Alopecia areata
Alopecia areata, also known as spot baldness, is a condition in which hair is lost from some or all areas of the body.[12][1] It often results in a few bald spots on the scalp, each about the size of a coin.[7] Psychological stress and illness are possible factors in bringing on alopecia areata in individuals at risk, but in most cases there is no obvious trigger.[7] People are generally otherwise healthy.[7] In a few cases, all the hair on the scalp is lost (alopecia totalis), or all body hair is lost (alopecia universalis). Hair loss can be permanent, or temporary.[7][1]
Alopecia areata
Alopecia Celsi, vitiligo capitis, Jonston's alopecia[1]
Childhood[7]
Family history, female sex, rheumatoid arthritis, type 1 diabetes, celiac disease[7][8][9]
topical minoxidil[10] and triamcinolone injections[11]
Does not affect life expectancy[7][1]
~2% (US)[7]
Alopecia areata is believed to be an autoimmune disease resulting from a breach in the immune privilege of the hair follicles.[12][13] Risk factors include a family history of the condition.[7] Among identical twins, if one is affected, the other has about a 50% chance of also being affected.[7] The underlying mechanism involves failure by the body to recognize its own cells, with subsequent immune-mediated destruction of the hair follicle.[7]
No cure for the condition is known.[7] Some treatments, particularly triamcinolone injections and 5% minoxidil topical creams,[11][10] are effective in speeding hair regrowth.[7][1] Sunscreen, head coverings to protect from cold and sun, and glasses, if the eyelashes are missing, are also recommended.[7] In more than 50% of cases of sudden-onset localized "patchy" disease, hair regrows within a year.[14][15][7] In patients with only one or two patches, this one-year recovery will occur in up to 80%.[16][17] However, many people will have more than one episode over the course of a lifetime.[15] In many patients, hair loss and regrowth occurs simultaneously over the course of several years.[7] Among those in whom all body hair is lost, fewer than 10% recover.[18]
About 0.15% of people are affected at any one time, and 2% of people are affected at some point in time.[7][18] Onset is usually in childhood.[7] Females are affected at higher rates than males.[9]
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Treatment[edit]
The objective assessment of treatment efficacy is very difficult and spontaneous remission is unpredictable, but if the affected area is patchy, the hair may regrow spontaneously in many cases.[38] None of the existing therapeutic options are curative or preventive.[38] A 2020 systematic review showed greater than 50% hair regrowth in 80.9% of patients treated with 5 mg/mL triamcinolone injections.[11] A Cochrane-style systematic review published in 2019 showed 5% topical minoxidil was more than 8x more associated with >50% hair regrowth at 6 months compared to placebo.[10] In cases of severe hair loss, limited success has been achieved by using the corticosteroid medications clobetasol or fluocinonide as an injection or cream. Application of corticosteroid creams to the affected skin is less effective and takes longer to produce results. Steroid injections are commonly used in sites where the areas of hair loss on the head are small or especially where eyebrow hair has been lost. Whether they are effective is uncertain. Some other medications that have been used are minoxidil, Elocon (mometasone) ointment (steroid cream), irritants (anthralin or topical coal tar), and topical immunotherapy ciclosporin, sometimes in different combinations. Topical corticosteroids frequently fail to enter the skin deeply enough to affect the hair bulbs, which are the treatment target,[20] and small lesions typically also regrow spontaneously. Oral corticosteroids may decrease the hair loss, but only for the period during which they are taken, and these medications can cause serious side effects.[20] No one treatment is effective in all cases, and some individuals may show no response to any treatment.[39]
For more severe cases, studies have shown promising results with the individual use of the immunosuppressant methotrexate or adjunct use with corticosteroids.[40]
When alopecia areata is associated with celiac disease, treatment with a gluten-free diet allows for complete and permanent regrowth of scalp and other body hair in many people, but in others, remissions and recurrences are seen.[27] This improvement is probably due to the normalization of the immune response as a result of gluten withdrawal from the diet.[27]
In June 2022, the U.S. Food and Drug Administration (FDA) authorized baricitinib, a Janus kinase (JAK) inhibitor, for the treatment of severe alopecia areata.[41]
Ritlecitinib (Litfulo) was approved for medical use in the United States in June 2023.[42]
Fecal matter transplants (FMT) have been shown to reverse AA and support hair growth, with long lasting results, even going as far as growing additional hair on arms and face while grey hairs even regained colour. This supports the idea of a connection between gut microbiota having a part in hair loss.[43]
Hair transplantation may be an alternative for patients with chronic local alopecia areata. The fact that the disease is autoimmune and progresses with relapses is one of the biggest question marks before surgery. There have been case reports in the literature since the early 2000s. However, in an article published long-term follow-up; It is reported that the hair transplanted to the eyebrow area falls out again due to the recurrence of the disease.[44] A similar situation was not mentioned in previous studies on this subject. Perhaps the long-term follow-ups of other studies were not sufficient.
Prognosis[edit]
In most cases that begin with a small number of patches of hair loss, hair grows back after a few months to a year.[21] In cases with a greater number of patches, hair can either grow back or progress to alopecia areata totalis or, in rare cases, alopecia areata universalis.[21]
No loss of body function occurs, and the effects of alopecia areata are psychological (loss of self-image due to hair loss), although these can be severe. Loss of hair also means the scalp burns more easily in the sun. Patients may also have aberrant nail formation because keratin forms both hair and nails.
Hair may grow back and then fall out again later. This may not indicate a recurrence of the condition, but rather a natural cycle of growth-and-shedding from a relatively synchronised start; such a pattern will fade over time. Episodes of alopecia areata before puberty predispose to chronic recurrence of the condition.[20]
Alopecia can be the cause of psychological stress. Because hair loss can lead to significant changes in appearance, individuals with it may experience social phobia, anxiety, and depression.[45]
Epidemiology[edit]
The condition affects 0.1%–0.2% of the population, with a lifetime risk of 1%-2%,[46] and is more common in females.[9]
Alopecia areata occurs in people who are otherwise healthy and have no other skin disorders.[20] Initial presentation most commonly occurs in the early childhood, late teenage years, or young adulthood, but can happen at any ages.[22] Patients also tend to have a slightly higher incidence of conditions related to the immune system, such as asthma, allergies, atopic dermatitis, and hypothyroidism.
Research[edit]
Many medications are being studied.[59]
In 2014, preliminary findings showing that oral ruxolitinib, a drug approved by the US Food and Drug Administration (FDA) for bone marrow disorder myelofibrosis, restored hair growth in three individuals with long-standing and severe disease.[60]
In March 2020, the US FDA granted breakthrough therapy designation to baricitinib for the systematic treatment of alopecia areata[61] and granted approval in June 2022,[41] with a 32% efficacy rate for people with 50% hair loss reaching 80% scalp coverage in 36 weeks.[62] It acts as an inhibitor of janus kinase (JAK), blocking the subtypes JAK1 and JAK2.[63]
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