Researchers in Israel have shown that caffeine makes existing brain cells swell and new ones grow.

Dr Menahem Segal, at the Weizmann Institute in Rehovot, told BBC News Online that making the connection between this growth and better memory and learning capability is "a long jump, but it is what we are aiming for".

The scientists grew rat neurones in the laboratory and then added caffeine. The brain cells, called dendritic spines and taken from a region of the brain called hippocampus, grew by 33% and new spines formed. The cells returned to their original shape after an hour or two.

Better learning

The results have not been tested in vivo

"We are studying the spines because everyone assumes that they are related to learning and memory and so intuitively you would say that the more spines there are, the better learner you are," said Dr Segal.

Having shown that the spines do grow, "the next step, which we have already begun, is to see if these cells with larger or longer spines can learn better," he added.

The growing brain cells produced "could be one reason" for the potential improvement in memory and learning ability brought about by drinking caffeine-containing drinks, such as tea and coffee.

Increased arousal

But there could be other factors: "We believe you may have other effects of caffeine which would help you through a hard day. Drinking coffee may help improve memory because of an increased attention and arousal level," said Dr Segal.

And he calculates that a lot of caffeine is needed to be sure of seeing the cell growth effect - about ten cups.