Teenagers who mix energy drinks with alcohol react as if they were on cocaine, a new study reveals.

The potentially lethal combination of caffeine and liquor - such as vodka and Red Bull - triggers exactly the same reaction in a young person's brain.

Just as with the Class A drug, the cocktail can have a devastating affect on the chemical balance of the brain that lasts long into adulthood.

Worryingly, the research team at Purdue University also found if teenagers mixed energy drinks with alcohol, and then tried cocaine, they would crave greater quantities of the drug to replicate the same high.

Dangerous: The potentially lethal combination of caffeine and liquor - such as vodka and Red Bull - triggers exactly the same reaction in a young person's brain as cocaine

'It seems the two substances together push them over a limit that causes changes in their behavior and changes the neurochemistry in their brains,' lead author Richard van Rijn, an assistant professor of medicinal chemistry and molecular pharmacology, said.

'We're clearly seeing effects of the combined drinks that we would not see if drinking one or the other.'

Van Rijn's team looked at how a cocktail of highly caffeinated energy drinks and highly caffeinated alcohol affected the brains of adolescent mice - since human tests are illegal.

Based on other drug studies in mice, he insists the study is an accurate reflection of how human teenagers would react.

The more the adolescent mice drank caffeinated alcohol, the more active they got - similar to how mice react on cocaine.

More worryingly, the researchers also spotted increased levels of a dangerous protein that is amplified in the brains of cocaine and morphine addicts.

The protein (ΔFosB) tends to trigger long-term changes in the chemical balance of the user's brain.

'That's one reason why it's so difficult for drug users to quit because of these lasting changes in the brain,' van Rijn said.

Those same mice, as adults, showed a different preference or valuation of cocaine.

Caffeinated alcohol had given their brains so many intense highs that it had stunted their brain's reward center.

As a result, mice exposed to caffeinated alcohol during adolescence were less sensitive to the pleasurable effects of cocaine.

It meant those mice would need more cocaine to get the same feeling that unaffected mice would get.

Van Rijn used saccharine - an artificial sweetener - as a substitute for cocaine to test the theory.

As predicted, the mice exposed to caffeinated alcohol in adolescence guzzled much more saccharine than the other mice.

'Mice that had been exposed to alcohol and caffeine were somewhat numb to the rewarding effects of cocaine as adults,' van Rijn said.