Alopecia and Its Causes
Hair Loss Causes and Conditions
Many things can cause hair loss in men and women, including disease, nutritional deficiency, hormone imbalance, certain medical treatments and stress. However, by far the most common cause of hair loss is a condition known as androgenetic alopecia (also known as male pattern baldness in men). Alopecia is simply the medical term for hair loss. Androgenetic refers to the fact that both genetic predispositions to balding, and the influence of androgens, or male hormones, play a part in this type of hair loss. And, there is a third factor--the passage of time. In other words, in order for androgenetic alopecia to occur, there must be:
* a genetic propensity for balding
* the presence of androgens, or male hormones
* enough aging time to allow the first two factors to exert their influence on the hair follicles
Contrary to myth, balding is not caused by wearing hats. Massaging or brushing the scalp will not help regrow hair and excessive cleaning of the scalp will not "unclog" follicles and allow hair growth. While extreme psychological stress may contribute to a form of hair loss known as alopecia areata, normal everyday stress does not contribute to balding and is not a cause of androgenetic alopecia.
Genetic predisposition is not always clear cut. Just the presence or absence of balding in one's parents or grandparents is not necessarily predictive of one's likelihood of balding. Certainly, if a man's father is completely bald, and this man begins to rapidly lose hair in his early twenties, it's a safe bet that he will develop extensive balding at some point. In short, it's very hard to accurately predict who will go bald and how rapidly.
Androgenic Hormones
All normal men and women produce "male" and "female" hormones. The most common are testosterone and estrogen. It is the exposure of the hair follicles to DHT in a genetically susceptible person, over a period of time, which leads to androgenetic alopecia, or male and female pattern baldness. How does exposure to DHT occur?
In certain cells of the hair follicle, and in the sebaceous glands, there are high levels of an enzyme called 5-alpha-reductase. This enzyme converts testosterone, which is delivered to these areas by the blood, into DHT.
DHT can cause hair follicles to shrink, and the hair consequently becomes thinner and shorter. The growing phase of the growth cycle becomes progressively shorter, which means more hairs are shed. Although the follicles still have an adequate blood supply, they continue to shrink, and some eventually die. Some follicles (usually those on the back or side of the head) can be resistant to the effects of DHT. These are potential donor sites for hair transplantation.