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New research probes the decision to use substances

May 6, 2009
by Gary A. Enos, Editor
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A better understanding of impulsivity’s role could improve intervention options

Would you be inclined to accept a $25 reward now or wait a year and receive $100 instead?

This type of questioning is frequently applied to the decision to use alcohol or drugs, with individuals who are prone to addiction tending to discount the value of delayed rewards. Yet the research community has often asked whether the impulsivity seen in many addicts preceded the addiction or followed it.

A new study from a pair of Indiana researchers, tracking behavior in mice bred to prefer or avoid alcohol, suggests that impulsivity is a predictive trait for alcoholism. The researchers emphasize that it is not known whether impulsivity causes alcoholism, but their data appear to indicate that higher impulsivity precedes drinking and could be associated with it.

“People have tried to understand how drugs act on the brain, but what is the drug-taking decision about?” says Nicholas Grahame, PhD, associate professor of psychology at Indiana University-Purdue University Indianapolis (IUPUI) and co-author of the study to be published in the July issue of Alcoholism: Clinical and Experimental Research. “What allows people not to take the drug? I believe the field will be turning to understanding the decision-making, not just the drug’s effect. Otherwise, you’re too late.”

Comparing choice behaviors among mice bred to be either high alcohol-preferring or low alcohol-preferring, the research team found that genetic differences in drinking were positively correlated with differences in impulsivity. They concluded from their findings that the “genetic risk factor for alcoholism in humans may be accounted for, at least in part, by an enhanced tendency to choose impulsively.”

Grahame says such findings could help sharpen the addiction field’s focus on identifying strategies to help people resist immediate impulses (i.e., to choose instead of drinking or drugs alternative activities that bring longer-term rewards, such as developing personal relationships). These strategies could take the form of behavioral interventions and even possibly drug treatments, Grahame believes.

In addition, Grahame says, the research findings help illustrate why it remains important for the addiction field also to pay attention to the link between alcohol use and other disorders associated with impulsivity, such as bipolar disorder and attention-deficit disorder.