I’m experimenting with audio for some of my posts. If you’d like to listen to me reading this one aloud, click the play button below:
Update, 1/12/14, 9:05pm: A bunch of scientists have pointed out on Twitter that this study suffers from a weak statistical analysis. So, interpret the following with that in mind.
Coffee fiends like me love to use scientific research to justify our habit. So, here goes. A new study finds that people who consume caffeine shortly after learning something show memory gains 24 hours later.
Scientists have long known that our memories are unstable in the minutes or hours after they’re first created. During this period, called ‘consolidation’, the memory moves into long-term storage and into a fairly stable molecular state. (Caveat: Stable memories become unstable again whenever you recall them, as I wrote about a few weeks ago.)
In the new study, published today in Nature Neuroscience, researchers from the University of California, Irvine, wanted to see whether caffeine affects the memory consolidation process. They recruited young adults who don’t usually drink much coffee — less than 500 milligrams of caffeine a week, or about five cups of coffee — and who hadn’t had any before the experiment. The volunteers were shown lots of pictures of objects, such as a seahorse, a basket, and a saxophone, and then asked whether each picture depicted an indoor or outdoor item. Soon after looking at the pictures, the volunteers took a pill containing either 200 milligrams of caffeine (which is equivalent to about two cups of coffee) or a placebo.
The volunteers returned to the lab the next day; by then the caffeine had washed out of their systems. They were shown another series of pictures, but their task this time was to determine whether each picture was “old,” meaning they’d seen it the previous day; “similar,” meaning they’d seen a similar picture the previous day, or “new,” meaning it had not been in the older set. The similar pictures were tricky. For instance, whereas one of the “old” pictures was a wicker basket with two handles, one of the “similar” pictures was a wicker basket with one handle and a blue blanket peeking out from under its lid.
All of the volunteers were pretty good at correctly labeling the old and new pictures, regardless of whether they had taken the caffeine pill. But their responses to the similar pictures were strikingly different. Volunteers who had taken the caffeine were more likely to correctly label similar pictures as similar, whereas those who had taken the placebo labeled the similar pictures as old. In other words, the caffeine group was better at spotting subtle visual differences, which means they were better at remembering the details of the original pictures.
This caffeine edge was about the same when researchers repeated the whole experiment with a higher dose of the drug — 300 milligrams, or about three cups of coffee — but the advantage disappeared when they dropped the dose to 100 milligrams, or about one cup of coffee.
For memory researchers, the most intriguing part of the study relates not to the dose, but the timing. In one experiment, instead of giving the volunteers caffeine during memory consolidation, the researchers gave it to them 24 hours after consolidation, and just one hour before the memory test. This time, the caffeine group’s responses were no more accurate than those of the placebo group.
Caffeine is a drug, and like all drugs, it carries risks. It can dehydrate you, or make you feel jittery. It can be dangerous for people with a heart condition or pregnant women. And its beneficial effects on cognition are only just beginning to be understood. Nobody knows, for example, how caffeine would improve memory. (One idea is that caffeine indirectly boosts levels of the chemical messenger norepinephrine, which is known to aid memory consolidation.)
It’s also unclear whether the caffeine-induced memory gain applies to people who drink a ton of coffee, like me. But I’ll assume that it does, for now, since I have some reading to do today.