Individual differences in the reinforcing and subjective effects of d-amphetamine: Dimensions of impulsivity

Previous research has shown a relationship between impulsive personality and the subjective and reinforcing effects of d-amphetamine. Impulsive personality, however, is comprised of multiple dimensions. The association between different dimensions of impulsive personality and the subjective and reinforcing effects of d-amphetamine is unknown. The objective of this study was to assess the independent contributions of the "sensation-seeking" and "impulsivity" dimensions of the impulsive sensation-seeking subscale of the Zuckerman-Kuhlman Personality Questionnaire (ZKPQ) to the subjective and reinforcing effects of d-amphetamine. Forty healthy emerging adults varying in scores on the sensation-seeking and impulsivity dimensions of the ZKPQ participated in a double-blind, placebocontrolled, randomized study comprised of 4 2-day blocks. Each 2-day block consisted of a sample day and self-administration day. Subjective effects and physiological measurements were taken prior to, and hourly for 3 hr following, dose administration. On sample days participants were given 8 capsules containing 0, 1, or 2 mg d-amphetamine. On self-administration days participants were able to earn capsules containing the same dose of d-amphetamine that was administered on the previous sample day by responding on a Modified Progressive Ratio Task. The "sensation-seeking" dimension was positively associated with drug taking on the Modified Progressive Ratio Task, subjective effects (e.g., "good effect"), and heart rate. However, no clear relationship between the "impulsivity" dimension and outcome measures was observed. In conclusion, these data suggest that the narrow sensation-seeking dimension of impulsive sensation-seeking is associated with initial drug liking and drug taking behavior and may be a key predictor of drug use initiation.