Hold the Red Bull

Mixing energy drinks with alcohol has become a hot-button issue, especially on college campuses. Some surveys show one in four college students reporting that they mix the two.

Marketing efforts that encourage combining caffeinated energy drinks with alcohol often try to sway young people into believing that caffeine will offset the sedating effects of alcohol and increase alertness and stamina.

But a new study led by researchers from the BU School of Public Health and the Center for Alcohol and Addiction Studies at Brown University has found that the addition of caffeine to alcohol—mixing Red Bull with vodka, for example—has no effect on enhancing performance on a driving test or on improving sustained attention or reaction times.

“There appears to be little or no protective benefit from the addition of caffeine to alcohol, with respect to the safe execution of activities that require sustained attention with rapid, accurate decisions,” according to the study, published in the February 2011 edition of the journal Addiction.

“The results of this study suggest that public education, via media and warning labels, should be considered regarding the safety of CABs [caffeinated alcoholic beverages], and that regulators should scrutinize energy drink and CAB advertising as it relates to promoting safety-related expectancies.”

The study, headed by Jonathan Howland, an SPH professor of community health sciences, comes amid increased government scrutiny of energy drinks, particularly when mixed with alcohol. Denmark has banned the sale of energy drinks, and the governments of Canada and Sweden have issued warnings about mixing energy drinks with alcohol.

In 2009, the U.S. Food and Drug Administration issued a statement expressing concern about the lack of safety data on CABs after survey results showed that consuming such beverages correlated with risky behavior among college students.

Howland and his coauthors note that while energy drink companies do not explicitly advertise that their products should be mixed with alcohol, “non-traditional youth-oriented marketing strategies” include claims that such drinks will “enhance attention, endurance, performance, weight loss, and fun, while reducing performance decrements from fatigue from alcohol.”

In the new study, the research team randomly put 129 participants, ages 21 to 30, into one of four groups: one that consumed caffeinated beer; a second that consumed noncaffeinated beer; a third that consumed caffeinated nonalcoholic beer; and a fourth that consumed noncaffeinated, nonalcoholic beer. Those drinking alcohol reached an average blood alcohol level of .12 grams percent, somewhat higher than 0.8 grams percent, the legal level for driving under the influence.

The participants were tested on a driving simulator and on a sustained attention/reaction time test 30 minutes after drinking.

The results indicate that caffeine does not mitigate the impairment effects of alcohol. On the driving test, the effect of alcohol on performance was significant, but the addition of caffeine did not make a noticeable difference. On the test for sustained attention and reaction times, the addition of caffeine made only a slight difference, which the study deemed “borderline significant.”

Howland sums up the study results: “It is important that drinkers understand that adding caffeine to alcohol does not enhance safety.”

Consumption of energy drinks mixed with alcohol has mushroomed since 2001. As well as the surveys showing that one in four college students mix the two, some studies have found that caffeine reverses alcohol-related performance impairment on tests of reaction time, attention, and psychomotor speed, but not on error rates. Other studies have found that caffeine does not significantly impact alcohol-induced impairment of motor coordination.

Howland says the new study was one of the first to provide “a controlled evaluation of the acute effects of caffeine on driving impairment” after drinking to intoxication levels. The institutional review boards of Boston Medical Center, Brown University, and the University of Michigan approved the study.

In addition to Howland, researchers on the study include Damaris J. Rohsenow of the Center for Alcohol and Addiction Studies at Brown University; J. Todd Arnedt of the Sleep and Chronophysiology Laboratory of the University of Michigan Medical School; Daniel J. Gottlieb of the BU School of Medicine; and Caleb A. Bliss, Sarah K. Hunt, Tamara Vehige Calise, Timothy Heeren, Michael Winter, and Caroline Littlefield, all of SPH.

The full study is available here.

Lisa Chedekel can be reached at chedekel@bu.edu.