From the Guidelines
Alopecia, or hair loss, is primarily caused by a chronic inflammatory disease affecting the hair follicles, which is likely mediated by T lymphocytes.
Causes of Alopecia
- The exact cause of alopecia is not fully understood, but it is believed to be related to an autoimmune response, with associations reported with various genes, including major histocompatibility complex, cytokine, and immunoglobulin genes 1.
- About 20% of people with alopecia areata have a family history, suggesting a genetic predisposition 1.
- The disease can also be associated with other autoimmune diseases, further supporting the idea of an autoimmune component 1.
Types of Alopecia
- Alopecia areata usually presents as patches of hair loss on the scalp, but any hair-bearing skin can be involved 1.
- There are different types of alopecia, including alopecia totalis (total loss of scalp hair) and alopecia universalis (loss of the entire scalp and body hair) 1.
Treatment and Prognosis
- The prognosis for alopecia areata varies, with some patients experiencing spontaneous remission within 1 year, while others may progress to more extensive hair loss 1.
- Treatment options are available, including intralesional corticosteroids, contact immunotherapy, and topical corticosteroids, but the effectiveness of these treatments can vary depending on the individual and the severity of the disease 1.
From the Research
Causes of Alopecia
The causes of alopecia, also known as hair loss, are complex and multifaceted. According to recent studies 2, 3, 4, 5, alopecia areata is considered an autoimmune disease, where the immune system attacks the hair follicles, leading to hair loss. The exact mechanisms of this autoimmune response are not fully understood, but it is believed to involve a combination of genetic and environmental factors.
Autoimmune Response
- The collapse of immune privilege in the hair follicle is thought to trigger an autoimmune response, leading to the destruction of hair follicles 2, 3, 4.
- Autoreactive cytotoxic CD8+NKG2D+ T cells are believed to play a key role in this autoimmune response, targeting exposed hair follicle autoantigens 2.
- The involvement of innate and acquired immunity in the pathogenesis of alopecia areata has been implicated by genome-wide association studies 4.
Other Factors
- Psychological stress may also contribute to the development of alopecia areata, although its significance is less emphasized in recent studies 2, 6.
- Systemic diseases, such as autoimmune diseases, endocrine disorders, and malnutrition, can also cause hair loss 6.
- Genetic factors, such as androgenetic alopecia, can also contribute to hair loss 6.
Types of Alopecia
- Nonscarring alopecias, including diffuse, patterned, and focal hair loss, can be caused by various factors, including autoimmune diseases, genetic disorders, and systemic diseases 6.
- Patterned hair loss, such as androgenetic alopecia, is the most common form of alopecia and is typically genetic 6.
- Focal hair loss, such as alopecia areata, can be treated with intralesional corticosteroid or oral immunosuppressant therapy 6.