Revolutionary hair loss treatments could be on the way after skin specialists found a link between a brain cell growth protein and the rate at which hair falls out.

The German scientists found that by increasing the body's levels of brain growth proteins they also increased the rate at which hair falls out.

Restricting levels meant hair was shed at a slower rate.

The finding could lead to improved treatments to get rid of unwanted hair and for treating baldness, according to a report in New Scientist magazine.

Mousy hair

Dr Ralf Paus and colleagues carried out the research at Humbolt University in Berlin.

US experiments last year produced extremely hairy mice

They looked at growth cycles of hair follicles and their relationship with brain cell development.

Their earlier research showed that when mice lost hair, there was a high concentration of brain-derived neurotrophic factor (BDNF) and neurotrophin-4 (NT-4) around their follicles.

BDNF and NT-4 are two growth factors thought to be important in the development of brain cells.

The earlier research also showed that the genes that make the proteins are abnormally active at the same time.

Balding from birth

For the new study, the team genetically-engineered mice to produce excess quantities of both the factors.

They found that the mice shed their hair abnormally early.

In mice engineered to produce neither factor, hair took longer than normal to fall out.

"This is the first evidence that growth factors previously thought to be important for the development of brain cells are also important for the growth of hair follicles," Dr Paus told the magazine.

The scientists think the proteins work by binding to a receptor called tyrosine kinase B.

Treatments in development

Practical uses of the finding would be increasing the presence of BDNF and NT-4 around unwanted hair or using drugs to block the receptor to hold baldness at bay.

Such drugs have already been developed for use in diseases such as Alzheimer's and multiple sclerosis, said Dr Paus.

"It's not too far-fetched to propose using them for hair disorders, particularly if you can apply them topically in lotions," he said.

However, it was too early to tell whether the findings in mice would apply to humans, he added.

This is because mice grow hair in synchronised waves whereas in humans each hair follicle grows independently.