Researchers from the Brookhaven National Laboratory and the National Institute on Drug Abuse (NIDA) have demonstrated that an area of the brain called the Anterior Cingulate Cortex (ACC) shows differences in levels of activity between cocaine users compared with non-users when performing a series of tasks, even though both groups are evenly matched demographically (socially, cognitively, educationally, etc.).

The study suggests that this difference in brain activity is not due to prior variance in cognitive ability or lack of motivation on the part of drug users, but rather because drug-users' brains act differently from non-users', Medical News Today reported May 26.

The researchers took 17 individuals with current cocaine-use disorders (CUD) and 17 demographically matched healthy controls and gave them several tasks to perform while the subjects underwent functional magnetic resonance imaging.

Both groups performed equally well at all the tasks. However, the levels of ACC activity differed between the two groups as the tasks were performed. In tasks that required monitoring behavior, activity in the ACC increased among the healthy non-drug users, but for the cocaine users this did not happen. Also, among the cocaine users the level of ACC activity was lowest in those who had used cocaine more frequently.

In other tasks in which emotion needs to be suppressed (emotion-monitoring), another part of the ACC becomes less active, but in the cocaine users this activity was not suppressed to the same extent as among non-drug users.  

The major functions of the ACC (behavior-monitoring and emotion-monitoring) are located in a pair of regions in the same area of the brain. When the researchers measured the subjects' responses to stimuli, these two regions of the brain behaved differently between the non-drug users and the drug users. Among the non-addicted subjects, the researchers found that the two parts of the ACC communicated with each other whereas among the cocaine users such communication did not take place. The researchers suggest that this was because the drug users experienced a disruption between the two functions of the ACC.

Lead author Rita Z. Goldstein, a psychologist at Brookhaven National Laboratories, said the study, "gives us some clues as to what happens when drug users are unable to suppress craving -- and how that might work together with a decreased ability to monitor behavior … to make some people more vulnerable to taking drugs."

The study was published online in the May 2009 issue of the Proceedings of the National Academy of Science.