Androgenetic Alopecia is a progressive loss of hair on the head caused by atrophy of the hair follicles under the influence of male sex steroids. It occurs in both men and women. Initially, diffuse thinning and thinning of the hair occurs, then the formation of bald patches and, finally, complete baldness of the frontal-parietal zone. During the diagnosis, a trichogram, biochemical and hormonal blood tests, and a scalp biopsy are performed. Hair growth stimulators, antiandrogens, physiotherapy, hair follicle transplantation from donor zones are used for treatment.
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Androgenetic (androgenic) alopecia is a type of baldness characterized by hair loss in the frontal-parietal region. It occurs in persons of both sexes, much more often in men. Males develop at any age after puberty, usually after 35-40 years. By the age of 50, about half of men suffer from androgenic baldness. In women, the peak incidence occurs in postmenopause: the frequency of alopecia increases from 2-5% in 30 years to 40% in 70 years. Modern trichology has accumulated sufficient scientific data on androgenic alopecia: its etiopathogenesis, clinical course and treatment.
Causes of androgenetic alopecia
To date, it is known that androgenic alopecia refers to genetically determined diseases associated with increased sensitivity of hair follicles of the scalp to androgens. At the same time, the predisposition in women is inherited autosomal recessive, in men – autosomal dominant or multigenic (alopecia is detected in 81.5% of sons whose fathers suffer from baldness). The candidate genes studied encode androgen receptors, histone deacetylases 4 and 9, and the Wnt10a protein.
In addition to the hereditary factor, age, other diseases, and lifestyle matter. The risk of androgenic alopecia increases in the presence of:
- bad habits: smoking, alcohol dependence;
- endocrinopathies: hypo- and hyperthyroidism, hypoparathyroidism, Cushing’s syndrome, PCOS, ovarian and adrenal tumors, hyperinsulinism;
- diseases of the scalp: seborrhea, folliculitis;
- stress factors;
- excessive exposure to ultraviolet light.
Alopecia in men can develop against the background of normal levels of androgenic hormones, in women there is always hyperandrogenism.
With certain differences in the mechanism of development of male and female androgenic alopecia, there are common pathogenetic links: high activity of 5-alpha-reductase, excess dihydrotestosterone (DHT) and hypersensitivity of hair follicles to DHT.
Under the influence of the enzyme 5-α-reductase present in the hair follicles, testosterone is transformed into the hormone dihydrotestosterone, which binds to androgen-sensitive receptors. There is an activation of genes that trigger the regeneration of hair follicles. The greatest density of androgen receptors is observed in the frontal-temporal region of the scalp and on the crown of the head, so alopecia develops mainly in these areas.
The follicles gradually decrease in size, as a result of which, instead of terminal hairs on the head, fluffy ones with a shorter length and diameter of the rod begin to grow. The life cycle of the hair is shortened. Over time, hypodermic capillaries undergo obliteration, hair bags sclerose and atrophy. Loose fibrous tissue is replaced by fatty tissue, hyperplasia of the sebaceous glands occurs. Hair growth stops, subtotal or total androgenetic alopecia is formed.
The differences between female and male alopecia are associated with the enzyme aromatase. Aromatase converts androgens into estrogens: testosterone into estradiol, DHT into estrone. This transformation modifies the effects of androgens and causes the development of female-type alopecia.
In addition to hormonal factors, the role of microinflammation in the pathogenesis of androgenic baldness is not excluded. Propionic bacteria, staphylococci, yeast fungi malassesia, which cause an inflammatory reaction of hair follicles and the development of perifollicular fibrosis, were found in the hair loss zone.
In the presence of the above factors, androgenetic alopecia develops in men according to the male type, in women – according to the female or male type. To classify male alopecia, the Norwood-Hamilton scale is used, according to which 7 stages are distinguished:
I. Thinning affects the marginal line of hair growth in the frontal-temporal corners.
II. Symmetrical triangular (up to 2 cm deep) frontal-temporal bald patches are formed, the hair on the crown is thinning.
III. Deep receding hairlines are formed in the frontal-temporal zone, hair loss on the crown of the head is progressing.
IV. The frontal and parietal areas of alopecia are separated from each other by a strip of preserved hair.
V. The hair on the growth boundary between the forehead and the crown of the head is thinning and thinning.
VI. The foci of alopecia in the forehead and crown merge into a single zone.
VII. Horseshoe-shaped hair is preserved only on the temples and the back of the head, but their density is noticeably reduced.
Androgenic alopecia in women goes through 3 stages in its development (according to E. Ludwig):
I. Thinning of the hair on the crown with preservation in the frontal zone.
II. Significant baldness of the crown.
III. Hair loss on the frontal-parietal area.
Symptoms of androgenetic alopecia
Alopecia in men
The first signs may become noticeable soon after the end of puberty, but more often appear in the fourth decade of life. First, the hair thinns, their total volume on the head decreases. This is due to the replacement of terminal–type hair, first with shorter and depigmented, and then with fluffy ones.
The line of natural growth on the forehead gradually moves deeper, forming symmetrical bald patches. They gradually become deeper with simultaneous hair loss in the area of the crown and crown. At the final stage of androgenic alopecia, all areas of baldness merge into one large one. The hair remains only on the temples and the back of the head. In the focus of baldness, the skin is shiny, smooth, without the mouths of hair follicles visible to the eye. At the same time, there is often an increased growth of beard, hair on the chest, under the arms, on the pubis.
Alopecia in women
The onset of androgenetic alopecia in the male type is indicated by a decrease in the volume of hair on the frontal-parietal area. Hair loss may increase during pregnancy, breastfeeding, menopause. With age, the hair becomes thinner, shorter, less pigmented. Often, along with ordinary hair, fluffy ones grow. Gradually, the distance between the hairs increases, small bald spots with a diameter of 0.5 cm are formed with a complete absence of hair.
Alopecia, occurring in the female type, is characterized by diffuse thinning of the hair. In all cases, total baldness, as a rule, does not develop, the natural growth boundary, the hair on the back of the head and temples remain normal.
Complications of androgenetic alopecia
In some cases (especially for women), androgenic alopecia is a serious cosmetic and psychological problem. Patients are forced to mask their bald head by modeling hairstyles, hairpieces, wigs, overlays. This brings significant discomfort into everyday life, hinders the building of harmonious relationships with the opposite sex. Baldness is often accompanied by seborrheic dermatitis of the scalp. In women, the “side effect” of hyperandrogenism is menstrual dysfunction, infertility, hirsutism, acne.
Diagnostics of androgenetic alopecia
The diagnostic examination plan for patients with androgenic alopecia includes consultation with a dermatologist-trichologist, carrying out an instrumental and laboratory complex of studies:
- Phototrichogram. Computer video diagnostics helps to identify androgenic alopecia even at the subclinical stage, to determine the ratio of hair in different phases, to calculate the rate of their growth. The dystrophy of hair follicles is indicated by a decrease in their size, deformation, hypopigmentation.
- Laboratory complex. In the blood, the content of luteinizing and follicle-stimulating hormones (in women), testosterone (total and free), DHT, prolactin, thyroid hormones is determined, in the urine – 17-CS, . In the biochemical analysis, serum iron, ferritin, and TIBC are examined.
- Biopsy. Taking a skin biopsy from the foci of baldness allows you to trace histopathological changes: to estimate the density of follicles per cm2, to find out the number of different types of hair, to identify areas of perifollicular fibrosis.
- Other research. To detect endocrine disorders, ultrasound of the ovaries, thyroid and parathyroid glands, and adrenal glands is performed. Women need to consult a gynecologist-endocrinologist.
During the diagnostic search, it is important to exclude other causes and etiological forms
- of baldness: nesting (focal);
- cicatricial (atrophic);
- alopecia caused by chemotherapy and radiotherapy;
- dermatomycosis: ringworm, favus.
Treatment of androgenetic alopecia
With the androgenetic nature of alopecia, systemic pharmacotherapy, local therapy, physiotherapy are used. In parallel, the treatment of background pathology is carried out. An important part of therapy is the selection of professional hair care products, the rejection of additional injury to the hair follicles (aggressive perming, coloring). The course of treatment includes:
- Systemic drug therapy. In women, drugs with antiandrogenic activity are used (some COCs, aldosterone antagonists, histamine H2 receptor blockers, etc.). Men are prescribed 5-alpha-reductase inhibitors.
- External therapy. It consists in applying lotions to the scalp that activate hair follicles and stimulate hair growth. Topical antiandrogen preparations, solutions based on phytoextracts, zinc, vitamin B6 may also be recommended. When alopecia is combined with dandruff and seborrhea, therapeutic shampoos are used.
- Physical therapy. Laser therapy has shown the greatest effectiveness in the complex therapy of androgenic alopecia. Head massage and cryomassage are also useful.
If conservative methods are ineffective, they resort to transplantation of their own hair from donor areas unaffected by baldness (nape, temples) by one of the methods: seamless, patchwork. After graft transplantation, hair growth in the problem area resumes after 3 months. To minimize the risk of rejection of transplanted hair in the postoperative period, plasma therapy sessions are performed.
Of the therapeutic methods that have not yet been widely used, it should be noted the introduction of botulinum toxin in the area of the temporal, frontal, occipital muscles. In an experimental study, botulinum therapy stopped the progression of androgenic alopecia in 39% of the subjects, while the amount of hair in the foci of baldness increased by 18%. The effect of botulinum toxin is associated with a local increase in blood flow and a decrease in the formation of DHT.
Another injection technique used for androgenic alopecia is PRP therapy. Injections of platelet-rich plasma promote the regeneration of hair follicles and the resumption of hair growth.
Prognosis and prevention
The decisive factor in the success of the fight against androgenetic alopecia is the time of the beginning of treatment. In the early stages, it is possible to stop hair loss in about a third of cases and even achieve new hair growth in 10% of patients. With advanced degrees, autotransplantation of hair follicles should be resorted to. Since androgenic alopecia is an inherited disease, it is practically impossible to prevent it. Nevertheless, with the help of modern methods of treatment, it is possible to significantly delay or slow down the process of hair loss.