Date of Award

6-2003

Degree Name

Doctor of Philosophy

Department

Psychology

Abstract

Methylphenidate (MPH) is widely used in the treatment of ADHD, and is associated with positive effects across a wide range of domains. In spite of the clinical effectiveness of MPH, concern has arisen with respect to its abuse potential. The present study examined the reinforcing effects and participant-rated effects of MPH in adults diagnosed with ADHD. Participants included 10 volunteers (ages 18-22) diagnosed with ADHD who were receiving MPH treatment. The reinforcing effects were assessed using a double-blind choice procedure with 4 sampling and 8 choice sessions. During sampling sessions, participants completed a self-report questionnaire before receiving either placebo or MPH in a labeled capsule (e.g., "A" or "B"), and again at 1.5 and 4 hours following capsule ingestion. The remaining 8 sessions were choice sessions wherein participants completed the self-report questionnaire, then chose whether to ingest capsule "A," "B," or "Neither." Results of this study revealed that 5 out of 10 participants chose MPH more often than placebo. Out of 80 total choices across subjects, 40 were MPH choices (50%), 26 were Placebo choices (32.5%) and 14 were "Neither" choices (17.5%). A chi-square analysis found that the number ofMPH, Placebo, and Neither choices differed significantly. Across MPH-choosers and non-choosers, MPH-choosers selected MPH significantly more often than non-choosers (77.5% vs. 22.5%), MPH-choosers chose Placebo significantly less often than non-choosers (7.5% vs. 57.5). Results from the two-way ANOVA indicate MPH was associated with a significant decrease in ADHD symptoms and stimulant effects among MPH-choosers. In addition, during sampling sessions, subsequent MPH-choosers had higher baseline ADHD symptoms and reported a greater decrease in ADHD symptoms, negative mood, and stimulant drug effects. These results suggest that the reinforcing effects of a clinically used drug may reflect therapeutic efficacy rather than abuse potential. Future work should examine the reinforcing effects of MPH and concomitant participant-rated effects in diagnosed and non-diagnosed populations to further explore the role of clinical effects in the reinforcing effects of this stimulant drug.

Access Setting

Dissertation-Open Access

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