Alopecia simply means hair loss (baldness).
The most common type of alopecia is androgenetic alopecia, which is an inherited condition. This type of alopecia affects as many as 30-40% of men and women. Androgenetic alopecia is the most common cause of hair loss in adolescents and can begin much earlier than most people think, as early as age 12 in boys and girls. Hair loss accounts for approximately 3% of children's visits to dermatologists.
Hair loss occurs for a great many reasons, from conditions that make people literally pull it out to complete hair loss caused by the toxicity of cancer chemotherapy. Some causes are considered natural, while others signal serious health problems. Some conditions are confined to the scalp. Others reflect disease throughout the body. Being plainly visible, the skin and its components can provide early signs of disease elsewhere in the body. Often, conditions affecting the skin of the scalp will result in hair loss. The first clue to the specific cause is the pattern of hair loss, whether it is complete baldness (alopecia totalis), patchy bald spots, thinning, or hair loss confined to certain areas. Another contributing factor is the condition of the hair and the scalp beneath it. Sometimes only the hair is affected; sometimes the skin is visibly diseased as well.
Alopecia results from a number of causes ranging from hereditary to psychological.
Dermatologists are skilled in diagnosis by sight alone. For more obscure diseases, a skin biopsy may be used to remove a specimen of the skin so that it can be examined under a microscope. Systemic diseases will require a complete evaluation by a physician, including specific tests to identify and characterize the problem.
Successful treatment of underlying causes is most likely to restore hair growth, such as the completion of chemotherapy, effective cure of a scalp fungus, or control of a systemic disease.
Over the past few decades a multitude of hair replacement methods have been performed by physicians and non-physicians. They range from simply weaving someone else's hair in with the remains of one's own to surgically transplanting thousands of hair follicles one at a time.
Hair transplantation is completed by taking tiny plugs of skin, each containing one to several hairs, from the back side of the scalp. The bald sections are then implanted with the plugs. Research has evaluated the technique of hair grafting, and found that micrografts (one or two hairs transplanted per follicle) resulted in fewer complications and the best results.
Another surgical procedure used to treat androgenic alopecia is scalp reduction. By stretching skin, the hairless scalp can be removed and the area of bald skin decreased by closing the space with hair-covered scalp. Hair-bearing skin can also be folded over an area of bald skin with a technique called a flap.
Stem cell research is generating new hope for baldness. Scientists know that a part of the hair follicle called the bulge contains stem cells that can give rise to new hair and help heal skin wounds. Research with mice and humans continues to show promise for identifying the genes that cause baldness and to identify drugs that can reverse the process.
Two drugs-minoxidil (Rogaine) and finasteride (Proscar)-promote hair growth in a significant minority of patients, especially those with male pattern baldness and alopecia areata. Both drugs have proved to be safe when used for this purpose. Minoxidil is a liquid that is applied directly to the scalp and finasteride is the first and only approved treatment for hair loss available in a pill form. Only minoxidil is used in women.
Minoxidil was approved for over-the-counter sales in 1996. When used continuously for long periods of time, minoxidil produces satisfactory results in about one-fourth of patients with androgenic alopecia and as many as half the patients with alopecia areata. There is also an over-the-counter extra-strength version of minoxidil (5% concentration) approved for use by men only. The treatment often results in new hair that is thinner and lighter in color. It is important to note that new hair stops growing soon after the use of minoxidil is discontinued.
Women with androgenetic alopecia who do not respond to treatment with minoxidil may be prescribed the drug spironolactone, which blocks the action of the hormone aldosterone. Results of a small study on 42 patients with alopecia areata reported in 2009 indicated that application of a 1% bexarotene gel applied daily to areas of alopecia areata for up to six months resulted in significant hair regrowth, even in areas of the scalp that had not been treated with the topical solution. Researchers in 2010 reported in the British Journal of Clinical Psychiatry that the drug olanzapine was a safe and effective treatment for alopecia associated with the condition trichotillomania.
The prognosis of alopecia varies with the cause. It is generally much easier to lose hair than to regrow it. Even when it returns, it is often thin and less attractive than the original.