Anne Fleur Kortekaas-Rijlaarsdam

CHAPTER 7 136 at the end of the task was the dependent variable. The results from this study indicate that all children profited equally from rewarded feedback, resulting in better math performance. The effects of MPH and rewarded feedback on math performance were additive. In line with the results from the meta-analysis and Chapter 3, children with ADHD were impaired on the math task compared to TD controls. However, children with ADHD did not profit more from feedback than TD controls did. These results emphasize the importance of motivational strategies such as positive feedback and small rewards to improve academic performance in both children with and without ADHD. General Discussion and Implications of the Results This thesis aimed to further investigate the effects of MPH, the most common stimulant for ADHD, on academic performance and learning. Key outstanding questions are (1) whether MPH affects the quality of academic work or merely results in increased effort; (2) whether the effects of MPH differ between core academic subjects; (3) whether improvements in behavior, cognition and motivation mediate the effects of MPH on academic performance; (4) how MPH affects feedback learning and the ability to profit from feedback and reward. This knowledge is necessary to manage the expectations of treating physicians, parents and teachers. Further, knowledge of moderators of the effects of MPH on academic performance could result in the identification of clinical subgroups for which higher or lower medication effectivity could be expected. MPH has Very Limited Effects on Academic Performance in Children with ADHD Our results reveal that improvements with MPH can be achieved over the short term (RCT with treatment duration of one week) but are very specific and limited to math (according to the meta-analysis and our experimental data) and reading (according to the meta-analysis). These results thus stress the importance of distinguishing between academic subjects (math, reading, spelling) when studying the effects of MPH on academic performance. Specifically, the results from our meta-analysis suggest that the potential for MPH to improve academic performance lies in those areas where underperformance is most apparent (i.e. math and reading, see also Frazier, Youngstrom, Glutting, &Watkins, 2007). This suggestion is confirmed by our findings from Chapter 3 showing that MPH improved academic performance only in those subjects (math productivity and accuracy) where children with ADHD underperformed in comparison to TD children. One explanation for the subject-specific effects of MPH on academic performance may be the focus of current research: Studies on the effects of MPH focus on math and reading and rarely report on other academic subjects (e.g. spelling, writing). Thus, perhaps the current amount of research is too little to reveal