Patterns of Hair Loss
The most common type of hair loss in women, accounting for over 95 per cent of cases, is androgenetic alopecia, or female pattern baldness. There’s a large genetic predisposition, which may be inherited from the father or mother. The cause of hair loss in this condition is a chemical called dihydrotestosterone, or DHT, which is made from androgens (male hormones that all men and women produce) by the action of an enzyme called 5-alpha reductase. People with a lot of this enzyme make more DHT, which in excess can cause the hair follicles to make thinner and thinner hair until they eventually pack up completely. The pattern of hair loss is different to the typical receding hairline and crown loss in men. Instead, there’s usually a general thinning of the hair with loss predominantly over the top and sides of the head. It usually gets worse with the menopause. Another common cause of hair loss in women is a condition called alopecia areata, an autoimmune disease that affects more than two per cent of the population. In this, the hair follicles are attacked by white blood cells. The follicles then become very small and hair production slows down dramatically, so there may be no visible hair growth for months and years. After some time, hair may regrow as before, come back in patchy areas or not at all. The good news is that in every case the hair follicles remain alive and can be switched on again; the bad news is that we don’t yet know how to do this.
The drug minoxidil was first developed for treating high blood pressure, which was found to have the side effect of thickening hair growth in some people. It’s now available as a lotion to apply directly to the scalp. No one really knows how it works, however, and it’s not effective for everyone. Studies show that only about 20 per cent of women between 18 and 45 have moderate regrowth using the drug, while another 40 per cent experience minimal regrowth. It works best on younger people with early hair loss. A big disadvantage is that you have to carry on using minoxidil indefinitely or the new hair will fall out. Another drug, finasteride, which was developed for treating prostate cancer, has also been found to be effective but is only available for men.
Surgical techniques for restoring hair have improved greatly in the past couple of decades, but this is still an option that requires careful consideration. There are two main options:
- Hair transplantation – tiny punch-holes of skin containing a few follicles of hair are taken from elsewhere in the body (such as the back of the head, if this is still well covered) and implanted into the thinning areas. Some surgeons use a needle to sew in just one or two hairs. However, as women are more likely to have diffuse loss of hair all over the scalp, this technique may not be possible. There has been little success with implanting artificial fibres.
- Scalp reduction – devices are inserted under the skin to stretch the areas of scalp that still have hair, then the redundant bald areas are removed. Alternatively, flaps of hairy scalp can be moved around the head.
This article was last medically reviewed by Dr Trisha Macnair in August 2005.
First published in November 1997.