At last a reason to jog - it makes your brain bigger

A REGULAR jog around the block might increase a person's intellectual performance, according to a study showing that brain cells proliferate after bouts of running.

Research revealed thatcaged mice that had access to running wheels had better developed hippocampi, the region of the brain known to be involved in learning and memory. Scientists who carried out the research at the Salk Institute for Biological Studies in La Jolla, California, cannot explain the findings but suggest they might also apply to humans.

"If you want to answer that, you're going to have to do some experiments in humans... More people in my lab have started running since we found this result," said Fred Gage, the leader of the research team.

Brain tissue is renowned for being unable to regenerate itself if damaged but recent studies in mice and monkeys have shown that cells within the hippocampus have the ability to proliferate in the adult animal.

Dr Gage has shown previously that the brain cells of mice living in cages with lots of toys are more likely to survive for longer than in animals with less enriched environments.

His latest research showed that mice who ran on a wheel regularly experienced more brain cell proliferation than mice that did not. "The difference was striking and because we now know that human brains also make new cells, it just might be that running or other vigorous exercise stimulates brain cell production in people as well," Dr Gage said.

The next stage is to assess whether the mice are smarter as a result. "It seems reasonable to think they might be - the new cell growth takes place in the hippocampus... And the enriched-environment mice in previous studies performed better on learning tests."

The findings, reported in the journal Nature Neurogenesis, could have serious implications for people at risk of developing brain disorders such as Alzheimer's, which is considered to result from the permanent loss of brain cells.

But it is not just any exercise that produced the effect. When mice were forced to swim, the effect on brain cell proliferation was not detected, indicating the voluntary nature of the phenomenon.