Blocking Drug Memories Can Help Fight Addiction, Researchers SaySeptember 16, 2005
Research Summary
Selectively blocking memories of past drug use could help people overcome their drug addictions, according to researchers who successfully eliminated such memories in animal tests.In one study, Jonathan Lee and colleagues at the University of Cambridge created memories of cocaine use in lab rats, then blocked the memory and redirected the cocaine reward mechanism used in the experiment in order to test a process called "reconsolidation" -- a theory that holds that recalled memories can be malleable and subject to disruption. The researchers injected the rats with a molecule that blocked the formation of cocaine-related memories and found that the rats' ability to push a lever to get cocaine was disrupted, even though their other behaviors were unaffected.
"Drug-associated stimuli are critically important in the acquisition of prolonged periods of drug-seeking behavior, maintenance of this behavior in the absence of reward, and precipitation of relapse to drug seeking in the absence of reward," Lee and colleagues wrote. "Therefore, the ability to disrupt retroactively the conditioned reinforcing properties of a drug cue provides a potentially powerful and novel approach to the treatment of drug addiction by diminishing the behavioral impact of drug cues and thereby relapse."
In another study, Courtney Miller and John Marshall of the University of California at Irvine looked at how the nucleus accumbens region of the brain is involved in cocaine-related memories. The researchers taught rats to associate one of two chambers with cocaine, and found that certain neural pathways in the brain were activated during cocaine seeking. When they blocked ERK, a molecular switch that activates these pathways, the rats could not remember which chamber contained the cocaine.
"To our knowledge, the current study is the first to identify a molecular mechanism that blocks both retrieval and reconsolidation of any type of memory," wrote Miller and Marshall. "While much remains to be understood concerning the cellular processes underlying the effects of ERK in drug-stimulus associations and other types of learning and memory, the present findings offer hope for treating cue-elicited relapse in addicts."
The studies appear in the Sept. 1, 2005 issue of the journal Neuron.
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