Effects of Dextroamphetamine Sulfate on Repeated Acquisition Behavior and Mood in Humans: A Preliminary Report

Abstract

The specific aim of the present investigation was the systematic assessment of the effects of nontoxic doses of orally administered dextroamphetamine sulfate on the learning behavior maintained by the repeated acquisition task in humans. Subjects were four healthy male humans ranging in age from 23 to 29 years. The participants reported to the experimental setting at a specified time for the duration of the experiment. Following assessment of physiologic parameters, subjects received either anhydrous dextrose placebo or 5, 10, or 15 milligrams (mg) dextroamphetamine sulfate. Two hours after drug administration participants returned to the experimental area where they completed two repeated acquisition sequences and two self-report scales—49 items from the Addiction Research Center Inventory and the 72-item Profile of Mood States. The 2-hour interval between drug administration and subsequent behavioral testing was necessary for assessment of peak drug effect. Learning of the behavioral chains of the repeated acquisition task, using light position as a discriminative stimulus, was characterized by a decrease in errors and an increase in response rate which was maximal at a dose of 10 mg drug. Subjective measure of drug effect on four mood clusters of the Profile of Mood States and five subscales of the Addiction Research Center Inventory demonstrated primarily a dose-related function.