The taste of beer, even without any effect from alcohol, triggers a key reward chemical in the brain, says a study on how people become hooked on booze.
Neurologists at the University of Indiana asked 49 men to drink either their favourite beer or Gatorade, the non-alcoholic sports drink, while their brains were scanned by positron emission tomography (PET). The goal was to look at dopamine, a chemical in a part of the brain called the ventral striatum that gives the sensation of reward.
The beer was rationed out in tiny amounts - just 15 millilitres, or about a tablespoon, every 15 minutes - so that the brain could be scanned without the influence of alcohol.
Just a taste of the beer lit up dopamine receptors, and the effect was far greater than for Gatorade, even though many volunteers said they preferred the taste of the soda, the investigators found.
The dopamine effect was significantly greater among volunteers with a family history of alcoholism, they reported.
"We believe this is the first experiment in humans to show that the taste of an alcoholic drink alone, without any intoxicating effect from the alcohol, can elicit this dopamine activity in the brain's reward centres," said David Kareken, a professor of neurology who led the experiments.
Dopamine has long been associated with substance craving, with anecdotal evidence suggesting it can be triggered by the sound, sight or smell of a pub.
As a result, researchers focus on techniques for avoiding or minimising such triggers.
The study was published on Monday in the journal Neuropsychopharmacology