MONDAY, April 15 (HealthDay News) -- Just as the smell of
freshly brewed coffee may compel you to pour a steaming cup of
java, a small taste of beer may activate part of your brain's
reward system and trigger the urge for more, a new study
Researchers have discovered that sensory cues associated with
drinking may stimulate certain parts of the brain and cause a
craving for more alcohol. Giving people a very small amount of the
brand of beer they most frequently consume produced a desire to
drink that was correlated with the release of dopamine, a
neurotransmitter that helps control the brain's reward-and-pleasure
The study also showed that the amount of dopamine released was
greater in those who had parents or siblings with alcoholism.
"This is the first human demonstration that a stimulus that is reliably associated with alcohol association -- that flavor alone, without any significant amount of alcohol -- is able to induce a dopamine response," said study author David Kareken, a professor at Indiana University School of Medicine.
The research, published in the April 15 issue of the journal
Neuropsychopharmacology, validates some findings from
earlier animal studies, making them more relevant to understanding
what's happening in people, Kareken said. "We have a long history
of developing alcohol-preferring rats and mice, and the last 20
years of research does show there are neurotransmitters that are
distinguishable in [rats and mice] that prefer alcohol."
Kareken said the study also may help reduce the stigma of
alcoholism. "This is really quite strong evidence that there are
genetic factors that change the brain's chemistry and may act as
risk factors for dependence," he explained.
For the study, 49 right-handed men in good physical and mental
health, with a mean age of 25, underwent two brain scans. None of
the participants had a history of significant drug or tobacco use,
although all of them expressed a preference for drinking beer (as
opposed to other alcoholic drinks). Women were excluded from the
study because it was difficult to find potential participants who
preferred beer and met the criteria for inclusion in the study.
Right-handedness was required because most people have language
capacity on the left side of the brain, and the researchers wanted
to make sure that any differences between the men would not
interfere with the study, Kareken explained. Data about ethnicity
or social or economic level was not collected.
The participants were tested while tasting 15 milliliters (about
half an ounce) of the beer they usually drank, and also while
The beer flavor was mixed with a small amount of alcohol -- not
enough to cause a pharmacological effect -- to help make sure the
participants were experiencing something close to what they would
sense when drinking beer, Kareken explained.
The researchers found that, compared to Gatorade, beer flavor
significantly increased a man's self-reported desire to drink, and
the scans showed that the alcohol-associated flavor induced the
release of dopamine in the brain's striatum region. The association
with dopamine release was greatest in those with parents and
siblings who were alcoholics.
Family history of alcoholism is one of the best ways to assess
genetic risk, explained Kareken. "Alcoholism isn't a simple
autosomal dominant genetic mechanism." (If a disease is autosomal
dominant, it means you only need to get the abnormal gene from one
parent to inherit the disease.) "There are probably many, many
genes that predispose people through different pathways to
eventually have alcoholism."
Dr. Scott Krakower, medical director of the Mineola Community
Treatment Center in Mineola, N.Y., said the research makes
"It's one of the first pieces of research that tests whether the flavor of something affects behavior," he said. "People tell me they can't be around alcohol at all because it immediately triggers them to start drinking," Krakower added.
"The research may change some physicians' advice to patients if they're aware there's an exponential increase in drinking, just due to the flavor of the drink," Krakower said. "We really promote complete abstinence; otherwise it's a slippery slope for people with a history of alcoholism."
Learn more about alcohol and health from the
Centers for Disease Control and Prevention.
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