of pathological drug-taking (and possibly anticipate all drug use). Research in animal models expands on this data by providing definitive evidence that individual differences in the propensity to engage in impulsive behavior predicts aspects of drug self-administration behaviors, and experience with the pharmacological effects of drugs, over the long-term, can cause abnormalities in action inhibition, waiting, delay discounting and risk-related decision-making. For all these reasons, and despite some inconsistency in the literature, impulsive behaviors do appear to play a key role in the various stages of substance use, abuse and dependence.
