Looking at Grandpa’s head
In the genetic hair loss lottery, Grandpa’s important, but doctors
actually look a few generations back on the entire family tree —
men and women — in order to determine if you’ve inherited a
genetic type of pattern baldness.
Everyone inherits genetic tendencies from their parents. As you
may or may not recall from biology class, pairs of DNA segments
called chromosomes carry the information that contains the potential
for different characteristics. A gene is a single bit of chemically
encoded hereditary instruction located on a chromosome.
The genetics of androgenetic alopecia (ANA), also called androgenetic
alopecia or male pattern baldness, is complicated. At least
four genes are responsible for hair loss. When several genes need
to be present for a trait such as hair loss, the trait is said to be
polygenic. Genes that are located on the X or Y chromosomes are
called sex-linked, and genes on the other 22 pairs of chromosomes
are called autosomal.
Currently, doctors believe that the genes governing common baldness
are autosomal (not tied to the sex chromosome) and therefore
can be inherited from the mother’s or the father’s side of the
family. The commonly held notion that baldness comes only from
the mother’s side of the family is false, although for reasons not
fully understood, the predisposition inherited from an affected
mother is of slightly greater importance than that inherited from
an affected father. Doctors also believe that the genes involved in
androgenetic alopecia are dominant, meaning that only one gene of
a pair is needed for the trait to show up in the individual. So even if
only one of your parents passed on the baldness gene, you’re likely
to have some hair loss.
The inherited gene isn’t always ‘expressed,’ so it’s possible to
carry the gene for balding and never become bald. It can skip a
generation or two, so only looking at the generation before you
doesn’t tell you what may happen on your head.
The ability of a gene to affect you is called expressivity.Expressivity
occurs depending on a number of factors, the major ones being
hormones and age, although stress and other factors may also play
a role. Put simply, a man whose father and uncles are severely bald
may have minimal hair loss because the expression of the baldness
gene is limited. If you are confused by this explanation, imagine the
experts who try to clarify the unexplainable by putting together
the many variables and not coming up with a logical, scientific
process.
The end goal of gene identification is to manipulate genes to prevent
or reverse common baldness. But doctors first need to find
and fully understand which genes cause the balding process and
why are these genes expressed one way in you and another way in
your brother.
Hormonal influences on hair
Hormones are very powerful biochemical substances produced by
various glands throughout the body. The primary male sex hormone
is testosterone. Testosterone and other related hormones
that have “masculinizing” effects are produced primarily in the testicles.
These same hormones are the cause of many changes that
occur in puberty in boys. The hormones that cause acne and beard
growth also can trigger the beginning of baldness. Testosterone is
also produced in women from the adrenal glands and the ovaries,
and it is produced in lower concentrations than the testicles produce
the hormone in men. In women, most of the testosterone is
converted into estrogen.
The hormone believed to be most directly involved in androgenetic
alopecia is dihydrotestosterone (DHT). DHT is formed by the
action of the enzyme 5-alpha reductase (5AR) on testosterone, and
it binds to special receptor sites on the cells of hair follicles to
cause the specific changes associated with balding.
The presence of androgens (steroid like substances), testosterone
(considered an androgen), and DHT cause some hair follicles to
regress and die. In addition to the testicles, the adrenal glands
located above the kidneys produce androgenetic hormones; this is
true for both sexes. In females, ovaries are the major source of hormones
that can affect hair. Androgenetic hormones stimulate many
of the male sex characteristics we see in adult men. Androgens like
testosterone, are converted into estrogens in women, which make
women develop their typical female sex characteristics.
Baring hair at the beach
The beach is an excellent place to observe hair patterns. Have you ever noticed
that men with hairy backs and shoulders often have a bald head or a hair replacement
system?
This indicates that the gene for hair on the back and shoulders is separate from the
gene for hair on the scalp. Although DHT acts like fertilizer for shoulder and back
hair, it causes reduction of head hair in many men.
Early in the 20th century, a psychiatrist discovered the specific
relationship between testosterone and hormone-induced hair loss.
The doctor noted that the identical twin brother of one patient was
profoundly bald while the mentally ill twin had a full head of hair.
The doctor decided to determine the effect of treating his patient
with testosterone, and injected him (the hairy twin) with the hormone.
Within weeks, the hairy patient began to lose all but his
wreath of permanent hair, just like his twin. The doctor stopped
administering testosterone, but his patient never regained his head
of hair.
Testosterone and DHT
The cause of pattern thinning in men is primarily related to two
sex hormones, testosterone and DHT. The body converts testosterone
into the hormone DHT by way of an enzyme found in various
tissues throughout the body.
In men with the genes for ANA, DHT increases the resting (telogen)
phase and decreases the growing (anagen) phase of hair. (We
explain the growth cycle more in the earlier section, “Examining
uniform hair loss.”) Consequently, as a man ages, less hair grows at
any given time, and the hair starts to thin as a normal consequence
of aging, especially in men with ANA. Eventually, baldness occurs.
In men who haven’t inherited the ANA balding genes, the combination
of DHT and testosterone doesn’t cause hair loss and may have
a lesser impact on aging hair.
Some areas of the scalp are more susceptible than others to the
affects of DHT. For example, the hormone doesn’t usually affect
hair on the back and side of the head, which is why these areas
retain hair. The term “male pattern thinning” is used because hair
loss occurs in a pattern — the back and side of the head retain hair
but the crown and frontal areas may lose it. The loss may be confined
only to the frontal area or the crown area based upon the
genetics that are inherited from the family tree.
DHT does play a role in the growth of beard hair; body hair; and
eyebrow, nose, and ear hair, but doctors don’t clearly understand
that role. Sometime after puberty, male hormones trigger a biological
clock that makes hair grow in these areas.
In men, the enzyme 5AR activity is higher in the balding area.
Women have half the amount of 5AR overall as compared to men
but have higher levels of the enzyme aromatase, especially in their
frontal hairlines. Aromatase decreases the formation of DHT, and
its presence in women may help to explain why female hair loss is
somewhat different than hair loss in males. (The section
“Examining Hair Thinning in Women” later in this chapter takes an
in-depth look at female hair loss.)
The only way to stop DHT is to block it with finasteride or dutasteride,
drugs that interfere with DHT production. (See Chapter 9 for
more on DHT and the drugs that fight hair loss.)
At present, only finasteride has been approved by the Federal Drug
Administration (FDA). Dutasteride is still being evaluated for its
safety and effectiveness for hair loss in young men. There are some
reports that dutasteride has significant effects on male sperm production;
as such, it may not be approved for men experiencing hair
loss. Blocking DHT in women with dutasteride hasn’t been shown
to prevent or reverse female hair loss or hair thinning. Its safety
with regard to breast cancer, particularly in women who carry the
breast cancer producing BRCA genes, is not understood.
Steroids and similar products
Anabolic steroids, the kind bodybuilders sometimes (illegally) use,
can cause hair loss if you’re genetically predisposed to it. And
there’s a direct link between taking human growth hormone (HGH)
and hair loss — probably caused by the same underlying mechanisms
as steroid use. Women body builders who take steroids
develop some male sex characteristics and some experience hair
loss.
HGH has become a trendy anti-aging tool. More and more men are
using it as a fountain of youth. Some men combine steroids and
HGH because they make them feel better and stronger. But we have
seen many men on HGH in our offices with “unexplained hair loss.”
No real mystery there.
Many men who take steroids also take Propecia (a DHT blocker) to
offset the negative effects of DHT. Propecia blocks DHT and causes
a rise in systemic testosterone by up to 18 percent. Indirectly,
Propecia may help muscle building if DHT levels go down (from the
Propecia) and testosterone levels go up to compensate.
Testosterone is a much stronger hormone than DHT, and the sum
of the effects of the rise in serum testosterone from taking a DHT
blocker such as Propecia and the steroids may very well produce
more hair loss, not less.
Everyone is different, so we can’t conclude if the muscle mass that
the men are seeking from steroid use can be offset. Recently,
Propecia was found to mask the blood measurements for other
steroids when used in athletes, which is why its use is banned for
professional athletes.
Fitness-focused individuals may take the following products for
their physical benefits, but these products can also cause hair loss:
Whey-based nutritional supplements: The use of growth hormones
in some dairy cows affects the milk they produce and,
in turn, the whey (a byproduct of cheese production). Even if
a person doesn’t take steroids, these products may have some
steroid-like impact from the milk source. People who take
whey-based nutritional supplements may experience steroidrelated
side effects if the cows were treated with steroids. It is
unclear how much of these steroids, if any, will survive transit
through the stomach to be eventually absorbed into the body.
DHEA: Some people take DHEA, which is found in the nutritional
section of many health food and vitamin stores and
doesn’t require a prescription. The DHEA sold in stores is
reportedly made by the adrenal glands and claims to help
reduce body fat stores while promoting sugar metabolism. It
also can cause hair loss. Other available supplements claim
testosterone or steroid-like characteristics. The desire for
men to add body mass and/or prevent hair loss drives them
to seek out such products.
Dose-pack steroids: A short course of steroids for medical
reasons (4–5 days) should not have an impact producing
hair loss.
Prednisone: People who are on this steroid for chronic medical
problems (arthritis, various autoimmune diseases) will
experience hair loss.
Hair loss is also a risk for women who use steroids, if they’re predisposed
to the condition. Women usually take steroids for diseases
that occur later in life, such as autoimmune disease,
temporal arteritis, rheumatoid arthritis.
Hair loss over time
The mere presence of the necessary genes and hormones for hair
loss isn’t enough to cause baldness. Susceptible hair follicles also
have to be exposed to the responsible hormones. The onset of hair
loss varies from one individual to another and is influenced by
genetic expression, the levels of testosterone and DHT in the
bloodstream, and age.
Hair loss doesn’t occur all at once, but is cyclical. People who are
losing their hair experience alternating periods of slow hair loss
and rapid hair loss, and even periods when hair loss stabilizes. The
factors that cause the rate of loss to speed up or slow down are
unknown.
Most men who have extensive balding develop much of it by age
30. Twenty-five percent of men will show clinical balding by age 30,
and half of the male population will show some degree of clinical
balding by age 45 to 50. Balding slowly continues into the next
decade or two, and then the process seems to slow down as men
approach 60 to 65. As this is a genetic process, it is probable that
the men who bald later in life rather than earlier also have a form
of genetic hair loss, just not the obvious process we see in the
younger men with classic pattern balding.
Men who continue the balding process well into their 30s and 40s
typically don’t lose their hair as quickly or as completely as men
who start balding in their early 20s. About 7 percent of men who
are balding develop the most complete form of balding (called the
Class VII pattern; see Figure 4-1), in which only the wreath of hair
exists around the head. Those men with Class VII balding patterns,
usually show those patterns before they reach 30 years old. This
wreath of hair is permanent hair in most men and measures about
21⁄2 inches in the mid-back of the head when the balding process
reaches completion. Most men who show balding don’t advance to
full balding.
To make matters more confusing, the age of onset discussed above
reflects the majority of men, yet there are still some men who start
the process later in life (in their 30s, 40s, and even 50s).
The most common balding patterns are seen at the frontal hairline
where frontal and temporal recession occurs, moving slightly
upward toward the top of the head. A bald spot may appear in the
crown and when it does, it seems to widen slowly as men age.
Sometimes, the crown balding area merges with the frontal recession,
clearing a wide bald channel in the center of the head that we
jokingly call the “runway.” Genetics determine the final pattern.
Stress
When the body experiences stress caused by a traumatic experience,
nutritional deficiency, or illness, the rate of hair loss can
increase. For example, a 39-year-old patient of Dr. Rassman lost his
4-year-old child to cancer and within just a few months, the man lost
all but the permanent wreath of hair around his head. He probably
had the genetics for this balding pattern, but only expressed that
pattern when it was induced by this extreme stressful situation.
Women’s hair seems to be more sensitive to the effects of stress
than men’s hair. This may be because women with a genetic predisposition
to hair loss usually have a higher percentage of fragile
miniaturized hair, which is hair with thinner than normal hair shaft
thickness. But unlike in men, the hair loss in women is often not
permanent or complete.
Stress generally causes a type of hair loss referred to as telogen
effluvium, which is very different from androgenetic alopecia (discussed
earlier in this chapter). Telogen effluvium is the reversible
shedding of hair in the resting phase when the body senses, for
reasons that are not clear, that it needs to divert its energies.
Therefore, stress temporarily changes the amount of hair that’s
shed, but the lost hair is likely to grow back. Turn to Chapter 5 for
more explanation of telogen effluvium.
Lack of blood supply
Some doctors assert that a lack of blood supply contributes to hair
loss. Bald skin gradually loses some of its blood supply and as a
result becomes thin and shiny. These changes, however, come only
after the loss of hair and is not the cause of the hair loss.
Hair follicles are some of the most rapidly metabolizing cells in the
body. Growing hair requires the proper oxygen and nutrition that
comes with a good blood supply in a healthy body. When hair follicles
are transplanted into skin grafts or scar tissue, both of which
may have a relatively poor blood supply, the presence of the
grafted hair causes the local blood supply to increase. The end
result is that as the hair grows, so does the blood supply.
Environmental issues
Can you eat yourself into a full head of hair? Probably not, but environmental
factors, including what you eat, can cause hair loss. The
following list breaks down some of the more prominent factors:
Selenium: The presence of selenium in food and water is
common around the world, but continued intake of selenium
to the point of selenium toxicity produces hair loss, among
other effects.
Lead, cadmium, mercury, iron, aluminum, and copper:
These are the most common environmental causes of hair
loss. Many of these substances are found in fish, reflecting
environmental contamination in the world’s oceans. Lead may
also be found in hair dyes and paint. Just how much of these
elements must be present to cause hair loss is unknown, and
a direct connection is hard to prove. Some labs will analyze
hair for the presence of these minerals, but their presence
doesn’t necessarily mean they caused hair loss.
Air pollution and smoking: These factors may also exacerbate
the genetic process carried by potentially balding men.
Scientists believe toxins and carcinogens found in polluted air
can stop hair growing by blocking the mechanisms that produce
the protein from which hair is made.
Doctors hope that science will discover ways to treat pollutant
contributions to hair loss with topical lotions to block the
effects of the pollutants on the hair follicles.
