Understanding Pattern Hair Loss—Hair Biology Impacted by Genes, Androgens, Prostaglandins and Epigenetic Factors

Abstract Pattern hair loss (PHL) is the most frequent cause of hair loss in men and women, accounting for 65% of consultations in a hair referral center. PHL is understood to represent a hereditary, age-dependent progressive thinning of the scalp hair, which follows distinct clinical patterns with notable differences depending on sex and age of onset. Clinical and investigative advances have helped us to understand some of the pathogenic steps, leading to PHL. Besides genetic factors and peculiarities of androgen metabolism, additional pathogenic factors that are suspected include microbiomata, oxidative stress, and microinflammation. While further suspects are likely to be exposed, individual diversity of causal agents, as well as of the sequence of events, or combined factors, must be kept in mind. A large number of therapeutic molecules claimed to be active and patented in this field, and their limited efficacy in offering a definitive cure of PHL confirm the complexity of PHL. The aim of therapy is to retard progression of hair thinning and increase hair coverage of the scalp. As yet, two FDA-approved drugs are available for this purpose, oral finasteride, and topical solution of minoxidil. Variations in posology and formulation allow for an enhancement of patient comfort and treatment efficacy. Antiandrogen treatments in women with normal androgen levels have questionable efficacy while having health risks.