Alopecia areata

Alopecia areata (AA), also known as spot baldness, is a condition in which hair is lost from some or all areas of the body.<ref name="Erjavec">Template:Cite journal</ref><ref name=NORD2004/> It often results in a few bald spots on the scalp, each about the size of a coin.<ref name=NIH2016/> 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.<ref name=NIH2016/> People are generally otherwise healthy.<ref name=NIH2016/> 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.<ref name=NIH2016/><ref name=NORD2004/>

Alopecia areata is believed to be an autoimmune disease resulting from a breach in the immune privilege of the hair follicles.<ref name="Erjavec"/><ref name=BJD2018>Template:Cite journal</ref> Risk factors include a family history of the condition.<ref name=NIH2016/> Among identical twins, if one is affected, the other has about a 50% chance of also being affected.<ref name=NIH2016/> The underlying mechanism involves failure by the body to recognize its own cells, with subsequent immune-mediated destruction of the hair follicle.<ref name=NIH2016>Template:Cite web</ref>

No cure for the condition is known.<ref name=NIH2016/> Some treatments, particularly triamcinolone injections and 5% minoxidil topical creams,<ref name="Yee2020JAAD">Template:Cite journal</ref><ref name="Freire2019">Template:Cite journal</ref> are effective in speeding hair regrowth.<ref name=NIH2016/><ref name=NORD2004/> Sunscreen, head coverings to protect from cold and sun, and glasses, if the eyelashes are missing, are also recommended.<ref name=NIH2016/> In more than 50% of cases of sudden-onset localized "patchy" disease, hair regrows within a year.<ref name="Paggioli2022">Template:Cite journal</ref><ref name="Alkhalifah2010">Template:Cite journal</ref><ref name=NIH2016/> In patients with only one or two patches, this one-year recovery will occur in up to 80%.<ref name="Spano2015">Template:Cite journal</ref><ref name="Mounsey2009">Template:Cite journal</ref> However, many people will have more than one episode over the course of a lifetime.<ref name="Alkhalifah2010"/> In many patients, hair loss and regrowth occurs simultaneously over the course of several years.<ref name=NIH2016/> Among those in whom all body hair is lost, fewer than 10% recover.<ref name=Bei2018>Template:Cite book</ref>

About 0.15% of people are affected at any one time, and 2% of people are affected at some point in time.<ref name=NIH2016/><ref name=Bei2018/> Onset is usually in childhood.<ref name=NIH2016/> Females are affected at higher rates than males.<ref name="occurrence" />

Signs and symptoms

File:Alopecia areata.jpg

Alopecia areata

Typical first symptoms of alopecia areata are small bald patches. The underlying skin is unscarred and looks superficially normal. Although these patches can take many shapes, they are usually round or oval.<ref name="Fitz2">Template:Cite bookTemplate:Page needed</ref> Alopecia areata most often affects the scalp and beard, but may occur on any part of the body with hair.<ref name=merck/> Different areas of the skin may exhibit hair loss and regrowth at the same time. The disease may also go into remission for a time, or may be permanent. It is common in children.Template:Citation needed

The area of hair loss may tingle or be mildly painful.<ref name=aocd>Template:Cite web Dermatologic Disease Database. Aocd.org. Retrieved on 3 December 2007.</ref> The hair tends to fall out over a short period of time, with the loss commonly occurring more on one side of the scalp than the other.<ref name=draelos/>

Exclamation point hairs, narrower along the length of the strand closer to the base, producing a characteristic "exclamation point" appearance, are often present.<ref name=draelos>Template:Cite web</ref> These hairs are very short (3–4 mm), and can be seen surrounding the bald patches.<ref name="Mounsey2009" />

When healthy hair is pulled out, at most a few should come out, and ripped hair should not be distributed evenly across the tugged portion of the scalp. In cases of alopecia areata, hair tends to pull out more easily along the edge of the patch where the follicles are already being attacked by the body's immune system than away from the patch where they are still healthy.<ref>Template:Cite journal</ref>

Nails may have pitting or trachyonychia.<ref name=merck/> Onychoptosis defluvium, also known as alopecia unguium, is casting off the nail seen in association with alopecia areata.<ref name="Fitz2003">>Template:Cite book</ref>Template:Rp

Causes

File:Alopecia areata.svg

In alopecia areata, a hair follicle is attacked by the immune system. T-cells swarm the roots, killing the follicle. This causes the hair to fall out and parts of the head to become bald.

Alopecia areata is thought to be a systemic autoimmune disorder in which the body attacks its own anagen hair follicles and suppresses or stops hair growth.<ref name=draelos/> For example, T cell lymphocytes cluster around affected follicles, causing inflammation and subsequent hair loss. Hair follicles in a normal state are thought to be kept secure from the immune system, a phenomenon called immune privilege. A breach in this immune privilege state is considered as the cause of alopecia areata.<ref name=BJD2018/> A few cases of babies being born with congenital alopecia areata have been reported.<ref name=LenanePope2005>Template:Cite journal</ref> It is recognized as a type 1 inflammatory disease.<ref name="Fukuyama Ito Ohyama 2021 pp. 19–36">Template:Cite journal</ref>

Alopecia areata is not contagious.<ref name=draelos/> It occurs more frequently in people who have affected family members, suggesting heredity may be a factor.<ref name=draelos/> Strong evidence of genetic association with increased risk for alopecia areata was found by studying families with two or more affected members. This study identified at least four regions in the genome that are likely to contain these genes.<ref>Template:Cite journal</ref> In addition, alopecia areata shares genetic risk factors with other autoimmune diseases, including rheumatoid arthritis, type 1 diabetes, and celiac disease.<ref name=HordinskyJunqueira2015>Template:Cite journalTemplate:Open access</ref> It may be the only manifestation of celiac disease.<ref name=CaproniBonciolini2012>Template:Cite journal</ref><ref name=TackVerbeek2010>Template:Cite journal</ref>

Lifestyle factors such as smoking, sleep quality, and obesity may also contribute to the onset and progression of alopecia areata.<ref name="Sánchez-Pellicer 1860">Template:Cite journal</ref> Studies indicate that smokers have a higher risk of developing the condition, potentially due to tobacco-induced Th17-mediated inflammation in hair follicles.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> While some research suggests a link between sleep disorders and alopecia areata, findings remain inconclusive.<ref name="Sánchez-Pellicer 1860"/> However, since sleep disturbances impact immune function, they may play a role in disease pathogenesis.<ref>Template:Cite journal</ref> Additionally, obesity is associated with an increased risk of alopecia areata, likely due to adipokine dysregulation, which promotes chronic low-grade inflammation and alters immune response, as seen in other inflammatory skin conditions.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>

Endogenous retinoids metabolic defect is a key part of the pathogenesis of the alopecia areata.<ref>Template:Cite journal</ref>

In 2010, a genome-wide association study was completed that identified 129 single nucleotide polymorphisms that were associated with alopecia areata. The genes that were identified include those involved in controlling the activation and proliferation of regulatory T cells, cytotoxic T lymphocyte-associated antigen 4, interleukin-2, interleukin-2 receptor A, and Eos (also known as Ikaros family zinc finger 4), as well as the human leukocyte antigen. The study also identified two genes, PRDX5 and STX17, that are expressed in the hair follicle.<ref>Template:Cite journal</ref>

There is emerging evidence suggesting a possible link between AA and vaccinations, including influenza, zoster, and human papillomavirus (HPV) vaccines.<ref>Template:Cite journal</ref> One possible explanation is that vaccinations could trigger immune system activation, which has been observed to exacerbate preexisting autoimmune or autoinflammatory conditions in at-risk populations.<ref>Template:Cite journal</ref> A small study observed hair loss exacerbation in three patients following COVID-19 mRNA vaccinations (Pfizer-BioNTech and Moderna).<ref name="COVID-19 vaccination related exacer">Template:Cite journal</ref> These patients, who were younger on average (30.6 years) compared to unaffected individuals (37.2 years), experienced worsening hair loss within two weeks post-vaccination.<ref name="COVID-19 vaccination related exacer"/> Similar cases have been reported with the AstraZeneca and Johnson & Johnson COVID-19 vaccines.<ref>Template:Cite journal</ref> However, AA flares have also been linked to SARS-CoV-2 infection, either as an exacerbation of preexisting disease or a new diagnosis.<ref name="COVID-19 vaccination related exacer"/> In the study's non-vaccinated AA cohort, the only observed case of hair loss worsening occurred after a COVID-19 infection.<ref name="COVID-19 vaccination related exacer"/> While causality remains unclear, these findings emphasize the need for further research into the relationship between vaccinations and AA progression.

A psychodermatological connection is noted with impairment in psychiatric comorbidities including mental well-being, self esteem and mental disorders acting as pathogenic triggers for alopecia areata.<ref name="Strazzulla Wang Avila Lo Sicco 2018 pp. 1–12">Template:Cite journal</ref><ref name="Lee Lee Lee Lee 2019 pp. 466–477.e16">Template:Cite journal</ref><ref name="Torales Castaldelli-Maia Ventriglio Almirón-Santacruz 2021 pp. 2318–2323">Template:Cite journal</ref><ref name="Minokawa Sawada Nakamura 2022 p=1038">Template:Cite journal</ref>

Diagnosis

Alopecia areata is usually diagnosed based on clinical features.

Trichoscopy may aid in establishing the diagnosis. In alopecia areata, trichoscopy shows regularly distributed "yellow dots" (hyperkeratotic plugs), small exclamation-mark hairs, and "black dots" (destroyed hairs in the hair follicle opening).<ref>Template:Cite journal</ref>

Oftentimes, however, discrete areas of hair loss surrounded by exclamation mark hairs is sufficient for clinical diagnosis of alopecia areata. Sometimes, reddening of the skin, erythema, may also be present in the balding area.<ref name="Bei2018" />

A biopsy is rarely needed to make the diagnosis or aid in the management of alopecia areata. Histologic findings may include peribulbar lymphocytic infiltration resembling a "swarm of bees", a shift in the anagen-to-telogen ratio towards telogen, and dilated follicular infundibulae.<ref name=HordinskyJunqueira2015 /> Other helpful findings can include pigment incontinence in the hair bulb and follicular stelae. Occasionally, in inactive alopecia areata, no inflammatory infiltrates are found.Template:Citation needed

Classification

File:Fox Plate V.jpg

Varying degrees of alopecia areata, along with alopecia totalis

Commonly, alopecia areata involves hair loss in one or more round spots on the scalp.<ref name=draelos/><ref name="Lookingbill">Template:Cite book.Template:Page needed</ref>

• Hair may also be lost more diffusely over the whole scalp, in which case the condition is called diffuse alopecia areata.<ref name=draelos/>
• Alopecia areata monolocularis describes baldness in only one spot. It may occur anywhere on the head.
• Alopecia areata multilocularis refers to multiple areas of hair loss.
• Ophiasis refers to hair loss in the shape of a wave at the circumference of the head.
• The disease may be limited only to the beard, in which case it is called alopecia areata barbae.<ref name=draelos/>
• If the person loses all the hair on the scalp, the disease is then called alopecia areata totalis.<ref name=NIH2016/>
• If all body hair, including pubic hair, is lost, the diagnosis then becomes alopecia areata universalis.<ref name=NIH2016/>

Alopecia areata totalis and universalis are rare.<ref name=WebMD>Template:Cite web</ref>

Treatment

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.<ref name=Shapiro2013>Template:Cite journalTemplate:Open access</ref> None of the existing therapeutic options are curative or preventive.<ref name=Shapiro2013 /> A 2020 systematic review showed greater than 50% hair regrowth in 80.9% of patients treated with 5 mg/mL triamcinolone injections.<ref name="Yee2020JAAD"/> A Cochrane-style systematic review published in 2019 showed 5% topical minoxidil was more than eight times more associated with >50% hair regrowth at 6 months compared to placebo.<ref name="Freire2019"/> 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.Template:Citation needed 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,<ref name=merck/> 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.<ref name=merck/> No one treatment is effective in all cases, and some individuals may show no response to any treatment.<ref>Template:Cite journal</ref>

For more severe cases, studies have shown promising results with the individual use of the immunosuppressant methotrexate or adjunct use with corticosteroids.<ref>Template:Cite journal</ref>

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.<ref name=CaproniBonciolini2012 /> This improvement is probably due to the normalization of the immune response as a result of gluten withdrawal from the diet.<ref name=CaproniBonciolini2012 />

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.<ref name="Lilly PR 20220613">Template:Cite press release</ref>

Ritlecitinib (Litfulo) was approved for medical use in the United States in June 2023.<ref>Template:Cite press release</ref>

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.<ref name="Barquero-Orias_2021">Template:Cite journal</ref>

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.<ref>Template:Cite journal</ref> A similar situation was not mentioned in previous studies on this subject. Perhaps the long-term follow-ups of other studies were not sufficient.

Deuruxolitinib (Leqselvi) was approved for medical use in the United States in July 2024.<ref>Template:Cite press release</ref>

Prognosis

In most cases that begin with a small number of patches of hair loss, hair grows back after a few months to a year.<ref name=aocd/> 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.<ref name=aocd/>

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.Template:Citation needed

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.<ref name=merck/>

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.<ref name=HuntMcHale2005>Template:Cite journal</ref>

Epidemiology

The condition affects 0.1%–0.2% of the population, with a lifetime risk of 1%-2%,<ref>Template:Cite journal</ref> and is more common in females.<ref name="occurrence">Template:Cite journal</ref>

Alopecia areata occurs in people who are otherwise healthy and have no other skin disorders.<ref name=merck>Template:MerckManual</ref> Initial presentation most commonly occurs in the early childhood, late teenage years, or young adulthood, but can happen at any ages.<ref name=draelos/> Patients also tend to have a slightly higher incidence of conditions related to the immune system, such as asthma, allergies, atopic dermatitis, and hypothyroidism.

Ethnic and socioeconomic disparities

The prevalence and impact of AA vary across different ethnic groups and socioeconomic backgrounds.<ref name="Thompson 924–935">Template:Cite journal</ref> Studies indicate that people of Asian descent have the highest risk, with nearly 6 cases per 100 people, compared to fewer than 2 cases per 100 people among White individuals.<ref name="Thompson 924–935"/> People living in urban or economically disadvantaged areas face a higher likelihood of developing AA.<ref name="Thompson 924–935"/> The effects of the condition also differ by ethnicity: individuals of Black descent with AA are more likely to experience anxiety and require medical leave from work.<ref name="Thompson 924–935"/> These findings suggest that genetic, environmental, and social factors may influence both the likelihood of developing AA and its broader personal and professional impact.<ref name="Thompson 924–935"/>

Society and culture

The term "alopecia", used by physicians dating back to Hippocrates, originates from the Greek word for fox, "alopex", and was so-named due to fur loss seen in fox mange. "Areata" is derived from the Latin word, "area", meaning a vacant space or patch.<ref>Template:Cite journal</ref>

Alopecia areata and alopecia barbae have been identified by some as the biblical Template:Transliteration condition that is part of the greater Template:Transliteration family of skin disorders; the said disorders are purported to being discussed in the Book of Leviticus, chapter 13.<ref>Template:Cite book</ref>

Notable people

NASCAR driver Joey Logano, obstacle athlete Kevin Bull,<ref>Template:Cite web</ref> politicians Peter Dutton<ref>Template:Cite news</ref> and Ayanna Pressley,<ref>Template:Cite web</ref> K-pop singer Peniel Shin of BtoB,<ref>Template:Cite web</ref> actors Christopher Reeve,<ref name="Groopman2003">Template:Cite magazine</ref> Anthony Carrigan,<ref>Template:Cite news</ref> Greg Grunberg and Alan Fletcher,<ref>Template:Cite news</ref> and actresses Jada Pinkett Smith,<ref>Template:Cite web</ref> May Calamawy,<ref>Template:Cite web</ref> and Lili Reinhart<ref>Template:Cite web</ref> all have some form of alopecia areata.

Research

Many medications are being studied.<ref>Template:Cite web</ref>

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.<ref>Template:Cite journal</ref>

In March 2020, the US FDA granted breakthrough therapy designation to baricitinib for the systematic treatment of alopecia areata<ref>Template:Cite press release</ref> and granted approval in June 2022,<ref name="Lilly PR 20220613" /> with a 32% efficacy rate for people with 50% hair loss reaching 80% scalp coverage in 36 weeks.<ref name="FDA PR 20220613">Template:Cite press release Template:PD-notice</ref> It acts as an inhibitor of janus kinase (JAK), blocking the subtypes JAK1 and JAK2.<ref name="CHMP">Template:Cite web</ref>

External links

• Template:DermAtlas