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Attention coffee drinkers: caffeine improves memory, study finds

Great news for coffee drinkers: caffeine improves memory. That is the conclusion reached by researchers at the Johns Hopkins University.

Michael Yassa, assistant professor of psychological and brain sciences in the Krieger School of Arts and Sciences at Johns Hopkins, and his colleagues discovered that caffeine has a positive impact on long-term memory in humans. Their work reveals that caffeine improves particular memories at least up to 24 hours after it is imbibed.

“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,” noted senior author Yassa in a statement released by the university. “We report for the first time a specific effect of caffeine on reducing forgetting over 24 hours.”

During the double-blind trial participants who did not normally eat or imbibe caffeinated products received either a placebo or a 200-milligram caffeine tablet five minutes after examining a series of photos. Salivary samples were obtained from the participants before they swallowed the tablets to determine their caffeine levels. Samples were obtained again one, three and 24 hours after taking the tablets.

The following day, both groups were asked to identify photos from the previous day’s work. On the test, some of the photos were the same as from the day before, some were new photos and some were similar but not the same as the photos previously seen. More participants in the caffeine groups were able to successfully recognize the new photos as “similar” to previously seen photos versus incorrectly citing them as the same.

The brain’s ability to determine the variation between two similar but not duplicate items, known as pattern separation, reveals a deeper level of memory retention, according to the researchers.

“If we used a standard recognition memory task without these tricky similar items, we would have found no effect of caffeine,” Yassa explained. “However, using these items requires the brain to make a more difficult discrimination — what we call pattern separation, which seems to be the process that is enhanced by caffeine in our case.”

According to the researchers, the hippocampus is the memory center in the brain. The majority of work done on memory is concentrated on this area of the brain.

Prior to this research, caffeine’s impacts on long-term memory had not been studied in detail. The general thinking was that caffeine had little or no impact on long-term memory retention.

This work is different from previous experiments because the participants swallowed the caffeine tablets only after they had seen and tried to commit the photos to memory.

“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. 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,” remarked Yassa.

Next, the researchers hope to determine the brain mechanisms behind this improvement.

The study’s findings are described in greater detail in the journal Nature Neuroscience.