Although there are many forms of alopecia, the most prevalent by far is androgenetic alopecia, better known as male pattern baldness. About 95% of all cases of hair loss are the result of male pattern baldness, but this number also includes women, who can have a version of hair loss referred to as female androgenetic alopecia or female pattern baldness. Approximately 25% of men begin balding by age 30; two-thirds begin balding by age 60. For women, androgenetic alopecia was found in 3% of women ages 20 to 29 years, 16 to 17% of women ages 30 to 49, 23 to 25% of women ages 50 to 69, 28% of women ages 70 to 79, and 32% of women ages 80 to 89. In some research, statistics indicate that 40% of women are affected by androgenetic alopecia. As you can tell by these numbers, female pattern baldness increases dramatically just before and after menopause.
For men, male pattern baldness develops in a horseshoe pattern, with the hair receding from the forehead back toward the neck. Male pattern baldness can also take place from the center of the scalp out toward the sides. For women, the location is more diffuse, with hair loss taking place all over the scalp (Sources: Male Pattern Baldness, American Medical Association Medical Library, www. medem. com; Hair Loss & Restoration in Women, International Society of Hair Restoration Surgery, www. ishrs. org; and Dermatologic Surgery, January 2001, pages 53-54).
The key element you need to be aware of to understand whether the products being sold to improve or restore hair growth will work is how hormones affect hair growth. This is because, for both male pattern baldness and female pattern baldness, hormones are the primary cause of hair loss. First, let’s start with some basic information about the hair growing on your head.
Hair growth basically has a lot to do with hormonal activity, and is especially related to the male sex hormone group called androgens. (Androgens are male hormones such as testosterone and dihydrotestosterone.) Many different types of hormones influence hair growth, but androgens are believed to have the largest impact on the process. Testosterone and dihydrotestosterone (DHT, a hormonal by-product of testosterone) are produced in large quantities by the testes in men, and in smaller quantities by the ovaries in women. These hormones are responsible for the development of secondary male sex characteristics for both genders. They are also responsible for increasing the size of hair follicles early in life, and, ironically, for decreasing and shrinking the hair follicles later in life.
Technically, what is in part believed to be taking place in the hair follicle is that over time testosterone is changed to dihydrotestosterone (DHT) by the enzyme 5-alpha reductase (5AR). When DHT becomes concentrated in the hair follicle it eventually slows, and ultimately stops, hair growth. It is also believed that the effect of DHT is compounded or enhanced by an individual’s genetic hair-follicle traits.
(Sources: Journal of the American Academy of Dermatology, October 2008, pages 547-566, and May 2004, pages 777-779; British Journal of Dermatology, April 2004, pages 750-752; Journal of Investigative Dermatology, December 2003, pages 1561-1564; American Journal of Clinical Dermatology, 2003, volume 4, issue 6, pages 371-378; Androgenetic Alopecia, October 2, 2003; www. emedicine. com; and Journal of Alternative and Complementary Medicine, April 2002, pages 143-152.)
For women, it appears that their increased levels of estrogen (the primary female sex hormone) act against the effects of male androgens on hair growth. This explains why, when estrogen levels decrease as women approach menopause, androgen-related balding can begin to appear. There is some research indicating that topical application of estrogen can induce hair growth in women (Source: Journal of Investigative Dermatology, January 2004, pages 7-13).