Heads up, kids. New research suggests that booze plus caffeine is a bad combination for the adolescent brain.
An alarming study published this week found that drinking highly caffeinated alcoholic beverages triggers chemical changes in the brain that are similar to taking cocaine. Researchers also found that the consequences of heavy alcohol-plus-caffeine use lasts well into adulthood, and may lead to serious emotional and substance abuse problems.
Richard van Rijn, assistant professor of medicinal chemistry and molecular pharmacology at Purdue University, set up a series of experiments looking at the effects of highly caffeinated energy drinks and alcohol in adolescent mice. Mouse brains have been shown to correlate with humans brains in many drug studies, van Rijn said in an email.
"Because of the legal drinking age, this type of study cannot be ethically performed in humans," he said. "But of course mixing of energy drinks and alcohol by adolescents does occur. At the moment this is our best way to get a sense of the potential risks associated with these type of drinks."
The results of the experiments were troubling. Mice given high-caffeine energy drinks - without alcohol - were not more likely than a control group to drink more alcohol or other substances as adults. But mice given a combination of caffeine and alcohol exhibited both physical and neurochemical changes that were very similar to mice given cocaine during adolescence.
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The researchers also detected increased levels of the protein DeltaFosB, which indicates long-term changes in neurochemistry and is typically elevated in those abusing drugs such as cocaine or morphine.
Van Rijn said the results are likely due to the extremely concentrated levels of caffeine in energy drinks, which in some products are 10 times higher than those found in cola or other soft drinks.
"These drinks are a different beast than rum-and-coke," he said.
Both alcohol and caffeine can cause the release of dopamine, the brain's feel-good reward chemical. Cocaine also triggers an excess of dopamine in the brain, but it's typically much more intense than anything a user could achieve with alcohol or caffeine individually.
"We worried that combining alcohol with high concentrations of caffeine could get dopamine levels in the brain close to those observed with cocaine," van Rijn said. "Our data suggests this to be the case."
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The experiments further suggest that adolescents who regularly consume alcohol with energy drinks may develop tolerance levels similar to those who use cocaine regularly. That means that it would take more of any given substance - cocaine, alcohol, caffeine - to achieve the same "reward" sensation in adulthood.
In fact, the mice hooked on alcoholic energy drinks consumed significantly more saccharine than mice exposed to water during adolescence, confirming that the caffeine/alcohol-exposed mice had experienced a chemical change in the brain.
"Their brains have been changed in such a way that they are more likely to abuse natural or pleasurable substances as adults," van Rijn said.
While the results are compelling, van Rijn also noted that the mice in the experiments were dosed with extreme amounts of caffeine and alcohol.
"Adolescence in mice only takes four weeks, and we exposed mice nearly every day for those four weeks," he said. "This would be the equivalent of a teenager consuming caffeinated alcohol on a very regular basis between the ages of 10 and 20.
"So clearly our model is on the extreme side, but it is also quite apparent that the mixture of caffeine and alcohol shows unique effects that are troublesome."
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