Androgenetic Alopecia

Androgenetic Alopecia, a genetic condition, is the most common form of hair loss affecting about 2/3 of men and 1/3 of women in their lifetime. It is also referred to as Male Pattern Baldness (MPB), Androgenic Hair Loss, and Common Baldness. In women it is referred to as Female Pattern Alopecia.

Androgenetic Alopecia is caused by the affect of DHT (a byproduct of Testosterone) on the hair follicle. DHT can cause the hair follicles in certain parts of the scalp to produce thinner, shorter hairs with weaker hair shafts. These hairs will become finer with each hair cycle until they are become vellus, almost invisible hairs or they die out altogether.

Briefly, DHT shortens the hair cycle so that the hair that we naturally shed is replaced by a thinner hair at a slightly faster rate. This process by which the hair becomes thinner and thinner, is referred to as miniaturization.

In men DHT affects mainly the front, top, and crown of the scalp, sparing the back and sides. In women the hair loss tends to be more generalized due to the effects of both DHT and the aromatase enzyme.

In order for the effects of Androgenetic Alopecia to show itself there must be three existing conditions: 1) the hereditary genes for hair loss, 2) DHT in sufficient quantities and 3) the passage of time. Patients with Androgenetic Alopecia generally lose their hair at a very gradual rate. Unfortunately, in patients who begin to bald at a relatively young age, the hair loss can be rapid.

In men, the pattern of this hair loss can be comparatively determined by using the Norwood Classification Table, a chart of hair loss patterns which can aid in determining current and future hair loss. In women the Ludwig classification is used.

The evaluation of the extent of Androgenetic Alopecia and the possible need for surgical or medical treatments is aided by the use of a densitometer. With densitometry, the physician can analyze the scalp hair under high-power magnification and look for changes in hair diameter called miniaturization – a sign that is literally diagnostic of androgenetic hair loss. Despite the utility of this technique, densitometry is still an art, and requires significant experience on the part of the physician to yield reliable information.

There are two FDA approved medications for hair loss, minoxidil and finasteride. Minoxidil, the first to be approved under the brand name Rogaine, stimulates miniaturized hair to turn back into thicker, healthier hair. Finasteride, a DHT blocking medication taken orally (brand name Propecia), is significantly more effective than minoxidil in treating hair loss. These medications can be used together and work in any areas of the thinning scalp to halt or reverse the process of miniaturization. The medications can be particularly effective if started when a person’s hair loss is still in its early stages.

In more advanced cases of hair loss, hair transplantation is needed to restore one’s hair. This procedure has advanced to the point where its results are imperceptible from existing hair. Follicular Unit Transplantation is the technique that currently procedures the best cosmetic results.

Robert M. Bernstein M.D., F.A.A.D.

Clinical Professor of Dermatology
College of Physicians and Surgeons of Columbia University
New York, New York
Bernstein Medical – Center for Hair Restoration