Genetics may determine to what extent you're swayed by the alcohol consumption of people around you, new research suggests.
A study published in a recent issue of Psychological Science found that people with a particular genetic profile are far more likely than others without the gene to drink more when they see someone else drinking heavily.
The finding is "quite meaningful" and "illustrates how much genetics determines drinking patterns of individuals exposed to other drinkers", said psychiatrist Dr Marc Galanter of New York University Langone Medical Center.
The study focused on different versions of a receptor for the neurotransmitter dopamine, which controls feelings of pleasure. Previous work had shown that one form of this receptor, which contains a series of seven repeats of the same DNA sequence, is associated with increased alcohol cravings in a variety of situations.
To see if this DNA influenced reactions to social drinking situations, Helle Larsen of Radboud University Nijmegen in The Netherlands, recruited young adult volunteers - allegedly to watch and evaluate TV commercials between 4 and 9pm in a setting that resembled a typical Dutch pub.
However, Larsen's real objective was to see how many drinks each person consumed during the study's break times.
The researchers also collected DNA samples from each participant to see which version of the dopamine receptor they possessed.
Larsen and her colleagues found that people with the seven-repeat version of the dopamine receptor were far more likely than those with a different version to drink heavily when they saw others doing so. The researchers suggest that individuals with this particular genetic background are much more sensitive to others' drinking behaviors.
The results provide an interesting view into "the interaction between genetics and reactions to environmental circumstances", Galanter said.
It's not clear why this particular version of the dopamine receptor might trigger increased responsiveness to others' drinking, Larsen said, although some researchers have speculated that people with this receptor are less sensitive to dopamine's actions, and so are likely to drink more to try to feel its pleasurable effects.
The authors also noted that seeing others drink lightly didn't boost the urge to drink more in those with the receptor; only witnessing heavy drinking triggered the desire.
While emphasizing that the results are preliminary and need replication, the authors said the study setup simulated a real-life situation, similar to that faced in a bar, restaurant or at a party.
Individuals with this genetic propensity may have to avoid many social drinking situations if they wish to curb their own alcohol intake, Larsen said.
"If you really don't want to drink or you know that it is difficult for you to refrain from drinking, maybe partly because of a genetic predisposition, then you should stay out of alcohol contexts, because these cues are so strong," Larsen said.
Social psychologist Henry Wechsler, of the Harvard School of Public Health, cautioned that a couple of aspects of the experiment may have influenced the results, however. The drinks offered during the study were free, but "studies have shown that price has a significant effect on drinking behavior," he said.
Also, it's possible that the participants' behaviour was altered because they thought of themselves as being under the watch of "responsible scientists," he said. "They may consider themselves protected from harms associated with heavy drinking." - (HealthDay News, August 2010)