Date of this Version
Psychostimulants such as mixed amphetamine salts (MAS, brand name Adderall) are widely used for cognitive enhancement by healthy young people, yet laboratory research on effectiveness has yielded variable results. The present study assessed the effects of MAS in healthy young adults with an adequately powered double-blind cross-over placebo-controlled trial. We examined effects in 13 measures of cognitive ability including episodic memory, working memory, inhibitory control, convergent creativity, intelligence and scholastic achievement, with the goals of determining (1) whether the drug is at least moderately enhancing (Cohen's d >= .5) to some or all cognitive abilities tested, (2) whether its effects on cognition are moderated by baseline ability or COMT genotype, and (3) whether it induces an illusory perception of cognitive enhancement. The results did not reveal enhancement of any cognitive abilities by MAS for participants in general. There was a suggestion of moderation of enhancement by baseline ability and COMT genotype in a minority of tasks, with MAS enhancing lower ability participants on word recall, embedded figures and Raven's Progressive Matrices. Despite the lack of enhancement observed for most measures and most participants, participants nevertheless believed their performance was more enhanced by the active capsule than by placebo. We conclude that MAS has no more than small effects on cognition in healthy young adults, although users may perceive the drug as enhancing their cognition.
NOTICE: This is the author’s version of a work that was accepted for publication in Neuropharmacology. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms, may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Neuropharmacology, volume 64, January 2013, 10.1016/j.neuropharm.2012.07.021.
Ilieva, I., Boland, J., & Farah, M. J. (2013). Objective and Subjective Cognitive Enhancing Effects of Mixed Amphetamine Salts in Healthy People. Neuropharmacology, 64 496-505. http://dx.doi.org/10.1016/j.neuropharm.2012.07.021
Date Posted: 15 May 2015
This document has been peer reviewed.