'Erasing' drug-associated memories may stop drug addictio...( 'Erasing' drug-associated memories m...)

'Erasing' drug-associated memories may prevent recovering drug abusers from relapsing, researchers at the University of Cambridge have discovered.

The team, led by Professor Barry Everitt, was able to reduce drug-seeking behaviours in rats by blocking a brain chemical receptor important to learning and memory during the recall of drug-associated memories. Their research, which was funded by the Medical Research Council, was reported in the 13 August issue of The Journal of Neuroscience.

The Cambridge scientists found that by disrupting or erasing memories associated with drug use during recall, they could prevent the memories from triggering relapses and drug taking.

Memories exist in different states depending on whether they are being recalled or not. When memories are recalled, they become 'unstable' or malleable and can be altered or erased during the process called reconsolidation. Because relapse by drug abusers is often prompted when they recall drug-associated memories, the scientists found that by blocking these memories they could prevent relapse.

In order to undertake the experiments, the researchers trained rats to associate the switching on of a light with cocaine. The researchers then exposed the rats to the light, thereby 'reactivating' the memory, without the cocaine. In an effort to receive more cocaine, the rats would perform tasks that the scientists had created which would turn on the light.

When the animals were given a chemical that interfered with the action of the NMDA-type glutamate receptor (which plays an important role in memory) prior to the 'reactivation' session, the rats showed reduced cocaine-seeking behaviours. A single treatment reduced or even stopped drug-seeking behaviours for up to four weeks.

In contrast, blocking the receptors after or without the reactivation session had no effect on subsequent drug-seeking behaviours, indicating that drug-associated memories can
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