Anne Fleur Kortekaas-Rijlaarsdam

CHAPTER 2 40 future, these should be replaced by validated tests (depending on the design of the study, with relevant norms). Further, researchers should always report both accuracy and productivity measures to allow for separate estimation of MPH effects on quantity and quality of academic performance. Moreover, by increasing the trial duration, more relevant measures like school grades can be included while still using randomized, placebo-controlled designs. Finally, more research on moderators and mediators of MPH efficacy is useful to isolate groups of patients who may benefit more or less from MPH and to reveal its mechanism of action. Although many studies have attempted to do so, measures of mediators and moderators are not uniform and generally not standardized, impeding (meta-analytic) aggregation of relevant results. In summary, our results indicated that MPH results in robust improvements in the number of reading items attempted and small to medium sized improvements in math productivity and accuracy. Improvements in academic quality (accuracy) were small (3.0%) and limited to math. The effects of MPH on math accuracy were not mediated by teacher-rated ADHD symptom-improvements, and MPH effects on math accuracy and productivity were not influenced by demographic variables, disorder related variables or study characteristics. The discrepancy between the large behavioral improvements seen with MPH and these smaller and selective improvements in academic performance is important for treatment guidelines. As academic improvement is often one of the main treatment goals, parents and teachers should be advised about the specificity and limited size of MPH-effects on academic performance.