Candidate: Emily Kathleen MacDonald

Degree of: Doctor of Philosophy

Department: Psychology

Title: An Evaluation of Methylphenidate Preference in Adults Diagnosed wtih Attention-Deficit/Hyperactivity Disorder

Committee:
Dr. Galen Alessi, Chair
Dr. Scott Gaynor
Dr. Lisa Baker
Dr. Scott Kollins

Date: Friday, April 11, 2003 1:00p.m.-3:00p.m.
2527 Wood Hall

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. As such, there is concern surrounding the use of MPH to treat individuals diagnosed with ADHD. Thus, it is critical to evaluate the reinforcing effects and abuse potential of MPH in a clinical sample. 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, the chose whether to ingest capsule "A", "B" or Neither. Results of this study revealed that 5/10 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 of MPH, Placebo and Neither choices differed significantly (X2=52.484, p<0.001). Results from a two-way ANOVA indicated that relative to placebo, MPH was associated with a significant decrease in ADHD symptoms and reported a greater decrease in ADHD symptoms, negative mood, and a greater increase in 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.

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