What causes hair loss in men?

From the Guidelines

Androgenetic alopecia (AGA) is the leading cause of hair loss in men, affecting 58% of men by age 50, and is characterized by a highly reproducible pattern of hair loss, preferentially affecting the temples, vertex, and mid-frontal scalp 1. The exact cause of AGA is not fully understood, but it is believed to be a combination of genetic factors and the hormone dihydrotestosterone (DHT), which shrinks hair follicles over time. Some key points to consider in the management of hair loss in men include:

• The Hamilton-Norwood classification system is commonly used to describe patterns of hair loss in men 1
• Effective treatments for AGA include topical minoxidil (Rogaine) and oral finasteride (Propecia), which work best when started early and used consistently 1
• Other causes of male hair loss include stress, nutritional deficiencies, certain medications, medical conditions like thyroid disorders, and autoimmune conditions such as alopecia areata
• Maintaining good overall health through proper nutrition, stress management, and gentle hair care practices can help support hair health alongside medical treatments
• Platelet-rich plasma (PRP) therapy has also shown promise in treating AGA, with studies demonstrating a significant increase in hair density and thickness after PRP injections compared to controls 1
• The use of platelet-rich fibrin (PRF) has also been proposed as a potential treatment for AGA, with some studies showing positive clinical results and a significant improvement in hair growth 1

From the Research

Causes of Hair Loss in Men

• Hair loss in men is primarily caused by androgenetic alopecia (AGA), a condition mediated by 5-alpha-reductase and dihydrotestosterone (DHT) 2
• DHT causes hair follicles to undergo miniaturization and shortening of successive anagen cycles, leading to hair loss 2
• Androgenetic alopecia is a highly heritable condition, with up to 80% of European men experiencing some degree of androgen-dependent hair loss during their lifetime 3
• The condition is characterized by an androgen-dependent, progressive loss of hair from the scalp, which may commence during puberty 3

Genetic Factors

• Molecular genetic studies have implicated 12 genomic regions in AGA and identified a number of candidate genes, including the androgen receptor (AR) and the WNT molecule WNT10A 3
• However, the majority of contributing genetic risk factors still await identification 3
• The genetic approach is considered a promising way to facilitate novel therapeutic approaches for AGA 3

Hormonal Factors

• Androgenetic alopecia is mediated by dihydrotestosterone, the potent form of testosterone 4
• The 5-alpha reductase inhibitors, such as finasteride and dutasteride, have demonstrated to be effective in improving androgenetic alopecia in men 5
• These inhibitors can maintain a positive response for many years, but there is widespread concern about sexual adverse effects among patients 5

Other Factors

• Other factors, such as age, stress, and certain medical conditions, may also contribute to hair loss in men, but the exact mechanisms are not fully understood 6
• Further research is needed to determine the relative importance of these factors and to develop effective treatments for AGA 6