While a cup of coffee can give you an extra boost of energy to power through your day, it may provide a memory boost as well.
A recent study found that patients who were given caffeine were better able to distinguish between an image they were shown a day prior and a similar but unidentical image they were shown the following day than participants who did not receive caffeine.
The study authors noted that based on their findings, the optimal amount of caffeine to consume seems to be 200 milligrams — which is about two six-ounce cups of coffee a day.
This study was led by Michael A. Yassa, PhD, in the Department of Psychological and Brain Sciences at Johns Hopkins University in Maryland. The research team examined the effects of caffeine on long-term and short-term memory in a group of young adults.
Dr. Yassa and team analyzed data from 60 healthy participants between the ages of 18 and 30 from the Johns Hopkins University undergraduate campus and the surrounding community.
Participants were not eligible for the study if they consumed more than 500 milligrams of caffeine per week, had any neurological, psychiatric, or medical condition, were habitual alcohol drinkers (more than 14 drinks per week), were current smokers, or if they formerly or currently used drugs.
Before the study began, participants were given a series of tests to measure their long-term memory, short term memory, processing speed (the speed at which one processes information) and IQ. In the 24 hours before the study began, participants were asked not to have any caffeine, alcohol or use any drugs, and to also get at least six hours of sleep and maintain their normal eating habits.
Participants were either assigned to the treatment group where they received 200 milligrams of caffeine after the study session or to the control group where they received a placebo (fake pill) after the study session.
In the study session, participants were shown a series of images, and five minutes after the session ended they were either given a dose of caffeine or a placebo.
Saliva samples were taken before participants took the caffeine as well as one, three and 24 hours after they took the caffeine to measure caffeine levels.
One day later participants were tested to see if they recognized the images they were shown during the testing session. Researchers also included some images that were similar but not identical to the images participants were shown to measure their ability to distinguish between the two images.
The researchers found no significant difference between the caffeine and placebo group in their ability to recognize the images they were shown in the testing session.
However, the researchers did find a significant difference between the groups in relation to distinguishing between images they saw and similar but not identical images. Participants who received caffeine were better able to distinguish between the two images than those who did not receive caffeine.
The researchers also checked to see if different doses of caffeine had different effects on memory. They found that the 200 milligram dose of caffeine led to greater memory compared to the 100 milligram dose. The 300 milligram dose did not lead to better memory compared to the 200 milligram dose, but more participants experienced side effects at this dose.
"Caffeine is the most used psycho-active drug in the world. It is a central nervous system stimulant explaining why it difficult to sleep if you have had too much caffeine," said Dr. Barry Sears, President of the non-profit Inflammation Research Foundation in Marblehead, MA and creator of The Zone Diet.
"Unfortunately it has side effects like increasing the sympathetic nervous system (that's why you get the jitters and an elevated heart rate) and potential withdrawal symptoms (headaches without your daily caffeine fix). The breakdown products of caffeine also stimulate insulin secretion. Bottom line, use it in moderation," said Dr. Sears, who was not involved in this study.
The study's authors concluded that based on their findings, caffeine does seem to improve memory but future studies should seek to understand how this improvement occurs.
This study was published on January 12 in Nature Neuroscience.
The study authors reported no competing interests.