It has been proven that one of the main reasons men have more significant hair loss than women has to do with hormones. Men have much higher levels of male hormones, or androgens – such as testosterone, androsteinedione, dihydrotestosterone, which increase alopecia in individuals who are genetically susceptible. One can determine if he has such a genetic inheritance simply by looking at the male members of the family – father, grandfathers; if they have what is called male pattern baldness, chances are he will experience it too, later in life.
Testosterone, a hormone that is present in large quantities in males after puberty, interacts with an enzyme called 5-alpha reductase, which resides in the hair cell, producing dihydrotestosterone (DHT). DHT acts on a hormone receptor on the hair follicle, causing the hair follicle to shrink; the hair follicle starts producing weaker, shorter hair, and sometimes hair growth is stopped.
Both men and women tend to lose hair thickness and amount as they age. Inherited or "pattern baldness" affects many more men than women. About 25% of men begin to bald by the time they are 30 years old, and about two-thirds are either bald or have a balding pattern by age 60.
Thus, common baldness in men, scientifically called androgenetic alopecia or male-pattern baldness, is the result of the contribution of three main factors: genetic inheritance, hormones and aging.
As proof that hormones play an important role in the process stands the fact that men who do not produce testosterone (because of genetic abnormalities or castration) do not develop this pattern of baldness. What is even more interesting and has not yet been explained is that DHT, while interfering with the growing process of scalp hair, is absolutely necessary for the growth of the beard and hair on the chest. This explains why bald men can have bushy beards and hairy chests.
Typical male pattern baldness involves a receding hairline and thinning around the crown with eventual bald spots. Ultimately, you may have only a horseshoe ring of hair around the sides.
The very first signs of the effects of these hormones on scalp hair growth may occur soon after puberty (in boys, around age 13), when the reproductive organs reach maturity; after puberty, the frontal hairline may recede. After that, in some men, male pattern baldness may come on very fast, in others may not come at all. Nobody can say to what extent an individual may lose his hair, as every individual is unique.
