A Cocaine Cue Acts as an Incentive Stimulus in Some but not Others: Implications for Addiction

Background: In addicts drug cues attract attention, elicit approach, and motivate drug-seeking and drug-taking behavior, and addicts find it difficult to resist such cues. In preclinical studies we have found, however, that food cues acquire incentive motivational properties only in a subset of individuals. For example, a food cue becomes attractive, eliciting approach and engagement with it, and acts as an effective conditional reinforcer in some rats but not others. We asked, therefore, whether rats that have a propensity to attribute incentive salience to a food cue are the same ones that attribute incentive value to a drug (cocaine) cue. Methods: We first used a Pavlovian conditioned approach procedure to determine which individual rats attributed incentive salience to a food cue. A second cue was then associated with the IV self-administration of cocaine. Later, the ability of the cocaine cue to maintain self-administration behavior and to reinstate self-administration after extinction was assessed. Results: We report that in individuals that had a propensity to attribute incentive salience to a food cue, a cocaine cue spurred motivation to take drugs (its removal greatly diminished self-administration) and reinstated robust drug-seeking after extinction. However, in those individuals that failed to attribute incentive salience to a food cue, the cocaine cue was relatively devoid of incentive motivational properties. Conclusions: We conclude that it is possible to determine, before any drug experience, which individuals will most likely have difficulty resisting drug cues, a trait that might confer susceptibility to addiction.