Despite what some may say, as an autoimmune disease, alopecia areata is not contagious.
There are more than 80 known types of autoimmune disease. In all autoimmune disease, the immune system mistakes healthy cells and tissues for invaders and attacks them to try and protect the body, triggering disease symptoms.
In AA, the immune system attacks the hair follicles, which are usually responsible for supporting hair growth. Hair follicles are like anchors for your hair: They extend into your top two layers of skin, called the dermis and epidermis, to support hair growth.
When these hair follicles become inflamed and do not function normally, such as when an immune system attack occurs, this can cause hair loss and make it difficult for the follicles to support new hair growth in their place.
The number of affected hair follicles and resulting hair loss also depends on the severity of the condition.
How quickly hair regrows depends on the person, the severity of the condition, and the site on the body where hair loss occurs. On the scalp, for example, the total growth phase of new hair can last two to six years.
Researchers do not yet know exactly what causes autoimmune disease. But experts believe autoimmune disorders like alopecia areata may develop from a combination of genetic and environmental factors, such as certain medications or exposure to microorganisms like bacteria and viruses.
Scientists also believe the genes associated with the development of AA may primarily trace back to the human leukocyte antigen (HLA) complex family of genes.
“Autoimmune conditions often travel in packs, so if you have one autoimmune disorder, such as thyroid or diabetes, it is not uncommon to have others,” says Brooke Jackson, MD, a board-certified dermatologist and dermatologic surgeon in Durham, North Carolina.
Many people develop alopecia areata alongside another type of autoimmune disorder, such as:
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