The fast-forward kick of caffeine is no news to the 80 percent of Americans who drink coffee or tea as an eye-opener. But while at Johns Hopkins University in Baltimore, Michael Yassa, now an assistant professor of neurobiology at the University of California at Irvine, and his colleagues pinpointed another use: memory enhancer.
The research, published in the journal Nature Neuroscience, shows that the stimulant strengthens memory up to 24 hours after consumption. We spoke to Yassa about their findings.
Previous studies have indicated caffeine has a positive effect on memory. What's new about your research?
We've suspected this effect in animals for a while. For example, Geraldine Wright of Newcastle University showed that honeybees that ingested caffeinated nectar were more likely to remember a flower's scent. But studies in humans have been inconclusive because the caffeine was administered before the memory test, so the result might have been confounded with other factors like its effect on vigilance or focus.
So you gave people who didn't regularly use caffeine either a placebo or a 200-milligram caffeine tablet five minutes after they studied a group of images. Both groups returned 24 hours later to be tested. The caffeine users remembered the images better.
Caffeine was first isolated from the coffee bean in the 19th century by a German chemist. Do we know exactly how it works?
There are several mechanisms. It acts on the adenosine receptors and increases heart rate, vigilance, blood pressure—the fight-or-flight response when you see a bear. It's what happens when someone says, "I get an adrenaline rush." It also acts on a small region of the hippocampus, which plays an important role in long- and short-term memory.
How much coffee do you have to drink to get 200 milligrams of caffeine?
It's about two shots of espresso.
Should we all rush out and order triple-shot grande lattes as a result of these findings?
Keep in mind that those drinks also involve lots and lots of sugar. I've been a coffee drinker for years, and I'm not going to double my dose.
Your research cohort was people who aren't normally coffee drinkers. Considering that caffeine is the world's most popular psychoactive drug, was it a problem finding enough research subjects?
We did have trouble, and also finding people who were honest about it. We did a salivary test beforehand to detect caffeine in the system, and some people had to be disqualified.
What's the downside to caffeine?
In large amounts you get jitteriness, headaches; absolutely, you can overdose on it. It's a stimulant. I don't think the results should be taken as license to take unlimited amounts of caffeine.
Tell me about down-the-road applications. Could caffeine be a remedy for Alzheimer's or dementia?
I don't think it would arrest it. But if somebody is at risk, perhaps caffeine could help. Our next step is to use brain-imaging techniques to do further research on the brain mechanisms.
Can I get back to you to check some of this information? You speak awfully fast.
It must be the caffeine in my system.