Mixing Alcohol, Caffeine Popular Among Underage Drinkers.

The practice of mixing caffeinated beverages and alcohol – popular among college-age drinkers – also has gained traction among adolescents, according to a new study co-authored by BU School of Public Health researchers.

The study – led by BUSPH student Kalé Z. Kponee and community health sciences professor Michael Siegel, and published in the journal Addictive Behaviors – indicates that mixing caffeine and alcohol is more common among underage drinkers and starts at a much earlier age that previously thought.

The research team, which includes David H. Jernigan from the Johns Hopkins Bloomberg School of Public Health, found that young people who consumed energy drinks mixed with alcohol were several times more likely to binge drink, get in fights and sustain alcohol-related injuries than those who did not.

Adolescents who consumed alcohol mixed with energy drinks had almost twice the average drinking days per month as those who did not mix caffeine with alcohol. They also consumed almost triple the total number of drinks per month compared to non-caffeine users.

“Our overall findings provide new information about how dangerous alcohol mixed with energy drinks are, compared to caffeinated-alcoholic beverages and caffeine-free alcohol,” said Kponee, who will graduate in January. “They also show that these drinks are being used in much younger and vulnerable populations, particularly among pre-collegiate youth.”

She said the findings suggest that “particular interventions should be tailored towards pre-collegiate underage drinkers and youth who mix their alcohol with energy drinks.”

Siegel and colleagues analyzed information from Internet surveys of 1,031 youths, ages 13 to 20, who reported having at least one alcoholic drink in the past month. The surveys asked participants whether they consumed energy drinks that contained alcohol, and if they mixed soda, coffee or tea with alcoholic drinks on their own.

Just over half of the participants reported drinking caffeine and alcohol together in the previous month. That included 48 percent of 13- to 15-year-old drinkers, 45 percent of 16- to 18-year-olds, and 58 percent of 19- and 20-year-olds.

More teens drank self-mixed caffeinated alcoholic beverages than energy drink mixtures – 46 percent compared to 20 percent.

“Our results suggest that the majority of (caffeinated alcohol) use is attributable to self-mixing . . . by the adolescents themselves, and that soda is the most commonly used caffeine additive to alcohol. This may reflect the widespread availability of soda and perhaps the ability to hide the use of alcohol by making it look like a youth is consuming soda,” the study says.

The research team found that the risks of adverse outcomes were even higher when energy drink mixtures, which contain large concentrations of caffeine, were consumed.

Mixing alcohol and caffeine can mask some of the feelings of intoxication, Siegel said.

“It’s particularly dangerous because the caffeine hides the cues that young people normally receive from alcohol to indicate intoxication, leading them to drink more than they intend,” he explained. “Our findings suggest that this is leading to severe adverse consequences.”

The researchers found that teens who started drinking between ages 11 and 13 were more likely to report recently drinking caffeinated alcoholic beverages than those who started later.

“This is alarming because earlier initiation of high-risk drinking among adolescents may lead to more adverse and prolonged outcomes later in life, such as heavy episodic drinking, alcohol tolerance, alcoholism, risky behavior, and adverse health outcomes,” the study team said.

Many products containing caffeine and alcohol, such as Four Loko, have been taken off the market or reformulated without caffeine, the researchers noted. But the study indicates that hasn’t stopped young people from mixing their own.

“While it is important to regulate the sale of pre-mixed caffeinated alcoholic beverages, our study suggests that these concoctions are still available to many teenage drinkers who prefer to mix their caffeinated alcoholic beverages themselves instead of buying them pre-mixed,” the authors said. “The use of self-mixed caffeinated alcoholic beverages suggests a more insidious problem that will prove difficult to regulate.”

Alcohol causes 4,700 deaths per year among people under 21, and alcohol use among high school students has been associated with a range of health risk behaviors, such as sexually promiscuous activity, being a victim of dating violence, attempting suicide, and using illicit drugs, with risk increasing with frequency of heavy binge drinking.

Siegel said efforts should be made to educate youths about the perils of mixing energy drinks, soda and other beverages with alcohol, and that parents should be made aware that underage youth “are often adding alcohol to non-alcoholic beverages, like soda and energy drinks.”

The National Institute on Alcohol Abuse and Alcoholism provided funding for the study.