What Causes Alopecia Areata?
is considered to be an autoimmune disease
, in which the immune system (which is designed to protect the body from foreign invaders such as viruses and bacteria) mistakenly attacks the hair follicles. This can lead to hair loss on the scalp and elsewhere.
Understanding the Immune System
In alopecia areata, white blood cells (which are part of the immune system) attack the rapidly growing cells in the hair follicles that make the hair. The affected hair follicles become small, which drastically slows down hair production. Fortunately, the stem cells that continually supply the follicle with new cells do not seem to be targeted, which means that the hair follicles always have the potential to grow more hair.
Do Genes Play a Role?
Scientists do not know how alopecia areata causes the hair follicles to slow down hair production. However, they do suspect that a combination of genes may predispose some people to alopecia areata. In those who are genetically predisposed, some type of trigger -- perhaps a virus or something in the person's environment -- brings on the attack against the hair follicles.