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Caffeine Doesn’t Reverse the Cognitive Impact of Alcohol

People who drink may want to know that coffee won’t sober them up, according to new laboratory research. Instead, a cup of coffee may make it harder for people to realize they’re drunk.

What’s more, popular caffeinated “alcohol-energy” drinks don’t neutralize alcohol intoxication, suggest the findings from a mouse study reported in Behavioral Neuroscience.

“The myth about coffee’s sobering powers is particularly important to debunk because the co-use of caffeine and alcohol could actually lead to poor decisions with disastrous outcomes,” says coauthor Thomas Gould, PhD, of Temple University, in extending the research to what it means for humans.

“People who have consumed only alcohol, who feel tired and intoxicated, may be more likely to acknowledge that they are drunk,” he adds. “Conversely, people who have consumed both alcohol and caffeine may feel awake and competent enough to handle potentially harmful situations, such as driving while intoxicated or placing themselves in dangerous social situations.”

In the laboratory, caffeine made mice more alert but did not reverse the learning problems caused by alcohol, including their ability to avoid things they should have known could hurt them, according to the study.

Scientists gave groups of young adult mice various doses, both separately and together, of caffeine and of ethanol (pure alcohol) at levels known to induce intoxication. The doses of caffeine were the equivalent of one up to six or eight cups of coffee for humans. Control mice were given saline solution.

Researchers then tested three key aspects of behavior: the ability to learn which part of a maze to avoid after exposure to a bright light or loud sound; anxiety, reflected by time spent exploring the maze’s open areas; and general locomotion.

Ethanol, as expected, increased locomotion and reduced anxiety and learning in proportion to the dose given. In other words, intoxicated animals were more relaxed and moved around more but learned significantly less well than control mice to avoid the part of the maze with the unpleasant stimuli.

By itself, caffeine increased anxiety and reduced both learning and locomotion. Compared to the control animals, mice given caffeine were significantly more inhibited, less mobile and less savvy about avoiding the unpleasant stimuli.

When the drugs were given together, ethanol blocked caffeine’s ability to make the mice more anxious. Conversely, caffeine did not reverse ethanol’s negative effect on learning. As a result, alcohol calmed the caffeine jitters, leaving an animal more relaxed but less able to avoid threats—a combination that the authors speculated could make people more likely to believe they are not drunk or not impaired enough to have problems functioning.

“The alcohol-energy drink combinations have skyrocketed in popularity,” Gould notes. He cited other evidence that these drinks produce deficits in general cognitive ability and raise the odds of alcohol-related problems such as drunken-driving citations, sexual misconduct, and needing medical assistance.

— Source: American Psychological Association