Coffee improves short-term memory and speeds up reaction times by acting on the brain’s prefrontal cortex, according to a new study.

Researchers used functional magnetic resonance imaging (fMRI) to determine how coffee activates different areas of the brain in 15 volunteers.

“Caffeine modulates a higher brain function through its effects on distinct areas of the brain,” explains Florian Koppelstätter, who carried out the research with colleagues at the Medical University at Innsbruck, Austria.

Prior to testing, the group fasted for 4 to 6 hours, and abstained from caffeine and nicotine for at least 24 hours. Then they were then given either a cup of strong coffee – containing 100 milligrams of caffeine – or a caffeine-free placebo drink. After 20 minutes all participants underwent fMRI scans while carrying out a memory and concentration test. A few days afterwards the experiment was repeated under the same conditions but each received the other drink.

Executive memory

During the memory tests, participants were shown a fast sequence of capital letters, then flashed a single letter on a screen and told to decide quickly whether this letter was the same as the one which appeared second-to-last in the earlier sequence. They had to respond by pressing a “Y” for yes or “N” for no.

“The group all showed activation of the working memory part of the brain," Koppelstätter explains. "But those who received caffeine had significantly greater activation in parts of the prefrontal lobe, known as the anterior cingulate and the anterior cingulate gyrus. These areas are involved in 'executive memory', attention, concentration, planning and monitoring."

“This type of memory is used when, for example, you look up a telephone number in a book and then mentally store it before dialling,” he adds.

Pick-me-up

Koppelstätter stresses that the study is preliminary and that he has yet to discover how long the memory effects last or what other effects coffee has on brain function. He adds that the long-term impact of caffeine use is also an important consideration.

But he says the study shows that coffee has an effect on specific brain regions involved in memory and concentration that tallies with anecdotal evidence of the drink's “pick-me-up” effect.

Caffeine is known to influence adenosine receptors which are found throughout the brain on nerve cells and blood vessels. It is thought that the drug inhibits these receptors and that this excites the nerve cells in the brain. “This may be the mechanism involved,” suggests Koppelstätter.

The research was presented at the annual meeting of the Radiological Society of North America.