Scientists Discover Genetic Link Among Alcoholism, Impulsivity, and Anxiety

Posted on April 14th, 2011
Posted in Alcoholism

Statistically, researchers often find substance abuse disorders to be comorbid with other mental health conditions—such as alcoholism and impulsive behavior—yet the mechanisms behind these associations has remained unidentified. Now, a new study by researchers at the University of Michigan’s Molecular and Behavior Neuroscience Institute has revealed that these conditions are in fact linked on a genetic level.

Variants of the gene known as GABRA2 (also called the inhibitory γ-amino butyric acid α2 receptor subunit) are some of the very few genetic associations that scientists have confirmed can differentiate alcoholics from non-alcoholics. For example, individuals with the gene are likely to act impulsively when under stress, such as engaging in alcohol-related risks, according to the researchers. In their study, lead researcher Sandra Villafuerte, Ph.D. and colleagues have uncovered two variants of the GABRA2 gene that are actually linked with one’s risk for alcoholism by influencing impulsive behavior in a region of the brain called the insula. Located within the cerebral cortex, the insula has already been found by previous research to be associated with addictive behavior since it controls cravings and anxiety. The two identified variants of the GABRA2 gene can influence brain processing of insula activity—leading to the externalization of impulsivity, thereby increasing one’s risk for alcoholism.

In their study, the researchers recruited 173 families, totaling 449 participants, with 129 of the families having at least one member with an alcohol abuse or dependency diagnosis. Participants who were carriers of the GABRA2 gene variants were more likely to have alcohol-dependency symptoms as well as impulsivity characteristics. Similar to other studies that have found men and women to have differing pathways to alcoholism, the current study also found women with the gene variants to have stronger associations to alcoholism and impulsive behavior than men.

Moreover, participants who were offspring of family members with alcohol-dependency diagnoses and who were genotyped for the GABRA2 variants (44 participants, 20 of which were female) were further asked to complete an incentive delay task in which they anticipated winning or losing money. Using functional magnetic resonance imaging (fMRI), participants’ insula activation, impulsivity, and alcoholism symptoms were recorded while they anticipated reward or loss in response to stimuli. From the recorded neuroimaging, researchers discovered that insula activity significantly increased in participants who carried the gene variant related to alcoholism as they anticipated reward and loss, compared to others who carried different gene combinations. Furthermore, this increase correlated with an increase in impulsive behavior in response to distress. Women, for instance, have been found to be likelier than men to use alcohol as a way to relieve distress or anxiety.

Although the researchers point out that genes alone do not simply determine whether someone will become an alcoholic or not, their study’s findings do show that individuals who carry the GABRA2 gene variants undergo greater stress within their neural system which influences their risk for impulsivity and eventual alcohol dependency behavior. Gene factors—such as the GABRA2 gene variants—as well as subsequent insula stimulation and impulsiveness can all impact one’s risk for alcoholism. For future investigation, the researchers hope to consider genetic influences combined with several environmental factors that influence such risky behavior as alcohol abuse and dependency. The researchers suggest that understanding problem alcohol behaviors through their multiple factors will help clinicians to create more effective prevention and treatment strategies in the future.

The researchers’ new study has been published online in the scientific journal Molecular Psychiatry.

Source: Medical News Today, New Link Between Genetics, Alcoholism And The Brain Explored By Scientists, April 12, 20111

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