Chewing gum can improve memory, say UK psychologists. They found that people who chewed throughout tests of both long-term and short-term memory produced significantly better scores than people who did not. But gum-chewing did not boost memory-linked reaction times, used as a measure of attention.
"These results provide the first evidence that chewing gum can improve long-term and working memory," says Andrew Scholey of the University of Northumbria in Newcastle, UK. "There are a number of potential explanations - but they are all very speculative."
One third of the 75 adults tested chewed gum during the 20-minute battery of memory and attention tests. One third mimicked chewing movements, and the remainder did not chew.
The gum-chewers' scores were 24 per cent higher than the controls' on tests of immediate word recall, and 36 per cent higher on tests of delayed word recall. They were also more accurate on tests of spatial working memory.
"The findings are intriguing, although it is clear that questions remain to be addressed," says Kim Graham of the Medical Research Council's Cognition and Brain Sciences Unit in Cambridge, UK. "In particular: what is the mechanism by which chewing improves memory?"
There are three main potential explanations, says Scholey. In March 2000, Japanese researchers showed that brain activity in the hippocampus, an area important for memory, increases while people chew - but it is not clear why.
Recent research has also found that insulin receptors in the hippocampus may be involved in memory. "Insulin mops up glucose in the bloodstream and chewing causes the release of insulin, because the body is expecting food. If insulin receptors in the brain are involved in memory, we may have an insulin-mediated mechanism explaining our findings - but that is very, very speculative," Scholey says.
But there could be a simpler answer. "One interesting thing we saw in our study was that chewing increased heart rate. Anything that improves delivery of things like oxygen in the brain, such as an increased heart rate, is a potential cognitive enhancer to some degree," he says.
But a thorough explanation for the findings will have to account for why some aspects of memory improved but others did not, Graham says. She points out that gum-chewers' ability to quickly decide whether complex images matched images they had previously been shown was no better than the controls'.
Scholey presented his research at the annual meeting of the British Psychological Society in Blackpool, Lancashire, UK.