Date of Award
Doctor of Philosophy
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.
MacDonald, Emily Kathleen, "An Evaluation of Methylphenidate Preference in Adults Diagnosed with Attention-Deficit/Hyperactivity Disorder" (2003). Dissertations. 1251.