Pattern hair loss
Medical condition / From Wikipedia, the free encyclopedia
Pattern hair loss (also known as androgenetic alopecia (AGA)[1]) is a hair loss condition that primarily affects the top and front of the scalp.[2][3] In male-pattern hair loss (MPHL), the hair loss typically presents itself as either a receding front hairline, loss of hair on the crown and vertex of the scalp, or a combination of both. Female-pattern hair loss (FPHL) typically presents as a diffuse thinning of the hair across the entire scalp.[3]
Pattern hair loss | |
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Other names | Male pattern baldness; female pattern baldness; androgenic alopecia; androgenetic alopecia; alopecia androgenetica |
Male-pattern hair loss shown on the vertex of the scalp | |
Specialty | Dermatology, plastic surgery |
Genetic research has identified alleles associated with male pattern hair loss.[4] These alleles appear to be undergoing positive sexual selection in European and East Asian populations, as male pattern baldness may be seen as a masculine attribute associated with seniority and higher social status.[4] The condition is caused by a combination of male sex hormones (balding never occurs in castrated men) and genetic factors.[5] Balding appears to follow an autosomal dominant pattern of inheritance, but paternally inherited genes may also be a factor, as roughly 80% of bald men have bald fathers.[6]
Some research has found evidence for the role of oxidative stress in hair loss,[7] the microbiome of the scalp,[8][9] genetics, and circulating androgens; particularly dihydrotestosterone (DHT).[3] Men with early onset androgenic alopecia (before the age of 35) have been deemed the male phenotypic equivalent for polycystic ovary syndrome (PCOS).[10][11][12][13]
The cause in female pattern hair loss remains unclear;[3] androgenetic alopecia for women is associated with an increased risk of polycystic ovary syndrome (PCOS).[14][15][16]
Management may include simply accepting the condition[3] or shaving one's head to improve the aesthetic aspect of the condition.[17] Otherwise, common medical treatments include minoxidil, finasteride, dutasteride, or hair transplant surgery.[3] Use of finasteride and dutasteride in women is not well-studied and may result in birth defects if taken during pregnancy.[3]
By the age of 50, pattern hair loss affects about half of males and a quarter of females.[3] It is the most common cause of hair loss. Both males aged 40–91[18] and younger male patients of early onset AGA (before the age of 35), had a higher likelihood of metabolic syndrome (MetS)[19][20][21][22] and insulin resistance.[23] With younger males, studies found metabolic syndrome to be at approximately a 4× increased frequency which is clinically deemed significant.[24][25] Abdominal obesity, hypertension and lowered high density lipoprotein were also significantly higher for younger groups.[26]