Hair loss is not uncommon, according to a survey, about 25% of young men over the age of 20 have varying degrees of hair loss, and by the age of 50, this percentage rises to about 50%. There are many types of hair loss, such as baldness, which is often referred to as “ghost shaving”, hair loss caused by chemotherapy is called anagen alopecia, and scarring alopecia may occur in some people with head boils or trauma scar formation. Androgenetic baldness, once called “seborrheic baldness” or “early baldness”, is currently the most common type of hair loss in young adult men, with an average of about one out of every five Chinese men suffering from the disease. Many patients feel that hair volume also represents a person’s youthfulness and energy level, and that hair loss makes them feel unattractive and even affects their job search and choice of spouse. Many patients feel that androgenetic alopecia is a “not a disease” because it has little to no impact on their health physiologically, but psychologically it is a “disease” that they find difficult to ignore! Who touched my hair? Androgens As the name implies, androgens play a very important role in the development of “androgenetic baldness”. Androgens in men are mainly produced by the testes, which stimulate the development and maturation of the sexual organs and have many important physiological effects. Androgens also have a role in the scalp, where they are converted to dihydrotestosterone by the enzyme 5-reductase in the scalp and act on the hair follicles. In patients with androgenetic alopecia, the hair follicles are more sensitive to androgens and produce more dihydrotestosterone, which has two effects on the hair follicles: (1) Degeneration of the hair follicles, shortening the growth period of hair, turning it from a “big tree” to a “small sapling”. (1) The hair follicle degenerates, shortening the growth period, turning the hair from a “big tree” to a “small sapling”, and entering the resting phase and shedding early. (2) The hair follicles gradually shrink and become smaller, and eventually disappear completely, so that the “roots” disappear and it is difficult to grow hair again. The “dense forest” becomes “barren” and eventually results in clinical baldness. Genetics Many patients find that their father or uncle also has hair loss, but they are “more unlucky” than their elders, with an earlier onset and more severe symptoms. This is because androgenetic alopecia is a polygenic genetic disorder, but the causative gene is still unclear. Since the disease is closely related to genetic factors, more than half of the patients have a family history. Moreover, there is a close relationship between the onset of the disease and the age of the patient, and it gets progressively worse with age. Men with a family history of hair loss often develop hair loss at an earlier age than their fathers. If androgens and genetics determine the onset of androgenic baldness, other factors such as mental factors and nutritional status contribute to the development of baldness and are the “catalysts” for the rejuvenation of hair loss. Nowadays, the pace of life and work is getting more and more intense, and the competitive environment for young people is getting more and more stressful for young men, which, together with some people’s bad habits, such as staying up late and surfing the Internet overnight, is causing more and more young people to develop androgenic baldness prematurely.