Scientists have found “significant abnormalities” in the brains of people addicted to cocaine, which could help explain some of the compulsive behavior associated with using the drug. It may also hint at why some people are more prone to addiction.
Brain scans revealed that cocaine users had a “dramatic decrease in gray matter” in their frontal lobes, researchers said, which affected key functions, including decisionmaking, memory and attention.
Karen Ersche of the Behavioural and Clinical Neuroscience Institute at the University of Cambridge, who led the latest work, found the longer a person had been using cocaine, the poorer their attention was and the more compulsively they used the drug.
“That is the hallmark of cocaine dependence — namely, that most of them are intelligent people who go to great extents to buy cocaine, to get more cocaine, to put their jobs at risk, their families at risk,” Ersche said.
The results were published in the journal Brain. Ersche and her team scanned the brains of 60 people who were dependent on cocaine and compared them to scans of 60 people without any history of drug-taking.
“We found significant abnormalities in the brains of the cocaine users,” she said.
Specifically, the amount of gray matter in the orbitofrontal cortex was reduced in people with cocaine addiction, an area involved in decisionmaking and goal-directed behavior.
Other affected areas included the insula, an area of the brain involved in feedback processing, learning and feelings of cravings. The gray matter in the anterior cingulate, involved in emotional processing and being attentive, was also reduced.
In contrast, a region deep in the brain associated with reward processing, attention and motor movements — the chordate nucleus — was enlarged in subjects who were addicted to the drug. This could explain why those subjects were more prone to addiction, but the scientists cannot be sure whether the enlargement is a result of cocaine use.
Ersche said her research was not conclusive on which came first.
“At the moment, correlation shows me a direct relationship — but I don’t know which direction the relationship is,” she said.
However, the work could be used to help in diagnosis and treatment of addiction.
“We basically show that cocaine is a disorder of the brain, which is a big step,” Ersche said.