"If the G allele affects subjective experience such as craving for alcohol after exposure, this could also have an influence on subsequent drinking behavior. It turns out that G allele carriers do crave significantly more for alcohol after alcohol exposure, compared with the A allele individuals."
"Studies like this one are important in terms of saying something about how a gene might be involved in alcohol dependence," said Kent Hutchison, associate professor at the University of Boulder, Colorado. "In this case, the study suggests that this genetic marker may be related to how much a person craves alcohol in a high-risk situation, that is, when someone hands him or her an alcoholic drink. At this point in time, this gene definitely seems to be one of the key genes related to alcohol dependence. There will undoubtedly be others."
Researchers recruited 108 male, heavy drinkers via flyers in and around the University of Maastricht. Participants were either homozygous for the A allele (n=84) or carrying at least one copy of the G allele (n=24). All participated in a cue-reactivity test where they were exposed to water and beer in three-minute trials. Dependent variables included subjective craving for alcohol, subjective arousal, and saliva production.
"By looking at cue-elicited craving in heavy drinkers, we look more specifically into a so-called 'endophenotype,'" explained van den Wildenberg. An endophenotype, she said, is like an intermediate phenotype. It lies "between" the genotype, referring to genes, and the phenotype, which refers to the disorder; reflecting a biological mechanism that underlies the disorder.
"Not only did G allele carriers report even significantly more craving for alcohol than the A allele individuals," said van den Wildenberg, "but G allele carriers reported more life-time drug use compared with the 'standard' genotype participan
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3-Jan-2007