Androgenetic Alopecia is the most common form of thinning hair in men, but is also a surprisingly common cause of female hair loss. Often known as Male Pattern Baldness, it results when:
1. Hair loss occurs at an abnormally high rate;
2. Hair replacement occurs at an abnormally slow rate;
3. Normal hairs are replaced by smaller, thinner hairs, called "miniaturization"
Androgenetic Alopecia affects approximately 30% of men before they reach the age of 30, and 50% of males over the age of 50. More surprisingly, it also affects 40% of women over the age of 50.
The causes of Androgenetic Alopecia are still not fully understood, although as its name suggests, it is widely thought to involve both hormonal (Androgens are hormones) and genetic causes. Of the many hormones that regulate hair on the scalp, Androgens have the largest effect.
Of the androgenic hormones, Testosterone and Dihdrotestosterone (DHT) have the greatest effect on hair loss. Testosterone is converted to DHT by enzymes all over the body, but there are high concentrations of these enzymes in the scalp, and especially inside the hair follicle. DHT is the active form of testosterone that interacts with your body's signaling pathways. In hair loss, DHT stimulates the mechanism that stops hair growth, and begins the hair's Catagen and Telogen Phases.
The genetic aspect of this may be twofold. Firstly there is evidence that some populations have higher basal concenrations of DHT, they simply have more naturally. This, like many hormonal differences, is probably genetically inherited. Also, there is a theory that a set of genes could make some people's hair follicles more sensitive to DHT. This means some people react more strongly to increase in DHT, and lose hair, while others do not from lose hair the same change in hormone level. However, even if you are genetically predisposed to thinning hair, there is no guarantee you will have it, in the same way that people in families with thinning hair often do not suffer from it.
Many women find that the hair on their head is thinning during menopause or pregnancy – this is due to changes in the levels of the hormone DHT in the scalp. Thinning hair in women is often referred to as hormonal hair loss rather than Androgenetic alopecia, but they are in fact the same condition.
In men, DHT is very important for reaching maturity; it is DHT that causes body and facial hair to begin growing. Later in life however, these same Androgens (primarily DHT) are responsible for the reduction in size of the follicles in the scalp.
The longer the hair follicle is kept in the presence of DHT, the more miniaturized the follicle becomes. Miniaturisation is caused by the shortening of the Anagen or growth phase, and is when the hair itself becomes shorter and thinner. DHT also increases the rate of hair loss by signaling to the hair to reach Telogen phase sooner, so more hair is lost is well; these factors combined give noticeable thinning hair.
If treatment is not administrated, this process continues, the follicles progressively become shorter and less visible, and some will eventually close completely and stop growing.
DHT is integral to the majority of androgenetic alopecia sufferer's problems. So it is clear that any hair loss treatment should begin by removing DHT or relieving the effects of DHT. There are many products available to inhibit DHT formation, the prescription option Finasteride is very effective, but unfortunately there is a wide variety of severe side effects, and can not be used by women. There are a variety of alternatives to Finasteride available; some like saw palmetto also prevent DHT production, and some like Minoxidil or Superoxide Dismutases work in a different way to reverse the effects of DHT.