Baldness
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
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 androgenetic 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. Some hair loss sufferers make use of "clinically proven treatments" such as finasteride and topically applied minoxidil (in 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 will help some of the users suffering from Androgenetic alopecia, and there are new technologies in cosmetic transplant surgery and hair replacement systems that can be completely undetectable.
Background, cause and incidence
The average human head has about 100,000 hair follicles. Each follicle can grow about 20 individual hairs in a person's lifetime.[1] Average hair loss is about 100 strands a day.
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.
Male pattern is characterized by hair receding from the lateral sides of the forehead, known as "receding hairline". Receding hairlines are usually seen in males above the ages of 25.
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, body, and facial hair growth promoter that can adversely affect the hair on the head and prostate.[2]
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. Male pattern baldness is classified on the Hamilton-Norwood scale I-VIII.
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)
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.
- 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 chemotherapy, childbirth, major surgery, poisoning, and severe stress may cause a hair loss condition known as telogen effluvium.[3]
- 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.
- Iron deficiency is a common cause of thinning of the hair, though frank baldness is not usually seen.
- 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.
- Some mycotic infections can cause massive hair loss.[4]
- 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).
- Hypothyroidism can cause hair loss, typically frontal, and is particularly associated with thinning of the outer third of the eyebrows (syphilis also can cause loss of the outer third of the eyebrows)
- Hyperthyroidism can also cause hair loss, which is parietal rather than frontal.
- Temporary loss of hair can occur in areas where sebaceous cysts are present for considerable duration; normally one to several weeks in length.
Etymology
The term alopecia (al-oh-PEE-she-uh) is formed from the Greek αλώπηξ (alopex), 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.[5]
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.
Latest research
The LIPH gene makes LIPH, a protein that isn't thoroughly understood but seems to play a role in normal hair formation and growth"
http://www.hon.ch/News/HSN/536000.html
http://www.webmd.com/news/20061109/inherited-hair-loss-may-be-upped-by-gene-glitch
http://www.forbes.com/forbeslife/health/feeds/hscout/2006/11/09/hscout536000.html
"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."
http://news.bbc.co.uk/1/hi/health/4283302.stm
DSG4 gene
http://www.hairlosstalk.com/newsletter/article209.htm http://www.hairlosstalk.com/download/CELL1132249.pdf
WNT GENE
http://news.bbc.co.uk/2/hi/health/6661849.stm
Approaches to baldness
Psychological effects
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 (alexithymia) and may be more prone to avoiding family conflicts. Family therapy can help families to cope with these psychological problems if they arise.[6]
Psychological problems due to baldness, if present, are typically most severe at the onset of symptoms.[7]
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
In the USA, there are only 2 drug-based 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.
Finasteride
A pharmaceutical company reportedly 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, 1 mg 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
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 topical Minoxidil solution directly to the scalp, it could prove to be beneficial to those experiencing 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.
Low-level laser therapy
A low level laser is shone directly on the scalp to stimulate hair growth through "Photo-Biostimulation" of the hair follicles. One product of these low level laser therapies is the "Hairmax Lasercomb". There is no peer-reviewed evidence to support this claim. There is some debate over the FDA's acknowledgment of the Lasercomb, but it has been accepted by the FDA as effective in the submitted claims.[8] The Lasercomb was cleared by the FDA as being Substantially Equivalent (SE) to predicate devices legally marketed before May 28, 1978. This clearance is not the same as approval because it only applies to the lasercomb and not to any other similar laser based hair devices. The devices that the lasercomb proved itself equivalent to were a variety of FDA approved laser based/non hair growth devices intended for hair removal and pain relief, and 2 non FDA approved non laser based/hair growth devices such as the Raydo & Wonder Brush and the Vacuum Cap. These last two devices were sold in the early 1900's and are well established as medical quackery, but they were legal to market at the time which does satisfy the FDA's 510k SE criterea. The 510k number for the Lasercomb is K060305. The Leimo laser was recently approved by the TGA (Therapeutic Goods Administration) of Australia as a Class IIa Medical Device that regrows hair. Its ARTG number is 139 456.
Surgery
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.
Hair multiplication
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 [2][3].
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.
Ketoconazole
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. [4]
Placebos
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.[9]
Exercise
Regular aerobic exercise can help keep androgen levels (particularly free testosterone levels) naturally lower while maintaining overall health, lowering stress and increasing SHBG. [5] [6]
Weight training without aerobic exercise may increase testosterone. [7]; [8] [9] [10] One study suggests that both heavy exercise and increased fat intake, in combination, are required for increased free testosterone in strength trainers. Increased total or free testosterone would help them build and repair muscle, but may cause susceptible individuals to lose hair. [11]
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.[10]
Stress reduction
Stress reduction can be helpful in slowing hair loss. (see Baldness Folklore)
Immunosuppressants
Immunosuppressants applied to the scalp have been shown to temporarily reverse alopecia areata, though the side effects of some of these drugs make such therapy questionable. [12][13]
Saw palmetto
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.[11] 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.[12][13][14]
Polygonum multiflorum
Polygonum Multiflorum is a traditional Chinese cure for hair loss. P. multiflorum contains stilbene glycosides similar to resveratrol. [14]
Beta sitosterol
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.
Anti-androgens
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.
Hedgehog agonists
Through 2006, a drug development company spent $1,000,000 on a hair growth program focused on the potential development of a topical hedgehog agonist for hair growth disorders, such as male pattern baldness and female hair loss. The hairloss research program was shut down in May 2007 because the process did not meet the proper safety standards.[15]
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.[15] [16] [17] [18] [19][20]
Concealing hair loss
Head
One method of hiding hair loss is the "comb over", which involves restyling the remaining hair to cover the balding area. It is usually a temporary solution, useful only while the area of hair loss is small. As the hair loss increases, a comb over becomes less effective. When this reaches a stage of extreme effort with little effect — it can make the person the object of teasing or scorn.
Another method is to wear a hat or a hairpiece — a wig or toupee. The wig is a layer of artificial or natural hair made to resemble a typical hair style. In most cases the hair is artificial. Wigs vary widely in quality and cost. In the United States, the best wigs — those that look like real hair — cost up to tens of thousands of dollars. Organizations 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.
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.
Embracing baldness
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.
Baldness folklore
There are many myths regarding the possible causes of baldness and its relationship with one's virility, intelligence, ethnicity, job, social class, wealth etc. While skepticism is warranted due to lack of scientific validation, some of these myths may have a degree of underlying truth.
- "You inherit baldness from your mother's father."
- Previously, early baldness of the androgenic type was thought to be sex linked dominant in males and to be sex linked recessive in females.
- Research suggests that the gene for the androgen receptor, which is significant in determining probability for hair loss, is located on the X chromosome and so is always inherited from the mother's side.[16]There is a 50% chance that a person shares the same X chromosome as their 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.[17][18]
Another model for the inheritance of baldness is "Autosomal dominant with mixed pentrance". That is, you can get it from either parent and it presents variably.
- "Intellectual activity or psychological problems can cause baldness."
- This notion may be due to the fact that 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. Of course, aside from all these scientific reasons, baldness could be linked to intellect or wisdom simply due to the fact that people go bald as they age and become more experienced.
- This is sometimes used as a stereotype in films, where the more intellectual or rather frustrated characters are most usually portrayed as bald and generally unattractive, as opposed to the main characters which are usually portrayed as attractive, fit, mentally stable and generally with no apparent hair problems.
- This same myth normally extends to considering people having intellectual jobs more prone to baldness problems compared to manual laborers, sometimes further extending the myth to male college or university students when compared to workers of the same age. The myth is suspect because counterexamples can be found in any case.
- There is evidence, confirmed by cross cultural studies, for an association between androgen levels and intellectual ability. These findings are controversial due to their implications regarding psychology and gender.
- 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.[19]
- "One's ethnicity can increase the chances of going bald."
- This idea has been seen as somewhat descriminative and sensitive in nature, however studies have shown that men of Greek or Macedonian heritage have the highest percentage of bald or balding men. (age group 16-28, typical, non married, non-drug using, males) Studies done between 6 countries in Western Europe, incl. Britain, France, Italy, Germany, Spain and Ireland and 4 countries in Eastern Europe including Greece, Macedonia, Bulgaria and Romania show that Greek men of the same age group and study period had the highest percentage of full crown baldness or Alopeciae totalis (front, top and back) Another typical study during the same period showed that Greek men, 1700 out of 2457 total studied males also suffered the highest amount of random alopecia areata among men (aged 16-28, typical, non-drug using males)
- "Baldness can be caused by emotional stress, sexual frustration etc."
- Emotional stress has been shown to accelerate baldness in genetically susceptible individuals.[20]
- Stress due to sleep deprivation in military recruits lowered testosterone levels, but is not noted to have effected SHBG.[21]
- Thus, stress due to sleep deprivation in fit males is unlikely to elevate DHT, which causes male pattern baldness. Whether it can cause hair loss by some other mechanism is not clear.
- "Bald men are more 'virile' or sexually active than others."
- Levels of free testosterone are strongly linked to libido and also DHT levels, but unless free testosterone is virtually 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.[22][23]
- "Shaving hair makes it grow back stronger"
- Proposed as a popular remedy against baldness, it is very probably just an illusion similar to the one perceived after shaving one's beard or mustache. Shaving one's head doesn't increase the number of healthy hair present on the scalp, and, after the remaining hair has grown a few millimeters, no enhancement in thickness or overall quality can be observed.
- "Frequent ejaculation causes baldness"
- There are many misconceptions about what can help prevent hairloss, one of these being that frequent ejaculation may have an influence on MPB. Depending on frequency, it can raise or lower plasma testosterone. [21] The claim that frequent ejaculations can cause baldness is often viewed with skepticism.
- "Standing on one's head alleviates baldness"
- The "blood-flow" theory, which led men to stand on their heads in the 1980s, can be found in the advertising for many of the fake hairloss treatments for sale on the internet. While Minoxidil is a vasodilator and is speculated to work, in part, by increasing blood flow to hair follicles, there is no evidence that standing on one's head can alleviate baldness.
- "Tight hats cause baldness."
- While this may be a myth, hats do cause hair breakage and, to a lesser degree, split ends. Since hats are not washed as frequently as other clothing, they can also lead to scalp uncleanliness and possible Pityrosporum ovale contamination in men with naturally oily scalps.
References
- ↑ "Growth of Human Hair" Procter & Gamble, 2003.
- ↑ Rebora A (2004). "Pathogenesis of androgenetic alopecia". J Am Acad Dermatol. 50 (5): 777–9. PMID 15097964.
- ↑ Nnoruka E, Nnoruka N (2005). "Hair loss: is there a relationship with hair care practices in Nigeria?". Int J Dermatol. 44 Suppl 1: 13–7. PMID 16187950. Unknown parameter
|month=ignored (help) - ↑ Pappas P, Kauffman C, Perfect J, Johnson P, McKinsey D, Bamberger D, Hamill R, Sharkey P, Chapman S, Sobel J (1995). "Alopecia associated with fluconazole therapy". Ann Intern Med. 123 (5): 354–7. PMID 7625624.
- ↑ Harper, Douglas. "Entry for "bald"". Online Etymology Dictionary. Retrieved 2006-12-07.
- ↑ Poot F (2004). "[Psychological consequences of chronic hair diseases]". Rev Med Brux. 25 (4): A286–8. PMID 15516058.
- ↑ Passchier J, Erdman J, Hammiche F, Erdman R (2006). "Androgenetic alopecia: stress of discovery". Psychol Rep. 98 (1): 226–228. PMID 16673981.
- ↑ LaserComb Controvery at Tressless: The Hairloss Encyclopedia
- ↑ Leyden J, Dunlap F, Miller B, Winters P, Lebwohl M, Hecker D, Kraus S, Baldwin H, Shalita A, Draelos Z, Markou M, Thiboutot D, Rapaport M, Kang S, Kelly T, Pariser D, Webster G, Hordinsky M, Rietschel R, Katz H, Terranella L, Best S, Round E, Waldstreicher J (1999). "Finasteride in the treatment of men with frontal male pattern hair loss" (pdf). J Am Acad Dermatol. 40 (6 Pt 1): 930–7. PMID 10365924.
- ↑ Ara, I.; Perez-Gomez, J.; Vicente-Rodriguez, G.; Chavarren, J.; Dorado, C.; Calbet, J. A. L. (2006). "Serum free testosterone, leptin and soluble leptin receptor changes in a 6-week strength-training programme". British Journal of Nutrition. 96 (6): 1053–9.
- ↑ Habib F, Ross M, Ho C, Lyons V, Chapman K (2005). "Serenoa repens (Permixon) inhibits the 5alpha-reductase activity of human prostate cancer cell lines without interfering with PSA expression". Int J Cancer. 114 (2): 190–4. PMID 15543614.
- ↑ Prager N, Bickett K, French N, Marcovici G (2002). "A randomized, double-blind, placebo-controlled trial to determine the effectiveness of botanically derived inhibitors of 5-alpha-reductase in the treatment of androgenetic alopecia". J Altern Complement Med. 8 (2): 143–52. PMID 12006122.
- ↑ Marks L, Hess D, Dorey F, Luz Macairan M, Cruz Santos P, Tyler V (2001). "Tissue effects of saw palmetto and finasteride: use of biopsy cores for in situ quantification of prostatic androgens". Urology. 57 (5): 999–1005. PMID 11337315.
- ↑ Iehlé C, Délos S, Guirou O, Tate R, Raynaud J, Martin P (1995). "Human prostatic steroid 5 alpha-reductase isoforms — a comparative study of selective inhibitors". J Steroid Biochem Mol Biol. 54 (5–6): 273–9. PMID 7577710.
- ↑ "Curis and Procter & Gamble Enter into R&D Agreement for Hair Growth Program". 2005. Retrieved 2006-08-24. Unknown parameter
|authro=ignored (help); Unknown parameter|month=ignored (help) - ↑ Hillmer A, Hanneken S, Ritzmann S, Becker T, Freudenberg J, Brockschmidt F, Flaquer A, Freudenberg-Hua Y, Jamra R, Metzen C, Heyn U, Schweiger N, Betz R, Blaumeiser B, Hampe J, Schreiber S, Schulze T, Hennies H, Schumacher J, Propping P, Ruzicka T, Cichon S, Wienker T, Kruse R, Nothen M (2005). "Genetic variation in the human androgen receptor gene is the major determinant of common early-onset androgenetic alopecia". Am J Hum Genet. 77 (1): 140–8. PMID 15902657.
- ↑ Chumlea W, Rhodes T, Girman C, Johnson-Levonas A, Lilly F, Wu R, Guo S (2004). "Family history and risk of hair loss". Dermatology. 209 (1): 33–9. PMID 15237265.
- ↑ Genetics of Pattern Baldness
- ↑ Christiansen K (1993). "Sex hormone-related variations of cognitive performance in !Kung San hunter-gatherers of Namibia". Neuropsychobiology. 27 (2): 97–107. PMID 8515835.
- ↑ Schmidt J (1994). "Hormonal basis of male and female androgenic alopecia: clinical relevance". Skin Pharmacol. 7 (1–2): 61–6. PMID 8003325.
- ↑ Remes K, Kuoppasalmi K, Adlercreutz H (1985). "Effect of physical exercise and sleep deprivation on plasma androgen levels: modifying effect of physical fitness". Int J Sports Med. 6 (3): 131–5. PMID 4040893.
- ↑ Toone B, Wheeler M, Nanjee M, Fenwick P, Grant R (1983). "Sex hormones, sexual activity and plasma anticonvulsant levels in male epileptics". J Neurol Neurosurg Psychiatry. 46 (9): 824–6. PMID 6413659.
- ↑ Davidson J, Kwan M, Greenleaf W (1982). "Hormonal replacement and sexuality in men". Clin Endocrinol Metab. 11 (3): 599–623. PMID 6814798.
See also
| File:Wiktionary-logo-en-v2.svg | Look up baldness in Wiktionary, the free dictionary. |
Footnotes
- Rossi S (Ed.) (2004). Australian Medicines Handbook 2004. Adelaide: Australian Medicines Handbook. ISBN 0-9578521-4-2
- Template:Note labelTemplate:1728
- Stárka L, Cermáková I, Dusková M, Hill M, Dolezal M, Polácek V (2004). "Hormonal profile of men with premature balding". Exp Clin Endocrinol Diabetes. 112 (1): 24–8. PMID 14758568.
- Nourkrin Man research on DHT. [22] 2006.
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