That ‘essential’ morning coffee may be a placebo, study finds

For many people, the day doesn’t really start until the first thing they do is drink a cup of coffee because it is thought to make you feel more alert and efficient and reduces fatigue.

Intrigued, scientists at Portugal’s University of Minho studied coffee drinkers to find whether that wakefulness effect is dependent on the properties of caffeine or whether it’s about the experience of drinking coffee.

“There is a common expectation that coffee increases alertness and psychomotor functioning,” said Prof Nuno Sousa, who was a lead author of the study in Frontiers in Behavioral Neuroscience that was entitled “Coffee consumption decreases the connectivity of the posterior Default Mode Network at rest.”

“When you get to understand better the mechanisms underlying a biological phenomenon, you open pathways for exploring the factors that may modulate it and even the potential benefits of that mechanism,” he explained.

The scientists recruited people who drank a minimum of one cup of coffee per day and asked them to refrain from eating or drinking caffeinated beverages for at least three hours before the study. They interviewed the participants to collect sociodemographic data and then did two brief functional MRI scans – one before and one 30 half an hour after either taking caffeine or drinking a standardized cup of coffee. During the functional MRI scans, the participants were asked to relax and let their minds wander.

Because of the known neurochemical effects of drinking coffee, the scientists expected that the functional MRI scans would show that the people who drank coffee had higher integration of networks that are linked to the prefrontal cortex, which is associated with executive memory, and the default mode network, which is involved in introspection and self-reflection processes. 

They found that the connectivity of the default mode network declined both after drinking coffee and after taking caffeine, which indicated that consuming either caffeine or coffee made people more prepared to move from resting to working on tasks.

However, drinking coffee also increased the connectivity in the higher visual network and the right executive control network – parts of the brain that are involved in working memory, cognitive control and goal-directed behavior. That didn’t occur when participants just ingested caffeine. In other words, if you want to feel not just alert but ready to go, caffeine alone won’t do; you need to experience that cup of coffee.

Some limitations of the study

“Acute coffee consumption decreased the functional connectivity between brain regions of the default mode network, a network that is associated with self-referential processes when participants are at rest,” said Dr/ Maria Picó-Pérez of Jaume University, who was the first author. “The functional connectivity was also decreased between the somatosensory/motor networks and the prefrontal cortex, while the connectivity in regions of the higher visual and the right executive control network was increased after drinking coffee. In simple words, the subjects were more ready for action and alert to external stimuli after having coffee.”

“Taking into account that some of the effects that we found were reproduced by caffeine, we could expect other caffeinated drinks to share some of the effects,” added Picó-Pérez. “But others were specific for coffee drinking, driven by factors such as the particular smell and taste of the drink, or the psychological expectation associated with consuming that drink.”

The authors pointed out that it’s possible that the experience of drinking coffee without caffeine could cause these benefits. Their study could not differentiate the effects of the experience alone from the experience combined with the caffeine. There is also a hypothesis that the benefits coffee drinkers claim could be due to the relief of withdrawal symptoms that this study did not test.