The resting period, or telogen phase, lasts for two to four months. In this phase, the follicle withers even further. Following the telogen phase, the next anagen phase begins, and the old hair is dislodged and falls out to make room for a new hair to begin growing in its place. DHT is found in several tissues in the body including the scalp. An enzyme is a protein that acts as a catalyst to speed up a chemical reaction.
Researchers now believe that the condition can be inherited from either side of the family.
It affects different populations at different rates, probably because of genetics. Up to half of male Caucasians will experience some degree of hair loss by age 50, while other population groups such as Japanese and Chinese men are far less affected. The severity of hair loss can be classified in several ways. Illustrated is the Norwood classification. The Norwood classification of male pattern alopecia.