Hair Structure
Common Types

Androgenetic Alopecia
Male Pattern Baldness / Female Pattern Baldness

Androgenetic Alopecia accounts for 95% of all hair loss. It can affect both men and women although men experience a much greater degree of loss. In women Androgenetic Alopecia appears as diffuse hair loss occurring over most of the scalp. In men however the pattern of loss usually starts with a receding hairline which then advances to thin the top of the head.

Causes of Androgenetic Alopecia

In 400 BC Hippocrates observed that eunuchs did not become bald. Later Aristotle noticed this also. In the 1940s Dr James Hamilton concluded that genetic predisposition in the present of the male hormone androgen where the factors that caused the development of Androgenetic Alopecia.

However it is now known that it is more specifically the male hormone dihydrotestosterone (DHT) which is converted from the enzyme testosterone by the enzymes 5 alpha reductase which contributes to Androgenetic Alopecia in those who are genetically predisposed. It is interesting to note that individuals with a deficiency in 5 alpha reductase do not develop Androgenetic Alopecia. This is because the body is unable to convert testosterone into dihydrotestosterone.

When Androgenetic Alopecia occurs large active hair follicles in specific areas begin to change to smaller less active ones that shrink slightly with each new growth cycle. The enzyme 5 alpha reductase is thought to be the major cause of this. Under the action of the enzyme the male hormone testosterone become dihydrotestosterone. This causes the hair shafts to narrow producing progressively finer hairs with each new growth cycle until eventually the hairs become transparent and stop emerging. If an individual has androgenetic alopecia the overall levels of testosterone may be normal however the activity of 5 alpha reductase is greater than normal which results in increased amounts of dihydrotestosterone in the hair follicle.

Treatments for Androgenetic Alopecia

Minoxidil is the most widely recommended treatment for Androgenetic Alopecia. In the United States topical Minoxidil is marketed under the brand name Rogaine in New Zealand it is marketed as Regaine and recently a generic version of topical Minoxidil has become available under the brand name Headway. Minoxidil appears to work by gradually enlarging and lengthening hair follicles which have been gradually shrinking due to Androgenetic Alopecia. The growth phase may also be extended giving the hairs an opportunity to reach a longer length before they fall out.

It is necessary to use Minoxidil for about 3-4 months to see evidence of regrowth and up to 6 months to get a proper estimate of whether Minoxidil will be helpful in a particular case. Minoxidil also requires continual use in order to be effective. Once application of Minoxidil is ceased the hair will return to the original state in about 3 months.

The two main disadvantages of using Minoxidil is that first of all its use must be continued in order to maintain the results achieved and the second disadvantage is the expense. Minoxidil is however becoming more affordable and the generic version Headway which is cheaper makes Minoxidil more affordable.

Propecia (finasteride)
Propecia is a relatively new drug produce by Merck. It is a tablet which is taken once a day and at this present time it is only approved for use in men. Propecia is not to be used by woman and children. Propecia is a 4 aza steroid compound that is a specific inhibitor of type 2 5 alpha reductase which is the enzyme that metabolises the androgen testosterone into dihydrotestosterone (DHT). In this way Propecia helps to prevent the continued miniaturisation of existing hair follicles and also assist in the recruitment of miniaturised hair follicles to become terminal hairs. Like Minoxidil, Propecia must be taken for a period of 3 months or more before any benefit is seen and it must be continued in order to maintain any benefits gained. Propecia is also expensive to maintain.

Retin-A / Tretinoin
Retin was originally used in the treatment of acne and other skin disorders. However studies have shown that Retin-A alone or in combination with Minoxidil can result in moderate to good hair growth in individuals with Androgenetic Alopecia and Alopecia Areata. Many dermatologist recommend using Tretinoin in combination with Minoxidil to increase the effects of both these products. Side effects of Retin-A include blistering, altered pigmentation and increased sensitivity to light. If a gel is used it is suggested that Minoxidil be applied in the morning a Retin-A gel in the evening to reduce the problems caused by sunlight.

Some vitamins have been shown to inhibit the activity of 5-alpha reductase and the subsequent production of (DHT) dihydrotestosterone. These vitamins therefore may be of great benefit in the treatment of Androgenetic Alopecia or pattern baldness. There have been studies in which Zinc is shown to inhibit 5 alpha reductase activity and it has therefore been concluded than Zinc is beneficial in disease and disorders related t an excess in dihydrotestosterone (DHT). There have also been studies which have shown that vitamin B6, Zinc and Azelaic Acid combined together even at very low concentrations reduced a 90% inhibition of 5 alpha reductase activity.

Skinoren / Azelaic Acid
Azelaic Acid like Retin-A is more commonly used in the treatment of acne and other skin conditions. Recently the potential effect of using Azelaic Acid in the treatment of Androgenetic Alopecia has been looked at and discussed.

Studies carried out in France in the late 80ís where to assess the effects of Zinc Sulphate, a Azelaic Acid on the human skin. The result of these studies demonstrated that at high concentrations Zinc could completely inhibit the activity of 5 alpha reductase. Azelaic Acid was also shown to be a potent inhibitor of 5 alpha reductase. Inhibition was detectable at concentrations as low as 0.2mmol/l and was complete at 3mmol/l. When Zinc, Vitamin B6 and Azelaic Acid where added together at very low concentrations which had been ineffective alone, 90% inhibition of 5 alpha reductase was achieved.

Saw Palmetto extract
Studies have shown that Saw Palmetto is an effective anti-androgen. It acts in a similar way that Propecia does. Firstly it lowers levels of DHT in the body by blocking 5 alpha-reductase. Secondly Saw Palmetto block receptor sites on cell membranes required for cells to absorb DHT. Although no studies have been carried out on Saw Palmetto and its relation to hair growth. Studies have been performed on the use of Saw palmetto in the treatment of benign prostatic disease which similar to Androgenetic Alopecia also depends on the production of dihydrotestosterone. All of the studies that have been performed to date show that Saw Palmetto is an effective antiandrogen and has shown conclusively to be effective in the treatment of benign prostratic disease.

One may assume from this that since Saw Palmetto is an effective antiandrogen and is used in the treatment of prostatic disease then it may also be effective in the treatment of Androgenetic Alopecia.

Treatments for Female Pattern Baldness

Diane 35 (Cyproterone Acetate with Ethinyloestradiol) used in the treatment of Androgenetic Alopecia
Diane 35 is a hormonal contraceptive tablet that is prescribed for the treatment of severe acne and hirsutism in women and for female pattern baldness or Androgenetic Alopecia in women. The aim of treatment with Diane 35 is to block the peripheral action of male hormones commonly present in the female body. It is possible for treatment to halt further hair loss and increase hair thickness within about a year. However this treatment needs to be continued long term in order to maintain the effect. Possible side effects include breast tenderness, headaches and decreased libido. One beneficial side effect is the Diane 35 helps prevent osteoporosis.

Cimetidine treatment for Androgenetic Alopecia in Women
Cimetidine is sold under the brand name Tagamet. It is commonly used to reduce secretion of acid in the stomach and to treat stomach and duodenal ulcers, inflammation of the oesophagus and other digestive disorders. However also has a anti androgenic effect. Cimetidine blocks the binding of dihydrotestosterone to its receptor. Cimetidine has been used to treat hirsuitism in women (excess facial hair) and studies in women with Androgenetic Alopecia have yielded promising results. Men however should not use Cimetidine to treat hair loss because of its feminizing effects.

Cyproterone Acetate
Cyproterone Acetate is used to reduce sex drive in men which have excessive sex drive and for the treatment of pronounced sexual aggression. It is also prescribed to treat severe hirsuitism in woman of childbearing age and also Androgenetic Alopecia in women. Like Cimitedine and other similar type drugs Cyproterone Acetate exerts its effects by blocking the binding of DHT dihydrotestosterone to its receptors.

Sprironolactone is commonly used to treat high blood pressure. However it also acts as an anti-androgen by decreasing the production of testosterone by the adrenal glands and by preventing dihydrotestosterone from binding to its androgenetic receptor similar to the way in which Cyproterone Acetate and Cimitidine also act. Like Cimetidine and Cyproterone Acetate the use of Spironolactone in men should be limited due to its feminizing effects.

Nizoral / Ketoconazole
Ketoconazole is currently used as an antifungal agent in the treatment of fungal infections. Ketaconazole is also known to have anti androgenic effects and Ketoconozole can cause a reduction in the production of testosterone and other androgens by the adrenal gland and by the male and female reproductive organs. Nizoral shampoo contains 2% Ketoconazole and is often prescribed for the treatment of fungal infections of the scalp and sebbhoreic dermatitis, however as it has anti androgenic properties it is used by some individuals in combination with other treatments in the treatment of Androgenetic Alopecia.

Title: Androgenetic Alopecia in men and women: an overview of cause and treatment

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