Alopecia areata: what it is and how to recognise it

One morning, while combing your hair, or because the barber comments on it, you discover a round, smooth patch with no hair at all, which was not there a few weeks before. It does not hurt, it does not itch, the skin looks normal. This is the most typical presentation of alopecia areata, popularly known as "spot baldness".

Alopecia areata is an autoimmune condition: the immune system attacks the hair follicles, which stop producing hair without being destroyed. That is why hair can grow back, sometimes on its own. But progression is unpredictable: some people have a single patch that disappears within months, and others lose all the hair on the head and body. In recent years, the arrival of new medicines has changed the treatment of severe forms.

What alopecia areata is

An autoimmune disease

Normally, the hair follicle is protected from the immune system (so-called "immune privilege"). In alopecia areata, this protection fails: T lymphocytes attack the base of the follicle in its growth phase, so the follicle halts hair production and enters a resting state. The follicle is not destroyed or replaced by scar tissue, which is why the hair can grow back.

A signalling pathway called JAK-STAT, which transmits inflammatory signals, takes part in this attack. The discovery of this pathway led to the most recent medicines, the JAK inhibitors.

Who it affects

• About 2% of people will have alopecia areata at some point in their lives.
• It affects men and women of any background.
• It can start at any age, including in childhood, but most cases appear before the age of 40, with a peak between the second and third decades.
• In 10% to 20% of cases there is a family history.

What triggers it

The cause is a combination of genetic predisposition and factors that activate the immune system. Many people associate the onset with a period of stress, an infection or a vaccine, but these associations are hard to prove and, in most cases, no clear trigger is identified. The person is not "to blame" and the condition is not the result of anything they did.

Associated conditions

People with alopecia areata are more likely to have other autoimmune or allergic conditions: thyroid disease (especially Hashimoto's thyroiditis), vitiligo, atopic dermatitis, asthma and allergic rhinitis, and, less often, coeliac disease or lupus. It is also associated with more anxiety and depression, which deserve their own attention. See Living with alopecia areata: the support that counts.

How to recognise it

The typical patch

• Round or oval, with well-defined edges, the size of a coin or larger.
• Smooth skin of normal appearance, without scaling or scarring; sometimes slightly pink.
• It appears within days to weeks.
• Usually without symptoms, although some people feel tingling or mild itching before the hair falls out.
• There may be one or several patches, on the scalp, beard, eyebrows, eyelashes or other parts of the body.

At the edge of the patch you may see so-called exclamation-mark hairs: short, broken hairs, thicker at the tip and thinner near the skin. When the hair returns, it often grows in white or fine first, regaining its colour over time. See Round patch in the hair: when it is worth assessing.

The clinical forms

The nails

In 10% to 40% of people, the nails also change: small pits in rows (pitting), ridges or roughness. They are more common in extensive forms and are associated with a poorer prognosis.

How the diagnosis is made

In most cases, the diagnosis is clinical, made from the history and examination.

Trichoscopy

Trichoscopy confirms the diagnosis and assesses activity. The typical signs are:

• yellow dots (empty follicular openings);
• black dots (hairs broken at skin level);
• exclamation-mark hairs and broken hairs, which indicate active disease;
• short, fine hairs, sometimes white, that indicate regrowth.

For more on the examination, see Trichoscopy: the examination that shows the scalp.

Measuring the extent: the SALT index

To track progress and decide on treatment, the SALT index (Severity of Alopecia Tool) is used, which estimates the percentage of the scalp without hair, from 0 to 100 (Olsen et al., 2004). A SALT of 50 or more means at least half of the scalp is affected and generally defines severe alopecia areata.

Blood tests

They do not confirm the diagnosis, but may be requested to screen for associated conditions (especially the thyroid) or before starting systemic treatments. See Blood tests for hair loss: what to ask for.

What can look like alopecia areata

How it progresses

Progression is unpredictable and varies greatly from person to person. In a review by Moussa, Bokhari and Sinclair (2022):

• About 40% of people have a single patch that regrows hair within six months, even without treatment.
• Another 27% develop more patches, but recover completely after a year.
• About a third have a chronic form, with patches that persist beyond 12 months. In this group, the risk of progressing to total or universal alopecia is considerable.

Across all people with alopecia areata, progression to the total or universal forms is less common, in the order of 5% to 10%. Relapses are common: even after hair returns, new patches can appear months or years later.

Factors linked to a poorer prognosis

• Onset in childhood or adolescence.
• Extensive loss (more than half of the scalp).
• Ophiasis form.
• Nail changes.
• Lasting more than a year.
• Family history, atopy or other autoimmune diseases.

Treatments

There is no definitive cure, but there are treatments that speed up regrowth and control the condition. The choice depends on the extent, duration, age and preferences of each person, and is always made at a consultation. For small, recent patches, observing without treating is also a reasonable option, given the high rate of spontaneous recovery.

Limited forms (few patches)

• Corticosteroids injected into the patch (intralesional): these are the first-line treatment in adults with few patches. They are repeated every 4 to 6 weeks. They can cause a slight, temporary depression of the skin at the site.
• Potent topical corticosteroids: an alternative, especially in children or in those who do not tolerate injections.
• Topical minoxidil: may be used as a complement.

Extensive forms

• Contact immunotherapy (for example, with diphencyprone): it causes a controlled dermatitis on the scalp that "diverts" the immune system; it requires several sessions and is done in experienced centres.
• Oral corticosteroids: they can induce regrowth, but are not suitable for prolonged use, because of adverse effects, and the loss tends to return on stopping.
• Other immunosuppressants (such as methotrexate), in selected cases.

JAK inhibitors: the big news

JAK inhibitors block the signalling pathway that fuels the attack on the follicle. In the European Union they are approved for severe alopecia areata:

• Baricitinib, in adults (approved in 2022). In the phase 3 trials BRAVE-AA1 and BRAVE-AA2, at the 4 mg dose, about 36% to 39% of patients reached 80% or more scalp hair coverage (SALT 20 or less) at 36 weeks, compared with 3% to 6% on placebo (King et al., 2022).
• Ritlecitinib, in adults and adolescents from 12 years of age (approved in 2023). According to the EMA, at 24 weeks, 23% of patients had more than 80% scalp hair coverage, compared with 1.5% on placebo; at 48 weeks, 31% were in near remission.

What is important to know:

• Results take months and are not the same for everyone.
• When you stop, the loss tends to return; treatment is long term.
• They require prior assessment (infections, blood tests, vaccination) and regular monitoring. Adverse effects include infections, acne and abnormal test results. The EMA recommends special care in people over 65, smokers or those with cardiovascular or cancer risk factors.
• These are medicines prescribed by specialists, dispensed in a hospital setting or on specific indication, and access may vary.

Camouflage and wellbeing

Wigs, hair prostheses, eyebrow micropigmentation, make-up and headscarves are legitimate options, with or without treatment. The emotional impact deserves its own attention and, when needed, psychological support.

When you should ask for an assessment

In children, patches should always be assessed, to distinguish them from tinea, which needs antifungal treatment.

At Luxmed, the hair medicine consultation includes a clinical history, examination, trichoscopy, SALT calculation and follow-up photographs. We agree with you the plan suited to the extent and activity of the condition and, in severe forms, we liaise with dermatology services for access to systemic treatments.

This article is for information purposes and does not replace a medical consultation. The results of any treatment vary from person to person.

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