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Alcoholism May Be Linked to Impulsivity Gene, Brain Differences
Researchers have made much progress recently in understanding the genetics of the predisposition for alcoholism. A new study finds some interesting connections between a certain gene that influences addiction and alcoholism, impulsive behavior, and a brain region that governs anxiety and craving.
The new study followed 173 families, 129 of whom had at least one person with alcoholism. The research team did genetic tests to determine which versions of a gene called GABRA2 they had: one variant of the gene has previously been linked to alcoholism and to certain changes in brain waves.
The study found that people with this version of the GABRA2 gene were more likely to be alcoholics than people with other variations of the gene. What’s more, people with this variant also showed more impulsiveness — especially women. Research has long shown that women and men differ in their triggers for alcoholism, and in the underlying physiological mechanisms. It’s likely that GABRA2 influences alcohol dependence through its effect on impulsive behaviors.
To see what was going on in the brain, the researchers had the participants undergo MRI scans while they played a game in which money was at stake. This allowed the team to see which parts of the brain were active as the participants anticipated rewards and losses.
The researchers found that people with the GABRA2 variant associated with alcoholism had different activity in a brain area called the insula, which is known to moderate craving, addictive behavior, and anxiety. These individuals also showed more impulsiveness at times when they felt distressed during the exercise. Author Mary M. Heitzeg says in the study’s press release that the "neuroimaging allowed us to see for the first time how these genetic variants create differences in how the brain responds in certain situations."
The study is important because it pulls together several puzzle pieces to help clarify the relationships between genes, the brain, and behaviors (alcoholism and impulsiveness). Study author Margit Burmeister explains that "[s]cientists often find a statistical association between behaviors and various genes, but the mechanism that’s at work frequently remains unclear. Here we took some steps toward explaining how specific genetic risk factors are influencing behavior and the brain."
Of course, there are also many environmental factors involved in alcohol dependence, which will need attention in follow-up studies. In this vein, Burmesiter says that in the future she and her team "hope to further examine the effects of family environment and other behavioral and environmental factors."
The research was carried out by a team at the University of Michigan, Ann Arbor, and published in the April 12, 2011 online issue of Molecular Psychiatry.
April 29, 2011