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Alcohol and energy drink combo boosts urge to drink

Priming effect Popular energy drinks that "give you wings" also give you a greater desire to keep drinking when mixed with alcohol, an Australian study finds.

The study, published today in the journal Alcoholism: Clinical & Experimental Research adds to concerns in the field of public health over the growing popularity of combining alcohol with energy drinks.

Senior author Dr Rebecca McKetin, a research fellow at the Centre for Research on Ageing, Health and Wellbeing at the Australian National University, says previous studies have shown young adults who mix alcohol with energy drinks have a tendency to drink more.

While the mechanism behind this was unknown, a US study published last year showed that the addition of energy drinks to alcohol boosted the "priming effect".

McKetin says this "priming effect" is a measure of how an alcoholic drink incites the urge to keep drinking.

She says there was some skepticism about the US results at the time, so it was important to replicate the study.

"People were a bit skeptical because these findings have strong implications for combining energy drinks with alcohol and whenever anything has strong implications it tends to be looked at more critically," she says.

Although McKetin says it was a well-controlled study, she did think its measure of the urge to drink alcohol "was a bit weak".

The Australian study involved 75 participants (46 women, 29 men) aged 18 to 30 years.

They were given a double shot of vodka (60 millilitres) combined with either soda water or an energy drink in a cocktail that also contained 200 millilitres of a fruit drink.

The participants were asked to complete a series of questionnaires before and after consuming the alcoholic drink, to gauge their ongoing desire to drink.

McKetin says the results show while there was an overall increase among all participants to keep drinking, those consuming the alcohol and energy drink combination showed "significantly higher ratings".

Confirms study

The findings support the US results, confirming the earlier study "isn't a chance finding", she says.

"We used a stronger measure of urge to drink alcohol and found the same effect," McKetin says.

"I think the importance of this is it suggests energy drinks may increase binge drinking in young adults and increase alcohol-related harm.

"We know there is a very strong association between energy drink consumption and heavy drinking, but up until this point it's been unclear whether energy drinks are leading to higher alcohol consumption."

Although more research is needed to understand the factors that cause this effect, McKetin says it is likely the caffeine in the energy drinks plays an important role in priming drinkers to want more alcohol.

"Caffeine is a prime candidate because it increases the stimulant effect of the alcohol and that effect is known to be linked at how much you like alcohol," she says.

McKetin says the high level of carbohydrate in energy drinks might also make the drinks more palatable and encourage people to want more.

Policy impact?

Although the work is significant, McKetin says it is unlikely to have an impact on policy.

"We've only measured people's self-reported desire to keep drinking … who knows in a material sense how much it is going to cause people to buy another drink," she says.

"Until we can demonstrate it does have a material impact on people's actual drinking behaviour it is going to be hard to push for public health warning or regulations over energy drinks."

Unfortunately, says McKetin, trying to determine the impact on behaviour is experimentally fraught.

"It is very difficult for ethical reasons to allow people to drink to their heart's content in an experimental situation," she adds.