A team of scientists led by Michael Yassa, an assistant professor of psychological and brain sciences in the Krieger School of Arts and Sciences at Johns Hopkins, shows that caffeine enhances certain memories up to 24 hours after it is consumed.
In a double-blind trial, participants who did not regularly eat or drink caffeinated products received either a placebo or a 200-milligram caffeine tablet five minutes after studying a series of images.
Salivary samples were taken from the participants before they took the tablets to measure their caffeine levels. Samples were taken again one, three and 24 hours afterwards, the researchers explained.
The next day, both groups were tested on their ability to recognize images from the previous day’s study session. On the test, some of the visuals were the same as the day before, some were new additions, and some were similar but not the same as the items previously viewed.
The researchers found that more members of the group that took the caffeine tablets were able to correctly identify the new images as “similar” to previously viewed images versus erroneously citing them as the same.
The brain’s ability to recognize the difference between two similar but not identical items, called pattern separation, reflects 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,” said Yassa, senior author of the paper, which was published in the journal Nature Neuroscience.
“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.”
Yassa noted that the Johns Hopkins research is different from prior experiments 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,” he said. “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.”
Yassa’s team completed the research at Johns Hopkins before his lab moved to the University of California-Irvine at the start of this year.
“The next step for us is to figure out the brain mechanisms underlying this enhancement,” he said. “We can use brain-imaging techniques to address these questions. We also know that caffeine is associated with healthy longevity and may have some protective effects from cognitive decline like Alzheimer’s disease. These are certainly important questions for the future.”
Source: Johns Hopkins University