From the Guidelines
Alopecia areata is primarily caused by an autoimmune response, with genetic predisposition playing a significant role, as approximately 20% of patients have a family history of the condition. The condition is characterized by the immune system mistakenly attacking hair follicles, leading to inflammation and disruption of normal hair growth. Several factors can contribute to the development of alopecia areata, including:
- Genetic predisposition, with associations reported with major histocompatibility complex (MHC) and cytokine genes 1
- Autoimmune diseases, such as thyroid disorders, vitiligo, or type 1 diabetes, which are associated with an increased risk of developing alopecia areata
- Stress and certain viral infections, which can trigger or worsen episodes by activating the immune response
- Micronutrient deficiencies, such as vitamin D, zinc, and folate, which have been found to be lower in patients with alopecia areata compared to controls 1 The exact cause of alopecia areata is still not fully understood, but it is believed to involve a complex interplay between genetic and environmental factors. The most recent and highest quality study suggests that genetic predisposition and autoimmune responses are the primary causes of alopecia areata 1. While micronutrient deficiencies may play a role in the development of the condition, further research is needed to fully understand their impact 1.
From the Research
Causes of Alopecia Areata
The causes of alopecia areata are complex and multifactorial. Some of the key factors that contribute to the development of the condition include:
- Genetic predisposition: Alopecia areata is considered an organ-specific autoimmune disease with a genetic background 2.
- Autoimmune response: The condition is characterized by an autoimmune response to hair follicle-associated antigens, with a predominant Th1 cytokine profile 3.
- Environmental factors: Environmental insults, such as viral infections and trauma, are also believed to contribute to the disease process 3.
- Immune privilege collapse: The collapse of the immune privilege of the hair follicle is thought to play a key role in the development of alopecia areata 4.
- Post-translational modifications: Post-translational modifications of hair follicle-restricted proteins may increase their antigenicity and contribute to the anti-hair follicle immune attack in alopecia areata 5.
Key Players in the Pathogenesis of Alopecia Areata
Some of the key players in the pathogenesis of alopecia areata include:
- CD4+ and CD8+ T cells: These cells are involved in the autoimmune response to hair follicle-associated antigens 3.
- IFN-γ: This cytokine is thought to play a key role in the development of alopecia areata, with IFN-γ-driven immune responses implicated in the pathogenesis of the condition 2.
- IgG antibodies: IgG antibodies against hair follicle cells are found in alopecia areata sufferers and may contribute to the development of the condition 6.
Complexity of the Condition
Alopecia areata is a complex condition with a multifactorial etiology. The exact mechanisms underlying the development of the condition are not yet fully understood, and further research is needed to elucidate the causes of alopecia areata and to develop effective treatments 4, 5, 3, 2, 6.