A piece of hair on the head is considered to be caused by baldness, and common causes include immune factors, genetic factors, mental factors, and so on. 1. Immune factors: if you suffer from vitiligo, dry syndrome, thyroiditis and other autoimmune-related diseases, it may lead to the destruction of the immune immunity mechanism of the hair follicle, inducing baldness, so that the patient has a piece of hairless head. 2. Hereditary factors: the occurrence of baldness has a certain genetic basis, if the parents suffer from baldness, their children’s chances of suffering from baldness will rise. 3. Mental factors: If you are usually under too much mental stress, too anxious, in a state of long-term depression or suffering from neurasthenia, it is easy to induce baldness. There are many reasons for inducing baldness, so patients are advised to go to the hospital to find out the cause of the disease.