The disease known as alopecia areata causes quick hair loss. It usually appears as patchy bald spots on the scalp, and in some cases can progress quickly until all body hair is gone.
Although the precise origins of alopecia areata are not known, medical researchers blame it on genetics. Several genes that are present in some, but not all, people can trigger an immune system response that targets the hair follicles, which are the shafts where hair grows on your scalp and other locations on the body. The immune system generates white blood cells that attack the follicles, causing them to shrink. This will slow hair production, and in some cases, halt it completely.
The change is not permanent because the stem cells, which supply the follicles with new cells, are not damaged by the white blood cell attacks. That leaves room for new hair to grow back. Unfortunately, in some cases, the hair grows back thinner or in a lighter color than previous hair growth.
The disease can strike at any age but mostly seems to attack people younger than age 20. Alopecia areata is an equal opportunity disease, attacking men and women in roughly equal numbers.
Alopecia areata can be a frustrating disease. There are no treatments, but drugs developed for other uses can help battle it. There is also no guarantee of hair regrowth. Some hair may sprout in the affected regions, only to fall out in another.