Drinking highly caffeinated beverages mixed with alcohol trigger changes in the adolescent brain which are similar to taking cocaine, suggests a study.
The energy drinks can contain as much as 10 times the caffeine as soda and are often marketed to adolescents.
The results published in the journal Alcohol showed that adolescent mice given high-caffeine energy drinks were not more likely than a control group to drink more alcohol as adults.
But when those high levels of caffeine were mixed with alcohol and given to adolescent mice, they showed physical and neurochemical signs similar to mice given cocaine.
"It seems the two substances together push them over a limit that causes changes in their behaviour and changes the neurochemistry in their brains. We're clearly seeing effects of the combined drinks that we would not see if drinking one or the other," said Richard van Rijn, Assistant Professor at the Purdue University.
With repeated exposure to the caffeinated alcohol, those adolescent mice became increasingly more active, much like mice given cocaine.
The researchers also detected increased levels of the protein FosB, which is marker of long-term changes in neurochemistry, elevated in those abusing drugs such as cocaine or morphine.
"That's one reason why it's so difficult for drug users to quit because of these lasting changes in the brain," van Rijn added.
Those same mice, as adults, showed a different preference or valuation of cocaine. They found that mice exposed to caffeinated alcohol during adolescence were less sensitive to the pleasurable effects of cocaine.
While this sounds positive, it could mean that such a mouse would use more cocaine to get the same feeling as a control mouse.
"Mice that were exposed to highly caffeinated alcoholic drinks later found cocaine wasn't as pleasurable. They may then use more cocaine to get the same effect," the researcher said.
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