Alopecia areata

Alopecia areata (patchy baldness) is a relatively common, non-contagious autoimmune disease that causes hair loss. It can occur on the scalp or other parts of the body in both men and women.

The cause of alopecia areata is unknown. It typically occurs first in childhood, and appears as one or more round bald patches on the scalp approximately the size of a quarter. The patches typically occur suddenly.

In most instances, alopecia areata does not progress beyond a few bald patches. However, complete baldness of the head (alopecia areata totalis) or complete hair loss on the head, face and body (alopecia areata universalis) may occur in very rare cases. Some individuals may also develop "pits" or "dents" in the fingernails as a result of the disease.

Each person sheds and regrows hair daily. Hair loss results when more hairs are being shed than regrown. Unlike animals, humans have a distinct pattern of growing, resting and shedding hair. Humans have a distinct number of terminal hair follicles at birth. These follicles grow and shed hairs in cycles.

During the normal cycle of hair growth, approximately 90 percent of the hair on a person’s scalp is growing at any one time. This growth (anagen) phase may last several years, with each hair growing about one centimeter per month during this time. When hair stops growing, it enters a resting (telogen) phase of three to four months. Hair is released from the hair shaft and shed from the scalp, initiating the next cycle of growth. Each day about 75 hairs are lost from a healthy person’s head.

The National Institutes of Health (NIH) estimates that alopecia areata affects approximately 4 million Americans at some point in their lives. Instances of the disease are commonly noted in people of both genders and of all ages and ethnic backgrounds. Alopecia areata is not painful or life-threatening and patients are often generally healthy otherwise.

Alopecia areata (patchy baldness) is a noncontagious, autoimmune disease in which white blood cells release chemical messengers known as cytokines to attack healthy cells located in hair follicles. This shrinks the follicle to a point where hair production is considerably reduced. However, new follicle cells being produced naturally by the body are not affected, making hair regrowth possible in all cases.

Exactly why alopecia areata occurs is unknown. Some research suggests a combination of certain genes may make some people more likely to develop the disease. It may be that some sort of biological (e.g., virus) or emotional trigger (e.g., stress) initiates alopecia areata in people genetically predisposed to the disease. People with family members affected by the disease have an increased risk for exposure, particularly if the initial hair loss occurs before the age of 30.

Children with the disease do not usually have a parent with the condition. It is generally believed that several genes cause alopecia areata. This makes it unlikely that a child born to one or both parents with alopecia areata would inherit all of the necessary genes to develop the disease. In addition, twins with identical genes that cause alopecia areata often do not develop the disease in unison, suggesting other factors besides genetics may play a role in how the disease is triggered.

People with asthma, thyroid disease or certain allergic conditions (e.g., atopic eczema, hay fever) are also at increased risk for alopecia areata. The condition also occurs more frequently in people with a family history of these conditions or other autoimmune diseases (e.g., diabetes, rheumatoid arthritis, vitiligo). However, patients with alopecia areata do not usually have other autoimmune diseases themselves. The condition is also common in people with Down syndrome or other chromosomal disorders.

Signs and symptoms of alopecia areata may vary depending on the individual, and include:

• Minimal hair loss, followed by regrowth with the condition never recurring
• Loss and regrowth of hair indefinitely
• Hair loss confined solely to the scalp
• Hair loss on the face and body
• Hairs tapered near the scalp (exclamation point hairs)

Alopecia areata can be diagnosed by a physician. In addition to taking a medical history and performing a physical examination, inspecting the scalp and pattern of hair loss is often sufficient to diagnose alopecia areata or a similar disorder (e.g., male pattern baldness, androgenetic alopecia). Hairs may also be tugged or pulled out to determine hair strength.

If a diagnosis is not clear, a physician may take a sample of hair and scalp for laboratory analysis (biopsy). In some cases, blood tests may be used to test for other medical conditions that cause hair loss (e.g., overproduction of thyroid hormone [hyperthyroidism]).

Treatment of alopecia areata is not necessary because the condition is not dangerous to a patient’s overall health. However, the disease can have an emotional impact, which may improve through treatment. Recurrent hair growth followed by hair loss is common in people with alopecia areata. There is no cure for the disease, nor are there any specifically approved treatments.

Hair regrowth is always possible for patients, regardless of the severity of hair loss, because follicle production is not affected. Regrown hair is often white and very fine at first, but over time it regains most or all of its normal color and texture. Regrowth of all the hair may take months or years.

Although they do not prevent new bald patches, some medications approved for other purposes may be useful in regrowing hair, including:

The cause of alopecia areata is unknown, making prevention of the disease impossible. Limiting stress may be beneficial for predisposed individuals, as stressful events may have a triggering effect. In addition, taking some preventative measures may minimize the embarrassment and dangers of extensive hair loss.

Because hair loss can take an emotional toll on a person, patients may benefit from joining an alopecia areata support group. Counseling from a mental health professional can also help boost a patient’s self-esteem.