Coffee, cola or an energy drink: Caffeine is the most consumed psychoactive substance. Researchers from the University of Basel have now shown in a study that regular caffeine intake can change the gray matter of the brain. However, the effect appears to be temporary.
No question – caffeine helps most of us feel more alert. However, it can disrupt our sleep if consumed at night. Sleep deprivation can again affect the gray matter of the brain, as previous studies have shown. So can regular caffeine consumption affect the brain structure due to poor sleep? A research team led by dr. Carolin Reichert and Professor Christian Cajochen of the University of Basel and UPK (the Psychiatric Hospital of the University of Basel) investigated this question in a study.
The result was surprising: the caffeine used as part of the study did not lead to poor sleep. However, the researchers observed changes in the gray matter, as they reported in the journal Cerebral cortex. Gray matter refers to the parts of the central nervous system that consist mainly of the cell bodies of nerve cells, while white matter contains mainly the neural pathways, the long extensions of the nerve cells.
A group of 20 healthy young individuals, all of whom drink coffee regularly on a daily basis, participated in the study. They were given tablets to take two periods of ten days, and they were asked not to use any other caffeine during this time. During one study period, they received tablets with caffeine; in the other, tablets without active ingredient (placebo). At the end of each ten-day period, the researchers examined the volume of the subjects’ gray matter by means of brain scans. They also examined the sleep quality of the participants in the sleep laboratory by recording the electrical activity of the brain (EEG).
Sleep untouched but not gray dust
From data comparison, it appears that the sleep depth of the participants was equal regardless of whether they took the caffeine or the placebo capsules. But they did see a significant difference in the gray matter, depending on whether the person received caffeine or the placebo. After ten days of placebo – ie ‘caffeine abstinence’ – the volume of gray matter was greater than in the same period with caffeine capsules.
The difference was particularly noticeable in the right medial temporal lobe, including the hippocampus, an area of the brain that is essential for memory consolidation. “Our results do not necessarily mean that caffeine consumption has a negative impact on the brain,” Reichert emphasizes. “But the daily consumption of caffeine apparently affects our cognitive equipment, which in itself should lead to further studies.” She adds that in the past, the health effects of caffeine have been studied primarily in patients, but there is also a need for research on healthy topics.
Although caffeine appears to reduce the volume of gray matter, it has only significantly recovered ten days of coffee abstinence in the subjects. “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 been lacking so far,” says Reichert.
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