Alopecia Areata
Alopecia areata is characterized by hair loss in small rounded patches. It is an autoimmune condition that, in most cases, resolves spontaneously over time.
Symptoms and Causes
Alopecia areata is a type of hair loss that, in most cases, has an autoimmune origin, meaning that the body's immune system mistakenly attacks the hair follicles. Although hair loss can occur anywhere on the body, it usually presents as rounded patches on the scalp or facial hair.
Alopecia areata may present in four forms:
- Single-patch alopecia areata: the most common presentation. A single oval or round hairless patch appears. There is no skin redness or scarring.
- Multifocal alopecia areata: also known as reticular alopecia areata, it presents with multiple bald patches on the scalp, beard, or eyebrows.
- Alopecia totalis: a severe form of the disease that causes complete loss of scalp hair.
- Alopecia universalis: the most severe form. It affects both the scalp and the rest of the body (eyebrows, eyelashes, and body hair).
Alopecia areata is a non-scarring form of hair loss, meaning that hair follicles can recover once inflammation subsides, as they remain dormant rather than permanently damaged. Even so, restoring lost hair growth is not always easy.
Symptoms
The hallmark symptom of alopecia areata is the sudden loss of scalp or body hair in patches. These hairless areas may progress in different ways:
- Ophiasis alopecia areata: hair loss occurs in a serpentine band along the posterior and lateral areas of the scalp.
- SISAIFO alopecia: an uncommon pattern. Hair loss affects the upper and central regions of the scalp.
- Diffuse alopecia areata: hair loss occurs throughout the scalp, affecting more than 70% of hair follicles instead of forming the characteristic patches of alopecia areata.
- Selective loss of pigmented hair: only pigmented hair is lost, while gray hair is spared, because the immune system exclusively targets melanocytes within the hair follicles.
The development of alopecia areata does not differ between men and women, as it presents similarly in both sexes. In men, it may manifest as bald patches in the beard area.
The skin in the affected area appears smooth, without redness or rash. Surrounding hairs are thinner at the base than at the tip and are often broken. Some patients report tingling or itching before hair loss occurs.
Causes
The primary cause of alopecia areata is an immune system malfunction that mistakenly attacks the hair follicles. In response, these small structures become inflamed, leading to hair loss.
Risk Factors
The risk of developing alopecia areata increases in the following situations:
- Age: it is more common in children and adults between 30 and 50 years of age.
- Hormonal alterations: hormonal imbalances affect the hair growth cycle:
- Severe stress: excessive increases in cortisol disrupt the hair growth cycle.
- Hypothyroidism or hyperthyroidism: these conditions affect thyroxine production, causing hair to become thinner and more prone to shedding.
- Polycystic ovary syndrome: increased androgen levels reduce the size of hair follicles.
- Menopause or the postpartum period: decreases in estrogen and progesterone, together with increased androgen levels, alter the hair growth cycle.
- Infectious processes: these may trigger an immune response against hair follicles:
- Epstein-Barr virus: a human herpesvirus commonly acquired during childhood or adolescence that causes mononucleosis.
- Hepatitis B and hepatitis C.
- COVID-19.
- Enteroviruses: responsible for hand, foot, and mouth disease.
- Staphylococci and streptococci: bacteria associated with folliculitis (inflammation of hair follicles).
- Other autoimmune diseases.
- Genetic predisposition.
- Family history of the disease.
Complications
The most common complications of alopecia areata include:
- Large hairless areas resulting from the merging of multiple patches.
- Complete loss of scalp or body hair, although this is uncommon.
- Psychological effects associated with hair loss:
- Low self-esteem.
- Social isolation.
- Anxiety.
- Skin sensitivity: areas where hair has been lost may become irritated or more sensitive to sun exposure.
- Nail changes: pitting or alterations in nail shape and color may occur.
- Increased susceptibility to developing other autoimmune diseases.
Prevention
Alopecia areata cannot be prevented, as it is an autoimmune condition whose exact cause remains incompletely understood.
Which specialist treats Alopecia Areata?
Alopecia areata is a condition managed within the specialty of Medical-surgical dermatology and Venereology.
Diagnosis
The diagnosis of alopecia areata is usually based on clinical observation, as the characteristic round hairless patches are highly distinctive. However, to confirm the condition, the specialist typically performs additional tests, such as:
- Trichoscopy: a device is used to obtain images of the scalp and hair follicles. Specialized software evaluates hair density and shaft diameter. In addition, the specialist assesses the condition of the skin (inflammation, scaling, redness) and hair quality.
- Scalp biopsy: a procedure used to determine whether hair loss is caused by alopecia areata or another type of alopecia. A small tissue sample, including both skin and a hair follicle, is collected and examined under a microscope in the laboratory. The incision is usually closed with sutures, which become barely noticeable over time as the hair grows back.
Treatment
Most patients regain lost hair after several months, even without treatment. In many cases, regrowth occurs once the underlying cause disappears, such as a stressful situation or hormonal imbalance.
In cases where hair loss is more extensive and no signs of regrowth are observed, treatment is tailored to each patient. The most effective options include:
- Topical medication: applied to the scalp as creams, foams, lotions, or patches:
- Corticosteroids: usually the first-line treatment. They reduce follicular inflammation.
- Vasodilators: stimulate hair growth.
- Tar derivatives: induce an immune response that promotes hair regeneration.
- Oral medication: Janus kinase (JAK) inhibitors, a class of enzymes involved in transmitting signals from outside the cell to the nucleus to regulate gene expression and inflammation, are used to suppress the inflammatory process responsible for hair loss.
- Steroid injections: act directly on the hair follicle to reduce inflammation and promote hair regrowth.
- Ultraviolet light therapy: narrowband UVB is commonly used to reduce inflammation, stimulate hair follicles, and restore lost hair. Treatment is usually administered for a few minutes during specialist consultations and is combined with oral or topical medication.
