Dr. Ping Wu is an assistant researcher at the National Institute on Drug Dependence, Peking University. She received her Ph.D in Neuropharmacology in 2011 under the supervision of Professor Lin Lu. Her research focuses on the neurobiological mechanisms underlying drug addiction and learning and memory.
What did you set out to discover with your research?
The study explores the effect of a retrieval-extinction procedure on drug craving and relapse.
What were your most significant findings?
Our study showed that drug-seeking behavior in rats and drug craving in humans can be prevented by a retrieval-extinction procedure.
In our studies, before each extinction session, we exposed the rats to a heroin-associated cue, so the extinction session would happen just as the rat's brain would be reconsolidating the emotional memory linking the cue to heroin. We found that this intervention prevented the rats' heroin-seeking responses from reemerging under conditions that would normally make them reemerge (such as injection of a small "priming" dose of heroin). What's more, this effect persisted even if the rats were tested in a different context. This finding strongly suggests that our procedure weakened the emotional memories the rats had previously learned. Timing was crucial; our procedure worked if pre-exposure to the heroin cue occurred 10 minutes before the extinction session, but not if it occurred six hours later. We believe that this reflects the time window during which the emotional memories are vulnerable to disruption.
We applied a very similar procedure to a group of 22 humans—specifically, in-patients who had recently undergone medically supervised detoxification from heroin. In these patients, videos showing heroin use and paraphernalia reliably induced heroin craving, as assessed by questionnaire responses and blood-pressure changes. We found that presenting a heroin-cue videotape 10 minutes before each extinction session (which consisted of exposure to heroin paraphernalia and simulated heroin) attenuated the patients' craving during the extinction session itself, and also prevented cue-induced craving for heroin 1, 30, and 180 days later. Again, timing was crucial; these benefits did not occur in 22 other patients whose video pre-exposure happened six hours later rather than 10 minutes before the extinction session or in a third group of 22 patients who weren't shown the video.
Were these surprising?
Yes, these findings were surprising. Previous studies in rats and humans have shown that drug related memories are vulnerable to interference during reconsolidation: certain drugs given during reconsolidation can make the memory weaker. Unfortunately, most of these drugs have undesirable side effects or are not approved for human use. What's new in our work is that we've found a way to achieve the same effect without giving any drugs.
What are the potential implications of your findings?
The prevention of craving and relapse is probably the greatest challenge in the treatment of addiction, and our procedure is effective in preventing drug craving and relapse without involving medication.
What is the next step for your research?
We still need to know more about whether this new procedure will help patients avoid relapsing when they return to their usual environments, but our rat data suggest that it might.
These are Dr. Ping Wu's written remarks. Please refer to the video interview for exact quotes.
Related Research Papers
A Memory Retrieval-Extinction Procedure to Prevent Drug Craving and Relapse
Press release: For ex-addicts, a drug-free way to prevent relapse?