Methylphenidate-Related Improvements in Math Performance Cannot Be Explained by Better Cognitive Functioning or Higher Academic Motivation: Evidence From a Randomized Controlled Trial

Abstract

Objective: This study investigated whether improvements in working memory, reaction time, lapses of attention, interference control, academic motivation, and perceived competence mediated effects of methylphenidate on math performance. Method: Sixty-three children (ADHD diagnosis; methylphenidate treatment; age 8-13; IQ > 70) were randomly allocated to a 7-day methylphenidate or placebo treatment in this double-blind placebo-controlled crossover study and compared with 67 controls. Data were collected at schools and analyzed using mixed-model analysis. Methylphenidate was hypothesized to improve all measures; all measures were evaluated as potential mediators of methylphenidate-related math improvements. Results: Controls mostly outperformed the ADHD group. Methylphenidate did not affect measures of cognitive functioning (p =.082-.641) or academic motivation (p =.199-.865). Methylphenidate improved parent ratings of their child’s self-perceived competence (p