Old hair loss may be caused by androgenetic alopecia, physiological reasons and genetic factors. 1. Androgenetic alopecia: seborrheic alopecia is a disease characterized by progressive reduction of hair on the top of the head, and patients will experience hair loss, itchy scalp, dandruff and other symptoms. 2. Physiological reasons: when the patient is under too much mental stress and tension in daily life, or stay up late for a long time and other bad habits may lead to the phenomenon of long-term hair loss. 3. Hereditary factors: It is also possible that androgenic alopecia is caused by genetic factors, and this kind of hair loss usually involves a decrease in hair from both sides of the hairline, and then the hair on the top of the head gradually falls out. There are many other causes of hair loss, when there is always hair loss, it is recommended to go to the hospital to consult the doctor’s advice, clear cause of the disease and actively cooperate with the doctor’s treatment.