Male Pattern Baldness
The science of Male Pattern Baldness
Male pattern baldness is also called male androgenetic alopecia, alopecia or genetic hair loss. Male pattern baldness is so named because it appears in a common pattern, beginning with a receding hairline at the temples creating an M pattern, progressing to diffuse thinning of the hair at the front and center, and eventually hair loss at the crown. Time to baldness has been reported to be 15-25 years. However, some men go bald in less than five years. Androgenetic alopecia tends to affect both men and women in the family.
What causes male pattern baldness?
Genetics and male sex hormones (androgens) play key roles in androgenetic hair loss. Human hair follicles have an inherited tendency for androgen-dependent growth beginning in puberty, which stimulates the growth of the beard, underarms and pubic areas. In male pattern baldness androgens suppress the growth of the hair.
- Heredity accounts for about 80% of the tendency toward male pattern baldness. The baldness genes modify the hair follicle’s response to androgens. If the tendency is strong, baldness happens earlier in life. If weak, it happens later. Less than 15% of men have little, or no baldness by age 70. Recent studies have shown that while the gene for male pattern baldness is on the X chromosome passed from mother to male child, additional genes from the father also contribute.
- The role of androgens or male hormones, specifically testosterone, is well established in genetic hair loss. Recent studies suggest that a range of hormones play a role in male pattern baldness. Studies also report that even normal levels of androgens are sufficient to cause hair loss in genetically vulnerable people.
- Male pattern baldness alters hair cycle development and causes follicular miniaturization and inflammation.
How do male hormones trigger baldness?
Hair grows in cycles. Each follicle normally grows for 2-6 years, during which new hair is formed and grows to push out the old hair. Next comes the resting phase which lasts about 3 months. After that, the hair is shed, and the next growth cycle begins.
In men with a genetic tendency, an enzyme called 5-alpha reductase that turns testosterone into dihydrotestosterone (DHT). DHT attaches to the hair follicles and causes them to shrink with every growth cycle. It also leads to shorter and shorter hair cycles and delays the growth of new hair to replace hair that has been shed. With time, the hair follicles become so small that they only grow short, fine hairs. This is called follicular miniaturization. Follicle miniaturization is a hallmark of male pattern baldness. Eventually, the follicles wear out and stop growing hair.
Another hormone (Prostaglandin D2) causes inflammation of the hair follicles which causes the hair follicles to stop growing hair. Only recently have other non-genetic factors been studied for their potential role in male pattern baldness.
Environmental factors like climate, lifestyle and socioeconomic factors related to your geographic location are involved. Body Mass Index is important, and the science is clear that heart disease, insulin resistance, hypertension, high cholesterol and obesity are linked to male pattern baldness. Some of these factors are modifiable, but the exact impact of lifestyle modifications on male pattern baldness is not yet known.
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