Androgenetic alopecia is the most common form of male baldness and represents 95% of alopecia cases. It occurs in women with some differences (female androgenetic alopecia).
Hair loss is initially observed in the frontal line and progresses to the upper part of the scalp. The back and sides retain, for the most part, the existing hair.
The medical term of hair loss is alopecia, and can be transient or permanent.
Androgenetic alopecia is a correlation of gene action and androgens (male hormones).
How it appears
Hair loss does not follow a steady trend and has periods of exacerbation and remission. It sometimes has recurrences and sometimes stabilization signals. It is important to clarify that it is due to the combination of the reduction of the density and the amount of hair:
- Hair degeneration causes discoloration and weakening of hair follicles
- Gradual loss of hair growth
The cause of androgenetic alopecia can be:
- Hereditary predisposition
- Androgens
Hereditary predisposition
At the center of each human cell there are 46 chromosomes that appear in pairs (one by the mother and one by the father).
The first 22 chromosomes are the same for both sexes. Couple 23 is different in men and women.
Each chromosome contains thousands of genes, which also appear in pairs and come from parents.
As for hair loss, you may have a history of hereditary on the part of both your father and mother, and sometimes may occur after many generations.
Even the fact that there is somebody in hereditary predisposition does not necessarily mean that hair loss can definitely happen, or it will be in the same form as their ancestors.
Hereditary predisposition is responsible not only for the appearance but also for the growth and development of the phenomenon during the life of the person.
Although genetic predisposition exists, hair loss is followed by androgen action and age. In essence hair loss is due to the inability of the body to produce the necessary number of new hair.
Androgens
The endocrine system of humans is made up of a set of glands located in various parts of the human body (pituitary, adrenal gland, hypothalamus, thyroid and parathyroid), with the production of hormones that regulate the activity of other organs and body tissues . An important role in hormone activity also has ovaries, testicles and pancreas.
Hormones are biochemical substances circulating in the blood that regulate the physiological functions of the body.
Androgens are hormones produced in humans and in small quantities in women. As for the male, they are responsible for the characteristics of masculinity. The major representative of androgens is testosterone.
To understand the mechanism of action of androgens, some key features of hair must be mentioned.
The hair sprouts in groups of 1-4 hair called hair follicles. The individual follicular units are distributed along the frontal line and, as you move into the scalp, the hair follicles form groups of 2, 3 or 4 hair. Each hair follicle is an integrated biological unit and contains nerves, blood vessels, sebaceous glands, collagen and muscle pili.
Each hair follicle is characterized by a predetermined genetic type.
In the case of hair loss, hair follicles at the top and front of the scalp are susceptible and sensitive to the presence of dihydrotestosterone (DHT). Testosterone, through the action of 5-alpha reductase (5-reductase) enzyme, is converted to DHT, which enters the follicles, acts on the receptors, and causes changes in their functioning.
As a result, hair follicles gradually narrow to each hair cycle: some of them are at idle and some are able to produce healthy hair: hair becomes smaller in diameter and length, and lighter ( miniaturization). This explains the fact that initially there is a decrease in hair density, but not due to hair loss, but due to progressive thinning.
As a result, hair loss occurs gradually and is the most common type of androgenetic alopecia.
In a more general description, it can be said that DHT action shortens the anagen phase (anagen phase) during which the hair grows.
As a result, the hair enters the telogen phase (telogen phase), during which hair growth stops, begins to weaken and apoptosis occurs.
It is also important to note that men with hair loss problems do not necessarily have higher levels of testosterone and other androgens in their bodies, only their hair follicles are more susceptible to androgenic influence than other men . The extent of DHT receptors or elevated levels of 5-alpha reductase may also be found. For example, men with low 5a-reductase levels have androgenetic alopecia. We therefore understand that androgens cause hair loss only in combination with the existence of hereditary predisposition.
Also interesting is the correlation between oil and hair loss. Since the skin sebum contains DHT, sebum hypersecretion maintains higher levels of DHT in contact with the hair follicles, increasing the effect of the hormone in it.
Both the exact start time of hair loss and its evolution differ from person to person.
Hair follicles genetically susceptible to androgen must be exposed for some time, usually for years in the presence of hormones to begin to weaken.
Hair follicles over time undergo atonies and produce less healthy, thinner and smaller hair and contribute to decreasing density. Some follicles become inactive and no longer produce hair, helping to cause hair loss.
