Researchers reported that volunteers who drank caffeinated coffee in the morning performed better than nondrinkers on tests that involved learning new information. Coffee can also improve cognitive function as we age. One study found that combining coffee with a sweet treat had an even bigger impact.
According to study researcher Josep M. Serra Grabulosa, from the Department of Psychiatry and Clinical Psychobiology at Universidad de Barcelona:
Our main finding is that the combination of the two substances improves cognitive performance in terms of sustained attention and working memory by increasing the efficiency of the areas of the brain responsible for these two functions. This supports the idea of a synergistic effect between two substances, in which each one boosts the effect of the other.