–
Defining Different Types of Hair Loss
How do you define hair loss? Do you consider you?re balding when you?ve lost 5 hairs, 5,000, or 50,000? Can you slow the balding process, stop it altogether, or should you just increase your baseball hat collection and live with it?
Examining uniform hair loss A small segment of people lose scalp hair uniformly (diffusely), rather than losing hair in specific scalp areas. Uniform hair loss isn?t as easy to detect as other types of hair loss because the hair is steadily lost all over the head. It?s much easier to detect a bald spot resulting from hair loss in a specific area of the scalp from diseases that cause uniform hair loss to the normal genetics of that particular person.
Briefly, uniform hair loss is the generalized balding of hair over a large area. In contrast with other patterns of baldness, it appears that uniform hair loss occurs across all the regions of the scalp. In contrast with another type of balding, which isolates portions of the scalp, U.H.L. causes hair to fall off at the front, side and back of the head.
Men that are supposedly at their ‘peak’ are not safe from uniform hair loss. Medical science has a different term for uniform hair loss that occurs at younger ages. The term is diffuse unpatterned alopecia. When you compare the symptoms and the rate of hair loss in senile alopecia and diffuse unpatterned alopecia, there are no essential differences.
The only difference perhaps can is the age when the two types of hair loss occur. When does diffuse patterned alopecia occur? Unfortunately for men, this type of balding can manifest itself as early as twenty years old.
Identifying dying hair cells
Apoptosis is a cell?s internal ?suicide? mechanism that causes cell death. The phenomenon has recently been studied very carefully, and what doctors know is that during the transition from anagen to catagen (that?s the growth phase to the changing phase), something happens in the hair follicle development. The cells within the hair follicles communicate with each other, and certain chemicals secreted in the hair follicle determine which hairs will survive for another growth cycle and which will die. Experts believe that the lifespan of each hair follicle ? and possibly each follicular unit ? is genetically programmed.
Because some of the hair follicles within the FU survive while others die, there?s some hope that the chemical inducers that determine the survivors can be identified and manipulated to prevent hair loss. We have identified some of the molecules that stimulate the process but others still need to be isolated. Maybe when all of the molecules are identified and isolated, we can stop the balding process from occurring.
Saving dying hair cells
The causes of cell death are complex. Research has shown that the cells that produce apoptosis-causing chemicals are found in every part of the hair follicle. It?s possible that different types of hair loss are influenced by different chemical problems in the pathways that control cell death.
Although the medical community is identifying many of these chemical pathways, it?s no closer to finding a cure for apoptosis than we would like. Interestingly, apoptosis typically doesn?t occur in cancerous cells, which are thought to be immortal, escaping their natural destiny of living a given number of cell cycles. For example, in breast cancer, a gene called BRCA causes the production of a particular enzyme that blocks apoptosis. Imagine if it were possible to bottle that enzyme to use on hair that?s dying off or, even better, create a cocktail that could make all the cells in the body immortal! At least we can dream.
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.
If you’re healthy but going bald, chances are that you have family members with the same problem. Baldness can be inherited from either side of the family. It’s not any one gene that causes people to lose their hair, but rather a combination of factors. Because of this, baldness may sometimes skip a generation.
Hereditary hair loss is known as androgenetic alopecia. While it is clearly genetic, there is not a single gene that guarantees that someone will go bald. A 2008 study found that a gene on the X chromosome, EDA2R, may play a major role in male pattern baldness. Men inherit their X chromosome from their mothers, meaning that the gene is passed through the maternal line. However, a woman inherits an X chromosome from her father as well as their mother. Other genes that may play a role in hair loss are not gender-linked.
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 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.
The role of DHT receptor sites in hair loss also linked to genetics and hormonal influences since each hair follicle has a predetermined amount of sites that DHT can attach to. In a study comparing the follicles between hair-covered and bald male scalps, it was found that bald scalps had twice as many sites for DHT as their covered counterparts.
Hormones also play a role in hair loss. At birth, each of us has a certain number of hair follicles (roughly 100,000 on the scalp). In the case of male pattern baldness, it appears that those follicles positioned over the crown and front of the head, the infamous balding horseshoe, are usually sensitive to DHT.
Also, in cases of hair loss in women, DHT is also responsible as women produce testosterone just like men, but in smaller amounts. This actually leads to often an overall thinning of the hair as middle age approaches.
Other reasons for hair loss in women are: hormonal imbalances due to puberty or menopause, pregnancy, postmenopausal trauma, birth control. Even nervous tension and various medications and treatments can stimulate hair loss.
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.
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.
Stress generally causes a type of hair loss referred to as telogen effluvium, which is very different from androgenetic alopecia
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
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 iscommon 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.
Leave a Reply