Dihydrotestosterone.

The primary cause of Pattern Baldness (androgenic alopecia) in both men and women is Dihydrotestosterone also known as DHT.

The hormone, testosterone, that is present in both males and females, converts to DHT with the help of an enzyme called Type II 5-alpha reductase. Once DHT builds up, it binds to receptors at the base of the hair follicle and blocks the absorption of vital nutrients from surrounding blood capillaries. This interferes with normal hair growth cycles prolonging the resting phase and shortening the growing phase which eventually causes baldness.

DHT Resistant Safe Area

An interesting characteristic of androgenic alopecia (pattern baldness) is that DHT only affects follicles in the frontal hairline, the vertex (the top of the head) or the crown. The sides and the back of the scalp remain unaffected.

This DHT ‘safe zone’ is where donor hair is harvested because when transplanted, these follicles remain resistant to DHT and continue to grow for a lifetime. This is referred to as donor dominance.

This principle is the foundation for every type of hair transplant. Without evidence of a safe zone, a hair transplant cannot be successful. That is why patients with diffuse unpatterned alopecia (hair loss) are not good candidates for a hair transplant because the hair in their donor area is thinning and unpredictable.

Propecia.

The best preventive treatment of hair loss caused by DHT is finesteride also known as Propecia. Although propecia does not regrow hair that is gone for good, it helps you keep the hair that you have. Less hairs lost means less hairs that must be replaced later. When a follicle stops producing hair altogether it will never come back. That is why it’s good to start hair loss prevention treatment as soon as you notice that your hair thinning. It’s important to note that propecia is only for men. Women should not even come in contact with the medication because it causes birth defects in unborn children.