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Baldness involves the state of lacking hair where it often grows, especially on the head. The most common form of baldness is a progressive hair thinning condition called androgenic alopecia or 'male pattern baldness' that occurs in adult male humans and other species. The severity and nature of baldness can vary greatly; it ranges from male and female pattern alopecia (androgenetic alopecia, also called androgenic alopecia or alopecia androgenetica), alopecia areata, which involves the loss of some of the hair from the head, and alopecia totalis, which involves the loss of all head hair, to the most extreme form, alopecia universalis, which involves the loss of all hair from the head and the body. Treatments for the various forms alopecia have limited success, but typical male pattern baldness is now a very preventable, and reversible (to a certain extent) condition. Thousands of individuals today make use of clinically proven treatments such as Avacor, Propecia and the new Rogaine Foam, to show noticeable regrowth and prevent any further loss. As a general rule, the more hair you've lost the harder it is to restore, but the treatments will help the vast majority of users, and there are new technologies in cosmetic transplant surgery and hair replacement systems that are completely undetectable.
There are several other kinds of baldness:
- Traction alopecia is most commonly found in people with ponytails or cornrows who pull on their hair with excessive force. Wearing a hat shouldn't generally cause this, though it is a good idea to let your scalp breathe for 7 hours a day[How to reference and link to summary or text].
- Traumas such as chemotherapy, childbirth, major surgery, poisoning, and severe stress may cause a hair loss condition known as telogen effluvium.
- Some mycotic infections can cause massive hair loss.
- Alopecia areata is an autoimmune disorder also known as "spot baldness" that can result in hair loss ranging from just one location (Alopecia areata monolocularis) to every hair on the entire body (Alopecia areata universalis).
- 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).
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.
The average human head has about 100,000 hair follicles. Each follicle can grow about 20 individual hairs in a person's lifetime. Average hair loss is about 100 strands a day.
Male pattern baldness is characterized by hair receding from the lateral sides of the forehead, known as "receding hairline".
An additional bald patch may develop on top (vertex). The trigger for this type of baldness (called androgenetic alopecia) is DHT, a powerful sex hormone and hair growth promoter that can adversely affect the hair and prostate.
Male pattern baldness is classified on the Hamilton-Norwood scale I-VIII.
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, in central Victoria (Australia) showed the prevalence of mid-frontal hair loss increases with age and affects 57% of women and 73.5% of men aged 80 and over.
The mechanism by which DHT accomplishes this is not yet understood. In genetically-prone scalps, DHT initiates a process of follicular miniaturization. Through the process of follicular miniaturization, hair shaft width is progressively decreased until scalp hair resembles fragile vellus hair or "peach fuzz" or else becomes non-existent. Onset of hair loss sometimes begins as early as end of puberty, and is mostly genetically determined. It was previously believed that baldness was inherited. 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" (see 'baldness folklore' below)
- Hypothyroidism can cause hair loss, especially thinning of the outer third of the eyebrows
- Temporary loss of hair can occur in areas where sebaceous cysts are present for considerable duration; normally one to several weeks in length.
Psychological causes of hair loss
Evolutionary theories of male pattern baldness
There is no consensus regarding the details of the evolution of male pattern baldness. Most theories regard it as resulting from sexual selection. A number of other primate species also experience hair loss following puberty, and some primate species clearly use an enlarged forehead, created both anatomically and through strategies such as frontal balding, to convey increased status and maturity. 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 women or women with high androgen levels often exhibit diffuse thinning of hair as opposed to male pattern baldness.
One theory, advanced by Muscarella and Cunningham, suggests baldness evolved in males through sexual selection as an enhanced signal of aging and social maturity, whereby aggression and risk-taking decrease and nurturing behaviours increase.(1) This may have conveyed a male with enhanced social status but reduced physical threat, which could enhance ability to secure reproductive partners and raise offspring to adulthood.
In a study by Muscarella and Cunnhingham, males and females viewed 6 male models with different levels of facial hair (beard and moustache or clean) and cranial hair (full head of hair, receding and bald). Participants rated each combination on 32 adjectives related to social perceptions. Males with facial hair and those with bald or receding hair were rated as being older than those who were clean-shaven or had a full head of hair. Beards and a full head of hair were seen as being more aggressive and less socially mature, and baldness was associated with more social maturity.
Approaches to baldness
The psychological effects for individuals experiencing hair loss vary widely. Some people adapt to the change comfortably, while others have severe problems relating to anxiety, depression, social phobia, and in some cases, identity change.
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 (what is called alexithymia) and may be more prone to avoiding family conflicts. Family therapy can help families to cope with these psychological problems if they arise.
Psychological problems due to baldness, if present, are typically most severe at the onset of symptoms.
Some balding men may feel proud of their baldness, feeling a kindred relationship with famous charismatic bald men such as Telly Savalas, Patrick Stewart, Sean Connery, Yul Brynner, Billy Corgan, Vin Diesel, Michael Chiklis, Michael Stipe, Ross Kemp, Jason Alexander, Larry David, Danny De Vito, Ben Kingsley or Bruce Willis; or politicians such as Ed Koch, John Reid, Menzies Campbell and James Carville; or sportsmen such as wrestler Stone Cold Steve Austin, footballers Zinedine Zidane, Bobby Charlton or tennis star Andre Agassi. Much of these celebrities' perceived masculinity and handsomeness derives from their most obvious distinguishing feature. Baldness has, in recent years, in any case become less of a (supposed) liability due to an increasing fashionable prevalence of very short, or even completely shaven, hair among men, at least in western countries. This is even true for women, as shown by the case of singer Sinead O'Connor who has a shaven head.
Many companies have built a successful business selling products that reverse baldness, by allegedly regrowing hair, transplanting hair or selling hairpieces. There is very little evidence that any of those which claim hair regrowth actually work.
Preventing and reversing hair loss
- Main article: Baldness treatments
In the USA, there are only 2 treatments that have been approved by the FDA (Food and Drug Administration) 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.
Merck Pharmaceuticals sought to find the smallest effective quantity of finasteride and test its long-term effects on 1,553 men between ages 18 and 41 with mild to moderate thinning hair. Based on their research, 1mg daily was selected, and after 2 years of daily treatment, over 83% of the 1,553 men experiencing male hair loss had actually maintained or increased their hair count from baseline. Visual assessments concluded that over 80% had improved appearances.
Minoxidil was first used in tablet form as a medicine to treat high blood pressure, but it was noticed that some patients being treated with Minoxidil experienced excessive hair growth (hypertrichosis) as a side-effect. Further research showed that by applying Minoxidil in solution form directly to the scalp, it could prove to be beneficial to those experiencing topical hair loss.
FDA clinical trials showed that 65% of men with androgenetic alopecia maintained or increased their hair count from the use of minoxidil 5% in liquid form. 54% of these men experienced moderate to dense regrowth and 46% experienced hair loss stabilisation and mild regrowth.
In controlled clinical studies of women aged 18-45, 2 out of 3 women with moderate degrees of hereditary hair loss reported re-growth after using 2% minoxidil. Initial results occur at 4 months with maximum results occurring at 8 months.
The FDA's test report said subjects who used the treatment "had significantly greater increases in mean terminal hair density" than those who used placebo in the tests.
As the device's name suggests, it combines a low-level laser with a comb. When drawn through the hair, the laser strikes the scalp to promote hair growth.
The LaserComb is the only drug-free product meant for home use in combating hair loss that's won the endorsement of the Food and Drug Administration.
Surgery is another method of reversing hair loss and baldness, although it may be considered an extreme measure. The surgical methods used include hair transplantation, whereby hair-producing follicles are taken from the back and sides of the head and injected into bald or thinning areas.
Looking forward, the prospective treatment of hair multiplication/hair cloning, which extracts self-replenishing follicle stem cells, multiplies them many times over in the lab, and microinjects them into the scalp, has been shown to work in mice, and is currently under development, expected by some scientists to be available to the public in 2009–2015. Subsequent versions of the treatment are expected by some scientists to be able to cause these follicle stem cells to simply signal the surrounding hair follicles to rejuvenate. See Baldness treatments
In October 2006, UK biotechnology firm Intercytex announced they have successfully tested a method of removing hair follicles from the back of the neck, multiplying them and then reimplanting the cells into the scalp (Hair multiplication). The initial testing resulted in 70% of male patients regrowing hair. This treatment method is expected to be available to the public by 2009 .
In January 2007, Italian stem-cell researchers say they've come up with a new technique for curing baldness. Pierluigi Santi of a Genoa clinic said stem cells could be used to "multiply" hair roots. He said the clinic would be ready to perform its first hair transplants on priority patients - those who have lost their hair in fires or other accidents - within a few months. After that, he said, "we'll open our doors to paying customers". Santi's approach works by splitting roots and growing new follicles.
Topical application of ketoconazole, which is both an anti-fungal and a potent 5-alpha reductase inhibitor, is often used as a supplement to other approaches.1
Unsaturated Fatty Acids
Particular unsaturated fatty acids such as gamma linolenic acid are 5 alpha reductase inhibitors if taken internally. 
Interestingly, placebo treatments in studies often have reasonable success rates, though not as high as the products being tested, and even similar side-effects as the products. For example, in Finasteride (Propecia) studies, the percent of patients with any drug-related sexual adverse experience was 3.8% compared with 2.0% in the placebo group.
Studies done on subjects of various ages suggests that weight training alone may increase testosterone in studies where aerobic exercise (only) was compared to either weight training (only) or a moderately sedentary life. ;    One study suggests that both heavy exercise and increased fat intake, in combination, are required for increased free testosterone in strength trainers. This would help them build muscle, but may cause susceptible individuals to lose hair. 
However, there is at least one study that indicates a decline in free testosterone combined with an increase in strength due to an (unspecified) strength training regime.
Saw Palmetto (Serenoa repens) is an herbal DHT inhibitor often claimed to be cheaper and have fewer side effects than finasteride and dutasteride. Unlike other 5alpha-reductase inhibitors, Serenoa repens induces its effects without interfering with the cellular capacity to secrete PSA. Saw palmetto extract has been demonstrated to inhibit both isoforms of 5-alpha-reductase unlike finasteride which only inhibits the (predominant) type 2 isoenzyme of 5-alpha-reductase.
Polygonum Multiflorum is a traditional Chinese cure for hair loss. Whether the plant itself is useful, the general safety and quality control of herbs imported from China can be questionable.
Beta Sitosterol, which is a constituent in many seed oils, can help to treat BHP by lowering cholesterol. If used for this purpose, an extract is best. Consuming large amounts of oil to get at small quantities of beta sitosterol is likely to exacerbate male pattern baldness.
Resveratrol, from grape skins.
While drastic, broad spectrum anti-androgens such as flutamide are sometimes used topically. Flutamide is potent enough to have a feminizing effect in men, including growth of the breasts.
In March 2006, Curis announced that it had received the first preclinical milestone, a $1,000,000 cash payment, in its hair growth program with Procter & Gamble Pharmaceuticals, a division of The Procter & Gamble Company. The program is focused on the potential development of a topical Hedgehog agonist for hair growth disorders, such as male pattern baldness and female hair loss. The curis hairloss research program was shut down in may 2007 because the process did not meet the proper safety standards.
WNT Gene Related
In May 2007, US company Follica Inc, announced they have licensed technology from the University of Pennsylvania which can regenerate hair follicles by reawakening genes which were once active only in the embryo stage of human development.    
Concealing hair loss
One method of hiding hair loss is the "comb over", which involves restyling the remaining hair to cover the balding area. It is usually a temporary solution, useful only while the area of hair loss is small. As the hair loss increases, a comb over becomes less effective. 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 such as Wigs for Kids and Locks of Love 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.
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.
Of course, instead of concealing hair loss, one may embrace it. A shaved head will grow stubble in the same manner and at the same rate as a shaved face. Many celebrities and athletes shave their heads. The general public has become accepting of the shaved head also.
Female baldness is less socially accepted.
The LIPH gene makes LIPH, a protein that isn't thoroughly understood but seems to play a role in normal hair formation and growth"
"The so-called hairless gene works by repressing the production of a protein called wise, which can hinder the process of hair growth if it is left to accumulate."
- Profinast- The newest natural way to stop hair loss and promote faster hair re-grown.
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