Alcoholism & Addiction

Study Links Impulsivity of Alcohol-Dependent Individuals to Brain Anomalies

Research has shown that alcohol dependence is strongly associated with impaired impulse control and the tendency to choose smaller, immediate rewards over larger, delayed rewards. A new study used functional magnetic resonance imaging (fMRI) to examine the neurological basis of impulsivity among those with alcohol use disorders found that impulsivity in alcohol dependence could be the result of functional anomalies in brain regions that are associated with cognition and emotions.

Eric D. Claus, first author of the study and a research scientist with the Mind Research Network, said that those with alcohol dependence score higher on tests that measure impulsivity (such as acting without thinking) and are less able to inhibit responses and delay gratification.

Claus said that the study was designed to look at the neural basis of the ability to delay immediate gratification and choose rewards in the future instead. He added that the researchers looked into this choice process in those with alcohol use problems, from alcohol abuse to severe alcohol dependency. He said this is the largest study to date to investigate the neural basis of impulsivity in alcohol dependence, which enabled them to look at the full range of alcohol use disorders.

For the study, the researchers looked at 150 people (103 males and 47 females) with various degrees of alcohol use. The participants completed a task where two rewards were available: a small monetary award that would be available immediately, or a larger monetary award that would be available in a few weeks. The task was completed while the participants were undergoing fMRI. The participants who selected the more immediate option were considered to be impulsive.

Claus said that the study replicated previous research by showing that alcohol use disorder severity was associated with a greater tendency to choose immediate rewards over future rewards. The study also showed that when individuals with more severe alcohol use disorders delayed gratification, regions of the brain that are involved in emotional processing and response conflict were used to a greater degree than those with less severe alcohol use disorders.

These findings suggest that the dysfunction in these brain regions increases with alcohol use disorder severity, showing that the brains of alcoholics aren’t that different from those of non-alcoholics during delay discounting but that the alcoholic brain has to work harder when they choose the delayed reward.

Daniel W. Hommer, chief of the Section of Brain Electrophysiology & Imaging at the National Institute on Alcohol Abuse and Alcoholism, said that many studies have shown that alcoholics have a greater increase in brain blood flow to perform the same task as non-alcoholics.

Claus said that their study suggests that individuals with more severe alcohol use disorders may be more impulsive because their brains are averse to delayed gratification, not because it is rewarding to be impulsive. This information could help researchers and clinicians better understand the difference between impulsive choice and delay discounting.

Source: Science Daily, Researchers Link Alcohol-Dependence Impulsivity to Brain Anomalies, April 15, 2011


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