Androgenetic Alopecia

The 2002 review on Androgenetic alopecia (AGA) discussed that AGA is a result of an androgen-dependent process and genetic transmission. In men, AGA is associated with an increase in 5 alpha reductase activity leading to an increase in local production of dihydrotestosterone, which is believed to inhibit cell proliferation in the dermal papilla and a vascular process based on the inhibition in local production of vascular endothelial growth factor (VEGF). This process is genetic and depends on androgen receptor polymorphism. Male AGA is also associated with an insulin-resistant process and a higher risk of polycystic ovary in the lineage. In women, alopecia is usually diffuse and the mechanisms are different and largely unknown. It is suggested that an auto-immune origin could be involved in some cases. Pharmacological doses of oestrogens have a beneficial effect on such alopecia. In practice, 5 alpha reductase inhibitors are ineffective in women. The review concluded that the predominance observed in the frontal and vertex areas in elderly women is likely a result of the two combined disorders, the almost physiological androgen-dependent hair loss combined with diffuse loss.