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Caffeine helps people remember fine distinctions between similar things at least up to 24 hours after it is consumed, new research shows.
“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, assistant professor of psychological and brain sciences at Johns Hopkins University.
The Yassa team’s paper in the journal Nature Neuroscience shows “for the first time a specific effect of caffeine on reducing forgetting over 24 hours,” he says.
Yassa and colleagues, led by undergraduate Daniel Borota, gave participants a series of images to study, and five minutes later gave them either a 200-milligram caffeine tablet or a placebo. The subjects provided saliva samples before taking their tablets to measure their caffeine levels. Saliva was taken again one, three and 24 hours later.
The next day, the caffeine group and controls were tested on their ability to remember the images from the previous day. Some of the visuals were the same, some were new and some were similar to but not the same. More members of the caffeine group were able to correctly identify new images as “similar” to previously viewed images vs. citing them as the same.
Until now, caffeine’s effects on long-term memory had not been examined in detail. From the few studies done, the general consensus was that caffeine had little or no effect on long-term memory retention.
The research is different from prior experiments in part because the subjects took the caffeine tablets only after they had viewed and attempted to memorize the images.
“Almost all prior studies administered caffeine before the study session, so if there is an enhancement, it’s not clear if it’s due to caffeine’s effects on attention, vigilance, focus or other factors,” Yassa says, “By administering caffeine after the experiment, we rule out all of these effects and make sure that if there is an enhancement, it’s due to memory and nothing else.”
The average adult has an intake of about 200 milligrams — the same amount used in the Yassa study — or roughly one strong cup of coffee or two small cups of coffee per day.