previous research has indicated that alcohol dependence (AD) is strongly associated with impaired impulse control or, more precisely, the inability to choose large, delayed rewards rather than smaller but more immediate rewards.
Now, a new study has suggested that impulsive choice in AD may be the result of functional anomalies in widely distributed but interconnected brain regions that are involved in cognitive and emotional control.
The study used functional magnetic resonance imaging to examine impulsive choices among people with a range of alcohol use disorders (AUDs).Individuals with AD score higher on questionnaires that measure impulsivity - for example, 'I act without thinking' - are less able to delay gratification, and are less able to inhibit responses," said Eric D. Claus, a research scientist with The Mind Research Network and first author of the study.
Claus and his colleagues examined 150 individuals -103 males, 47 females- with various degrees of alcohol use.
All of the participants completed a delay-discounting task - during which two options were presented, a small monetary reward available immediately or a larger monetary reward available in time- while undergoing fMRI.
Impulsive choice was defined as the selection of the more immediate option.
"We replicated previous research by showing that AUD severity was associated with a greater tendency to discount future rewards," said Claus.
"In addition, we showed that when individuals with more severe AUDs did delay gratification, they engaged the insula and supplementary motor area - regions involved in emotional processing and response conflict - to a greater degree than individuals with less severe AUDs.
"In summary, these findings suggest that the dysfunction in these regions is graded and increases as a function of AUD severity, rather than operating as an all-or-none function," he added.
The findings are available at Early View.