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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 patern of loss usually starts with a receding hairline which then advances to thin the top of the head.
Cause 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 know 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.
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