Drinking a cup of coffee may wake you up in the morning, but that hot jolt of caffeine may even help jog your memory.
Whether it’s a cup of black tea, a morning espresso or an afternoon energy drink, there may be another purpose for your routine pick-me-up, John Hopkins University researchers say. "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," lead scientist Dr. Michael Yassa said. For the first time, his research suggests that caffeine "enhances" certain memories at least up to 24 hours. These results were published in the journal Nature Neuroscience.
 |
Two side-by-side images of rubber ducks show slight
differences in characteristics. The caffeinated group was
more easily able to distinguish between the two in a
memory test, according to Johns Hopkins University researchers. |
The study
Yassa and colleagues at Johns Hopkins University recruited 160 young, healthy participants, who did not regularly consume caffeinated products. The participants studied a series of images, then five minutes later, took either 200 milligrams of caffeine in tablet form, about the amount of caffeine in a strong cup of coffee, or a placebo.
The next day, participants were asked to identify images they had seen the day before. Some images were new, and some were similar but not exactly the same. For example, if they were shown a picture of a yellow rubber duck originally, the next day, it was a picture of a rubber duck that was shorter and thicker, says Yassa. The people who consumed caffeine were more likely to correctly identify the similar items as slightly different from the original picture.
"We found that those who were administered caffeine actually had better retention of the information we taught them the day before," Yassa said. "The caffeine enhanced their ability to say, 'This item was similar but not identical to the one I'd seen before.'" This pattern separation ability reflects a deeper level of memory retention, the researchers said, because a standard recognition test omitting the "tricky similar items" would likely show the caffeinated and non-caffeinated groups performing equally. Another example of pattern separation is remembering where one's car is parked today vs. yesterday, he says. "This type of discrimination is involved in every facet of memory," Yassa says.
A key aspect was the caffeine was administered after the memory task, rather than before it, which ensures that other caffeine-related factors, like attention, anxiety or energy are not what’s driving the phenomenon. "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 said.
Bottom line
The researchers also had participants consume 100 milligrams and 300 milligrams of caffeine and found 100 milligrams was not effective at getting the memory boost, Yassa says. The 300-milligrams dose was no more effective than 200 milligrams, and at the higher amount, people started to report some side effects such as headaches and feeling jittery, he says. "The 200-milligram might be the most optimal dose to get this memory boost."
One strong cup of coffee might contain 200 milligrams of caffeine, he says. A typical espresso has 80 milligrams, so a double-shot latte will have 160 milligrams, he says.
According to the US Food and Drug Administration, 90% of people worldwide consume caffeine in one form or another. The average adult has an intake of about 200 milligrams, the same amount used in the study, or roughly one strong cup of coffee or two small ones a day.
Dr Yassa said: "The next step for us is to figure out the brain mechanisms underlying this enhancement. We can use brain imaging techniques to address these questions. We also know 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."
Added Dr Yassa: "Caffeine enhanced performance 24 hours after administration. We conclude caffeine enhanced consolidation of long term memories in humans. Future experiments should be conducted to understand the mechanisms by which caffeine can potentiate memory. Given the widespread use of caffeine and the growing interest in its effects both as a cognitive enhancer and as a neuroprotectant, these questions are of critical importance."
Sources: http://consumer.healthday.com/, http://www.usatoday.com/, http://www.wardheernews.com/, http://www.cbc.ca/news/, http://globalnews.ca/news/