Study Finds Association between Gene Variations and Risk of Alcoholism

Researchers have discovered a new link between genetic variations associated with alcoholism, impulsive behavior, and a brain region that is involved in craving and anxiety. Their study suggests that variations in the GABRA2 gene contribute to the risk of alcoholism by influencing impulsive behaviors through a part of the brain called the insula.

Senior author Margit Burmeister, Ph.D., research professor at the University of Michigan Health System’s Molecular and Behavioral Neuroscience Institute, said that scientists often find an association between genes and behaviors, but the underlying mechanism remains a mystery. In this study, the researchers help explain how specific genetic risk factors influence the brain and behaviors.

Lead author Sandra Villafuerte, Ph.D., a research investigator at the University of Michigan’s Molecular and Behavioral Neuroscience Institute and Department of Psychiatry, added that having a better understanding of the various genetic and environmental factors that are involved with risky behaviors can help develop effective prevention efforts and treatment methods in the future.

The researchers examined 449 people from 173 families, 129 of whom had at least one member diagnosed with alcohol dependence or abuse. They found that those with certain variations of the GABRA2 gene were more likely to have symptoms of alcohol dependence and higher impulsivity in response to distress. The study also found stronger associations in women than men.

Burmeister said that these findings wouldn’t be surprising to an alcohol researcher, as men and women respond to alcohol differently, and women tend to drink to relieve anxiety and stress more often than men do.

The researchers also used functional magnetic resonance imaging (fMRI) to examine changes in blood flow in the brains of 44 young adults from these families as they completed a task in which they anticipated losing or winning money.

The brain scans allowed the researchers to see how the genetic variants create differences in the ways the brain responds in certain situations, according to Mary M. Heitzeg, Ph.D., a research assistant professor in U-M's Department of Psychiatry and U-M's Addiction Research Center.

The study also found that those with one form of the GABRA2 gene that is associated with alcoholism showed significantly higher activation in the insula when anticipating rewards or losses compared to those with other combinations of the gene. The heightened activation was associated with a greater level of impulsiveness in response to anxiety and distress.

The insula has long been associated with addictive behavior. A 2007 study found that smokers who had stroke-induced insula damage found it much easier to give up cigarettes than smokers without damage to the insula.

Burmeister said that the findings suggest that GABRA2 influences an underlying neural system that impacts early risk factors for alcohol abuse and dependency. The authors concluded that they hope to examine the effects of family environment and other behavioral and environmental factors in the future.

Source: Science Daily, Scientists Explore New Link Between Genetics, Alcoholism and the Brain, April 13, 2011

Posted on April 22nd, 2011

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