April 15, 2013
If you take just a sip of beer, and moments later—before you’ve had close to enough alcohol to get intoxicated, perhaps even before the beer has hit your stomach—feel a distinctly pleasurable sensation, it might not be strictly due to subtle aromas that result from the beverage’s blend of malt, hops and yeast. The cause of your pleasure might be due to tangible changes in your brain chemistry—specifically, a surge in levels of the neurotransmitter dopamine.
Scientists have long known that part of the reason alcohol induces pleasure is that intoxication leads to the release of dopamine, which is associated with the use of other drugs (as well as sleep and sex) and acts as a reward for the brain. But new research suggests that, for some people, intoxication isn’t necessary: Simply the taste of beer alone can provoke a release of the neurotransmitter within minutes.
A group of researchers led by David Kareken of Indiana University came to the finding, published today in the journal Neuropsychopharmacology, by giving tiny amounts of beer to 49 adult men and tracking changes in their brain chemistry with a positron emission tomography (PET) scanner, which measures levels of various molecules in the brain. They chose participants with varying levels of typical alcohol consumption—from heavy drinkers to near-teetotalers—and even tested them with the beer they reported that they drank most frequently. Because they used an automated system to spray just 15 milliliters (about half an ounce) of beer on each participant’s tongue over the course of 15 minutes, they could be sure that any changes in brain chemistry wouldn’t be due to intoxication.
The effect was significant. When the men tasted the beer, their brains released much higher levels of dopamine within minutes, compared to when the same test was conducted on the subjects at other times with both water and Gatorade. They were also asked to rate how much they “craved” a beer at several points during the experiment, and perhaps less surprisingly, their cravings were generally much higher after tasting beer than Gatorade or water.
Interestingly, the amount of dopamine release per person wasn’t random. People who had a family history of alcoholism (as reported on a survey) showed notably higher dopamine levels after tasting beer as compared to others. But participants who were heavy drinkers but didn’t have the family history had merely average dopamine levels.
The researchers believe this could be a clue as to why some people are predisposed towards alcoholism—and why it’s more difficult for them stay on the wagon if they’re trying to quit. The immediate release of dopamine from just a taste of beer would likely serve as a powerful mechanism that drives their cravings, and a tendency towards experiencing this burst of pleasure might be genetically inheritable. This could be part of the reason that people with a family history of alcoholism are twice as likely to experience alcoholism themselves.
Previous work has shown that in people with alcoholic tendencies, stimuli that are merely associated with drinking (such as the smell and sight of a alcoholic drinks or a bar) can trigger dopamine release in the brain. This work shows that for an unlucky group predisposed to suffering from alcoholism, bursts of dopamine can occur even if they’re not heavy drinkers—and it only takes a sip for the pattern to start.
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