Caffeine boosts long-term memory, study shows

Caffeine is the most used stimulant in the world, with about 90 per cent of the globe's population consuming it in some form. Whether through a hot cup of tea, coffee or cocoa, many cultures rely on caffeine's wakeful jolt to get them going in the morning.

In addition to its stimulating properties, new U.S. research suggests caffeine can also boost long-term memory.

"We've always known that caffeine has cognitive-enhancing effects, but its particular effects on strengthening memories and making them resistant to forgetting has never been examined in detail in humans," says Michael Yassa, lead researcher and psychology professor at Johns Hopkins University.

The new study, published by the journal Nature Neuroscience, shows that caffeine enhances a particular type of memory up to 24 hours after it is consumed.

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Researchers examined 160 participants aged 18-30 who did not regularly eat or drink caffeinated products in a double-blind trial. Participants were given either a placebo pill or a 200-milligram caffeine pill -- roughly the equivalent of a two small cups of coffee -- five minutes after studying a series of images.

The next day, they were shown a series of images -- some exactly the same as the day before, others completely new, and a final set that were similar to the previous day's images, but slightly altered.

Researchers found that those who took the caffeine supplements had a better time differentiating the similar but not identical pictures the following day.

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"We found that those who were administered caffeine actually had better retention of the information we taught them the day before," Yassa explains to CBC. "The caffeine enhanced their ability to say, 'This item was similar but not identical to the one I'd seen before.'"

This specific type of memory is called pattern separation and reflects a deeper level of memory retention. It helps humans recognize whether a piece of information is foreign and must be assigned new meaning.

"If we used a standard recognition memory task without these tricky similar items, we would have found no effect of caffeine," Yassa says. "However, using these items requires the brain to make a more difficult discrimination."

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He claims his study is different from previous caffeine-memory studies in that it had participants consume caffeine after, rather than before, they attempted to learn new information. This was done to rule out the possibility that improvements in memory could be attributed to the greater attention and focus caffeine brings.

Yet he cautions that recklessly consuming excessive amounts of caffeine in hopes that it will give you a killer memory is misguided.

"Everything in moderation," he tells BBC. "Caffeine can have side effects like jitteriness and anxiety in some people. The benefits have to be weighed against the risks."