Caffeine, a psychostimulant commonly used to combat high sleep pressure on a daily basis, changes the structures of gray matter. However, according to new studies by the University of Basel, the effect appears to be only temporary.
“Caffeine is the most widely used psychostimulant worldwide and is mainly consumed in the form of coffee, tea, energy drink and soda,” said lead author Professor Christian Cajochen from the Center for Chronobiology at the University of Basel and colleagues.
“Although caffeine is mostly viewed as non-addictive, the observed physical and psychological dependence consolidates its regular consumption through the caffeine-induced reinforcement effects and the motive to resist withdrawal symptoms and increase alertness.”
“A higher level of vigilance after acute caffeine consumption reflects reduced homeostatic sleep pressure, which is also noticeable in a reduced depth of sleep.”
“We hypothesized that daily caffeine intake changes gray matter structures through its effects on sleep homeostasis.”
The researchers looked at the effects of 10-day caffeine (3 × 150 mg / day) on gray matter volume and cerebral blood flow compared to 10-day placebo.
The study included a group of 20 habitual caffeine users (mean age – 26.4 years, self-reported daily caffeine intake – 474.1 mg / day).
At the end of each 10 day period, the scientists examined the subjects’ gray matter volume using fMRI.
They also examined the participants’ sleep quality in the laboratory by recording the electrical activity of the brain (EEG).
They found that the subjects’ depth of sleep was the same regardless of whether they took the caffeine or placebo capsules.
However, they saw a significant difference in gray matter depending on whether the subject received the caffeine or the placebo.
After 10 days of placebo, the gray matter volume was greater than after the same period with caffeine capsules.
The difference was particularly noticeable in the right medial temporal lobe, including the hippocampus, a region of the brain essential for memory consolidation.
“Our results don’t necessarily mean that caffeine consumption has a negative impact on the brain,” said co-author Dr. Carolin Reichert, also from the Center for Chronobiology at the University of Basel.
“But daily caffeine consumption obviously affects our cognitive hardware, which in itself should lead to further study.”
“In the past, the health effects of caffeine have mainly been studied in patients, but research is also needed in healthy volunteers.”
“Although caffeine appears to reduce gray matter volume, it was significantly regenerated in the test subjects after only 10 days of coffee abstinence.”
“The changes in brain morphology appear to be temporary, but systematic comparisons between coffee drinkers and those who normally consume little or no caffeine have so far been lacking.”
The results were published on February 15, 2021 in the journal Cerebral Cortex.
Yu-Shiuan Lin et al. Daily caffeine intake induces concentration-dependent medial temporal plasticity in humans: A multimodal randomized controlled double-blind study. Cerebral Cortex, published online February 15, 2021; doi: 10.1093 / cercor / bhab005