Sorry, Caffeine Isn't a Memory Cure Yet

If you’re a coffee drinker, or are friends with one, you’re probably going to be unable to avoid people sharing stories about a recent study that suggests caffeine can boost your long-term memory. It’s the latest news story to do the rounds about how great—or how terrible—drinking coffee can actually be for you, from improving your mood to making you hallucinate Bing Crosby songs.

We just love it when cold hard science justifies our habits, especially when it flies in the face of health gurus and their New Year juice diets. Unfortunately, that’s why it’s so easy to share these stories without actually considering the evidence they're based on. So let’s take a closer look at this new study, which was conducted by psychologists and chemists at John Hopkins University in Maryland and published in Nature Neuroscience this week.

The title of the study claimed, “Post-study caffeine administration enhances memory consolidation in humans,” and the authors explained in their introduction that they wanted to look at “whether caffeine has an enhancing effect on long-term memory in humans.” They did this by setting participants a learning task—in this case studying images of objects—and then giving them either a 200mg caffeine pill (equivalent to about two cups of coffee, probably less if you drink Starbucks), or a placebo.

The following day, the participants were presented with more images of objects and had to distinguish between which were the same as the previous day, which were completely new, and which were similar to the previous day but not quite the same. The caffeine was given after the initial learning task so as to measure its effect only on memory and not other benefits such as increased awareness when first looking at the images.

Sure enough, the people who were given caffeine rather than a placebo (it was a double-blind study) completed the task a bit better. “We conclude that caffeine enhanced consolidation of long-term memories in humans,” wrote the researchers.

That’s all very interesting. But it doesn’t follow that downing an espresso after a revision session will make you perform better in an exam the next day, as some reports would have you believe.

What actually happened in the study is that those who had caffeine were better at spotting which images were similar but not exactly the same to the previous day’s. They weren’t significantly better at spotting which images were brand new and which were the same. That’s quite a specific effect observed, then, and one that doesn’t immediately transfer into real-life applications.

Then, of course, there’s the fact that the study size was quite small (160 people), so chance could play a part in the findings. Oh, and for all you regular coffee drinkers, it’s worth noting that all of the participants in the study reported consuming less than 500mg caffeine a week, so the results probably wouldn’t hold for you. And don’t think you can just up the dose; in this instance the researchers found 300mg of caffeine had no more effect than 200mg.

That’s not to say the study doesn’t hold merit; it achieved what it set out to do. But the only conclusion to draw really is that it’s an interesting observation, and we should maybe do some more studies in the area. Indeed, that’s what the authors of the paper concluded. “Future experiments should be conducted to understand the mechanisms by which caffeine can potentiate memory,” they wrote. “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.”

But people don’t tend to think along those subtle lines, and “caffeine might have an effect your memory in one specific way, but we need to do more studies really” doesn’t make a very catchy headline. And that’s a problem if people actually take findings like this onboard. It even prompted a blog on the NHS site (the UK’s health service) to respond with an impressively thorough report on the study, and to emphasise, “If you do have a big exam coming up, we would recommend that you stick to plain old tap water instead.”

It’s all too easy to forget the potential downsides of caffeine—insomnia, jitteriness, headaches, even diarrhea—when a headline’s sold it to you as a miracle memory cure.

So for now, feel free to stick to your usual coffee-drinking habits. Just don’t try to pretend they’re giving you some sort of superpowers.

@VickiTurk