Causes and Treatment of Alopecia Areata
Alopecia areata, also known as spot baldness or patch baldness, is a type of hair loss characteristic for its patchy form. Although it usually affects scalp hair, it can also cause a loss of other body hair, e.g. beard. It is the second most common type of baldness, affecting about 2% of the population – men, women as well as children. The hair sometimes grows back and may or may not fall out again or another bald spot develops. In about 1% of cases the baldness spreads to the whole scalp, what is called alopecia totalis, or the entire body – alopecia universalis.
Causes of Alopecia Areata
Alopecia areata is thought to be an autoimmune disorder and it occurs when the body’s immune system mistakenly identifies its own tissue (hair follicles) as a foreign element and attacks and destroys it. This reaction causes inflammation of the affected hair follicles and subsequent hair loss. Heredity may also play some role. Interestingly, gray hair is rarely affected by alopecia areata.
Signs of Alopecia Areata
The typical sign of alopecia areata is its round or oval balding pattern and a small size of the bald patch, which initially is a size of a larger coin. A patient may experience hair loss in one spot and hair regrowth in another, happening at the same time. Several bald patches may develop and overlap each other, forming a large bald area that can cover a significant portion of the scalp. Hair loss due to alopecia areata is usually rapid and a bald spot develops within several weeks.
Diagnosing Alpecia Areata
Due to its patchy balding pattern, alopecia areata is easy to diagnose. Trichoscopy may sometimes be used to check for destroyed hairs in the hair follicle opening and for small exclamation-mark hairs, which are a hallmark of alopecia areata and so confirm the initial diagnosis. Biopsy is rarely needed.
Treatments for Alopecia Areata
Alopecia areata, though an unpredictable disease, is a harmless condition. Many patients, especially those who only have a few small bald patches, decide to take no treatment at all and wait to see how the condition develops. Hair sometimes grows back after a few years with no treatment needed. Several treatments are available for those who would like to see faster results but their effectiveness varies significantly:
Corticosteroid injections are given directly into the bald spot to suppress the autoimmune reaction. Repeated injections are needed and they are painful.
Corticosteroid cream or gel is a less painful treatment option than injections but the effectiveness is lower due to less than perfect absorption of steroids through the skin to affect the hair bulbs and it also takes much longer to notice results.
Oral corticosteroids are much more effective than topical applications but they are rarely prescribed because of their serious side effects.
Minoxidil is probably the second most commonly recommended treatment for alopecia areata. Some patients, especially those with a small bald patch, may benefit from using topical minoxdil, though it was approved for hereditary hair loss and not for alopecia areata. Minoxidil can be used either alone or in combination with corticosteroid injections, cream or gel.
Dithranol or anthralin is a synthetic tar used to treat psoriasis, which also happens to be an autoimmune disease. Dithranol can be applied to the bald spots for about 30-60 minutes to induce hair regrowth. For improved results, it is often used in combination with topical minoxidil.
Topical immunotherapy with cyclosporine or diphencyprone and their combination with other immunosuppressants, applied to the bald spot once a week for several weeks causes a mild skin inflammation, which, paradoxically, seems to suppress alopecia areata and trigger hair regrowth. Topical immunotherapy is usually prescribed to patients with extensive alopecia areata.
PUVA (psoralen plus ultraviolet A radiation) is a therapy consisting of oral or topical drug psoralen with subsequent ultraviolet radiation. PUVA is used for extensive alopecia areata when other treatments have failed but its effectiveness varies from patient to patient.