Solving the age-old chicken and the egg dilemma, Indiana University-Purdue University Indianapolis researchers report that genetic predisposition to impulsivity is a trait predictive of alcoholism.
The study appears on the July print issue of the journal Alcoholism: Clinical and Experimental Research, available online on April 22.
The researchers, led by Nicholas Grahame, Ph.D., associate professor of psychology at the IUPUI School of Science, used selective breeding for 30 generations to produce mice who were high volume alcohol drinkers and others who avoided consuming alcohol. The genetically different mice were presented with a choice between a small, immediate reward and a large, delayed reward. By adjusting the quantity of the immediate reward up and down based on choice behavior, the task allowed the researchers to test the impulsivity of the rodents.
The mice with high alcohol preferring genes were more impulsive than their low drinking counterparts demonstrating that predisposition to impulsivity is predictive of alcoholism.
"Selective breeding allowed us to focus on whether changing genes changes behavior. Just like golden retrievers are bred to retrieve, we were able to breed mice genetically predisposed to drink alcohol voluntarily. Many drink enough to reach a blood alcohol level of .08," said Dr. Grahame, who is a behavioral geneticist.
In humans a blood alcohol level of .08 is produced by the consumption of two drinks an hour by a 120-pound individual or 3 drinks an hour by a 180-pound individual. At that level human concentration and judgment are impaired and all 50 states prohibit operation of a motor vehicle.