If your child is college-aged you might want to pay attention to his or her drinking habits – not just alcoholic beverages, but energy drinks as well. A new study reports that college students who drink more high-caffeine drinks (such as Red Bull) also consume significantly more alcoholic beverages. Separately, the FDA issued a warning that caffeine and alcohol can be a deadly combination.

Not only did the students who consumed more energy drinks also drink alcohol more frequently, they also drank more heavily and were more likely to have blackouts, hangovers, and meet the standard psychological criteria for alcohol dependence. …[But] cause and effect have not been shown.

In the first study, almost 1,100 college seniors were quizzed about their alcohol use and energy drink consumption over the past year. Energy drinks can contain anywhere from 50-500 mg of caffeine per can (to put this in perspective, a typical cup of coffee contains about 100 mg of caffeine). About 10% of the students drank energy drinks on at least a weekly basis, with some students consuming the drinks every day.

Not only did the students who consumed more energy drinks also drink alcohol more frequently, they also drank more heavily and were more likely to have blackouts, hangovers, and meet the standard psychological criteria for alcohol dependence. Students who drank the most energy drinks averaged about six alcoholic drinks on the days they consumed alcohol (which was about 142 days/year), while students who drank fewer energy drinks averaged about 4.6 alcoholic drinks on the days they drank alcohol (which was about 103 days/year).

Though the link between energy drinks and alcohol consumption is clear, the cause is not: because cause and effect have not been shown in this study, it’s still a chicken-or-egg situation. As the authors point out, it may be that students are using the energy drinks to cope with hangovers the day after a drinking binge, or, along the same lines, "if chronic partying interferes with their study habits they might consume energy drinks to pull 'all-nighters' before exams." Or it may be that students who are prone to substance abuse in the first place may look to alcohol and energy drinks for different "highs" at different times. Whatever the mechanism, the authors say more research will be needed to understand it further.

In a similar vein, the FDA released a warning to drink makers that the caffeine that is sometimes added to alcoholic beverages should be considered an "unsafe food additive". Principal Deputy Commissioner Joshua M. Sharfstein says that the "FDA does not find support for the claim that the addition of caffeine to these alcoholic beverages is ‘generally recognized as safe,’ which is the legal standard. To the contrary, there is evidence that the combinations of caffeine and alcohol in these products pose a public health concern." The FDA concluded that having both drugs in one’s system can lead to "risky behaviors and…life-threatening situations."

Clearly mixing caffeine and alcohol is not a wise idea, and parents should be particularly attentive to what their kids are drinking, whether for energy or for entertainment.

The first study was carried out by Amelia M. Arria the University of Maryland, and published in the February 2011 online issue of Alcoholism: Clinical & Experimental Research.