Background information :
The human body is mostly covered with hair. The hair plays a part in maintaining the thermal balance of the body, in addition to appearance. Starting from the 2nd month of pregnancy, the first buds of hair start to appear on the upper lip, eyebrows and cheeks. These buds are in the form of cell clusters, which increase in number and spread throughout the body starting from the 4th month. In a normal adult, there are approximately 5.6 million hairs. The condition that causes an abnormal amount of hairs in some people is called Hirsutism. The congenital lack of hair is called Atrichia. There are, on average, 100.000 hairs on a full head of hair. The average lifespan of a hair is 2-7 years. At the end of this period, the hair falls out and a new hair starts to grow out of the hair follicle.
What is Hair?
Human hair is comprised of a special protein called keratin. Keratin is a sturdy material that is found in fingernails. The hair grows out of a sheath, which is created by the outermost layer of the skin, called the epidermis, by reaching into the skin like a glove finger. This is called the external sheath. Between this and the hair’s body, there is the internal sheath. The cuticle layer is located between the internal sheath and the hair. These layers which surround the hair go into the skin together to form a knob. This is called the bulb. The lower tip of the bulb creates a cavity like a glove finger. This cavity contains the “papilla”.
How Is the Hair Color Determined?
Hair color is affected by genetic factors. The hair’s color depend on the thickness of the hair and the quality and quantity of the color pigment. Greying of the hair may also occur depending on genetic factors. Androgenetic Alopecia is the most common cause of hair loss in men. Androgenetic alopecia is a condition affected by androgens, which are male sex hormones, occurring in genetically predisposed men after puberty, during the 20s and 30s, first with the receding of the hairline in the forehead region, then with the thinning and opening of the crown area. Although this condition is known by many names, the most commonly used names are Androgenetic Alopecia, Male pattern alopecia and ordinary baldness. It may affect the entire head, but most commonly it will not affect the temples and the nape. It is not considered a disease, but rather a characteristic attribute of men. Androgenetic Alopecia can also be seen in women, however the way it occurs is different. During post-puberty, approximately half of all men can encounter androgenetic alopecia. Three main factors play a role in androgenetic alopecia:
Advanced age
An aging organism loses its endurance. As hair is a part of the organism, years also affect the durability of the hair. The ratio of the hair loss increases over time in genetically predisposed individuals.
Hormones
Research on baldness began 4000 years ago in Egypt. It is said that the first medical description of androgenetic alopecia was given by Aristotle in 4th century BC. The philosopher described the relationship between baldness and sexuality. Years later, some studies focused on this topic, determining that men who were sterilized did not go bald, and they conducted further research during the reign of Abdülhamit. All studies, old and new, have revealed that there is a relationship between baldness and the male hormone. Androgen is the male hormone. Testosterone, an androgen hormone, is converted into dihydrotestosterone (DHT) by an enzyme called Alpha-5 reductase. DHT acts by binding to the receptors on the hair follicles. Hair loss does not occur in men with alpha-5 reductase enzyme deficiency. DHT shortens the duration of the anagen phase in genetically predisposed individuals. This leads to a further shortening of the anagen phase in each hair life cycle. This means a reduction in the maximum hair length that can be reached and a relative decrease in the amount of hair in the anagen phase in the hair’s general appearance. The catagen and telogen phase (transitional phase and resting phase) end with hair loss. No change occurs in the duration of these phases. However, when the anagen phase is shortened, the ratios of all hair masses at any given moment increase relatively. This means that the amount of hair loss will be proportionally higher. Normally, two types of hair are produced in the anagen phase: 1. Terminal (thick and colored) hair 2. Vellus (thin and colorless) hair. As it is known, vellus hair sheds more quickly. Again, in people with Androgenetic Alopecia, with the effect of the hormones and the genes, an exponential reduction (miniaturization) occurs in the terminal hair follicles. As a result, terminal hair begins to resemble vellus hair. Weak, thin and colorless (vellus) hair begins to grow out of miniaturized follicles. When the follicles that keep shrinking are put under a microscope after a while, it can be observed that they have turned into the residue of the cell sheath, thereby effectively destroying the hair follicle. Both men and women have the androgen hormone. One may ask that, since everyone has these hormones, why doesn’t everyone experience hair loss? In addition to being a genetic carrier, the following will also play an important role:
1. The number of androgen receptors in the hair of people with Androgenetic Alopecia is high. Although the hormone is at a normal level, because the number of receptors that bind the hormone is high, the hormone’s effect on the hair becomes bigger.
2. The receptors of people with Androgenetic Alopecia are more sensitive.
3. The Alpha-5 reductase enzyme activity of Androgenetic Alopecia cases is higher.
Incidence
It was reported that after puberty, 94.96% of white men had a receding hairline on the forehead area, and about 50% had hair loss on the forehead and crown areas. 30% of men at the age of 25, 40% at the age of 40, and 50% at the age of 50 show signs of Androgenetic Alopecia. Androgenetic Alopecia is encountered in 20-30% of women.