What is alopecia areata?

Alopecia is a general term for hair loss. Alopecia areata is a common cause of non-scarring (does not cause scarring to the scalp) hair loss that can occur at any age. It usually causes small, coin-sized, round patches of baldness on the scalp, although hair elsewhere such as the beard, eyebrows, eyelashes, body and limbs can be affected. In some people larger areas are affected and occasionally it can involve the whole scalp (alopecia totalis) or even the entire body and scalp (alopecia universalis).

It is not possible to predict how much hair will be lost. Regrowth of hair in typical alopecia areata is usual over a period of months or sometimes years, but cannot be guaranteed. The chances of the hair regrowing are better if less hair is lost at the beginning. Most people, with only a few small patches get full regrowth within a year. If more than half the hair is lost then the chances of a full recovery are not good. The hair sometimes regrows white, at least in the first instance. Most people get further attacks of alopecia areata. In alopecia totalis and alopecia universalis, the likelihood of total regrowth is less.

What causes alopecia areata?

Hair is lost because it is affected by inflammation. The cause of this inflammation is unknown but it is thought that the immune system, the natural defence which normally protects the body from infections and other diseases, may attack the growing hair. Why this might happen is not fully understood, nor is it known why only localised areas are affected and why the hair usually regrows again.

Someone with alopecia areata is slightly more likely than a person without it to develop other autoimmune conditions such as thyroid disease, diabetes, lupus and vitiligo (white patches on the skin), although the risk of getting these disorders is still very low. If you have other symptoms then discuss these with your doctor. Your doctor may suggest a blood test.

Alopecia areata is not catching and no connection has been made with food or vitamin deficiencies. Stress occasionally appears to be a trigger for alopecia areata, but it is possible that this link may be coincidental as many of those affected have no significant stress.

Is alopecia areata hereditary?

There is a genetic predisposition to alopecia areata. About 20% of people with alopecia areata have a family history.

• Can it be cured ?

No, alopecia areata cannot be cured. Depending on the extent of hair loss there is a good chance that, for 4 out of 5 affected people, complete regrowth will occur within 1 year without treatment. There may, however, be further episodes of hair loss in the future. If there is very extensive hair loss from the start, the chances of it regrowing are not as good. Those with more than half the hair lost at the beginning or with complete hair loss at any stage have only about a 1 in 10 chance of full recovery. The chances of regrowth are not so good in young children and those with the condition affecting the hairline at the front, side or back.

• How can alopecia areata be treated?

People with mild early alopecia areata may need no treatment, as their hair is likely to come back anyway without it. Some treatments can induce hair growth, though none is able to alter the overall course of the disease. Any treatments that carry serious risks should be avoided, as alopecia areata itself has no adverse effect on physical health.

Causes of Alopecia

Alopecia is caused by an immune system disorder where the body gets confused and attacks itself. It’s believed to be an inherited condition, so if one of your family members has it, there is a higher probability you may eventually develop symptoms as well. You’re particularly at risk if any type of autoimmune disease runs in your family.

Who gets alopecia areata?

Alopecia areata can affect males and females at any age. It starts in childhood in about 50%, and before the age of 40 years in 80%. Lifetime risk is 1–2% and is independent of ethnicity.

A family history of alopecia areata and/or of other autoimmune disease are present in 10–25% of patients.

At least 8 susceptibility genes have been detected.

Patients with alopecia areata have higher than expected rates of thyroid disease, vitiligo and atopic eczema.

There is an increased prevalence in patients with chromosomal disorders such as Down syndrome.

It’s possibly drug-induced when arising in patients on biologic medicines.

Alopecia areata is classified as an autoimmune disorder. It is histologically characterised by T cells around the hair follicles. These CD8(+)NK group 2D-positive (NKG2D(+)) T cells release pro-inflammatory cytokines and chemokines that reject the hair. The exact mechanism is not yet understood.

The onset or recurrence of hair loss is sometimes triggered by:

• Viral infection

• Trauma

• Hormonal change

• Emotional/physical stressors.

Patchy alopecia areata has three stages.

1. Sudden loss of hair

2 . Enlargement of bald patch or patches

3 . Regrowth of hair

The bald areas may have a smooth surface, completely devoid of hair or with scattered ‘exclamation mark’ hairs.

References… ( Dermnet ( Alopecia areata))

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