Male Pattern Baldness
On average, there are 100,000 to 150,000 hairs on the human scalp. The hairs grow from hair roots, or follicles (saclike structures under the skin). Blood vessels at the base of each follicle provide the nourishment necessary for hair growth. Hair growth in each root occurs in a cycle independent of the other roots. At any time about 90 percent of the hairs on the scalp are in the growth phase, while the other 10 percent are in the resting phase. The growth phase lasts an average of four to five years, after which the follicle enters the resting phase, which lasts about two months to four months. At the end of the resting phase, the hair falls out naturally and is replaced by a new hair. Consequently, some hair loss is a normal part of the hair growth cycle. In fact, on a typical day, about 50 to 150 scalp hairs are lost. Baldness (or alopecia) results when hair loss occurs at an abnormally high rate; when hair replacement occurs at an abnormally slow rate; or when normal hairs are replaced by thinner, shorter ones.
What is male pattern baldness?
About 95 percent of all cases of hair loss are the result of androgenetic alopecia
(also known as male pattern baldness in men). Androgenetic alopecia occurs much
more frequently in men than in women. It affects roughly 40 million men in the
United States. Approximately 25 percent of men begin balding by age 30; two-thirds
begin balding by age 60.
While some types of hair loss are easily reversible, male pattern baldness is
more permanent. It occurs in a characteristic pattern on the scalp: hair loss
usually begins at the temples and at the top of the head toward the back, causing
a receding hairline and a bald spot. Hair loss may continue until the two sections
become joined, leaving a horseshoe-shaped area of hair on the sides and back
of the head. Balding may begin at any age after puberty, even in the middle
teens, and can range from partial loss to complete baldness. Male pattern baldness
progresses slowly and is not associated with redness, itching, or pain. Currently,
there is no way to prevent male pattern baldness from occurring.
What causes male pattern baldness?
The causes of male pattern baldness are thought to be complex and are not completely
understood. However, as suggested by its medical name (androgenetic alopecia),
male pattern baldness seems to involve both hormonal (androgen) and genetic
factors. Many different types of hormones play roles in the regulation of scalp
hair, but the hormones with the largest effect are the androgens. Testosterone
and its more potent derivative dihydrotestosterone (DHT) are responsible for
increasing the size of hair follicles in areas such as the beard and underarm
during puberty, but can also cause hair follicles in the scalp to decrease in
size later in life. These contrasting responses to DHT might be explained by
genetic differences in the individual hair follicles. Similarly, in men who
are balding, genetically determined characteristics of hair follicles in the
scalp may cause the follicles to be more likely to degrade in the presence of
androgens. Hair follicles become miniaturized, 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.
Whatever the exact causes of male pattern baldness may be, it is a hereditary
trait. There are multiple genetic factors that influence male pattern baldness.
A tendency toward baldness in the men on either the mother's or father's side
of a man's family indicates a genetic predisposition to baldness. The speed,
pattern, time of onset and degree of balding are all influenced by heredity.
Generally, the earlier the onset of balding, the more extensive the degree of
hair loss will eventually be.
Contrary to popular 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.
Other Pages
Male Pattern Baldness 1
Male Pattern Baldness 2
Male Pattern Baldness 3
