Androgenetic alopecia is characterised by progressive, patterned hair loss from the scalp. Recently the pathogenesis and genetic basis of the hair loss have been better understood, as has the distress experienced by men who have lost their hair. There have also been breakthroughs in the treatment of androgenetic alopecia.
The prerequisites for premature androgenetic alopecia are a genetic predisposition and sufficient circulating androgens. Eunuchs do not go bald. Every white man possesses the autosomal inherited predisposition, and 96% lose hair to some degree, but because of the variabity of gene expression far fewer have appreciable premature hair loss.
Nearly all balding persons suffer from Androgenetic Alopecia or Pattern Baldness. Men with Androgenetic Alopecia incur a higher degree of hair loss than women. The process of hair loss usually starts with a receding hair line. DHT (short for dihydrotestosterone) is a significant contributing factor to Androgenetic Alopecia. DHT is an important hormone but after adulthood, the body requires much less of it. If excess DHT is produced, it binds / clings to the hair follicles and creates a waxy substance that builds up under the skin on the top of the head. The hair follicles are slowly smothered and choked from receiving nutrients and they shrink and become unable to sustain hair growth.
Androgenetic alopecia is also androgen dependent. Androgens are the hormones that stimulate the development of male sex characteristics. Testosterone is one type of androgen. Androgens induce alopecia by shortening the anagen phase and increasing the number of hairs that are in the telogen phase. Some women with androgenetic alopecia have abnormally elevated levels of androgens in their bodies as a result of underlying ovarian or adrenal gland disorders.
Men with androgenetic alopecia typically have a receding hairline and moderate to extensive loss of hair, especially on the front and top of the head. The remaining hair tends to feel a little finer and shorter than normal. Male pattern baldness can start as early as the teenage years.
Women with androgenetic alopecia experience overall thinning of their hair. For example, where there used to be five hairs, there may only be two. Most of the hair that's lost is on the crown of the head or at the hairline. Female pattern baldness usually starts around age 30 and becomes noticeable around age 40.
