The male sex hormone testosterone plays a key role, as do genetic factors. They cause the hair follicles to shrink, eventually becoming so small that they are invisible, leading to the appearance of baldness.
Baldness is hair thinning or partial or complete lack of hair. Male pattern baldness is characterized by hair receding from the lateral sides of the forehead (known as a “receding hairline”) and/or a thinning crown (balding to the area known as the ‘vertex’).Both become more pronounced until they eventually meet, leaving a horseshoe-shaped ring of hair around the back of the head.
The incidence of pattern baldness varies from population to population and is based on genetic background. Environmental factors do not seem to affect this type of baldness greatly. A rough rule of thumb is that the incidence of baldness in males corresponds to chronological age. For example, according to Medem Medical Library’s website, male pattern baldness (MPB) affects roughly 40 million men in the United States. Approximately 25 percent of men begin balding by age 30; two-thirds begin balding by age 60.
In studies of bald men and laboratory mice, US scientists pinpointed a protein that triggers hair loss.
Drugs that target the pathway are already in development, as per report in the journal Science Translational Medicine.
The research could lead to a cream to treat baldness.
Reverse balding?
Now, researchers at the University of Pennsylvania have analysed which genes are switched on when men start to go bald.
They found levels of a key protein called prostaglandin D synthesis are elevated in the cells of hair follicles located in bald patches on the scalp, but not in hairy areas.
Mice bred to have high levels of the protein went completely bald, while transplanted human hairs stopped growing when given the protein.
Prof George Cotsarelis, of the department of dermatology, who led the research, said: “Essentially we showed that prostaglandin protein was elevated in the bald scalp of men and that it inhibited hair growth. So we identified a target for treating male-pattern baldness.
“The next step would be to screen for compounds that affect this receptor and to also find out whether blocking that receptor would reverse balding or just prevent balding – a question that would take a while to figure out.”
The inhibition of hair growth is triggered when the protein binds to a receptor on the cells of hair follicles, said Prof Cotsarelis.
Several known drugs that target this pathway have already been identified, he added, including some that are in clinical trials.
The researchers say there is potential for developing a treatment that can be applied to the scalp to prevent baldness and possibly help hair regrow.
he#� dnh L�Ff Hygiene and Tropical Medicine, said: “In virtually all around the world, women do have a slight advantage.”
Countries with lower levels of life expectancy, such as in sub-Saharan Africa, showed very little difference between the genders. This was due to the prevalence of infectious diseases which “are not picky about men and women”, he said.
In countries that had defeated most infectious diseases, such as in Eastern Europe, “there is a much bigger difference, mostly dominated by lifestyle factors”.
At one point in the 1990s, the gap between life expectancies in Russia reached 13 years. Prof Leon said it was an “absolutely massive” difference in a “very gendered society”.
He said: “Men are getting a bit better behaved and women are adopting male life expectancies.”