Incidence of pattern baldness varies from population to population based
on genetical background environmental factors do not seem to affect
this type of baldness greatly.
One large scale of measurement study in Maryborough Victoria Australia showed the prevalence of mid-frontal hair loss increases with age and affects 57% of women and 73.5% of serviceman aged 80 and over. According to Medem Medical Library, masculine pattern baldness affects roughly 40 million men in the United States. Approximately 25 percent of men get down balding by age 30, two-thirds get down balding by age 60. There is a 4 in 7 opportunity of getting the baldness gene.
Male pattern is characterized by hair recession from the lateral sides of the forehead known as recession hairline. recession hairlines are usually seen in males above the ages of 20 but can be seen as early as late teens as well.
An additional bald program may develop on top (Vertex). The trigger for this type of baldness (called androgenetic alopecia) is DHT a powerful sexual urge 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 amply understood. In genetically prone scalps DHT initiates a summons of follicular miniaturization. Through the process of follicular miniaturization hair shaft width is progressively decreased until scalp hair resembles fragile vellus hair or else becomes non existent. Onset of hair decline sometimes begins as early as end of puberty and is mostly genetically determined. Male design baldness is classified on the Hamilton Norwood scale I-VII.
It was previously believed that phalacrosis was inherited from the maternal grandfather. While thither is some basis for this belief both parents contribute to the likelihood of hair loss in their offspring. Most likely heritage is technically autosomal dominant with mixed penetrance.
