Baldness

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Alopecia
Classification and external resources

Man displaying male pattern baldness
ICD-10L65.9
ICD-9704.0
DiseasesDB14765
MeSHD000505
 
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Alopecia
Classification and external resources

Man displaying male pattern baldness
ICD-10L65.9
ICD-9704.0
DiseasesDB14765
MeSHD000505

Baldness implies partial or complete lack of hair. Balding is part of the wider topic of "hair thinning". The degree and pattern of baldness can vary greatly, but its most common cause is male and female pattern baldness, also known as androgenic alopecia, alopecia androgenetica or alopecia seborrheica – an alternative term used primarily in Europe.

Pattern balding should not be confused with alopecia areata, which commonly involves patchy hair loss. Extreme forms of alopecia areata are alopecia totalis, which involves the loss of all head hair, and the most extreme form, alopecia universalis, which involves the loss of all hair from the head and the body.

Contents

Cause

More than 95% of hair thinning in men is male pattern baldness,[1] or androgenic alopecia. Male pattern baldness is characterized by hair receding from the lateral sides of the forehead (known as a "receding hairline") and/or a thinning crown (balding to the area known as the ‘vertex’). Both become more pronounced until they eventually meet, leaving a horseshoe-shaped ring of hair around the back of the head.

The incidence of pattern baldness varies from population to population based on genetic background. Environmental factors do not seem to affect this type of baldness greatly. One large scale study in Maryborough, Victoria, Australia showed the prevalence of mid-frontal baldness increases with age and affects 73.5 percent of men and 57 percent of women aged 80 and over. A rough rule of thumb is that the incidence of baldness in males corresponds to chronological age. For example, according to Medem Medical Library's website, male pattern baldness (MPB) affects roughly 40 million men in the United States. Approximately 25 percent of men begin balding by age 30; two-thirds begin balding by age 60.

There is a 4 in 7 chance of receiving the baldness gene.[2] Onset of hair loss sometimes begins as early as the end of puberty, and is mostly genetically determined. It was previously believed that baldness was inherited from the maternal grandfather. While there is some basis for this belief, both parents contribute to their offspring's likelihood of hair loss. Most likely, inheritance is technically "autosomal dominant with mixed penetrance"[citation needed].

The trigger for this type of baldness is DHT, a powerful[clarification needed] sex hormone, body- and facial-hair growth promoter that can adversely affect the prostate as well as the hair located on the head.[3] The mechanism by which DHT accomplishes this is not yet fully understood. In genetically-prone scalps, i.e. those experiencing male or female pattern baldness, DHT initiates a process of follicular miniaturization, in which the hair follicle begins to deteriorate. As a consequence, the hair’s growth phase (anagen) is shortened, and young, unpigmented vellus hair is prevented from growing and maturing into the deeply-rooted and pigmented terminal hair that makes up 90 percent of the hair on our heads.[4] In time, hair becomes thinner and its overall volume is reduced, resembling fragile vellus hair or "peach fuzz" until, finally, the follicle falls dormant and ceases producing hair completely.

There are several other kinds of hair thinning:

Evolutionary hypotheses

There is no consensus regarding the details of the evolution of male pattern baldness. The assertion that MPB is intended to convey a social message is supported by the fact that the distribution of androgen receptors in the scalp differs between men and women, and older men or women with high androgen levels often exhibit diffuse thinning of hair as opposed to male pattern baldness.

Male pattern baldness is mostly the result of a genetic event that causes dihydrotestosterone (DHT), a male hormone, to cause the hair follicles to atrophy. The hair produced is progressively smaller, until it is practically invisible (or may disappear completely). It has been speculated that this is an evolutionary event that signifies maturity and conveys greater authority on affected men.

In a study by Muscarella and Cunningham,[11] males and females viewed 6 male models with different levels of facial hair (beard and mustache or none) and cranial hair (full head of hair, receding and bald). Participants rated each combination on 32 adjectives related to social perceptions. Males with facial hair and those with bald or receding hair were rated as being older than those who were clean-shaven or had a full head of hair. Beards and a full head of hair were seen as being more aggressive and less socially mature, and baldness was associated with more social maturity.

Other evolutionary hypotheses include genetic linkage to beneficial traits unrelated to hair loss, and genetic drift.

Non-human baldness

Baldness is not only a human trait. Some other primates, such as chimpanzees, stump-tailed macaques, and South American uakari show progressive thinning of the hair on the scalp after adolescence[citation needed]. Adult stump-tailed macaques, in fact, are commonly used in laboratories for the testing of hair-regrowth treatments.[citation needed]

One interesting case study is the maneless male Tsavo lion. The Tsavo lions prides are unique in that they frequently have only a single male lion with an average of 7 to 8 adult females, opposed to 4 females in other lion species prides. It is theorized that Tsavo males may have heightened levels of testosterone, which could explain both their reputation for aggression and dominance, indicating that manelessness may at one time have had an alpha correlation.[12]

Genetics

Much research went into the genetic component of male pattern baldness, or androgenetic alopecia (AGA). Research indicates that susceptibility to premature male pattern baldness is largely the cause of sex-influenced inheritance (because males can pass on the trait to their sons which would be impossible if it were x-linked). Other genes that are not sex linked are also involved.

German researchers name the androgen receptor gene as the cardinal prerequisite for balding.[13] They conclude that a certain variant of the androgen receptor is needed for AGA to develop. In the same year the results of this study were confirmed by other researchers.[14] This gene is recessive and a female would need two X chromosomes with the defect to show typical male pattern alopecia. Seeing that androgens and their interaction with the androgen receptor are the cause of AGA it seems logical that the androgen receptor gene plays an important part in its development.

Other research in 2007 suggests another gene on the X chromosome, that lies close to the androgen receptor gene, is an important gene in male pattern baldness. They found the region Xq11-q12 on the X-chromosome to be strongly associated with AGA in males. They point at the EDA2R gene as the gene that is mostly associated with AGA. This finding has been replicated in at least three following independent studies.

Other genes involved with hair loss have been found, including a gene located at 3q26.[15] This gene is also involved in a type of baldness associated with mental retardation. This gene is recessive .

Another gene that might be involved in hair loss is the P2RY5. This gene is linked to hair structure. Certain variants can lead to baldness at birth while another variant causes "wooly hair".[16]

Recent research confirmed the X linked androgen receptor as the most important gene, with a gene on chromosome 20 being the second most important determinant gene (snpedia). This research suggests that heredity of AGA is X linked, however, research has also shown that a person with a balding father has a significantly greater chance of experiencing hair loss. Men whose fathers had experienced hair loss were 2.5 times more likely to experience hair loss themselves, regardless of the mother's side of the family, which may suggest Y linked heredity plays a role.[17][18]

Female hair loss

Although baldness is not as common in women as in men, the psychological effects of hair loss tend to be much greater. Typically the frontal hairline is preserved but the density of hair is decreased on all areas of the scalp. Previously it was believed to be caused by testosterone just as in male baldness, but most women who lose hair have normal testosterone levels.[19]

However, female hair loss has become a growing problem which, according to the American Academy of Dermatology, affects around 30 million women in the United States. Although hair loss in females normally occurs after the age of 50 or even later when it does not follow events like pregnancy, chronic illness, crash diets, and stress among others, it is now occurring at earlier ages with reported cases in women as young as 15 or 16.[20]

Causes of female hair loss may vary from those that affect men. In the case of androgenic alopecia female hair loss occurs as a result of the action of androgens hormones (testosterone, androsteinedione, and dihydrotestosterone (DHT)). These male hormones normally occur in small amounts in women.

However, according to Ted Daly, MD, a dermatologist from Nassau University Medical Center on Long Island, androgenic alopecia is not the main cause of hair loss in women and dermatologists now prefer to call this condition female pattern hair loss (or Ludwig Pattern Baldness after the scale developed to diagnose it) instead of using the term androgenic alopecia. He adds that the female pattern is diffuse and goes around the whole top of the head and can affect women at any time.[21]

There are other instances in which the actions of hormones may also cause female hair loss. Some examples are: pregnancy, menopause, presence of ovarian cysts, birth control pills with a high androgen index, polycystic ovary syndrome. Also thyroid disorders, anemia, chronic illness and some medications can also cause female hair loss.[22]

Signs and symptoms

Excessive daily hair loss

It is generally accepted that each person has between 100,000 and 150,000 hairs on their head (blondes have the most, followed by brunettes and redheads). Advice about how many strands it is normal to lose per day varies, but recent studies suggest an average of 100.[23] In order to maintain a normal volume it must be replaced at the same rate. The first signs of hair thinning that people will often notice are more hairs than usual left in their hairbrush after brushing, or in the basin after shampooing. Styling can also reveal areas of thinning, such as a wider parting or thinning crown.

Skin conditions

A substantially blemished face, back and limbs could point to cystic acne. The most severe form of the condition, cystic acne arises from the same hormonal imbalances that cause hair loss, and is associated with DHT production.[24] Seborrheic dermatitis, a condition in which an excessive amount of sebum is produced and builds up on the scalp (looking like an adult cradle cap) is also a symptom of hormonal imbalances, as is an excessively oily or dry scalp. Both can cause hair thinning.

Management

Diagnosing and testing

Noticing thinning

Hair stylists can play an important role in diagnosing thinning. In many cases, they will be the first person to notice it, and they can often recommend a solution based on the specific needs of their client.

Testing

There are two types of identification tests for female pattern baldness: the Ludwig Scale and the Savin Scale. Both track the progress of diffused thinning, which typically begins on the crown of the head behind the hairline, and becomes gradually more pronounced. For male pattern baldness, the Hamilton–Norwood scale tracks the progress of a receding hairline and/or a thinning crown, through to a horseshoe-shaped ring of hair around the head and on to total baldness.

Medical consultation

In almost all cases of thinning, and especially in cases of severe hair loss, it is recommended to seek advice from a doctor or dermatologist. Many types of thinning have an underlying genetic or health-related cause, which a qualified professional will be able to diagnose.

Psychological effects

Background

Perhaps unsurprisingly, hair thinning and baldness causes stress for sufferers, a fact which can be attributed to the psychology of appearance. Although societal interest in appearance has a long history, this particular branch of psychology came into its own during the 1960s and has gained momentum as messages associating physical attractiveness with success and happiness grow more prevalent.[25] In 1984, psychologist Dr. Stephen L. Franzoi and Dr. Stephanie A. Shields developed the Body Esteem Scale,[26] which aims to achieve a comprehensive overview about how participants feel about their bodies (including their hair), and is still used today.

Emotional reactions

The psychology of hair thinning is a complex issue. Hair is considered an essential part of overall identity: especially for women, for whom it often represents femininity and attractiveness. Men typically associate a full head of hair with youth and vigor. Although they may be aware of pattern baldness in their family, many are uncomfortable talking about the issue. Hair thinning is therefore a sensitive issue for both sexes. For sufferers, it can represent a loss of control and feelings of isolation. People experiencing hair thinning often find themselves in a situation where their physical appearance is at odds with their own self-image, and commonly worry that they appear older than they are or less attractive to others. Psychological problems due to baldness, if present, are typically most severe at the onset of symptoms.[27]

Alopecia induced by cancer chemotherapy has been reported to cause changes in self-concept and body image. Body image does not return to the previous state after regrowth of hair for a majority of patients. In such cases, patients have difficulties expressing their feelings (alexithymia) and may be more prone to avoiding family conflicts. Family therapy can help families to cope with these psychological problems if they arise.[28]

Some balding men may feel proud of their baldness, feeling a kindred relationship with famous charismatic bald men, such as Michael Jordan, Yul Brynner, Bruce Willis, Vin Diesel, Jack Nicholson, Sean Connery, Jason Statham, Patrick Stewart, Ben Kingsley, "Stone Cold" Steve Austin, Tupac Shakur, Michael Chiklis, Grant Morrison, Jason Alexander, Telly Savalas, Steve Wilkos, and Jeffrey Eugenides. Larry David specifically uses his baldness as a form of self-deprecating humor in his TV shows Seinfeld and Curb Your Enthusiasm. Baldness has, in recent years, become less of a liability due to an increasing fashionable prevalence of very short, or even completely shaven, hair among men in western countries. For instance, Patrick Stewart was called "The Sexiest Man on TV" for his charismatic role as Captain Jean-Luc Picard on Star Trek: The Next Generation.

Preventing and reversing hair loss

There is currently no way to instigate permanent re-growth of hair that has been lost through genetic or hormonal causes. However, it is widely regarded that with early detection, professional consultation and specialist products, the effects of hair thinning can be reduced or delayed. If the cause is reversible, such as an underlying medical condition, it is possible to stop hair thinning by treating the deficiency.[29] There are also several measures sufferers can take to give hair a thicker appearance and to create an optimum scalp environment for new hair to grow and thrive.

A variety of medications have been proven to slow hair thinning, help grow new hair or enlarge existing hairs to create better coverage. Most require long-term use as, if stopped, hair loss returns.[30] Some treatments are topical, and activated by being sprayed or rubbed into the scalp, while others are taken in pill form. One of the most popular medications, corticosteroids, are either injected into the scalp, taken in pill form or applied in an ointment, and are used especially to treat patchy hair loss.

Treatments for the various forms of alopecia have limited success. Some hair loss sufferers make use of clinically proven treatments such as finasteride, dutasteride and topically applied minoxidil solution, in an attempt to prevent further loss and regrow hair. As a general rule, it is easier to maintain remaining hair than it is to regrow; however, the treatments mentioned may prevent hair loss from Androgenetic alopecia.

Unlike any drug, a dietary supplement, TRX2, is introduced by Oxford BioLabs, after the Oxford Scientists' research on small proteins called "potassium channels". Similar to Minoxidil, TRX2 works by reactivating potassium channels. The treatment contains L-Carntine-tartrate, which has been documented to induce hair growth in humans.[31][32]

In the United States, there are only two drug-based treatments that have been approved by the U.S. Food and Drug Administration (FDA) and one product that has been cleared by the FDA for the treatment of androgenetic alopecia, otherwise known as male or female pattern hair loss. The two FDA approved treatments are finasteride (marketed for hair loss as Propecia) and minoxidil.

Stress reduction (corticotrophin-releasing factor)

Stress reduction can be helpful in slowing hair loss. In 2011, US researchers from the University of California and the US Veterans Administration found that mice who had been genetically engineered to produce excessive levels of Corticotropin-releasing hormone (CRF),[33][34][35] lost hair from their backs.[33][34][35] The high amounts of Corticotropin-releasing hormone created a chronic stress condition in the mice.[33][34][35] After treatment with Astressin-B, a CRF blocker, the mice had regrown the hair they had lost, four months later.[33][34][35]

Surgical treatments

Hair transplant surgery was developed during the 1950s, although the earliest successful hair transplantation research was done in 1939 by a Japanese dermatologist, Dr. Okuda.[36] Usually carried out under local anaesthetic, a surgeon will move healthy hair from the back and sides of the head to areas of thinning, helping to restore a natural look. The procedure can take anything between four and eight hours, and additional sessions can be carried out to make hair even thicker. Transplanted hair falls out within a few weeks, but regrows permanently within months.[37] A decision to proceed with medication or hair restoration should always be made in consultation with a medical professional.

Immunosuppressants

Immunosuppressants applied to the scalp have been shown to temporarily reverse alopecia areata, though the side effects of some of these drugs make such therapy questionable.[38][39]

Treating the scalp

As an extension of facial skin, effective cleansing and moisturizing of the scalp can help keep follicles open and create an optimum environment for healthy hair to grow and mature, preventing miniaturization and controlling thinning. Certain products on the market are specially designed to remove the styling build-up, environmental pollutants and excess sebum that block follicles and inhibit hair growth, and nourish the scalp skin and hair to reduce breakage and promote health.[citation needed]

Concealing hair loss

Head

One method of hiding hair loss is the "comb over", which involves restyling the remaining hair to cover the balding area. It is usually a temporary solution, useful only while the area of hair loss is small. As the hair loss increases, a comb over becomes less effective. When this reaches a stage of extreme effort with little effect—it can make the person the object of teasing or scorn.

Another method is to wear a hat or a hairpiece—a wig or toupee. The wig is a layer of artificial or natural hair made to resemble a typical hair style. In most cases the hair is artificial. Wigs vary widely in quality and cost. In the United States, the best wigs—those that look like real hair—cost up to tens of thousands of dollars. Organizations also collect individuals' donations of their own natural hair to be made into wigs for young cancer patients who have lost their hair due to chemotherapy or other cancer treatment in addition to any type of hair loss.

Lastly a number of alternative topical camouflages exist such as Nanogen (Europe) and Toppik (U.S.) and these are very popular as non-wig cosmetics which add electrostatic microfibres to your own hair.

Eyebrows

Though not as common as the loss of hair on the head, chemotherapy, hormone imbalance, forms of alopecia, and other factors can also cause loss of hair in the eyebrows. Artificial eyebrows are available to replace missing eyebrows or to cover patchy eyebrows. Micro tattooing is also available.

Embracing baldness

Instead of concealing hair loss, one may embrace it. A shaved head will grow stubble in the same manner and at the same rate as a shaved face. The general public has become accepting of the shaved head as well, though female baldness can be considered less socially acceptable in various parts of the world.[citation needed]

Society and culture

There are many myths regarding the possible causes of baldness and its relationship with one's virility, intelligence, ethnicity, job, social class, wealth etc. While skepticism is warranted due to lack of scientific validation, some of these myths may have a degree of underlying truth.

Note that testosterone levels are not a good marker of baldness and many studies actually show a paradoxical low testosterone in balding persons although research on the implications of this is limited.

The only published study to test ejaculation frequency to baldness was probably large enough to detect an association (1390 subjects) and found no correlation although bald persons had had fewer sexual partners. One study may not be enough especially in baldness where there is a complex with age. [50] Marital status has been shown in some but not all studies to influence hair loss in cross sectional studies (NHANES1).

Etymology

The term alopecia (play /ˌælˈpʃə/) is formed from the Greek alópex (αλώπηξ), meaning fox. The origin of this usage is because this animal sheds its coat twice a year.

The term bald likely derives from the English word balde, which means "white, pale", or Celtic ball, which means "white patch or blaze", such as on a horse's head.[51]

Research

Research is looking into connections between hair loss and other health issues. While there has been speculation about a connection between early-onset androgenetic alopecia and heart disease, a review of articles from 1954 to 1999 found no conclusive connection between baldness and coronary artery disease. The dermatologists who conducted the review suggested further study was needed.[52]

Environmental factors are under review. A 2007 study indicated that smoking may be a factor associated with age-related hair loss among Asian men. The study controlled for age and family history, and found statistically significant positive associations between moderate or severe androgenetic alopecia and smoking status.[53]

In May 2007, researchers at the University of Pennsylvania unveiled a new scientific breakthrough that may cure baldness with stem cells. A product could be on the market within three years.[54][55] The researchers discovered that the growth of new hair producing follicles could be stimulated in mice by damaging their skin.[56]

In February 2008 researchers at the University of Bonn announced they have found the genetic basis of two distinct forms of inherited hair loss, opening a broad path to treatments for baldness. The fact that any receptor plays a specific role in hair growth was previously unknown to scientists and with this new knowledge a focus on finding more of these genes may be able to lead to therapies for very different types of hair loss.[57][58]

An eight month study performed at the School of Pharmaceutical Sciences at the University of Science Malaysia showed daily supplements of a patented tocotrienol (vitamin E) complex may increase hair growth in people with male pattern baldness by 42 percent.[59]

In May 2009, researchers in Japan identified a gene, SOX21, that appears to be responsible for hair loss in people.[60]

In December 2010, scientists at the Berlin Technical University in Germany revealed they have grown the world's first artificial hair follicles from stem cells. Research leader Roland Lauster said within five years millions of hair-loss sufferers could grow new hair from their own stem cells and have it implanted into their bald spots. He also announced that preparations for clinical trials were "already in motion".[61]

In 2011, research showed that treatment with astressin-B caused the sudden growth of hair in mice bred for a propensity for stress. Astressin-B ia a nonselective corticotropin-releasing hormone receptor antagonist. This may possibly be used in the future to aid in the regrowth of human hair.[citation needed] Later, Yale researchers found signals in fat cells that cause hair to grow.[62][63] Researchers used genetic twins to determine environmental vs. genetic causes of baldness. Only 66 subjects were used but the use of twins allows control for age and genetics, two powerful confounders. They found baldness associated with genetics, age, smoking, sun exposure, dandruff, a history of cancer, hypertension, sedentariness, and paradoxically, low testosterone. The latter was cited as supporting 5-alpha-reductase inhibitors which would increase the testosterone/DHT ratio. Hypertension (specifically high Diastolic blood pressure) was also found in the NHANES1 study and several others to be associated with baldness. The researchers also found marriage status in women to be associated with hair loss. [64]

In August 2012, Scientists at the University of Pennsylvania announced that they had discovered an enzyme which caused baldness. They found that the enzyme Prostaglandin D2 (PGD2) was found to be present on the scalp of balding men at far higher levels than normal, preventing hair follicles from maturing and therefore stopping them from working and growing hair. Dr George Cotsarelis and his dermatological team at the University say that they are in talks with several pharmaceutical companies about developing treatments which could be available in two years.[65][66][67]

See also

References

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Further reading

External links