I, for one, would welcome solid research showing that caffeine does more than just perk me up in the morning. After all, I rely on the stuff — heavily — to help me write this daily column. Wouldn’t it be great if the caffeine in my morning coffee bestowed other benefits — like, say, enhancing my long-term memory?
So I read with interest a new and rather cleverly designed study published last week in Nature Neuroscience. Its findings suggest that caffeine helps our brains consolidate memories, thus moving those memories into permanent storage.
Not surprisingly (given that 64 percent of Americans report drinking at least one cup of coffee each day), the study’s results made headlines: “Scientists Reveal Caffeine Provides Huge Boost to Your Short-Term Memory” stated one media outlet. “Drink Up — You’ll Remember It Later,” declared another.
Well, not so fast. For, as science writer Bethany Brookshire explains in an article for Science News, once you dive deeper into the study, you discover its results are accompanied by some rather important caveats.
“While it’s an interesting finding,” she writes, “the scientific brew may not be strong enough to justify your habit.”
First, here’s a brief summary of the Nature Neuroscience study:
A team of researchers from Johns Hopkins University recruited 180 college students, aged 18 to 30, to participate in the study. None of the students regularly consumed caffeinated beverages.
The participants were shown a series of images and then given either a placebo or a pill with 200 milligrams of caffeine — about the equivalent of a single, strong cup of coffee. (The study was doubled-blinded; neither the students nor the researchers knew which students received which pill.)
The students returned to the lab the following day and were shown another set of images. They were asked to rate each image as “old” (one they had seen the previous day), “new” (one they hadn’t seen), or “similar” (an image that was the same shape, but a different color, for example).
The study found that the students who had taken the caffeine were not more likely to correctly differentiate between old and new images, but they were more likely to recognize the subtly similar images.
The authors of the study believe this finding suggests that caffeine helps with a deeper level of memory known as pattern separation. (We rely on pattern separation, for example, to remember the different places we park our car each time we go to our local shopping mall.)
Further experiments revealed that caffeine has a U-shaped dose response. Students who were given 200 milligrams of caffeine did better on the memory test than those who received 100 milligrams. But no improvement was found at 300 milligrams. In fact, the students started complaining of side effects.
An interesting study, yes. But a definitive one — one that means we should all drink coffee to improve our long-term memory? Hardly. As Brookshire points out, “Although the study shows a new role for caffeine in memory consolidation, it may not be the whole bean on caffeine.”
She offers several reasons for caution. To begin with the effect of the caffeine on consolidation memory was very small — “only about a 10 percent gain in some places,” one of the study’s authors acknowledged to Brookshire.
The small number of participants — only 180 — is also a concern. Because of that number, “the data just passed, but didn’t soar beyond, statistical muster,” writes Brookshire.
“I wish they had tested a few more participants and reported a few more statistical tests, so that the fascinating findings the authors think they have observed would be demonstrated more convincingly,” Jon Simons, a cognitive neuroscientist at the University of Cambridge in England, told Brookshire.
Another British neuroscientist, George Kemenes of the University of Sussex, expressed similar concerns. “I found the whole experimental design very elegant and satisfying the highest professional standards,” he said. “The problem with the weakness of the statistics may indeed have arisen because of the relatively low number of experimental subjects.”
Results may differ with regular users
In addition, the participants were not regular caffeine consumers. Individuals who already drink coffee or other caffeinated beverages may not experience any memory benefit from the stimulant.
Furthermore, writes Brookshire, “while memory consolidation and pattern separation are important aspects of memory, they are not all there is to remembering. So while you might think that drinking a coffee after class will perk up your chances on the next day’s exam, the effect in this paper probably isn’t large enough to depend on.”
“By all means have your latte,” she adds, “but throw in a little studying on top.”