Cues Give Clues in Relapse Prevention

More than 85% of people who give up an addictive drug begin using it again within a year. Relapse can occur following exposure to cues that are found in the environment which trigger the memory of their drug-taking experience. These cues might be situations, places, sensations or objects and may grow in strength over time, a phenomenon called “incubation of craving”. Animal models of incubation have typically focused on how rats respond to cues that were present when they were previously taking drugs (conditioned stimuli) and cues indicating the availability of drugs (discriminative stimuli).

A recent study has sought to understand the contribution of discriminative stimuli to the incubation phenomenon.

Rats were trained to press a lever to receive cocaine or pleasant food under discriminative stimuli environment where one light signalled the availability of the drug, and another light indicated that cocaine would not be available. They also tested discriminative stimuli-controlled incubation of craving in the absence of conditioned stimuli.

Results from the study show that:

• Rats readily learned to respond to the discriminative stimuli for both cocaine and food. 
• Discriminative-stimuli control seeking incubated over 60 days of abstinence and persisted up to 300 days
• Incubation was specific for cocaine only.

This study indicates that discriminative stimuli can be powerful and persistent drivers of drug-craving and provides a model for examining the neural mechanisms of how cues promote relapse.