride.
Androgenetic Alopecia and Minoxidil, a growth enhancer.
We are now going to analyse the main features of Minoxidil. It was discovered in 1980. At the beginning it was used against hypertension, thanks to its vasodilator ability.
Among the side effects there was hirsutism, a great growth of hair and body hair. For this reason, the drug was at least approved against androgenetic alopecia.
Today it is used both topically and orally, expecially for men. It is present on the market under different names, such as Amexidil, Aloxidil, Regaine and many more.
Androgenetic Alopecia and Finasteride, anti-DHT.
Finasteride takes action by inhibiting the type 2 5-alfa-reduttasi enzyme. It was discovered as a drug against bening prostatic hypertrophy and it is produced by the pharmaceutical company Merck.
It was introduced in the USA in 1992 under the name “proscar” against the prostatic hypertophy and in 1997 under the name “propecia” against androgenetic alopecia. The sale of it against androgenetic alopecia in Italy was approved in 1999.
In the picture two examples of patients who suffer from DUPA (spread androgenetic alopecia), a spread thinning condition that affects the donor area too: