Androgenetic alopecia, known as “common baldness,” is the most common cause of scalp thinning. It occurs in about 70% of men and 40% of women.
The causes of the condition are indicated by the term itself. “Andro” indicates the action of androgenic hormones, “genetic” emphasizes the need for a genetic predisposition for hormones to affect the proper functioning of the life cycle of hair follicles.
The enzyme 5-alpha-reductase type 2 is responsible for the transformation of testosterone into dihydrotestosterone (DHT). Only if there is a genetic predisposition, as we have said, DHT affects the hair follicles leading to their miniaturization and consequent hair loss.
This occurs because the growth phase of the hair, defined as anagen, is increasingly reduced, leading the follicle into the involution phase, catagen, and finally to rest, telogen.
It occurs in both men and women.
Androgenetic alopecia manifests itself differently in men and women. Generally, in men it affects first of all the fronto-temporal areas and the crown area and then extends, in some cases, to the frontal, mid scalp and vertex. In women, however, the hair line is spared, and there is a widespread thinning in the upper part of the scalp.
We speak, in the latter case, of “female androgenetic alopecia“. However, it should be noted that this pattern of thinning occurs, albeit more rarely, in male individuals.
Two diagrams indicating the degrees of androgenetic alopecia have been developed. The Hamilton-Norwood Scale measures the degree of baldness in male individuals, while the Ludwig Scale classifies the degree of baldness in women.
What genes are involved?
Experts are not yet able to answer this question. The numerous studies conducted have not allowed to identify the genes that predispose to hair loss.
For this reason, androgenetic alopecia is defined as a polygenic pathology, that is, caused by different genes.
The androgen receptor gene, for example, is identified in the X chromosome. It is inherited by the male from the maternal family. Scholars have discovered other genes that contribute to a predisposition to androgenetic alopecia, and research in this field is taking place constantly.
Treatments to counteract myiniaturization
The Food and Drug administration (FDA), the U.S. agency that deals with the regulation and certification of pharmaceutical and food products, has so far recognized two drugs indicating them as effective against baldness: Minoxidil and Finasteride.
Androgenetic Alopecia and Minoxidil, growth stimulator
Below we briefly analyze its characteristics. Discovered in 1980, Minoxidil was initially used against hypertension, thanks to its vasodilatory capacity.
Among the side effects was observed a tendency to hirsutism, ie a growth of hair and hair. For this reason it was approved as a drug against androgenetic alopecia.
Today it is used for topical and oral use, especially for men. It is on the market under different names, such as Amexidil, Aloxidil, Regaine, among many others.
Alopecia Androgenetica and Finasteride, anti DHT.
Finasteride acts through the inhibition of the enzyme 5-alpha-reductase type 2. Discovered as a drug against benign prostatic hypertrophy, it is produced by the pharmaceutical company Merck.
It was introduced in the USA in 1992 under the name Proscar against prostatic hypertrophy and in 1997 under the name Propecia against androgenic alopecia. The sale in Italy for use against androgenetic alopecia was approved in 1999.
DUPA: photographs and explanation
In the picture below two examples of patients suffering from DUPA (diffuse androgenetic alopecia),
or a condition of diffuse miniaturization that also affects the donor area: