Everything about Male Pattern Baldness totally explained
Androgenic alopecia (also known as
androgenetic alopecia or
alopecia androgenetica) is a common form of
hair loss in both male and female
humans,
chimpanzees, and
orangutans. In male humans in particular, this condition is also commonly known as
male-pattern baldness. Hair is lost in a well-defined pattern, beginning above both temples. Over time, the hairline recedes to form a characteristic "M" shape. Hair also thins at the crown of the head, often progressing to partial or complete baldness.
The pattern of hair loss in women differs from male-pattern baldness. In women, the hair becomes thinner all over the head, and the hairline doesn't recede. Androgenetic alopecia in women rarely leads to total baldness.
A variety of genetic and environmental factors likely play a role in causing androgenetic alopecia. Although researchers are studying risk factors that may contribute to this condition, most of these factors remain unknown. Researchers have determined that this form of hair loss is related to hormones called
androgens, particularly an androgen called
dihydrotestosterone (DHT). Androgens are important for normal male sexual development before birth and during puberty. Androgens also have other important functions in both males and females, such as regulating hair growth and sex drive.
Hair loss and genetics
Researchers suspect that several
genes inherited from both
parents play a role in androgenetic alopecia. Paternal hair loss has been shown to correlate with chances of alopecia in
sons, while variations in the androgen receptor gene (
AR), which can also correlate with baldness, are X linked and thus inherited from one's maternal grandfather or grandmother.
Androgen receptors allow the body to respond appropriately to dihydrotestosterone and other androgens. Studies suggest that variations in the
AR gene lead to increased activity of androgen receptors in hair follicles. It remains unclear, however, how these genetic changes increase the incidence of patterned hair loss in men and women with androgenetic alopecia.
The inheritance pattern of androgenetic alopecia is unclear because many genetic and environmental factors are likely to be involved. This condition tends to cluster in families, however, and having a close relative with patterned hair loss appears to be a risk factor for developing the condition.
Hormone levels correlated with androgenetic alopecia
Men with androgenic alopecia typically have lower levels of total
testosterone, higher levels of unbound/free testosterone, and higher levels of total free androgens including DHT.
5-alpha-reductase is responsible for converting free testosterone into DHT. The genes for 5alpha-reductase are known. The enzymes are present predominantly in the scalp and prostate. Levels of 5alpha-reductase are one factor in determining levels of DHT in the scalp and drugs which interfere with 5alpha-reductase (such as finasteride, which inhibits the predominant type 2 isoform ) have been approved by the FDA as treatments for hair loss.
Sex hormone binding globulin (SHBG), which is responsible for binding testosterone and preventing its bioavailability and conversion to DHT, is typically lower in individuals with high DHT. SHBG is downregulated by insulin.
Increased levels of Insulin Growth Factor-1 (
IGF-1) have been correlated to vertex balding
High insulin levels seem the likely link between metabolic syndrome and baldness. Low levels of SHBG in men and non-pregnant women are also correlated with glucose intolerance and diabetes risk, though this correlation disappears during pregnancy.
Hair loss and lifestyle
While genetic factors seem to play the principal role in the development and progression of androgenetic alopecia, lifestyle also plays a minor role as demonstrated by the vast increase in male and female pattern baldness in
Japan after
World War II, when the country moved to a higher calorie, higher fat diet and a more sedentary lifestyle. Also, pattern baldness (androgenic alopecia) was either rare or non-existent among hunter-gatherer and other, less westernized societies eating in their traditional manner.
Daily, vigorous aerobic exercise (as opposed to short workout periods designed to raise androgen levels and build muscle or more sporadic exercise) has been shown to reduce baseline insulin levels as well as baseline total and free testosterone, significantly lowering baseline DHT. It has been suggested that weight training may have a detrimental effect on hair by increasing testosterone levels; however, there's at least one study that indicates a decline in free testosterone as result of weight training.
Treatments
While most people with male pattern baldness choose to accept the condition as they accepted their hair color or shape, there are
baldness treatments which can reduce or halt hair loss, and in early stages or in rare cases, reverse it entirely. Treatments include:
Future Cures
In May 2008, researchers at the University Pennsylvania unveiled a new scientific breakthrough that may cure baldness with stem cells. A product could be on the market within three years.
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Further Information
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