Cocaine addicts' brains predisposed to abuse

Cocaine addicts may have brain deficits that predispose them to drug abuse, and abusing drugs appears to make matters worse, U.S. researchers said on Wednesday.

They said images of cocaine addicts' brains reveal abnormalities in the cerebral cortex - the brain's outer surface - and these changes relate to dysfunction in areas responsible for attention and decision-making.

"These data point to a mixture of both drug effects and predisposition underlying the structural alterations we observed," said Dr. Hans Breiter of Massachusetts General Hospital, whose research appears in the journal Neuron.

Breiter and colleagues compared magnetic resonance images, or MRIs, of 20 cocaine addicts with 20 carefully matched volunteers to map out cocaine-related differences in the brain.

Compared to their healthy counterparts, cocaine addicts had far less overall volume in the cortex, the outer layer that helps plan, execute and control behavior. These differences were especially pronounced in areas regulating reward, attention and decision-making.

They also noticed that while the healthy volunteers tended to have thicker areas in some frontal regions on the right side of the brain, this was reversed in the addicts. And overall, the addicts had less variation in the thickness of their cortex.

Differences in the right and left side of the brain are important because they typically suggest a genetic cause, Breiter said.

The researchers also found changes in the cingulate - another reward center - that appeared to correspond with the length of cocaine use but not nicotine or alcohol use, suggesting that these changes were the result of long-term cocaine exposure.

"Human studies have shown differences in how addicts make judgments and decisions, but it is not well understood how these differences relate to alterations in the structure of the brains of addicts," Breiter said in a statement.

The researchers said the findings underscore the importance of keeping vulnerable people from using cocaine. And they said follow-up studies should be done to see if similar changes are present in people with other addictions.

CHICAGO (Reuters)