Androgenetic alopecia. Modelling progression and regrowth.

Abstract

Androgenetic alopecia (AGA) produces the phenotypes of male pattern hair loss and female pattern hair loss. The pathogenesis of AGA involves hair follicle miniaturization and changes to the hair cycle. Hair follicle miniaturization involves conversion of terminal hairs into secondary vellus hairs. This is recognized in scalp biopsies, unit area trichograms and phototrichograms as a reduction in the number of terminal hairs per cm2 and an increase in the number of vellus hairs per cm2.. In addition, a small reduction in the total number of hair follicles detectable on scalp biopsy occurs with advancing age. So, how can we incorporate these findings into our current model of the pathogenesis of androgenetic alopecia?