What Causes Alopecia Areata?

• What Are Autoantigens?
• What Diseases Cause AA?
• What Drugs May Cause AA?
• Can Alopecia Areata Be Cured?

Both genetics and environmental factors contribute to the risk of developing alopecia areata (AA). The hair loss can occur on the scalp, face, and body. Evidence from multiple studies strongly suggest that it is an autoimmune condition that is linked to other autoimmune disorders.^(122, 123)

Evidence that Alopecia Areata is an Autoimmune Condition

Autoimmune disorders are characterized by the body's own immune system attacking its own cells. These attacks are triggered by specific antigens that are targeted by the immune system.^(122, 123)

What Is Immune Privilege?

Alopecia areata behaves like an autoimmune disease. It even creates antibodies that specifically attack hair follicles. Further, genetic and cell studies indicate that hair follicle cells affected by this type of hair loss appear to have lost the special type of immunity that normal hair follicles possess.^(122, 123)

Under normal conditions, these cells are considered one of the few areas in the body that has immune privilege. This special type of immunity limits the typical inflammatory responses to triggers that non-privileged cells are subject to. Part of immune privilege comes from the lack of certain proteins on the surface of these privileged cells which serve as markers that interact with the immune system. In alopecia areata, these follicle cells actually have these markers, indicating the loss of immune privilege.^(122, 123)

What Are Autoantigens?

In many autoimmune diseases, the immune system targets a specific marker, or autoantigen on cells. For many years the self-antigen remained unidentified in alopecia areata, leading many to question whether it was truly an autoimmune disease.^(122, 123)

Some researchers believe they have found an autoantigen involved with alopecia areata. It originates in either the melanocytes or the keratinocyte proteins located in the dermal papilla, hair shaft matrix, and external hair follicle sheath.^(124, 125)

Evidence of Possible Related Conditions and Risk Factors for Alopecia Areata

Additional research (including results from a recently published 12-year analysis if over 4300 patients with AA in the National Health Insurance Database of Taiwan) suggests that other types of health conditions are associated with alopecia areata, occurring at significantly higher rates than in the general population.^(121, 126)

Risk factors and health disorders associated with alopecia areata include:^{(30, 121, 122, 126, 127, 418-420)}

Can Drugs Cause Alopecia Areata?

Case reports also suggest a link between alopecia areata and the following drugs:

• Anti-TNF biologic drugs⁽⁴²²⁾
• Dupilumab biologic therapy (used for atopic dermatitis)⁽⁴²³⁾
• Hepatitis B (HBV) vaccines⁽⁴²¹⁾
• Interferon therapy⁽⁴²¹⁾

Interestingly, patients with inflammatory bowel disease (IBD) who were being treated with anti-TNF therapy appeared to be less at risk of hair loss.⁽⁴²⁴⁾

Prognosis for Patients with Alopecia Areata

The age of first onset of the disease varies, but family history increases the risk of AA occurring before age 30. Those that have one episode of AA are at greater risk of recurrence.⁽²⁶⁾

The usual course of the disease is rapid development of small bald patches that stabilize at six months to a year. Regrowth (initially white) typically occurs by 18 months, although some experts suggest as early as a year in 80% of cases. In AA linked with tick bites, hair usually fully regrows in about two months. Rare cases of larger patches or alopecia totalis/universalis have a poorer prognosis. Still, promising new treatments (including immune-regulating drugs and laser therapy) have been developed that improve the chances of hair regrowing in people with AA.^{(13, 26, 127, 418)}

Stress and Alopecia Areata

Studies show that there are biochemical changes in the nervous system associated with alopecia areata, as well as abnormal nerve function in the skin's peripheral nervous and immune systems. Although there is some conflicting data on how important stress is as a cause of AA, this type of hair loss can be particularly traumatic and devastating. As in other types of hair loss, the psychological effects may be worse in women.^(122, 128)

More importantly, managing anxiety and stress from hair loss can be remarkably helpful in dealing with AA. Clinical trials show that dealing with the anxiety and depression of alopecia areata can actually reduce the hair loss itself and help with hair regrowth.⁽¹²²⁾

In one study involving 21 patients with severe AA, hypnotherapy improved overall mood in all patients. In fact, 12 patients regrew 75-100% of scalp hair after only 3-8 sessions. Cosmetic solutions should be used to relieve the immediate impact of hair loss psychologically.⁽¹²²⁾