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Gene links alcoholism, impulsivity

U. MICHIGAN (US) — New research links a genetic variation with alcoholism, impulsive behavior, and an area of the brain involved with craving and anxiety.

The finding could have potential for the development of future prevention and treatments.

“Scientists often find a statistical association between behaviors and various genes, but the mechanism that’s at work frequently remains unclear,” says Margit Burmeister, research professor of molecular and behavioral neuroscience and professor of psychiatry and human genetics at the University of Michigan.

“Here we took some steps toward explaining how specific genetic risk factors are influencing behavior and the brain.”

Individuals under distress who have the genetic variation tend to act impulsively, which can lead to the development of alcohol problems, says research investigator and lead author Sandra Villafuerte.

The research is published online in Molecular Psychiatry.

The study included 449 people, who came from 173 families—129 of whom had at least one member diagnosed with alcohol dependence or abuse. Those with certain variations in the GABRA2 gene were more likely to have alcohol dependence symptoms and higher measures of impulsiveness in response to distress. Stronger associations were found in women than in men.

“This wouldn’t be a surprise to an alcohol researcher,” Burmeister says. “Men and women tend to have different pathways to alcoholism. Drinking to relieve anxiety and distress is seen more in women.”

Using functional magnetic resonance imaging (fMRI), the researchers were able to observe changes of blood flow in the brains of 44 young adults from these families as they performed a task in which they anticipated winning or losing money.

“The neuroimaging allowed us to see for the first time how these genetic variants create differences in how the brain responds in certain situations,” says Mary Heitzeg, research assistant professor of psychiatry.

Individuals with one form of the GABRA2 gene associated with alcoholism showed significantly higher activation in the insula when anticipating rewards and losses than those with other combinations. This higher activation was also related to a greater level of impulsiveness in response to distress.

The insula’s association with addictive behavior is well known. For example, in a previous study, smokers who had insula damage due to stroke found it much easier to give up cigarettes.

“We believe these results suggest GABRA2 exerts an influence on an underlying neural system that impacts early risk factors and, later, alcohol dependency,” says Burmeister.  “In the future, we hope to further examine the effects of family environment and other behavioral and environmental factors.”

The authors stress that genetic risk factors don’t act alone and simply having them does not mean that someone will become an alcoholic.

The study was funded by the National Institutes of Health.

More news from University of Michigan: www.ns.umich.edu/

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