||It has been suggested that this article be merged with Alopecia. (Discuss) Proposed since July 2012.|
|Classification and external resources|
Man displaying male pattern baldness
Baldness is the partial or complete lack of hair growth, and part of the wider topic of "hair thinning". The degree and pattern of baldness varies, but its most common cause is androgenic alopecia, alopecia androgenetica, or alopecia seborrheica, with the last term primarily used in Europe.
Pattern balding is distinct from 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.
Male pattern hair loss 
More than 95% of hair thinning in men is male pattern baldness, 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 and is 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. 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".
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. 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. In time, hair becomes thinner, and its overall volume is reduced so that it resembles fragile vellus hair or "peach fuzz" until, finally, the follicle goes dormant and ceases producing hair completely.
Other causes 
Besides the most common cause, male pattern baldness, there are several other causes of hair thinning or loss:
- Traction alopecia is most commonly found in people with ponytails or cornrows who pull on their hair with excessive force. In addition, rigorous brushing and heat styling, rough scalp massage can damage the cuticle, the hard outer casing of the hair. This causes individual strands to become weak and break off, reducing overall hair volume.
- Trichotillomania is the loss of hair caused by compulsive pulling and bending of the hairs. Onset of this disorder tends to begin around the onset of puberty and usually continues through adulthood. Due to the constant extraction of the hair roots, permanent hair loss can occur.
- Traumas such as childbirth, major surgery, poisoning, and severe stress may cause a hair loss condition known as telogen effluvium, in which a large number of hairs enter the resting phase at the same time, causing shedding and subsequent thinning. The condition also presents as a side effect of chemotherapy – while targeting dividing cancer cells, this treatment also affects hair’s growth phase with the result that almost 90% of hairs fall out soon after chemotherapy starts.
- Radiation to the scalp, as when radiotherapy is applied to the head for the treatment of certain cancers there, can cause baldness of the irradiated areas.
- Temporary or permanent hair loss can be caused by several medications, including those for blood pressure problems, diabetes, heart disease and cholesterol. Any that affect the body’s hormone balance can have a pronounced effect: these include the contraceptive pill, hormone replacement therapy, steroids and acne medications.
- Worrisome hair loss often follows childbirth without causing actual baldness. In this situation, the hair is actually thicker during pregnancy due to increased circulating oestrogens. After the baby is born, the oestrogen levels fall back to normal prepregnancy levels, and the additional hair foliage drops out. A similar situation occurs in women taking the fertility-stimulating drug clomiphene.
- Studies have shown that poor nutrition, limited food intake, and deficiencies in certain nutrients can cause thinning. These include deficiencies of biotin, protein, zinc and poor human iron metabolism, although complete baldness is not usually seen. A diet high in animal fats (often found in fast food) and vitamin A is also thought to have an effect on hair loss.
- Stress has been shown to restrict the blood supply to capillaries, inhibiting oxygen and nutrient uptake of hair follicles and inhibiting hair growth, in an effect similar to that from having poor circulation.
- Air and water pollutants as well as minerals in water and the phototoxic effects of sunlight can cause thinning by aging the scalp skin and damaging hair.
- Some treatments used to cure mycotic infections can cause massive hair loss.
- Alopecia areata is an autoimmune disorder also known as "spot baldness" that can result in hair loss ranging from just one location (Alopecia areata monolocularis) to every hair on the entire body (Alopecia areata universalis). Although thought to be caused by hair follicles becoming dormant, what triggers alopecia areata is not known. In most cases the condition corrects itself, but it can also spread to the entire scalp (alopecia totalis) or to the entire body (alopecia universalis).
- Localized or diffuse hair loss may also occur in cicatricial alopecia (lupus erythematosus, lichen plano pilaris, folliculitis decalvans, central centrifugal cicatricial alopecia, postmenopausal frontal fibrosing alopecia, etc.). Tumours and skin outgrowths also induce localized baldness (sebaceous nevus, basal cell carcinoma, squamous cell carcinoma).
- Hypothyroidism (an under-active thyroid) and the side effects of its related medications can cause hair loss, typically frontal, which is particularly associated with thinning of the outer third of the eyebrows (also seen with syphilis). Hyperthyroidism (an over-active thyroid) can also cause hair loss, which is parietal rather than frontal.
- Temporary loss of hair can occur in areas where sebaceous cysts are present for considerable duration (normally one to several weeks).
- Congenital triangular alopecia – It is a triangular, or oval in some cases, shaped patch of hair loss in the temple area of the scalp that occurs mostly in young children. The affected area mainly contains vellus hair follicles or no hair follicles at all, but it does not expand. Its causes are unknown, and although it is a permanent condition, it does not have any other effect on the affected individuals.
- Gradual thinning of hair with age is a natural condition known as involutional alopecia. This is caused by an increasing number of hair follicles switching from the growth, or anagen, phase into a resting phase, or telogen phase, so that remaining hairs become shorter and fewer in number.
- An unhealthy scalp environment can play a significant role in hair thinning by contributing to miniaturization or causing damage. Air and water pollutants, environmental toxins, conventional styling products and excessive amounts of sebum have the potential to build up on the scalp. This debris can block hair follicles and cause their deterioration and consequent miniaturization of hair. It can also physically restrict hair growth or damage the hair cuticle, leading to hair that is weakened and easily broken off before its natural lifecycle has ended.
- Demodex folliculorum, a microscopic mite that feeds on the sebum produced by the sebaceous glands, denies hair essential nutrients and can cause thinning. Demodex folliculorum is not present on every scalp and is more likely to live in an excessively oily scalp environment.
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, 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.
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. Adult stump-tailed macaques, in fact, are commonly used in laboratories for the testing of hair-regrowth treatments.
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, as 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.
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. 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. 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. This gene is also involved in a type of baldness associated with mental retardation. This gene is recessive.
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.
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.
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.
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.
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.
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. Information on how many strands are normally lost in a day varies, but recent studies suggest an average of 100. In order to maintain a normal volume, hair must be replaced at the same rate at which it is lost. The first signs of hair thinning that people will often notice are more hairs than usual left in the hairbrush after brushing or in the basin after shampooing. Styling can also reveal areas of thinning, such as a wider parting or a 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. 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.
Diagnosing and 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 
Perhaps unsurprisingly, hair thinning and baldness cause 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. In 1984, psychologists Dr. Stephen L. Franzoi and Dr. Stephanie A. Shields developed the Body Esteem Scale, 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.
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.
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, Louis C.K., "Stone Cold" Steve Austin, Tupac Shakur, Michael Chiklis, Grant Morrison, Jason Alexander, Telly Savalas, Ross Kemp, Steve Wilkos, and Jeffrey Eugenides. Larry David specifically uses his baldness as a basis for 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 shaved, 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 
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.
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. 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. 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.
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), lost hair from their backs. The high amounts of Corticotropin-releasing hormone created a chronic stress condition in the mice. After treatment with astressin-B, a CRF blocker, the mice had regrown the hair they had lost, four months later.
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. It is 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 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. A decision to proceed with medication or hair restoration should always be made in consultation with a medical professional.
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.
Concealing hair loss 
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.
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.
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. Loss of growth in the outer one third of the eyebrow is often associated with hypothyroidism. 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.
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.
|“||You inherit baldness from your mother's father.||”|
Previously, early baldness of the androgenic type was thought to be sex-linked dominant in males and to be sex-linked recessive in females. Research suggests that the gene for the androgen receptor, which is significant in determining probability for hair loss, is located on the X chromosome and so is always inherited from the mother's side for men. There is a 50% chance that a person shares the same X chromosome as his maternal grandfather. Because women have two X chromosomes, they will have two copies of the androgen receptor gene while men only have one. However, research has also shown that a person with a balding father also has a significantly greater chance of experiencing hair loss. Men whose fathers had experienced hairloss were 2.5 times more likely to experience hairloss themselves, regardless of the mother's side of the family.
|“||Weight Training and other types of physical activity cause baldness.||”|
Because it increases testosterone levels many internet forums have put forward the idea that weight training and other forms of exercise increase hair loss in pre-disposed individuals. Although scientific studies do support a correlation between exercise and testosterone, no direct study has found a link between exercise and baldness. However a few have found a relationship between a sedentary lifestyle and baldness suggesting that some exercise is beneficial. It is possible that the type or quantity of exercise may influence hair loss; more studies are needed. Note that testosterone levels are not a good marker of baldness, and many studies actually show paradoxical low testosterone in balding persons, although research on the implications is limited.
|“||Intellectual activity or psychological problems can cause baldness.||”|
This notion may have arisen because cholesterol is involved in the process of neurogenesis and is also the base material from which the body ultimately manufactures DHT. While the notion that bald men are more intelligent may lack credibility in the modern world, in the ancient world if a person was bald it was likely that he had an adequate amount of fat in his diet. Thus, his mental development was probably not stunted by malnutrition during his crucial formative years, he was more likely to be wealthy, and also to have had access to a formal education. However, a sedentary lifestyle is less likely to correlate with intelligence in the modern world, and dietary fat content is not linked to economic class in modern developed countries. Another possibility is that for some people, social standing accrued through intelligence can in mating compensate for physical attractiveness lowered by hair loss and therefore produce male offspring who are prone to both high intellect and hair loss. However, by way of better socioeconomic standing and in turn more access to hair loss treatments, an association between intelligence and actual hair loss is less likely in recent times. Total testosterone exhibits a positive relation to tactual-spatial abilities and to the degree of lateralization. Total testosterone is negatively correlated with verbal fluency. Testosterone in the saliva is also significantly positively correlated to tactual-spatial test scores and, in addition, to field independence. DHT and the ratio DHT/total testosterone are positively related to verbal fluency and negatively to the degree of lateralization of tactual-spatial performance.
|“||Baldness can be caused by emotional stress, sexual frustration, etc.||”|
Emotional stress has been shown to accelerate baldness in genetically susceptible individuals. Stress due to sleep deprivation in military recruits lowered testosterone levels, but is not noted to have affected SHBG. Thus, stress due to sleep deprivation in fit males is unlikely to elevate DHT, which causes male pattern baldness. Whether it can cause hair loss by some other mechanism is not clear.
|“||Bald men are more 'virile' or sexually active than others.||”|
Levels of free testosterone are strongly linked to libido and also DHT levels, but unless free testosterone is virtually nonexistent, levels have not been shown to affect virility. Men with androgenic alopecia are more likely to have a higher baseline of free androgens. However, sexual activity is multifactoral, and androgenic profile is also not the only determining factor in baldness. Additionally, because hair loss is progressive and free testosterone declines with age, a male's hairline may be more indicative of his past than his present disposition.
|“||Frequent ejaculation causes baldness.||”|
There are many misconceptions about what can help prevent hair loss, one of these being that lack of sexual activity will automatically prevent hair loss. While a proven direct correlation exists between increased frequency of ejaculation and increased levels of DHT, as shown in a recent study by Harvard Medical School, the study suggests that ejaculation frequency is a sign, rather than a cause, of higher DHT levels. Moreover, MBP is genetically determined and theoretically occurs even with low levels of DHT. On the other hand, another study shows that although sexual arousal and masturbation-induced orgasm increase testosterone concentration around orgasm, they reduce testosterone concentration on average(especially before abstinence) and because about 5% of testosterone is converted to DHT, ejaculation does not elevate DHT level.
The only published study to test correlation between ejaculation frequency and 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. Marital status has been shown in some but not all studies to influence hair loss in cross-sectional studies (NHANES1).
|“||Standing on one's head alleviates baldness.||”|
While this may be a myth, increased circulation to the scalp can help provide hair follicles with needed nourishment to grow strong healthy hair.
|“||Tight hats cause baldness.||”|
While this may be a myth, hats do cause hair breakage and, to a lesser degree, split ends. Since hats are not washed as frequently as other clothing, they can also lead to scalp uncleanliness and possible Pityrosporum ovale contamination in men with naturally oily scalps. Some scalp infections, if left untreated, can cause hair loss.
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.
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.
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.
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. The researchers discovered that the growth of new hair producing follicles could be stimulated in mice by damaging their skin.
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.
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.
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".
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. Later, Yale researchers found signals in fat cells that cause hair to grow. 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. 
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.
In April 2013, a meta-analysis of six observational studies with a total of 36 690 participants showed that vertex baldness is associated with an increased risk of CHD and that the relationship depends upon the severity of baldness, while frontal baldness is not. Thus, vertex baldness might be a marker of CHD and is more closely associated with systemic atherosclerosis than frontal baldness.
See also 
- Alopecia areata
- Alopecia universalis
- Bald cap, actors' makeup simulating baldness
- Baldness treatments
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Further reading 
|Wikisource has the text of the 1911 Encyclopædia Britannica article Baldness.|
- Cyclopaedia, London: Ephraim Chambers, 1728.
- Rossi S (Ed.) (2004). Australian Medicines Handbook 2004. Adelaide: Australian Medicines Handbook. ISBN 0-9578521-4-2
- Stárka L, Cermáková I, Dusková M, Hill M, Dolezal M, Polácek V (2004). "Hormonal profile of men with premature balding.". Exp Clin Endocrinol Diabetes 112 (1): 24–8. doi:10.1055/s-2004-815723. PMID 14758568.
- Nourkrin Man research on DHT.  2006.
- No Cure For Baldness? Wojnicki, P (2008) ISBN 1-4348-4178-2  2006
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