Choice reveals that rats are majoritarily resilient to cocaine addiction

Abstract

Assessing the relative reward value of cocaine and how it changes with repeated use represents a long-standing goal in addiction research. Surprisingly, recent experimental research in rats – the most frequently used animal model in the field – suggests that the reward value of cocaine may in fact be relatively weak at least in the majority of individuals. Here, we provide strong additional evidence that confirms and extends the validity and generality of this research. Specifically, we demonstrate that no matter how heavy is past cocaine self-administration, most rats value cocaine poorly and readily decide to quit when offered the opportunity of making a different choice (i.e., drinking water sweetened with saccharin, an otherwise biologically inessential rewarding behavior). On average, rats estimate that cocaine is worth about 10 times less than the alternative reward. Only a small minority of rats prefer to continue taking cocaine when offered the choice. These findings reveal the existence of a genuine resilience to cocaine addiction in the majority of rats, a phenomenon that has long been suspected, though not firmly demonstrated, in humans. Only a minority would be prone to develop this disorder. We propose that choice should serve as a behavioral screening assay to identify vulnerable individuals, among the resilient majority, in future experimental research on the determinants of cocaine addiction.