Blocking Drug-Related Memories May Prevent Relapses

It may be possible to prevent a drug addiction relapse by disrupting the brain's attempts to retrieve drug-associated memories, according to new research.

U.K. researchers reduced drug-seeking behaviors in rats by blocking their brain's NMDA-type glutamate receptor, which is vital for learning and memory, during the recall of drug-associated memories. Researchers have known that recalling memories linked to previous drug use, such as environmental cues, can cause recovering drug addicts to relapse.

The findings are published in the Aug. 13 issue of The Journal of Neuroscience.

In the study, researchers at the University of Cambridge trained rats to associate a light going on with receiving a dose of cocaine. They "reactivated" the memory by exposing the rats to the light without the cocaine infusion. Later, the rats continued to perform behaviors that turned on the light or learned to perform new behaviors to try to get more cocaine.

The rats' cocaine-seeking behaviors were reduced after the researchers gave the animals a chemical that interfered with the NMDA-type glutamate receptor. When the single treatment was given just prior to the reactivation session, it reduced or even stopped drug-seeking behavior for up to a month; however, when given after or without the reactivation session, it had no effect on subsequent drug-seeking behaviors.

The findings suggest combining existing therapy with properly timed use of NMDA receptor inhibitors may help addicts kick their habits. The U.S. Food and Drug Administration already has approved several NMDA receptor inhibitors, including the cough suppressant dextramethorphan and the Alzheimer's disease drug memantine.

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