"The genetic findings raise the hopeful possibility that treatments aimed at raising dopamine levels could be effective treatments for some individuals with addictive disorders," said Fields, who is senior author of the study.
Most addiction imaging studies have focused on the brain response to drug-related stimuli.
Boettiger used functional magnetic resonance imaging (fMRI), which shows brain activity while a subject performs a function, to see what happened inside their heads when sober alcoholics and people in a non-alcoholic control group made decisions between immediate and delayed rewards.
Boettiger recruited 24 subjects; 19 provided fMRI data, nine were recovering alcoholics in abstinence and 10 had no history of substance abuse. Another five were included in the genotyping analysis.
At the fMRI research facility at the University of California, Berkeley, the subjects were asked to decide between receiving a small monetary award immediately or wait for a larger payoff. The scenarios were hypothetical, but the tasks measured rational thinking and impulsivity; sober alcoholics chose the "now" reward almost three times more often than the control group, reflecting more impulsive behavior.
While decisions were being made the imaging detected activity the predicted individual choice in regions associated with decision making -- the posterior parietal cortex, the dorsal prefrontal cortex, the anterior temporal lobe and the orbital frontal cortex.
People who sustain damage to the orbital frontal cortex generally suffer impaired judgment; they manage money poorly and act impulsively. Boettiger's study revealed reduced activity in the orbital frontal cortex in the brains of subjects who preferred "now"over "later," most of whom had a history of alcoholism.
The orbital frontal cortex activity may be a neural equivalent of long-term consequenc
|Contact: Clinton Colmenares|
University of North Carolina at Chapel Hill