Evidence for addiction-like behavior in the rat

Although the voluntary intake of drugs of abuse is a behavior largely preserved throughout phylogeny, it is currently unclear whether patholog-ical drug use (“addiction”) can be observed in species other than humans. Here, we report that behaviors that resemble three of the essential diag-nostic criteria for addiction appear over time in rats trained to self-administer cocaine. As in humans, this addiction-like behavior is present only in a small proportion of subjects using cocaine and is highly predictive of relapse after withdrawal. These findings provide a new basis for devel-oping a true understanding and treatment of addiction. The voluntary intake of drugs of abuse is a behavior largely conserved throughout phy-logeny. Preferences for drug-associated en-vironments or drug-reinforced learning of tasks have been found in several species (1–6). The possibility of studying thes