What are the treatments and causes of alopecia areata?

Treatment and Causes of Alopecia Areata

Causes of Alopecia Areata

Alopecia areata is a tissue-specific autoimmune disease that affects up to 2% of the general population 1. The pathogenesis involves:

• Primary mechanism: Collapse of the immune privilege of the hair follicle caused by immunological mechanisms 1
• Contributing factors: Multiple genetic and environmental factors 1
• Immunological basis: CD8+ T-cell-mediated immune attack on hair follicles 2

Treatment Approach

Intralesional corticosteroid injections are the first-line treatment for limited patchy alopecia areata, with a success rate of approximately 62% of patients achieving regrowth. 3

First-Line Treatments for Limited Patchy Alopecia Areata

1. Intralesional corticosteroids:

   • Most effective first-line treatment 3
   • Success rate: ~62% of patients achieve regrowth 3
   • More effective than topical steroids due to better penetration to the dermis where hair follicles reside 2
   • Limitations: Pain during procedure 2

2. Topical corticosteroids:

   • Alternative if intralesional steroids are not tolerated 3
   • Moderate efficacy in mild AA 2
   • Safe and well-tolerated 2
   • Limitations: Limited efficacy evidence, high recurrence after treatment cessation 3, 2

3. Topical minoxidil 5% solution:

   • Results typically take 3-6 months to become visible 3
   • Hair regrowth effects last up to 48 weeks in clinical trials 3
   • Side effect: May cause scalp irritation 3

Second-Line and Alternative Treatments

1. Systemic therapies:

   • Baricitinib (JAK 1/2 inhibitor): EMA-approved for adults with severe AA; high-certainty evidence shows increased short-term and long-term hair regrowth compared to placebo (RR 7.54 and 8.49, respectively) 4, 5
   • Ritlecitinib (JAK 3/TEC inhibitor): EMA-approved for individuals aged 12 and older with severe AA 5
   • Methotrexate (15-25 mg/week): With or without prednisolone; retrospective data showed 14 of 22 patients with AT/AU achieved complete regrowth 3
   • Systemic corticosteroids: Used as pulse or continuous therapy; concerns about side effects vs. efficacy ratio 3
   • Cyclosporine: Limited evidence of efficacy in severe disease; side effects limit long-term use 3
   • Sulfasalazine: Uncontrolled studies show partial response but high relapse rate 3

2. Contact immunotherapy:

   • Recommended for extensive patchy hair loss 3
   • Agents include diphenylcyclopropenone 3
   • Response rate: 50-60% achieving worthwhile response 3
   • Side effects: Occipital/cervical lymphadenopathy, severe dermatitis, pigmentary complications in racially pigmented skin 3

3. Other alternatives:

   • Dithranol (anthralin): Limited efficacy (18% achieve cosmetically worthwhile regrowth) 3
   • Prostaglandin F2α analogues (latanoprost, bimatoprost): Mixed results; one study showed 45% achieved complete/moderate regrowth after 2 years 3
   • Oral minoxidil: Considered adjuvant therapy with limited efficacy data 5

Special Considerations

Severity Assessment

• Severity of Alopecia Tool (SALT) score: Score ≥20 constitutes indication for systemic therapy 5
• Alopecia Areata Scale (AAS): Moderate to severe AA is considered indication for systemic treatment 5

Children with Alopecia Areata

• Intralesional corticosteroids often poorly tolerated 3
• Many clinicians reluctant to use aggressive treatments like contact immunotherapy 3
• Short-contact anthralin therapy shows promise in children 6
• Ritlecitinib is approved for individuals aged 12 and older with severe AA 5

Extensive Hair Loss

• Wigs or hairpieces are practical solutions 3
• Acrylic wigs: Cheaper and easier to maintain 3
• Human hair wigs: Better fit and wider range of activities 3

Spontaneous Remission

• Up to 80% of patients with limited patchy hair loss of short duration (<1 year) may experience spontaneous remission 3
• "No treatment" is a valid option for patients with limited patchy hair loss 3

Diagnostic Approach

Useful diagnostic tools include:

• Pull test: Gently tugging on hair clusters to assess fragility and shedding 3
• Trichoscopy: Specialized magnifying device to examine scalp and hair follicles 3
• Hair count: Counting hairs in specific areas before and after treatment 3

Common Pitfalls and Caveats

1. Treatment expectations: Alopecia areata has an unpredictable course not easily altered by treatment; different treatments may provoke regrowth but not prevent further hair loss 6

2. Recurrence risk: High recurrence rates after treatment cessation, especially with topical treatments 2

3. Monitoring: Regular follow-up visits with repeat photography to document changes are important 3

4. Psychological impact: Consider psychological support and referral to patient support groups due to significant emotional distress 3

5. Treatment duration: Patience is required as treatments like minoxidil typically take 3-6 months to show visible results 3