Brain Imaging Predicts Relapse to Cocaine
September 14, 2015
People who are addicted to cocaine focus obsessively on obtaining and using the drug, neglecting normal goals and satisfactions. Researchers have linked this lost motivation for non-drug pursuits to reduced activity in brain areas that evaluate the results of our actions and determine whether the actions are worth repeating. Now, a NIDA-supported study has found that a cocaine-addicted person’s chance of managing 1 whole year of abstinence correlates with activity levels in these impaired motivational and decision-making brain areas.
The study’s findings suggest that more severe cocaine-induced impairment in these brain areas makes people more susceptible to relapse after treatment for cocaine addiction. As a result, functional magnetic resonance imaging (fMRI) of these brain areas might be a useful tool for assessing patients’ treatment needs and tracking their progress in recovery.
An Easy Game
Dr. Jennifer Stewart, Dr. Martin Paulus, and colleagues at the University of California, San Diego performed fMRI on 30 patients who were starting treatment for cocaine addiction. The scans recorded activity in three brain areas while the patients played a computerized version of the game Paper-Scissors-Rock (P-S-R).
The scans recorded activity in areas that studies have shown to be weakened in cocaine addiction: the insula, striatum, and prefrontal cortex (PFC). Together, these areas learn to associate actions with good or bad experiences that follow, identify opportunities to repeat the actions and re-experience those outcomes, and weigh the opportunities against the risks of going ahead.
To test the vitality of the three brain areas, the researchers modified the traditional P-S-R game to engage these functions (see Figure 1). Each patient played 120 rounds of the game in six 20-round blocks. The computer was programmed to be rather predictable and make the same play—paper, scissors, or rock—90 percent of the time in each block. Thus, patients should be able to readily pick up on the computer’s pattern and, once they did, win 9 rounds out of 10 by making the correct counter-play. The researchers awarded $1 for each round won against the computer and subtracted $1 for each round lost.
The researchers also asked the patients how badly they wanted to win. A year later, they re-contacted all 30 patients and learned who had relapsed in the interim and who had not.
Stewart, J.; Connolly, C.; May, A. et al. Cocaine dependent individuals with attenuated striatal activation during reinforcement learning are more susceptible to relapse. Drug and Alcohol Dependence, 2014. Full text
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