Impulsivity and history of drug dependence.

Impulsivity was contrasted between 32 subjects with a history of drug-dependence (DRUG+) and 26 subjects with no drug use history (DRUG-) using both behavioral and self-report measures. The hypothesis was that the DRUG+ group would be more impulsive than the DRUG- group. Subjects in the DRUG+ group self-reported more of a tendency toward impulsivity than the DRUG- group in the situations posed in questionnaires. In the behavioural paradigm involving a choice between a smaller intermediate reward and a larger but delayed reward, DRUG+ subjects selected the impulsive option more often, but these differences were not significant. The DRUG+ and DRUG- groups did differ on the mean delay interval for the larger reward, indicating less ability to tolerate longer delays for the larger reward. A frequency distribution of delay intervals for the larger reward indicated that DRUG+ subjects were more likely to maintain very short intervals and less likely to maintain longer intervals.