A review of female pattern hair loss
Doctor Vera H. Price, at the Department of Dermatology at the
University of California San Francisco, conducted a review of
female pattern hair loss and its diagnosis based on her own
research and medical journal publications by other dermatologists
and scientists.
Androgenetice alopecia (AGA) in women is also known as female
pattern hair loss or female pattern baldness. AGA in women is
similar to AGA (male pattern baldness) in men. AGA is surprisingly
common in women with up to 40% of women affected at some point
in their lives. In spite of its prevalence, many clinicians
and clinical investigators have difficulty making the diagnosis
in women. Studies by scientists Hamilton and Trancik found that
it can begin as early as 12 years or or as late as 40 in either
sex. Other studies found that nearly half of the population
experiences some degree of this hair loss condition before the
age of 50. It can be an inherited from either one, or both sides
of the family. These studies were done by Venning, Dawber, Olsen,
Kuster, Happle, and Sreekumar.
Both women and men with AGA can have increased levels of dihydrotestosterone
(DHT). It is thought that DHT is responsible for the miniaturization
of hair follicles in found in patients with AGA. In genetically
susceptible hair follicles, DHT binds to the hormone-receptor
complex on hair follicle cells and activates the genes responsible
for the gradual transformation of large, terminal follicles
to miniaturized follicles. While the number of follicles in
an area remains the same, they are miniaturized in two ways;
the growth-stage of the hair follicle is much shorter than normal
and the hair follicles are much smaller than normal terminal
scalp hair follicles. Consequently, the miniaturized hair follicles
produce thinner and shorter hair fibers than they should. In
women with AGA, the extent of hair loss is generally less than
in men. This discovery was the result of several studies by
Price, Uno, Messenger, and Kaufman.
It has commonly been assumed that the hormonal basis for AGA
is similar in women as in men although earlier studies did not
include female subjects and focused exclusively on men. In order
to compare and clarify the underlying hormonal basis in women
as compared to men, a study was conducted among 24 people with
AGA: 12 women between the ages of 14 and 33 and 12 men between
the ages of 18 and 30. The study measured a variety of factors
in the subjects’ scalp skin and hair follicles and found
that both genders had higher levels of “5a-reductase and
androgen receptors” in the hair follicles toward the front
of their head compared to the hair follicles around the back
of their head. However the women only had about half of the
level found in the men. Meanwhile, the women had higher levels
of “cytochrome p-450 aromatase” in the follicles
in the front of their scalp. Aromatase can convert testosterone
into estradiol. Overall, this study indicated that women experience
a lower level of AGA than men due possibly in part by the lower
levels of 5a reductase in the frontal follicles compared to
men, and that the higher levels of aromatase in women creates
more estradiol in women than men… and less 5a reduced
products, like DHT.
What does this mean? It seems that; 1) AGA hair loss is actually
the minimization of hair. 2) DHT is linked to the cause of the
minimization of hair. 3) 5a –reductase creates DHT. 4)
Men have more 5a-reductase than women. 5) Women have some 5a-reductase
but the increased presence of aromatase in the skin and hair
follicles takes testosterone and converts it to estradiol so
overall there is less DHT in the skin of women. Because of this
advantage, women may be less likely to suffer from AGA than
men.
While not necessarily discovered in this study, Price adds
the results of this study to the ongoing study of hair loss
in many clinics and laboratories and lists some other conclusions
in the field:
•
even though women experience hair loss, it is not as widespread
across the scalp as in men.
•
The front and top of the scalp experience more thinning then
the back. In fact, the back of the scalp has the greatest hair
density.
•
It is possible that in the embryonic stage of development, the
top of the scalp and the back of the scalp develop from different
points. This is also true in birds, as found in a study by Ziller.
In fact, cell growth and cellular interaction may influence
the hair follicles differently in the two regions because of
their different origin.
•
Women first notice their hair thinning over the front region
of the scalp and over time the scalp becomes more visible as
the hair loss moves to the top of the scalp. Generally, women
do retain a rim of hair along the front of the hairline and
hair loss starts behind the rim.
•
Although hair density is the same, the new hairs are shorter
and thinner.
•
AGA in women is usually not accompanied with any increase in
the rate of shedding of the hair.
The diagnosis of AGA in women is supported by the appearance
of baldness at an early age and the pattern of increased hair
thinning over the front and top of the scalp. She notes that
one should be aware that while AGA is common, there may be other
causes of hair loss as well that need to be taken into consideration.
A careful history will usually identify the cause of profuse
hair shedding such as high fever, severe dietary protein
deficiency, chronic blood loss, or drug use.
Dr Price suggests topical minoxidil solution is the only approved
drug available for promoting hair growth in women with AGA.
Its usefulness has been demonstrated in controlled studies using
hair counts and hair weight as the primary measurements. In
Dr Price’s own evaluation studies, minoxidil-treated women
had significantly higher hair counts and an increase in hair
weight compared to women who received placebo.
A
review of female pattern hair loss references
- Price VH.
Androgenetic alopecia in women.
J Investig Dermatol Symp Proc. 2003 Jun;8(1):24-7.
PMID: 12894991
- Price VH, Menefee E. Quantitative
estimation of hair growth. I. androgenetic alopecia in women:
effect of minoxidil. J Invest Dermatol. 1990 Dec;95(6):683-7.
PMID: 2250110
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