Coffee’s ability to enhance alertness is commonly attributed to caffeine, but new research suggests there may be other, additional mechanisms contributing to this effect. Certain compounds in coffee, both caffeine and chlorogenic acids, have been documented to have psychoactive effects, but the psychological impact of coffee and caffeine consumption remains a matter of debate.
Scientists have proceeded to investigate the neurobiological effect of coffee consumption on the way it affects brain connectivity, using resting state functional magnetic resonance imaging (fMRI). The study was published online in Frontiers in Behavioral Neuroscience with title “Coffee consumption decreases the connectivity of the posterior Default Mode Network (DMN) at rest“.
“Everyone who drinks coffee regularly expects that coffee enhances their alertness and psychomotor performance. With a deeper understanding of the mechanisms behind this biological phenomenon, the way is opened to investigate the factors that can influence it. We can also investigate the potential advantages of these mechanisms,” said study leader Nuno Souza from the University of Minho in Braga, Portugal.
Caffeine isn’t everything
The researchers recruited 47 healthy adults, with an average age of 30, of whom 31 were women, who regularly drank at least one cup of coffee a day. Participants refrained from eating or drinking caffeinated beverages for at least 3 hours before undergoing the fMRI.
To investigate the specific effect of caffeinated coffee intake, the researchers gave 30 habitual coffee drinkers – average age 32, of whom 27 were women – hot water that contained the same amount of caffeine, but was not coffee.
The researchers performed two fMRI scans – one before and one 30 minutes after drinking coffee or caffeinated water.
Both coffee consumption and plain caffeine consumption reduced the connectivity of the brain’s network defined by its automatic physiological function, which is normally active during resting states.
That is, as the researchers explained, this finding suggests that drinking either coffee or plain caffeine increased people’s readiness to switch from a state of rest to engaging in work-related activities.
Better memory and goals
However, drinking a cup of coffee was found to additionally boost connectivity in the superior visual network and the right executive control network, which are linked to working memory, cognitive control and one’s goal-directed behavior – something that did not result from drinking plain water with caffeinated water.
“Simply put, subjects showed a heightened state of alertness, responding and being more attentive to external stimuli after drinking coffee,” said study first author Maria Pico-Peres of the University of Minho.
He added, however, that “given that some of the effects of coffee occurred only with caffeine, it is reasonable to speculate that other caffeinated beverages may have similar effects.”
However, some effects emerged from drinking coffee alone, “likely influenced by factors such as the distinct aroma and taste of coffee or the psychological expectations associated with drinking that particular beverage,” the researcher wrote.
The researchers report that these observations could provide a scientific basis for the belief that coffee increases alertness and cognitive function. But further research is needed to differentiate the effects of caffeine compared to the overall experience of drinking coffee.
A limitation of the study is the absence of a non-drinking control sample (to rule out a withdrawal effect) or an alternative group that consumed decaffeinated coffee (to rule out a placebo effect of coffee intake) – something that should be considered in future studies , the researchers note.
