In Experiments, Caffeine Accelerates the Brain’s Verbal Processing

A cup or two of coffee doesn’t just give you energy—it might make you a think a little more quickly. That’s not exactly a shocker, but for coffee drinkers, a new study showing that caffeine can improve verbal processing speed should put a nice perk in your day.

Despite conventional wisdom that caffeine is a harmful drug, a growing body of research is demonstrating that it can confer a wide range of benefits when consumed in moderation. Within the past year, studies have indicated that caffeine can help improve muscle strength for seniors, delay the onset of Alzheimer’s and reduce the risk of skin cancer.

Now, a study published today in the journal PLOS ONE suggests that 200 mg of caffeine—the equivalent of a couple of cups of coffee—can help the brain identify words more quickly and precisely. In a study conducted by psychologists Lars Kuchinke and Vanessa Lux from Ruhr University in Germany, healthy young adults given a 200 mg caffeine tablet exhibited improved speed and accuracy while completing a word recognition task.

The task involved looking at a string of letters, presented one at a time for 150 milliseconds each, and deciding as quickly as possible whether they constituted an actual word or a made up word. When compared to a control group that was given a placebo (a lactose tablet), those given the caffeine pill decided more quickly and were correct a higher percentage of the time—at least for words that were deemed to have a positive emotional association.

Why only for positive words? The researchers designed the experiment not to demonstrate benefits of caffeine, but in order to use the drug to answer an existing question about the underlying architecture of the brain. It has long mystified cognitive scientists why, when completing these types of word processing tasks, people consistently demonstrate a quicker response time for words with a positive emotional valence (like “love” or “happy”) than those with a negative connotation (like “bored” or “angry”).

Kuckinke and Lux, recognizing that caffeine stimulates the release of the neurotransmitter dopamine, decided to use the drug to test a hypothesis, to see if dosing study participants would further increase their speed and accuracy for positive words. The caffeine did indeed make them even better at completing the task for positive words—but not for negative or neutral ones—leading the researchers to conclude the involvement of the dopamine system is at least part of the explanation for the phenomenon.

Additionally, the researchers zeroed in on the region of the brain responsible for the effect. When they showed the study participants the letters, they did so directly in front of either their left or right eyes, flashing them so quickly that only the half of the brain directly wired to the particular eye would have time to process them. Because the brain is cross-wired—so the right half of the field of vision is most immediately connected with the left hemisphere—and the accelerated processing effect was only for letters shown in front of the participants’ right eyes, it seems to be rooted in the language-dominated left hemisphere.

Scientists still have many questions about this effect, and this pair notes the need for further study to understand how it is involved with the dopamine system, frequently associated with reward centers in the brain.

On a more practical level? You might consider applying these current findings by drinking a cup of coffee when your thought processes seem a little slow.

Joseph Stromberg | | READ MORE

Joseph Stromberg was previously a digital reporter for Smithsonian.