Scientists from the University of Coimbra (Portugal) have found that regular caffeine consumption, rather than coffee in general, prevents memory and mood impairments caused by chronic stress. The study's findings were published in the journal Neurobiology of Stress.

The experiment involved 24 adult mice, divided into four groups. One group was not stressed and drank water, while the other three were subjected to chronic, unpredictable stress for three weeks, with a variety of stimuli, including wet bedding, cold baths, and a tilted cage. The stress groups received regular water, caffeinated coffee extract, or decaffeinated coffee extract, respectively.

According to the results of the experiment, mice that drank water under stress conditions demonstrated weight loss, increased anxiety, signs of anhedonia, and impaired spatial memory. In animals given caffeine, behavioral indicators were virtually indistinguishable from those in the stress-free control group—caffeine completely prevented the negative consequences. Decaffeinated coffee, however, did not show a protective effect: mice in this group showed almost the same impairments as the group drinking water.

Brain tissue analysis confirmed the behavioral observations. Mice exposed to stress without caffeine showed a significant reduction in long-term potentiation in the hippocampus—a process underlying memory formation—and decreased levels of brain-derived neurotrophic factor in the frontal cortex. In animals given caffeine, both parameters remained normal, whereas decaffeinated coffee failed to prevent these changes.

The authors note that the study was conducted on a mixed group of males and females, without accounting for possible gender differences, and the precise caffeine levels in the animals' blood and tissues were not measured. The generalization of the findings in mice to humans requires further study, given the greater complexity of the human diet, stress factors, and brain biochemistry.