FRIDAY, April 15 (HealthDay News) -- Combining the caffeine jolt of energy drinks with the intoxicating effects of alcohol is riskier than drinking alcohol alone, a new study suggests.
Adding to growing research on the effects of trendy cocktails such as vodka and the energy drink Red Bull, scientists from Northern Kentucky University split 56 college students between the ages of 21 and 33 into four groups. The students received either an alcoholic beverage, an energy drink, a mixed drink with both ingredients, or a placebo.
All drinks were made to look and taste like alcoholic energy drinks, so participants did not know which they were consuming. Researchers measured how quickly the students could execute and suppress actions after the dose and asked them to rate feelings such as stimulation, sedation, impairment and levels of intoxication.
All of the students who drank alcohol showed impaired impulse control. But those who drank the alcoholic energy drink perceived themselves to be less impaired than those who drank the same dose of alcohol alone, the study authors said, which could make them more likely to take risks such as driving while intoxicated.
"This study demonstrates these drinks are different . . . and consumers should be aware," said study author Cecile Marczinski, an assistant professor in the department of psychological science. "It might be appropriate to put warning labels on energy drinks saying they should not be mixed with alcohol."
While combining alcohol with caffeinated beverages is nothing new -- hence the ubiquitous rum and Coke -- energy drinks contain about three times the amount of caffeine as cola, making them especially stimulating, Marczinski said.
Prior surveys suggest that 30 to 50 percent of U.S. teenagers and young people consume energy drinks, which may also contain stimulants such as guarana. The U.S. Food and Drug Administration banned ready-made alcoholic beverages with added caffeine in November 2010 after a year-long review of scientific literature.
Preparing and serving mixed drinks that combine caffeine and alcohol in bars, parties or elsewhere is legal, however.
The stimulation from caffeinated alcoholic drinks counters the sedating effects of alcohol, making drinkers feel like they're not quite as affected by the liquor, Marczinski said. However, the energy drinks don't alter the level of behavioral impairment, just the perception of it.
"I'm most concerned about impaired driving," she said. "Typically, a lot of people's judgment is not good even at the best of times when they're drinking alcohol. It's really that sleepy feeling that cues people it's time to go home. This might extend the whole party experience longer than it should."
She and the other researchers noted that further studies are needed to determine whether the energy drink cocktails are escalating risky drinking practices among young people, who already demonstrate high levels of binge drinking.
The study is published online in advance of the July 2011 print issue of Alcoholism: Clinical & Experimental Research.
Bruce Goldberger, director of toxicology at the University of Florida College of Medicine, said his research in this area indicates that drinkers are more likely to drive if they mix alcohol with energy drinks. Other studies show increased risks of violence, unprotected sex and even sexual assault among those who consume this combination, he said.
"There's this perception that if you drink caffeine, it will sober you up, and it's just completely not true," Goldberger said. "Because the effects of the caffeine work in one region of the brain and the effects of the alcohol work in another, so they don't cancel each other out. Some people call it wide-awake drunk."
The U.S. National Institute on Alcohol Abuse and Alcoholism has more information on drinking drinking in young adults.
SOURCES: Cecile Marczinski, Ph.D., assistant professor, department of psychological science, Northern Kentucky University, Highland Heights, KY; Bruce Goldberger, Ph.D., director, toxicology, University of Florida College of Medicine, Gainesville; July 2011 issue, Alcoholism: Clinical & Experimental Research.
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