Coffee can alter brain structures related to memory.
A recent study published recently in Cerebral Cortex, a team of researchers led by the University of Basel, Switzerland, found in a randomised, double-blind crossover trial that regular coffee (with caffeine) does not affect sleep quality. Still, it does change brain structures related to memory. Again, however, this effect appears to be temporary. If consumed in excess or too late during the day, coffee may cause insomnia, and the ensuing lack of sleep can have a negative impact on the brain. Previous studies have shown that sleep deprivation affects the volume of grey matter in the brain.
A team of researchers from the University of Basel conducted a randomised, double-blind crossover controlled trial with 20 healthy volunteers included in the study, all of whom had a daily coffee drinking habit.
The researchers randomised the participants into two groups and gave them two 10-day courses of tablets, and asked them not to consume any other caffeine during this period. During the first 10-day phase, one group of participants took a pill containing caffeine (3 x 150mg/day), and the other group took a placebo pill without the active ingredient (3 x 150mg/day); during the second 10-day phase, the two groups were swapped.
At the beginning of the study and the end of each trial phase, the researchers examined the participants' grey matter volume and cerebral blood flow by brain scans. They quantified the stress of slow-wave sleep by EEG activity to investigate the quality of their sleep.
The study results were surprising, as brain scans of the caffeine group after ten days showed a significant reduction in the volume of their medial temporal lobe grey matter compared to the placebo group. This area also includes the hippocampus, which is crucial for learning, emotion and memory consolidation. Cerebral blood perfusion was reduced in the caffeine group compared to the placebo group. Caffeine intake did not lead to a decrease in sleep quality in participants. Therefore, these data do not suggest a link between deep sleep and brain morphology changes following daily caffeine intake.
The researchers said that daily caffeine intake might lead to neuroplasticity in the medial temporal lobe, but this depends on the individual's metabolic processes.
Dr Carolin Reichert said, "Our findings do not necessarily mean that caffeine intake negatively affects the brain, but daily caffeine intake does affect the areas responsible for cognitive function, and this warrants further study."
While caffeine may reduce the brain's grey matter volume, the study found that the changes did not last long if caffeine intake was stopped. The researchers said that after taking the placebo for ten days, the participants had a significant grey matter increase.