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Pattern hair loss

life science Maturity 11-13 Next article →

Pattern hair loss is the most frequent cause of hair loss in humans.

Skin
Skin

Scientists formally call this condition androgenetic alopecia, or AGA. It is a non-scarring form of hair loss. This means the hair follicles are not permanently destroyed. Instead, they often become dormant, or inactive. This condition affects the top and front of the scalp. It is a complex process involving hormones, genetics, and metabolic health. Understanding how it works helps us see the connection between our genes and our bodies.

The mechanism of hair loss involves a specific hormonal process. The body uses an enzyme called 5-alpha-reductase to create dihydrotestosterone, or DHT.

WNTPathway
WNTPathway

DHT is a powerful androgen, which is a type of male sex hormone. In many parts of the body, androgens stimulate hair growth. However, in the scalp, DHT has the opposite effect. This creates what scientists call the "androgen paradox." In the scalp, DHT can stimulate certain proteins like TGF β1 and TGF β2. These proteins lead to catagenic miniaturization. This is a process where the hair follicles shrink over time. As the follicles get smaller, the hair they produce becomes thinner and shorter.

Pattern hair loss presents differently depending on biological sex. In male-pattern hair loss (MPHL), loss usually starts at the temples or the vertex, which is the crown of the head. This can result in a ring of hair at the sides and rear. This pattern is known as a "Hippocratic wreath."

Greek philosopher busts
Greek philosopher busts

In female-pattern hair loss (FPHL), the hair typically shows diffuse thinning across the entire scalp. Women rarely experience total hair loss. Doctors use the Ludwig scale to grade the severity of thinning in women.

Stages of Female Pattern Baldness
Stages of Female Pattern Baldness

This scale tracks how much of the scalp becomes visible through the thinning hair.

Research into the history and genetics of AGA reveals unique human traits. Scientists found that humans have a specific sensitivity to androgens that our great ape cousins do not share. For example, a protein called KRT37 is found in the hair follicles of chimpanzees. However, it is not detected in the head hair of modern humans. This lack of KRT37 may explain why human head hair has such long growth cycles. Genetics also play a major role in how hair loss is passed down. While it often follows autosomal dominant inheritance, research shows that 80% of bald men have bald fathers. This suggests a possible paternal route of inheritance through the Y-chromosome.

The significance of pattern hair loss is seen in its high prevalence. By the age of 50, approximately half of all males experience AGA. About one quarter of females are also affected. Beyond appearance, AGA is linked to broader health patterns. Men who experience early-onset AGA, before age 35, show a higher likelihood of metabolic syndrome (MetS).

Mutation and selection diagram
Mutation and selection diagram

This group of health issues includes insulin resistance and hypertension. Studies found that younger males with early hair loss had a 4× increased frequency of metabolic syndrome. This is considered a clinically significant finding in medical research.

There are several ways people manage the condition today. Some individuals choose creative styling or decide to shave their heads for aesthetic reasons. Medical treatments are also common. These include low-level laser therapy and platelet-rich plasma. There are also medications like minoxidil, finasteride, and dutasteride. Some people opt for hair transplant surgery to restore hair. However, doctors note that finasteride and dutasteride must be used carefully by women. These specific drugs may cause birth defects if taken during pregnancy.

Finally, AGA connects to the wider study of metabolic and endocrine systems. There is a strong link between low levels of sex hormone-binding globulin (SHBG) and insulin resistance. Obesity can also impact these levels by increasing insulin and decreasing SHBG. Furthermore, the growth of hair follicles is tied to insulin-like growth factor (IGF). The production of IGF is stimulated by growth hormone, which peaks during deep sleep. Because of these links, medical experts suggest that those with early hair loss may benefit from screening for glucose metabolism disorders. This shows how a single condition can be a window into the body's entire chemical balance.

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File:Skin.png
Skin.png
File:WNTPathway.png
WNTPathway.png
File:Stages of Female Pattern Baldness.png
Stages of Female Pattern Baldness.png
File:Mutation and selection diagram.svg
Mutation and selection diagram.svg
File:Greek philosopher busts.jpg
Greek philosopher busts.jpg
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