Previous research found a strong correlation between impulsivity and alcohol abuse, but did not discern whether this link was caused by social factors, genetics, or chemical changes resulting from alcohol. Alcohol can damage the brain in myriad ways, so many doctors speculated that over-consumption could also damage systems of self-restraint. However, a study led by Dr. Nicholas Grahame, published in this month’s issue of Alcoholism: Clinical and Experimental Research, found compelling proof that the correlation is primarily genetic.

Dr. Grahame bred 30 generations of mice until he had two groups, one that disliked alcohol and one that greedily consumed it. Then he took a generation of these mice that had never tasted alcohol and tested them for impulsivity by allowing them the choice between a small but immediate reward and a large delayed reward. The group genetically inclined to abuse alcohol was significantly more likely to impulsively choose the smaller reward.

The results of this study form solid evidence that the genes for impulsivity and alcoholism are connected, perhaps because both problems stem from insufficient levels of dopamine and the need for stimulation. This knowledge is important because it warns doctors to look for signs of alcoholism whenever a patient is diagnosed with something that includes impulse problems, such as bipolar disorder or attention deficit disorder.