Using an animal model of drug craving in laboratory rats, researchers at the Intramural Research Program of the National Institute on Drug Abuse (NIDA) have found that craving for cocaine seems to increase, rather than decrease, in the days and months after drug use has stopped.
"This phenomenon helps explain why addiction is a chronic, relapsing disease," says NIDA Director Dr. Alan I. Leshner. "Craving is a powerful force for cocaine addicts to resist, and the finding that it persists long after last drug use must be considered in tailoring treatment programs."
The research team, which included Drs. Jeff Grimm, Bruce Hope, Roy Wise and Yavin Shaham, published its findings in the July 12, 2001, issue of Nature.
In the study, the scientists found that sensitivity to drug-associated environmental cues that often accompany drug craving and relapse increased over a 60-day withdrawal period. Cocaine craving was inferred from the behavior of rats trained to press a lever to receive intravenous cocaine injections. Once the animals had learned to associate the lever-pressing with receiving cocaine, they were tested under conditions where they could continue to press the lever, but no longer received cocaine.
In humans, drug-associated environmental cues often stimulate cocaine craving and accompany relapse to drug-using behavior. The NIDA investigators wrote in their report to Nature that "the data from this study suggest that an individual is most vulnerable to relapse to cocaine use well beyond the acute drug withdrawal phase."
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