Female pattern hair loss typically will present with diffuse thinning of the hair on the top and crown of the scalp without hairline recession, and the hair loss rarely progresses to total or near total hair loss.
Panama City, Panama - Female pattern hair loss typically will present with diffuse thinning of the hair on the top and crown of the scalp without hairline recession, and the hair loss rarely progresses to total or near total hair loss.
“Female pattern hair loss is a source of significant anxiety and distress in the affected patient. Identifying the age of onset of pattern hair loss is instrumental in helping clinicians better manage the hair thinning and lead to better patient expectations,” says Vera H. Price, M.D., professor, department of dermatology, University of California, San Francisco School of Medicine. Dr. Price spoke recently at the North American Dermatologic Society annual meeting.
Pattern hair loss is characterized by hair miniaturization, or follicle downsizing, due to anagen shortening and matrix reduction.
In women, pattern hair loss includes three stages of hair miniaturization based on age of onset, and these stages are referred to by different names. Androgenetic alopecia (AGA) is a genetically determined androgen-mediated trait that is generally considered the female equivalent of male androgenetic alopecia.
The term female pattern hair loss is gaining in popularity as a less committal term when the role of androgens is less clear-cut and other hormonal and non-hormonal factors may play a role. The term senescent alopecia refers to age-related hair thinning, and is distinct from AGA and is not dihydrotestosterone (DHT)-mediated.
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The onset of androgenetic alopecia is between puberty and age 40, whereas female pattern hair loss is a term reserved for pattern hair loss that appears between ages 45 to 55. Senescent alopecia refers to hair thinning that appears at about age 60 and older. According to Dr. Price, medical management should address hair loss based on the age of onset.
“In patients with AGA, there is increased 5 alpha-reduction of testosterone to dihydrotestosterone (DHT) in scalp hair follicles of affected patients, and DHT activates genes responsible for the miniaturization of the follicles. Treatments aimed at reversing the effects of DHT in the scalp can be quite effective when used appropriately,” Dr. Price says.
Next: Managing miniaturization
The medical management of miniaturization includes minoxidil, estrogen, and various androgen-blocking agents such as 5 alpha-reductase inhibitors (finasteride and dutasteride) and androgen receptor inhibitors (spironolactone and cypropterone acetate).
Minoxidil, a potassium channel opener, is a non-specific medication for AGA that helps to prolong the anagen phase in “suboptimal” or miniaturized follicles. Minoxidil foam 5 percent is an effective hair-growth promoter when applied to the scalp once daily, whereas minoxidil solution 2 percent or 5 percent must be applied twice daily.
In contrast, finasteride 1 mg oral tablet is a 5 alpha-reductase inhibitor that is specific for AGA. Both minoxidil and finasteride can achieve excellent results when used daily and consistently, and the extent of stabilization and improvement in hair growth after two years is similar in both. Finasteride, however, is contraindicated in women who are or may be pregnant and must be used with caution, as exposure to the drug will cause genital defects (hypospadius) in male fetuses.
According to Dr. Price, senescent alopecia is not a continuum of AGA and is a distinct entity. Studies in women and men show a significant decrease in scalp 5 alpha-reductase types 1 and 2 and in androgen receptor in patients with onset of hair thinning at age 60.
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Although AGA and age-related hair thinning share a similar histology, they differ significantly in hormonal activity as well as in gene array studies. Studies have shown that in hair follicles of men ages 18 to 30 with AGA, there are higher levels of 5 alpha-reductase types 1 and 2 and androgen receptor in the frontal follicles than in the occipital follicles, and in hair follicles in men with senescent alopecia, there is a nearly two-fold decrease in levels of 5 alpha-reductase types 1 and 2 and androgen receptor when compared to males with AGA (Sawaya ME, Price VH. J Invest Dermatol. 1997;109(3):296-300).
Gene expression profiles show that in AGA, hair growth cycle genes are differentially expressed whereas in senescent alopecia, systemic senescent/aging genes are differentially expressed. The very different gene expression profiles suggest that AGA and senescent alopecia are two distinct disorders. Minoxidil can be useful in patients with senescent alopecia whereas finasteride will not be effective in this patient population.
Future treatment approaches for hair growth promotion could be agents that stimulate existing hair follicles Dr. Price said, including prostaglandin analogues such as bimatoprost (Latisse, Allergan). Another treatment approach could be aimed at stimulating new hair follicle formation via superficial skin wounding, first introduced by George Cotsarelis, M.D.
“The medical management of female pattern hair loss requires agents that prolong anagen and reverse matrix reduction. Topical minoxidil is an appropriate treatment, irrespective of age of onset. While the judicious off-label use of finasteride has shown efficacy in selected pre-menopausal women, the medication is not effective in senescent or age-related alopecia, Dr. Price says.
Disclosures: Dr. Price is a consultant for Allergan and Follica.