Scientists are testing a theory that people's sense of balance is an accurate forecaster of their future decline in physical and mental ability as they grow older. They believe the balance test could indicate a person's rate of ageing.
The theory is that the back part of the brain, the cerebellum, is involved in both maintaining balance and controlling higher mental functions. As the cerebellum declines with age, then the detrimental effects on a person's sense of balance become a good measure of future mental decline.
Professor Patrick Rabbitt, director of the age research centre at Manchester University, told the British Association that there is convincing evidence that balance could become the simplest and most reliable way of measuring a person's rate of ageing.
"Anything that is bad for the cerebellum is not only bad for your balance, but is also bad for cognitive processes. It may be possible to predict people's rate of ageing in the future," Professor Rabbitt said.
More people than ever are living longer, with life expectancy over the past 60 years increasing by an average of 15 years, yet 11 of these years are spent living with the degenerative illnesses of old age.
"We've increased the time people live with various medical problems," said Dr Alf Game, from the Biotechnology and Biological Sciences Research Council, which announced an extra pounds 5m yesterday for studies on ageing. Professor Rabbitt has led the biggest study, monitoring 6,500 people since 1982 for the effects of ageing. Part of the tests involved monitoring their ability to balance themselves on machines designed to test how their muscles control swaying and stability.
The study also found that some people went into a far faster rate of physical and mental decline than others. "The best 70-year-olds were quite comparable to 40-year-olds. The picture is that some individuals are relatively well preserved for a very long time," Professor Rabbitt said.
Researchers at the Max Planck Institute in Berlin were the first to show that balance could be used to forecast more than 80 per cent of the variation in the age-related decline.
"Balance is a complicated thing, because you are using visual information, you are using information from your [middle ear], you are using information from your muscle receptors. If you lose muscle strength, as you do when you get older, you may lose your balance for that reason," Professor Rabbitt said.