MPH enhances cognitive performance in adults with poor baseline capacities regardless of ADHD diagnosis

We compare the view that the effect of Methylphenidate (MPH) is selective to individuals with Attention Deficit Hyperactivity Disorder (ADHD) with an alternative approach suggesting that its effect is more prominent for individuals with weak baseline capacities in relevant cognitive tasks. To evaluate theses two approaches, we administered sustained attention, working memory, and decision making tasks to 20 ADHD adults and 19 healthy controls, using a within-subject placebo-controlled design. The results demonstrated no main effects of MPH in the decision making tasks. In the sustained attention and working memory tasks, MPH enhanced performance of both ADHD and non-ADHD adults to a similar extent compared to placebo. Hence, the effect of MPH was not selective to ADHD adults. Additionally, those benefitting most from MPH in all three task domains tended to be individuals with poor task performance. However, in most tasks individuals whose performance was impaired by MPH were not necessarily better (or worse) performers. The findings suggest that the administration of MPH to adults with ADHD should consider not only clinical diagnosis but also their functional (performance-based) profile.