Hair is Lost
Ninety-five percent of hair loss in men is caused by androgenetic
alopecia, male pattern baldness. It is not caused by clogged
pores, lack of oxygen in scalp blood vessels, or wearing
a tight ball cap. As noted in the hair
loss history section, male pattern baldness
is driven by 3 factors, of which the first one is the most
- Androgens (male hormones)
- Genetic predisposition
DHT and Miniaturization
Although Hamilton's observations (see History)
of eunuchs (castrated men and men who failed to develop
sexually) led him to understand that androgens were the
culprit behind male pattern baldness, it wasn't until the
1970s or 80s that scientists began to understand that when
an enzyme called 5-alpha-reductase combined with testosterone,
it created dihydrotestosterone, or DHT.
Dihydrotestosterone causes hair to fall out through a gradual
miniaturization process that begins along the same patterns
as outline in the Norwood Charts: either at the temples
and crown as Norwood's "Regular Type," or as Type
A Variant where DHT attacks the hair follicles in the temple
and frontal region, gradually sweeping it's way backwards
over the mid-scalp, but not affecting the crown until the
This DHT is harmful to hair follicles and "attacks"
it, slowly breaking it down, reducing the diameter and length,
so that the hair follicle becomes smaller and smaller while
the color fades away. This kind of hair is known as vellus
hair. Soon, this vellus hair will fall out and will not
be replaced by new hair.
In men with MPHL all the hairs in a DHT affected area may
eventually (but not necessarily) become involved in the
process and may with time cover the region with fine (vellus)
hair. Pigment (color) production is also terminated with
miniaturization so the fine hair becomes lighter in color.
The lighter color, miniaturized hairs cause the area to
first appear thin.
In men, hair that grows near the temple region, front,
mid-scalp (top) and crown (back top of head where it starts
to go in a 90 degree angle toward the neck) are most susceptible
to DHT. Hair on the back and sides of the head (above the
ear but below the top, are the LEAST susceptible to hair
In addition, miniaturization and detectable hair
loss is not evident to the naked eye until more than 50%
of normal (non-miniaturized) hair is lost. As a result,
many men/women do not seek help until significant miniaturization
has already taken place. (10)
Enzyme 5 Alpha Reductase
5-Alpha reductase is a naturally occuring enzyme involved
in steroid metabolism. When it combines with testosterone,
it becomes dihydrotestosterone, DHT, which scientist recognize
as the culprit behind male pattern hair loss. DHT attacks
the hair follices as demonstrated in Fig 1, slowly breaking
them down, reducing the diameter of the follicle until it
eventually falls out, never to return.
There are 2 types of 5-alpha-reductase. Type I and Type
II. [Note] Finasteride
only inhibits Type II 5-alpha-reductase, which means it
will never be 100 percent effective in stopping DHT. There
are medications that stop both, including dutasteride, which
we report more on here.
As Dr. Hamilton noted in 1941, genetic disposition was
a factor in male pattern baldness. Dermatologists and hair
transplant doctors would often tell their patients that
if you wanted to know how your hair loss pattern would look
like, or how severe it would get, take a collective view
of all the males in your family. However, this "guesswork"
didn't answer the quantifying questions of what are my chances
of going bald? A 2004 study that looked at "Family
History and Risk of Hair Loss" determined that:
"...men whose fathers had hair loss were 2.5
times as likely to have had some level of hair loss
compared to men whose fathers had no hair loss.
"Likewise, men whose fathers had hair loss
were twice as likely to have hair loss than men whose
fathers had no hair loss even after adjusting for age.
Conclusion: Results suggest that the probability of
male pattern hair loss is dependent on family history
and age. Hair loss in a man's father also appears to
play an important role in increasing a man's risk of
hair loss, either in conjunction with a history of hair
loss in the mother or hair loss in the maternal grandfather."
So that leads into another aspect of the genetics question
which is, which side is more responsible for my hair
loss? My mother's or my father's? Many hair
transplant doctors and dermatologists will tell you it's
a myth to assume it's either one, especially the maternal
side which has been the popular "suburban myth"
among men for decades. It's nonsense talk, they say. Look
at both sides. Well, maybe, but maybe it's not nonsense.
Take a look at a 2005 German study that says heredity hair
loss was partially traced back "...to a series
of areas on various chromosomes. In an area where the largest
contribution was suspected lay the gene for the androgen
receptor. " (4) - The gene for this androgen receptor
lays with the X chromosome, which men inherit from their
mothers, leading one to assume that men's hairlines might
lean more towards their maternal grandfather, instead of
looking more like their paternal grandfather.
But even the German study says, 'maybe.' The study is quick
to hedge themselves by saying that the hereditary genes
for male pattern baldness are not that simple and there
can be more than one suspect gene or culprit gene that is
guilty. "We have indications that other genes are
involved which are independent of the parents' sex,"
Prof. N�then stresses.. "The hereditary defect
can therefore sometimes also be passed on directly from
father to son." (4)
Incidence of male pattern baldness, including crown hair
loss, and age has not been definitively determined. For
example, WebMD says that by age 35, 2/3 of all men will
experience hair loss to some degree. By age 50, 85 percent
of all men will experience thinning hair to a larger degree
while an unfortunate 25 percent of young men under the age
of 21 will experience some degree of hair loss. (5).
According to the International Society of Hair Restoration
Surgeons, 20 percent of men in their 20s will have hair
loss, 30 percent in their 30s, and so, adding 10 percent
of the population for each decade. Using this scale, 50
percent of men in their 50s will have hair loss and 90 percent
in their 90s will have hair loss.(1)
In building his classification chart, Norwood was able
to get exact numbers for each chart class of hair loss based
on age, (see Table below). Notice that in his findings,
3 out of 185 men (2 percent) age 18-29 are already a class
5. In the 40 to 49 age category, 15 men were class 4, and
5 were class 7, and so on. In the 70 to 79 group, 64 out
of 102 men had class 3 or higher male pattern baldness.(1)
Unfortunately, his study only looked at 1,000 white males,
and did not include blacks, asians, pacific islanders, latins
and men from middle eastern descent.
Incidence of Male Pattern Baldness
(Percentage rate of baldness types in men)
Pattern Baldness: Classification and Incidence,
Southern Medical Journal, O'Tar T. Norwood, MD, Nov. 1975.
- Male Hormone Stimulation is Prerequisite
and an Incitant in Common Baldness.
- Miniaturization and Hair
Loss - More Than Meets the Eye, baldingblog.com,
by Jae P. Pak, M.D., William R. Rassman, M.D., August
History and Risk of Hair Loss,
Dermatology 2004, W. Cameron Chumleaa, Thomas Rhodesb,
Cynthia J. Girmanb, Amy Johnson-Levonasc, Flavius R.W.
Lillyd, Ruishan Wua, Shumei S. Guoa
To Hair Loss Inherited From The Mother,
Professor Markus Nöthen & Dr. Roland Kruse, via
ScienceDaily.com, May 2005,
- Hair Loss Health Center:
Male Pattern Baldness,
WebMD Medical Reference from the American Hair Loss Association,
March 1, 2010.
- Rogaine Seeks Place In
the Morning Routine, Andrew Adam
Newman, NY Times, January 24, 2008