Baldness
Encyclopedia
Baldness implies partial or complete lack of hair and can be understood as 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.
. 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 hair loss increases with age and affects 73.5 per cent of men and 57 per cent 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 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 per cent of the hair on our heads. 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:
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 perception
s. 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
.
s, stump-tailed macaque
s, and South America
n 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.
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. One of them being a gene on chromosome 3. The gene is located at 3q26. 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
".
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 suggest that heredity 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 hairloss were 2.5 times more likely to experience hairloss themselves, regardless of the mother's side of the family, which may suggest Y linked heredity plays a role.
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.
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.
in men is an indication that hair thinning of the head might occur. Studies have shown that if a man has complete chest hair, he is around 50% more likely to become bald, increasing to 90% if he has total body hair. In women, excessive body hair (hirsutism
) or a sudden appearance of body hair may indicate the same hormonal imbalances that cause hair loss.
or health
-related cause, which a qualified professional will be able to diagnose.
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 charisma
tic 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
, 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
.
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.
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
.
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.
surgery was developed during the 1950s, although the earliest successful hair transplantation research was done in 1939 by a Japanese dermatologist, Dr. Okuda. 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. A decision to proceed with medication or hair restoration should always be made in consultation with a medical professional.
s 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.
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.
", 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.
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, but female baldness is less socially acceptable.
, 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.
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.
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 May 2009, researchers in Japan
identified a gene
, SOX21
, that appears to be responsible for hair loss in people.
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 Dr 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 baldness. 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.
In 2011 Yale researchers found signals in fat cells that cause hair to grow.
Pattern balding should not be confused with alopecia areata
Alopecia areata
Alopecia areata is a medical condition in which hair is lost from some or all areas of the body, usually from the scalp. Because it causes bald spots on the scalp, especially in the first stages, it is sometimes called spot baldness. In 1–2% of cases, the condition can spread to the entire scalp ...
, which commonly involves patchy hair loss. Extreme forms of alopecia areata are alopecia totalis
Alopecia totalis
Alopecia totalis is the loss of all head hair. Its causes are unclear, but it is currently believed to be an autoimmune disorder. Stress is sometimes thought to be a contributor in alopecia areata...
, which involves the loss of all head hair, and the most extreme form, alopecia universalis
Alopecia universalis
Alopecia universalis or alopecia areata universalis is a medical condition involving rapid loss of all hair, including eyebrows and eyelashes. It is the most severe form of alopecia areata, with an incidence of .001%...
, which involves the loss of all hair from the head and the body.
Cause
More than 95% of hair thinning in men is defined as male pattern baldness, or androgenetic alopeciaAndrogenetic alopecia
Androgenic alopecia is the most common cause of hair loss and thinning in humans. Variants appear in both men and women. Androgenic alopecia also occurs in chimpanzees, and orangutans. In humans, this condition is also commonly known as male pattern baldness...
. 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
Vertex (anatomy)
In arthropod and vertebrate anatomy, the vertex refers to the upper surface of the head.In humans, the vertex is formed by four bones of the skull: the frontal bone, the two parietal bones, and the occipital bone...
’. 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 hair loss increases with age and affects 73.5 per cent of men and 57 per cent 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
Puberty
Puberty is the process of physical changes by which a child's body matures into an adult body capable of reproduction, as initiated by hormonal signals from the brain to the gonads; the ovaries in a girl, the testes in a boy...
, and is mostly genetically
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
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
Penetrance
Penetrance in genetics is the proportion of individuals carrying a particular variant of a gene that also express an associated trait . In medical genetics, the penetrance of a disease-causing mutation is the proportion of individuals with the mutation who exhibit clinical symptoms...
".
The trigger for this type of baldness is DHT
Dihydrotestosterone
Dihydrotestosterone is an androgen or male sex hormone. The enzyme 5α-reductase synthesises DHT in the prostate, testes, hair follicles, and adrenal glands...
, a powerful 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
Dihydrotestosterone
Dihydrotestosterone is an androgen or male sex hormone. The enzyme 5α-reductase synthesises DHT in the prostate, testes, hair follicles, and adrenal glands...
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
Hair follicle
A hair follicle is a skin organ that produces hair. Hair production occurs in phases, including a growth phase , and cessation phase , and a rest phase . Stem cells are principally responsible for the production of hair....
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
Terminal hair
Terminal hairs are thick, long, and dark, as compared with vellus hair. During puberty, the increase in androgenic hormone levels causes vellus hair to be replaced with terminal hair in certain parts of the human body...
that makes up 90 per cent of the hair on our heads. In time, hair becomes thinner and its overall volume is reduced, resembling fragile vellus hair or "peach fuzz" until, finally, the follicle
Hair follicle
A hair follicle is a skin organ that produces hair. Hair production occurs in phases, including a growth phase , and cessation phase , and a rest phase . Stem cells are principally responsible for the production of hair....
falls dormant and ceases producing hair completely.
There are several other kinds of hair thinning:
- Traction alopeciaTraction alopeciaTraction alopecia is a form of alopecia, or gradual hair loss, caused primarily by pulling force being applied to the hair. This commonly results from the sufferer frequently wearing his/her hair in a particularly tight ponytail, pigtails, or braids...
is most commonly found in people with ponytailPonytailA ponytail is a hairstyle in which most or all of the hair on the head is pulled away from the face, gathered and secured at the back of the head with a hair tie, clip or similar device, and allowed to hang freely from that point. It gets its name from its resemblance to the undocked tail of a...
s or cornrows who pull on their hair with excessive force. In addition, rigorous brushing and heat styling, rough scalp massage can damage the cuticleCuticle (hair)The hair cuticle is the outermost part of the hair shaft. It is a hard shingle-like layer of overlapping cells, some five to twelve deep. It is formed from dead cells which form scales that gives the hair shaft strength and do the best job of providing protection for it...
, 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. It tends to occur more in children than in adults. In this condition the hairs are not absent from the scalp but are broken. Where they break near the scalp they cause typical, short, "exclamation mark" hairs.
- Traumas such as, childbirth, major surgery, poisoning, and severe stress may cause a hair loss condition known as telogen effluviumTelogen effluviumTelogen effluvium is a scalp disorder characterized by thinning/shedding of hair resulting from the early entry of hairs into the telogen phase.Emotional or physiological stressful events may result in an alteration of the normal hair cycle....
., 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 chemotherapyChemotherapyChemotherapy is the treatment of cancer with an antineoplastic drug or with a combination of such drugs into a standardized treatment regimen....
– 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 happens 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 pressureBlood pressureBlood pressure is the pressure exerted by circulating blood upon the walls of blood vessels, and is one of the principal vital signs. When used without further specification, "blood pressure" usually refers to the arterial pressure of the systemic circulation. During each heartbeat, BP varies...
, diabetesDiabetes mellitusDiabetes mellitus, often simply referred to as diabetes, is a group of metabolic diseases in which a person has high blood sugar, either because the body does not produce enough insulin, or because cells do not respond to the insulin that is produced...
, heart diseaseHeart diseaseHeart disease, cardiac disease or cardiopathy is an umbrella term for a variety of diseases affecting the heart. , it is the leading cause of death in the United States, England, Canada and Wales, accounting for 25.4% of the total deaths in the United States.-Types:-Coronary heart disease:Coronary...
and cholesterolCholesterolCholesterol is a complex isoprenoid. Specifically, it is a waxy steroid of fat that is produced in the liver or intestines. It is used to produce hormones and cell membranes and is transported in the blood plasma of all mammals. It is an essential structural component of mammalian cell membranes...
. Any that affect the body’s hormone balance can have a pronounced effect, and these include the contraceptive pill, hormone replacement therapyHormone replacement therapy (menopause)Hormone replacement therapy is a system of medical treatment for surgically menopausal, perimenopausal and to a lesser extent postmenopausal women...
, steroidsSteroidA steroid is a type of organic compound that contains a characteristic arrangement of four cycloalkane rings that are joined to each other. Examples of steroids include the dietary fat cholesterol, the sex hormones estradiol and testosterone, and the anti-inflammatory drug dexamethasone.The core...
and acneAcne vulgarisAcne vulgaris is a common human skin disease, characterized by areas of skin with seborrhea , comedones , papules , pustules , Nodules and possibly scarring...
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 pre-pregnancy 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 nutritionNutritionNutrition is the provision, to cells and organisms, of the materials necessary to support life. Many common health problems can be prevented or alleviated with a healthy diet....
, limited food intake, and deficiencies in certain nutrients can cause thinning. These include in biotinBiotinBiotin, also known as Vitamin H or Coenzyme R, is a water-soluble B-complex vitamin discovered by Bateman in 1916. It is composed of a ureido ring fused with a tetrahydrothiophene ring. A valeric acid substituent is attached to one of the carbon atoms of the tetrahydrothiophene ring...
, protein or zincZincZinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...
and human iron metabolismIronIron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
, although complete baldness is not usually seen. A dietDiet (nutrition)In nutrition, diet is the sum of food consumed by a person or other organism. Dietary habits are the habitual decisions an individual or culture makes when choosing what foods to eat. With the word diet, it is often implied the use of specific intake of nutrition for health or weight-management...
high in animal fats (often found in fast foodFast foodFast food is the term given to food that can be prepared and served very quickly. While any meal with low preparation time can be considered to be fast food, typically the term refers to food sold in a restaurant or store with preheated or precooked ingredients, and served to the customer in a...
) and Vitamin AVitamin AVitamin A is a vitamin that is needed by the retina of the eye in the form of a specific metabolite, the light-absorbing molecule retinal, that is necessary for both low-light and color vision...
is also though to have an effect on hair loss. - StressStress (biology)Stress is a term in psychology and biology, borrowed from physics and engineering and first used in the biological context in the 1930s, which has in more recent decades become commonly used in popular parlance...
has been shown to restrict the blood supply to capillariesCapillaryCapillaries are the smallest of a body's blood vessels and are parts of the microcirculation. They are only 1 cell thick. These microvessels, measuring 5-10 μm in diameter, connect arterioles and venules, and enable the exchange of water, oxygen, carbon dioxide, and many other nutrient and waste...
, inhibiting oxygen and nutrient uptake to hair folliclesHair follicleA hair follicle is a skin organ that produces hair. Hair production occurs in phases, including a growth phase , and cessation phase , and a rest phase . Stem cells are principally responsible for the production of hair....
and inhibiting hair growth, in a similar effect to 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 mycoticFungusA fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...
infections can cause massive hair loss. - Alopecia areataAlopecia areataAlopecia areata is a medical condition in which hair is lost from some or all areas of the body, usually from the scalp. Because it causes bald spots on the scalp, especially in the first stages, it is sometimes called spot baldness. In 1–2% of cases, the condition can spread to the entire scalp ...
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, it is not known for sure what triggers alopecia areata. In most cases the condition corrects itself, but it can also spread to the entire scalp (alopecia totalisAlopecia totalisAlopecia totalis is the loss of all head hair. Its causes are unclear, but it is currently believed to be an autoimmune disorder. Stress is sometimes thought to be a contributor in alopecia areata...
) or to the entire body (alopecia universalisAlopecia universalisAlopecia universalis or alopecia areata universalis is a medical condition involving rapid loss of all hair, including eyebrows and eyelashes. It is the most severe form of alopecia areata, with an incidence of .001%...
). - 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).
- HypothyroidismHypothyroidismHypothyroidism is a condition in which the thyroid gland does not make enough thyroid hormone.Iodine deficiency is the most common cause of hypothyroidism worldwide but it can be caused by other causes such as several conditions of the thyroid gland or, less commonly, the pituitary gland or...
(an under-active thyroidThyroidThe thyroid gland or simply, the thyroid , in vertebrate anatomy, is one of the largest endocrine glands. The thyroid gland is found in the neck, below the thyroid cartilage...
) 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). HyperthyroidismHyperthyroidismHyperthyroidism is the term for overactive tissue within the thyroid gland causing an overproduction of thyroid hormones . Hyperthyroidism is thus a cause of thyrotoxicosis, the clinical condition of increased thyroid hormones in the blood. Hyperthyroidism and thyrotoxicosis are not synonymous...
(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 cystSebaceous cystA sebaceous cyst is a term that loosely refers to either epidermoid cysts or pilar cysts . Because an epidermoid cyst originates in the epidermis and a pilar cyst originates from hair follicles, by definition, neither type of cyst is strictly a sebaceous cyst...
s are present for considerable duration; normally one to several weeks in length. - 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 alopeciaAlopeciaAlopecia means loss of hair from the head or body. Alopecia can mean baldness, a term generally reserved for pattern alopecia or androgenic alopecia. Compulsive pulling of hair can also produce hair loss. Hairstyling routines such as tight ponytails or braids may induce Traction alopecia. Both...
. This is caused by an increasing number of hair folliclesHair follicleA hair follicle is a skin organ that produces hair. Hair production occurs in phases, including a growth phase , and cessation phase , and a rest phase . Stem cells are principally responsible for the production of hair....
switching from the growth, or anagen phase, into a resting phase, or telogen phase, so 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 folliclesHair follicleA hair follicle is a skin organ that produces hair. Hair production occurs in phases, including a growth phase , and cessation phase , and a rest phase . Stem cells are principally responsible for the production of hair....
and cause their deterioration and consequent miniaturization of hair. It can also physically restrict hair growth or damage the hair cuticleCuticle (hair)The hair cuticle is the outermost part of the hair shaft. It is a hard shingle-like layer of overlapping cells, some five to twelve deep. It is formed from dead cells which form scales that gives the hair shaft strength and do the best job of providing protection for it...
, leading to hair that is weakened and easily broken off before its natural lifecycle has ended. - Demodex folliculorumDemodex folliculorumDemodex folliculorum is a species of face mite. D. folliculorum is one of the parasitic face mites that occur on people . Demodex derives from the Greek roots, demos- fat, and dex- worm. When large numbers of D...
, a microscopic mite that feeds on the sebum produced by the sebaceous glandSebaceous glandThe sebaceous glands are microscopic glands in the skin that secrete an oily/waxy matter, called sebum, to lubricate and waterproof the skin and hair of mammals...
s, 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 consensusScientific consensus
Scientific consensus is the collective judgment, position, and opinion of the community of scientists in a particular field of study. Consensus implies general agreement, though not necessarily unanimity. Scientific consensus is not by itself a scientific argument, and it is not part of the...
regarding the details of the evolution
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...
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
Dihydrotestosterone
Dihydrotestosterone is an androgen or male sex hormone. The enzyme 5α-reductase synthesises DHT in the prostate, testes, hair follicles, and adrenal glands...
(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
Facial hair
Facial hair is a secondary sex characteristic of human males. Men often start developing facial hair in the later years of puberty or adolescence, approximately between 17–20 years of age, and most do not finish developing a fully adult beard until their early 20s or even later...
(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 perception
Perception
Perception is the process of attaining awareness or understanding of the environment by organizing and interpreting sensory information. All perception involves signals in the nervous system, which in turn result from physical stimulation of the sense organs...
s. 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
Genetic linkage
Genetic linkage is the tendency of certain loci or alleles to be inherited together. Genetic loci that are physically close to one another on the same chromosome tend to stay together during meiosis, and are thus genetically linked.-Background:...
to beneficial traits unrelated to hair loss and genetic drift
Genetic drift
Genetic drift or allelic drift is the change in the frequency of a gene variant in a population due to random sampling.The alleles in the offspring are a sample of those in the parents, and chance has a role in determining whether a given individual survives and reproduces...
.
Non-human baldness
Baldness is not only a human trait. Some other primates, such as chimpanzeeChimpanzee
Chimpanzee, sometimes colloquially chimp, is the common name for the two extant species of ape in the genus Pan. The Congo River forms the boundary between the native habitat of the two species:...
s, stump-tailed macaque
Stump-tailed Macaque
The stump-tailed macaque , also called the bear macaque, is a species of macaque found in Southern Asia. In India, it is found in south of the Brahmaputra river, in northeastern part of the country.Its range in India extends from Assam and Meghalaya to eastern Aruanchal Pradesh, Nagaland, Manipur,...
s, and South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
n uakari
Uakari
Uakari is the common name for the New World monkeys of the genus Cacajao. Both the English and scientific names are believed to have originated from indigenous languages....
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.
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 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
EDA2R
Tumor necrosis factor receptor superfamily member 27 is a protein that in humans is encoded by the EDA2R gene.EDA-A1 and EDA-A2 are two isoforms of ectodysplasin that are encoded by the anhidrotic ectodermal dysplasia gene. Mutations in EDA give rise to a clinical syndrome characterized by loss of...
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. One of them being a gene on chromosome 3. The gene is located at 3q26. 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
Wooly hair
Wooly hair is the presence of hair typical of those of sub-Saharan ancestry on people from other ethnic backgrounds, hair which, under the microscope, appears tightly coiled, and presents at birth or infancy usually as a solitary inherited trait in an autosomal dominant fashion.- See also :* Wooly...
".
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 suggest that heredity 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 hairloss were 2.5 times more likely to experience hairloss 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
American Academy of Dermatology
The American Academy of Dermatology is the largest organization of dermatologists in the world. It was founded in 1938 and represents 17,000 dermatologists in the United States, Canada, and around the world. The Academy grants Fellowships and Associate Memberships, as well as Fellowships for...
, affects around 30 million women in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
. Although hair loss in females normally occurs after the age of 50 or even later when it does not follow events like pregnancy
Pregnancy
Pregnancy refers to the fertilization and development of one or more offspring, known as a fetus or embryo, in a woman's uterus. In a pregnancy, there can be multiple gestations, as in the case of twins or triplets...
, chronic illness, crash diets, and stress
Stress (biology)
Stress is a term in psychology and biology, borrowed from physics and engineering and first used in the biological context in the 1930s, which has in more recent decades become commonly used in popular parlance...
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
Testosterone
Testosterone is a steroid hormone from the androgen group and is found in mammals, reptiles, birds, and other vertebrates. In mammals, testosterone is primarily secreted in the testes of males and the ovaries of females, although small amounts are also secreted by the adrenal glands...
, androsteinedione, and dihydrotestosterone
Dihydrotestosterone
Dihydrotestosterone is an androgen or male sex hormone. The enzyme 5α-reductase synthesises DHT in the prostate, testes, hair follicles, and adrenal glands...
(DHT)). These male hormones normally occur in small amounts in women.
However, according to Ted Daly, MD, a dermatologist from Nassau University Medical Center
Nassau University Medical Center
Nassau University Medical Center is a teaching hospital affiliated with the Health Sciences Center of the State University of New York at Stony Brook...
on Long Island
Long Island
Long Island is an island located in the southeast part of the U.S. state of New York, just east of Manhattan. Stretching northeast into the Atlantic Ocean, Long Island contains four counties, two of which are boroughs of New York City , and two of which are mainly suburban...
, 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
Human head
In human anatomy, the head is the upper portion of the human body. It supports the face and is maintained by the skull, which itself encloses the brain.-Cultural importance:...
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
Menopause
Menopause is a term used to describe the permanent cessation of the primary functions of the human ovaries: the ripening and release of ova and the release of hormones that cause both the creation of the uterine lining and the subsequent shedding of the uterine lining...
, presence of ovarian cysts, birth control pills with a high androgen index, polycystic ovary syndrome. Also thyroid
Thyroid
The thyroid gland or simply, the thyroid , in vertebrate anatomy, is one of the largest endocrine glands. The thyroid gland is found in the neck, below the thyroid cartilage...
disorders, anemia
Anemia
Anemia is a decrease in number of red blood cells or less than the normal quantity of hemoglobin in the blood. However, it can include decreased oxygen-binding ability of each hemoglobin molecule due to deformity or lack in numerical development as in some other types of hemoglobin...
, chronic illness and some medications can also cause female hair loss.
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. 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 acneAcne vulgaris
Acne vulgaris is a common human skin disease, characterized by areas of skin with seborrhea , comedones , papules , pustules , Nodules and possibly scarring...
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
Cradle cap
Cradle cap is a yellowish, patchy, greasy, scaly and crusty skin rash that occurs on the scalp of recently born babies. It is usually not itchy, and does not bother the baby. Cradle cap most commonly begins sometime in the first 3 months...
) is also a symptom of hormonal imbalances, as is an excessively oily or dry scalp. Both can cause hair thinning.
Body hair
Excessive body hairAndrogenic hair
Androgenic hair, colloquially body hair, is the terminal hair that develops on the body during and after puberty. It is differentiated from the head hair and less visible vellus hair, which are much finer and lighter in color. The growth of androgenic hair is related to the level of androgens in...
in men is an indication that hair thinning of the head might occur. Studies have shown that if a man has complete chest hair, he is around 50% more likely to become bald, increasing to 90% if he has total body hair. In women, excessive body hair (hirsutism
Hirsutism
Hirsutism or frazonism is the excessive hairiness on women in those parts of the body where terminal hair does not normally occur or is minimal - for example, a beard or chest hair. It refers to a male pattern of body hair and it is therefore primarily of cosmetic and psychological concern...
) or a sudden appearance of body hair may indicate the same hormonal imbalances that cause hair loss.
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 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 geneticGenetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
or health
Health
Health is the level of functional or metabolic efficiency of a living being. In humans, it is the general condition of a person's mind, body and spirit, usually meaning to be free from illness, injury or pain...
-related cause, which a qualified professional will be able to diagnose.
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. In 1984, psychologist 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 psychologyPsychology
Psychology is the study of the mind and behavior. Its immediate goal is to understand individuals and groups by both establishing general principles and researching specific cases. For many, the ultimate goal of psychology is to benefit society...
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
Chemotherapy
Chemotherapy is the treatment of cancer with an antineoplastic drug or with a combination of such drugs into a standardized treatment regimen....
has been reported to cause changes in self-concept and body image
Body image
Body image refers to a person's perception of the aesthetics and sexual attractiveness of their own body. The phrase body image was first coined by the Austrian neurologist and psychoanalyst Paul Schilder in his masterpiece The Image and Appearance of the Human Body...
. 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
Alexithymia
Alexithymia from the Ancient Greek words λέξις and θυμός modified by an alpha-privative—literally "without words for emotions"—is a term coined by psychotherapist Peter Sifneos in 1973 to describe a state of deficiency in understanding, processing, or describing...
) 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 charisma
Charisma
The term charisma has two senses: 1) compelling attractiveness or charm that can inspire devotion in others, 2) a divinely conferred power or talent. For some theological usages the term is rendered charism, with a meaning the same as sense 2...
tic bald men, such as Michael Jordan
Michael Jordan
Michael Jeffrey Jordan is a former American professional basketball player, active entrepreneur, and majority owner of the Charlotte Bobcats...
, Yul Brynner
Yul Brynner
Yul Brynner was a Russian-born actor of stage and film. He was best known for his portrayal of Mongkut, king of Siam, in the Rodgers and Hammerstein musical The King and I, for which he won an Academy Award for Best Actor for the film version; he also played the role more than 4,500 times on...
, Bruce Willis
Bruce Willis
Walter Bruce Willis , better known as Bruce Willis, is an American actor, producer, and musician. His career began in television in the 1980s and has continued both in television and film since, including comedic, dramatic, and action roles...
, Vin Diesel
Vin Diesel
Vin Diesel is an American actor, writer, director and producer. He became known in the early 2000s, appearing in several successful Hollywood films, including The Fast and the Furious and xXx...
, Jack Nicholson
Jack Nicholson
John Joseph "Jack" Nicholson is an American actor, film director, producer and writer. He is renowned for his often dark portrayals of neurotic characters. Nicholson has been nominated for an Academy Award twelve times, and has won the Academy Award for Best Actor twice: for One Flew Over the...
, Sean Connery
Sean Connery
Sir Thomas Sean Connery , better known as Sean Connery, is a Scottish actor and producer who has won an Academy Award, two BAFTA Awards and three Golden Globes Sir Thomas Sean Connery (born 25 August 1930), better known as Sean Connery, is a Scottish actor and producer who has won an Academy...
, Jason Statham
Jason Statham
Jason Statham born 12 September1967) is an English actor and former diver, known for his roles in the Guy Ritchie crime films Revolver, Snatch and Lock, Stock and Two Smoking Barrels...
, Patrick Stewart
Patrick Stewart
Sir Patrick Hewes Stewart, OBE is an English film, television and stage actor, who has had a distinguished career in theatre and television for around half a century...
, Ben Kingsley
Ben Kingsley
Sir Ben Kingsley, CBE is a British actor. He has won an Oscar, BAFTA, Golden Globe and Screen Actors Guild awards in his career. He is known for starring as Mohandas Gandhi in the film Gandhi in 1982, for which he won the Academy Award for Best Actor...
, "Stone Cold" Steve Austin, Tupac Shakur
Tupac Shakur
Tupac Amaru Shakur , known by his stage names 2Pac and Makaveli, was an American rapper and actor. Shakur has sold over 75 million albums worldwide as of 2007, making him one of the best-selling music artists in the world...
, Michael Chiklis
Michael Chiklis
Michael Charles Chiklis is an American actor, voice actor, occasional director and television producer. Some of the previous roles for which he is best known include Commissioner Tony Scali on the ABC police drama The Commish, LAPD Detective Vic Mackey on the FX police drama The Shield, Thing in...
, Jason Alexander
Jason Alexander
Jay Scott Greenspan , better known by his professional name of Jason Alexander, is an American actor, writer, comedian, television director, producer, and singer. He is best known for his role as George Costanza on the television series Seinfeld, appearing in the sitcom from 1989 to 1998...
, Telly Savalas
Telly Savalas
Aristotelis "Telly" Savalas was an American film and television actor and singer, whose career spanned four decades. Best known for playing the title role in the 1970s crime drama Kojak, Savalas was nominated for an Academy Award for Best Supporting Actor for his performance in Birdman of Alcatraz...
, Steve Wilkos
Steve Wilkos
Steven John "Steve" Wilkos is an American television personality, a former U.S. Marine and officer with the Chicago police. He currently hosts his own talk show, The Steve Wilkos Show, but is best known as the former director of security on The Jerry Springer Show...
, and Jeffrey Eugenides
Jeffrey Eugenides
Jeffrey Kent Eugenides is an American Pulitzer Prize-winning novelist and short story writer. Eugenides is most known for his first two novels, The Virgin Suicides and Middlesex . His novel The Marriage Plot was published in October, 2011.-Life and career:Eugenides was born in Detroit, Michigan,...
. Larry David
Larry David
Lawrence Gene "Larry" David is an American actor, writer, comedian and producer. He is best known as the co-creator , head writer, and executive producer of the television series Seinfeld from 1989 to 1996, and for creating the 1999 HBO series Curb Your Enthusiasm, a partially improvised sitcom in...
specifically uses his baldness as a form of self-deprecating humor in his TV shows Seinfeld
Seinfeld
Seinfeld is an American television sitcom that originally aired on NBC from July 5, 1989, to May 14, 1998, lasting nine seasons, and is now in syndication. It was created by Larry David and Jerry Seinfeld, the latter starring as a fictionalized version of himself...
and Curb Your Enthusiasm
Curb Your Enthusiasm
Curb Your Enthusiasm is an American comedy television series produced and broadcast by HBO, which premiered on October 15, 2000. As of 2011, it has completed 80 episodes over eight seasons. The series was created by Seinfeld co-creator Larry David, who stars as a fictionalized version of himself...
. 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
Patrick Stewart
Sir Patrick Hewes Stewart, OBE is an English film, television and stage actor, who has had a distinguished career in theatre and television for around half a century...
was called "The Sexiest Man on TV" for his charismatic role as Captain Jean-Luc Picard
Jean-Luc Picard
Captain Jean-Luc Picard is a Star Trek character portrayed by Patrick Stewart. He appears in the television series Star Trek: The Next Generation and the feature films Star Trek Generations, Star Trek: First Contact, Star Trek: Insurrection, and Star Trek Nemesis...
on Star Trek: The Next Generation
Star Trek: The Next Generation
Star Trek: The Next Generation is an American science fiction television series created by Gene Roddenberry as part of the Star Trek franchise. Roddenberry, Rick Berman, and Michael Piller served as executive producers at different times throughout the production...
.
Preventing and reversing hair loss
There is currently no way to instigate permanent re-growth of hair that has been lost through geneticGenetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
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
Finasteride
Finasteride is a synthetic antiandrogen that inhibits type II 5-alpha reductase, the enzyme that converts testosterone to dihydrotestosterone...
, dutasteride
Dutasteride
Dutasteride is a dual 5-a reductase inhibitor that inhibits conversion of testosterone to dihydrotestosterone ....
and topically applied minoxidil
Minoxidil
Minoxidil is an antihypertensive vasodilator medication which also slows or stops hair loss and promotes hair regrowth. Now off-patent, it is available over-the-counter for the treatment of androgenic alopecia. Minoxidil must be used indefinitely for continued support of existing hair follicles and...
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.
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
Androgenetic alopecia
Androgenic alopecia is the most common cause of hair loss and thinning in humans. Variants appear in both men and women. Androgenic alopecia also occurs in chimpanzees, and orangutans. In humans, this condition is also commonly known as male pattern baldness...
, otherwise known as male or female pattern hair loss. The two FDA approved treatments are finasteride (marketed for hair loss as Propecia) and minoxidil
Minoxidil
Minoxidil is an antihypertensive vasodilator medication which also slows or stops hair loss and promotes hair regrowth. Now off-patent, it is available over-the-counter for the treatment of androgenic alopecia. Minoxidil must be used indefinitely for continued support of existing hair follicles and...
.
Stress reduction (corticotrophin-releasing factor)
Stress reduction can be helpful in slowing hair loss. In 2011, US researchers from the University of CaliforniaUniversity of California
The University of California is a public university system in the U.S. state of California. Under the California Master Plan for Higher Education, the University of California is a part of the state's three-tier public higher education system, which also includes the California State University...
and the US Veterans Administration
United States Department of Veterans Affairs
The United States Department of Veterans Affairs is a government-run military veteran benefit system with Cabinet-level status. It is the United States government’s second largest department, after the United States Department of Defense...
found that mice who had been genetically engineered to produce excessive levels of Corticotropin-releasing hormone
Corticotropin-releasing hormone
Corticotropin-releasing hormone , originally named corticotropin-releasing factor , and also called corticoliberin, is a polypeptide hormone and neurotransmitter involved in the stress response...
(CRF), lost hair from their backs. The high amounts of Corticotropin-releasing hormone created a chronic stress
Chronic stress
Chronic stress is the response to emotional pressure suffered for a prolonged period over which an individual perceives he or she has no control. It involves an endocrine system response in which occurs a release of corticosteroids...
condition in the mice. After treatment with Astressin-B
Astressin-B
Astressin-B is a nonselective corticotropin releasing hormone antagonist that reduces the synthesis of ACTH and cortisol.Reducing ACTH synthesis, it improves the sexual drive of rats under stressing conditions....
, a CRF blocker
Corticotropin releasing hormone antagonist
A Corticotropin releasing hormone antagonist is a specific type of receptor antagonist which blocks the receptor sites for Corticotropin releasing hormone , blocking therefore the consequent secretions of ACTH and cortisol.There are four subtypes of this receptor known at present, defined as CRF-1,...
, the mice had regrown the hair they had lost, four months later.
Surgical treatments
Hair transplantHair transplantation
Hair transplantation is a surgical technique that involves moving individual hair follicles from one part of the body to bald or balding parts . It is primarily used to treat male pattern baldness. It this case, grafts containing hair follicles that are genetically resistant to balding are...
surgery was developed during the 1950s, although the earliest successful hair transplantation research was done in 1939 by a Japanese dermatologist, Dr. Okuda. 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. A decision to proceed with medication or hair restoration should always be made in consultation with a medical professional.
Immunosuppressants
ImmunosuppressantImmunosuppressant
An immunosuppressant is any substance that performs immunosuppression of the immune system. They may be either exogenous, as immunosuppressive drugs, or endogenous, as ,e. g., testosterone...
s 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.
Treating the scalp
As an extension of facial skin, effective cleansing and moisturizing of the scalp can help keep folliclesHair follicle
A hair follicle is a skin organ that produces hair. Hair production occurs in phases, including a growth phase , and cessation phase , and a rest phase . Stem cells are principally responsible for the production of hair....
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
Hair follicle
A hair follicle is a skin organ that produces hair. Hair production occurs in phases, including a growth phase , and cessation phase , and a rest phase . Stem cells are principally responsible for the production of hair....
and inhibit hair growth, and nourish the scalp skin and hair to reduce breakage and promote health.
Head
One method of hiding hair loss is the "comb overComb over
A comb over or combover is a hairstyle worn by bald or balding men in which the hair on one side of the head is grown long and then combed over the bald area to minimize the display of baldness. A variation of the comb over where baldness is concealed by long hair combed in three separate...
", 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
Hat
A hat is a head covering. It can be worn for protection against the elements, for ceremonial or religious reasons, for safety, or as a fashion accessory. In the past, hats were an indicator of social status...
or a hairpiece—a wig or toupee
Toupee
A toupée is a hairpiece or partial wig of natural or synthetic hair worn to cover partial baldness or for theatrical purposes. While toupées and hairpieces are typically associated with male wearers, some women also use hairpieces to lengthen existing hair, or cover partially exposed scalp...
. 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
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...
patients who have lost their hair due to chemotherapy
Chemotherapy
Chemotherapy is the treatment of cancer with an antineoplastic drug or with a combination of such drugs into a standardized treatment regimen....
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 stubbleStubble
Stubble is the regrowth of shaven hair, when it is short and has a rough, abrasive texture.-Facial:During the 1980s, facial stubble on men became fashionable, partly due to being popularized by the singer George Michael, as well as Miami Vice. This was also known as designer stubble and was...
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, but female baldness is less socially acceptable.
Society and culture
There are many myths regarding the possible causes of baldness and its relationship with one's virilityMasculinity
Masculinity is possessing qualities or characteristics considered typical of or appropriate to a man. The term can be used to describe any human, animal or object that has the quality of being masculine...
, intelligence, ethnicity, job, social class
Social class
Social classes are economic or cultural arrangements of groups in society. Class is an essential object of analysis for sociologists, political scientists, economists, anthropologists and social historians. In the social sciences, social class is often discussed in terms of 'social stratification'...
, 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 dominantSex linkageSex linkage is the phenotypic expression of an allele related to the chromosomal sex of the individual. This mode of inheritance is in contrast to the inheritance of traits on autosomal chromosomes, where both sexes have the same probability of inheritance...
in males and to be sex linked recessiveSex linkageSex linkage is the phenotypic expression of an allele related to the chromosomal sex of the individual. This mode of inheritance is in contrast to the inheritance of traits on autosomal chromosomes, where both sexes have the same probability of inheritance...
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. 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.
- Previously, early baldness of the androgenic type was thought to be sex linked dominant
- "Intellectual activity or psychological problems can cause baldness."
- This notion may be because cholesterol is involved in the process of neurogenesis and 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 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. Of course, aside from all these scientific reasons, baldness could be linked to intellect or wisdom simply because people go bald as they age and become more experienced.
- 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 stressStress (medicine)Stress is a term in psychology and biology, borrowed from physics and engineering and first used in the biological context in the 1930s, which has in more recent decades become commonly used in popular parlance...
has been shown to accelerate baldness in genetically susceptible individuals. - Stress due to sleep deprivationSleep deprivationSleep deprivation is the condition of not having enough sleep; it can be either chronic or acute. A chronic sleep-restricted state can cause fatigue, daytime sleepiness, clumsiness and weight loss or weight gain. It adversely affects the brain and cognitive function. Few studies have compared the...
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.
- Emotional stress
- "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 non-existent 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 person's hairline may be more indicative of their past than 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 there has been proven to be a direct correlation between increased frequency of ejaculationEjaculationEjaculation is the ejecting of semen from the male reproductory tract, and is usually accompanied by orgasm. It is usually the final stage and natural objective of male sexual stimulation, and an essential component of natural conception. In rare cases ejaculation occurs because of prostatic disease...
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. While reducing or even abstaining from sexual activity may not completely prevent hair loss in men who are genetically prone to it, it may slow down the process of balding due to the resulting lower levels of DHT, which causes male pattern 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 there has been proven to be a direct correlation between increased frequency of ejaculation
- "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 hatHatA hat is a head covering. It can be worn for protection against the elements, for ceremonial or religious reasons, for safety, or as a fashion accessory. In the past, hats were an indicator of social status...
s cause baldness."- While this may be a myth, hats do cause hair breakage and, to a lesser degree, split endsTrichoptilosisTrichoptilosis , schizotrichia, and informally split ends, is the splitting or fraying of the hair-shaft due to excessive heat and mechanical stress.-Causes:Thermal, chemical or mechanical stress can cause split...
. 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.
- While this may be a myth, hats do cause hair breakage and, to a lesser degree, split ends
Etymology
The term alopecia (icon) is formed from the GreekGreek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
alópex (αλώπηξ), meaning fox
Fox
Fox is a common name for many species of omnivorous mammals belonging to the Canidae family. Foxes are small to medium-sized canids , characterized by possessing a long narrow snout, and a bushy tail .Members of about 37 species are referred to as foxes, of which only 12 species actually belong to...
. 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.
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.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
University of Pennsylvania
The University of Pennsylvania is a private, Ivy League university located in Philadelphia, Pennsylvania, United States. Penn is the fourth-oldest institution of higher education in the United States,Penn is the fourth-oldest using the founding dates claimed by each institution...
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
University of Bonn
The University of Bonn is a public research university located in Bonn, Germany. Founded in its present form in 1818, as the linear successor of earlier academic institutions, the University of Bonn is today one of the leading universities in Germany. The University of Bonn offers a large number...
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 May 2009, researchers in Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
identified a gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
, SOX21
SOX21
Transcription factor SOX-21 is a protein that in humans is encoded by the SOX21 gene. It is a member of the Sox gene family of transcription factors.- Function :...
, that appears to be responsible for hair loss in people.
In December 2010, scientists at the Berlin Technical University in Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
revealed they have grown the world's first artificial hair follicles from stem cells. Research leader Dr 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
Astressin-B
Astressin-B is a nonselective corticotropin releasing hormone antagonist that reduces the synthesis of ACTH and cortisol.Reducing ACTH synthesis, it improves the sexual drive of rats under stressing conditions....
caused the sudden growth of hair in mice bred for a propensity for baldness. 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.
In 2011 Yale researchers found signals in fat cells that cause hair to grow.
See also
- Alopecia areataAlopecia areataAlopecia areata is a medical condition in which hair is lost from some or all areas of the body, usually from the scalp. Because it causes bald spots on the scalp, especially in the first stages, it is sometimes called spot baldness. In 1–2% of cases, the condition can spread to the entire scalp ...
- Alopecia universalisAlopecia universalisAlopecia universalis or alopecia areata universalis is a medical condition involving rapid loss of all hair, including eyebrows and eyelashes. It is the most severe form of alopecia areata, with an incidence of .001%...
- Bald capBald capA bald cap is a wig-like cap simulating the appearance of a bald or partially bald head. As part of an actor's make-up, it is often used to make a person appear older....
, actors' makeup simulating baldness - Baldness treatmentsBaldness treatmentsBaldness treatment is a US $1 billion per year industry. In males past their early 20s, the incidence of balding is roughly equivalent to chronological age. Thus, by age 50, roughly half of men experience male pattern baldness . Beginning in the 1980s, drug therapy has increasingly become a...
- DihydrotestosteroneDihydrotestosteroneDihydrotestosterone is an androgen or male sex hormone. The enzyme 5α-reductase synthesises DHT in the prostate, testes, hair follicles, and adrenal glands...
- TrichotillomaniaTrichotillomaniaTrichotillomania, which is classified as an impulse control disorder by DSM-IV, is the compulsive urge to pull out one's own hair leading to noticeable hair loss, distress, and social or functional impairment. It is often chronic and difficult to treat....
Further reading
- CyclopaediaCyclopaedia, or Universal Dictionary of Arts and SciencesCyclopaedia: or, An Universal Dictionary of Arts and Sciences was an encyclopedia published by Ephraim Chambers in London in 1728, and reprinted in numerous editions in the eighteenth century...
, London: Ephraim ChambersEphraim ChambersEphraim Chambers was an English writer and encyclopaedist, who is primarily known for producing the Cyclopaedia, or a Universal Dictionary of Arts and Sciences.-Early life:...
, 1728. - Rossi S (Ed.) (2004). Australian Medicines HandbookAustralian Medicines HandbookAustralian Medicines Handbook is an independent medicines reference tool for medical practitioners, pharmacists, nurses, students and any health practitioner with an interest in the quality use of medicines in Australia....
2004. Adelaide: Australian Medicines Handbook. ISBN 0-9578521-4-2 - Nourkrin Man research on DHT. http://nourkrinman.googlepages.com/home 2006.
- No Cure For Baldness? Wojnicki, P (2008) ISBN 1-4348-4178-2 http://nocureforbaldness.co.uk 2006