Common baldness in women, also called female pattern alopecia, is genetically inherited and can come from either the mother’s or father’s side of the family. Female alopecia most commonly presents in a diffuse pattern, where hair loss occurs over the entire scalp . Less commonly, Womens Hair Loss exhibits a patterned distribution where most of the thinning occurs on the front and top of the scalp with relative sparing of the back and sides.
The type of hair loss, diffuse or patterned, has important implications for treatment. Women with diffuse hair loss are generally best treated medically, whereas women with patterned hair loss may be good candidates for hair transplant surgery. Interestingly, patterned hair loss is the most common type seen in men and accounts for why a greater proportion of men are candidates for surgery compared to women. In women who are genetically predisposed to hair loss, both diffuse and patterned distributions are caused by the actions of two enzymes: aromatase (which is found predominantly in women) and 5-a reductase (which is found in both women and men). Diffuse hair loss is most often hereditary, but it can also be caused by underlying medical conditions, medications, and other factors; therefore, a thorough medical evaluation is an important part of the management.
In the next sections, we will take a closer look at both the mechanisms of genetically induced female hair loss as well as the medical conditions and drugs that can cause diffuse hair loss in women.
Mechanism of Genetic Hair Loss in Women
As with hair loss in men, female genetic hair loss largely stems from a complex stew of genes, hormones and age. However, in women there are even more players. In addition to 5-a reductase, testosterone, and dihydrotestosterone (DHT); which are also found in men’s hair loss; also present in women are the enzyme aromatase and the female hormones estrone and estradiol. So let’s break down the process that leads to common hair loss in women. In both men and women, 5-a reductase reacts with testosterone to produce DHT, the hormone responsible for the miniaturisation (shrinking) and gradual disappearance of affected hair follicles. This explains why both men and women lose their hair. But one of the reasons why women seldom have the conspicuous bald areas that men do is because women naturally have only half the amount of 5-a reductase compared to men.
Adding to this complexity, in women, the enzyme aromatase is responsible for the formation of the female hormones, estrone and estradiol, counteract the action of DHT. Women have higher levels of aromatase than men, especially at the frontal hairline. It is this presence of aromatase which may help explain why hair loss in women looks so different than in men, particularly with respect to the preservation of the frontal hairline. It may also explain why women have a poor response to the drug finasteride (Propecia), a medication widely used to treat hair loss in men that works by blocking the formation of DHT.