Anne Fleur Kortekaas-Rijlaarsdam

CHAPTER 6 116 However, treatment with MPH normalized the reward threshold of these children, suggesting interactive effects between MPH and rewarded feedback. In line with these results are the findings from an older study showing that MPH increased the reward value of reinforcers: Specifically, this study showed that, when treated with MPH compared to placebo, children with MPH were more motivated to continue a task for a long time to earn a monetary reward. These findings suggest that stimulants may improve task performance in children with ADHD by increasing the value of reward. In line with this suggestion are studies showing that the combination of rewarded feedback and MPH treatment result in better performance than either treatment alone. For example, Strand et al. (2012). showed that the combined effects of rewarded feedback (stars combined with points) and MPH resulted in better working memory performance than either treatment alone. A more recent study on the unique end combined effects of reward (points) and MPH on response inhibition corroborates these findings: The combination of low dose MPH (0.3 mg/kg) and reward was more effective than either treatment alone (Rosch et al., 2016). Whereas these improvements in cognitive abilities are promising for academic performance, to the best of our knowledge only study investigated the interplay between the effects of reward and MPH on academic performance: That study showed that the combination of reward (points) and MPH yielded greater spelling improvements than either treatment alone (Pelham, Milich, & Walker, 1986). However, not all evidence suggests a synergy between effects of reward and MPH. For example, a recent study showed that MPH did not add to the effects of reward and punishment on temporal information processing (Luman, Papanikolau, & Oosterlaan, 2015). This study corroborates findings of an older study by Solanto and colleagues (1997) suggesting that MPH does not affect reward threshold or the ability to profit from reward in children with ADHD. In their study, Solanto et al. showed that the addition of reward to MPH treatment on a continuous performance task, did not improve performance in children with ADHD. Taken together, current literature on the impact of stimulant medication on the ability to profit from reward and feedback in children with ADHD is scarce and somewhat inconsistent. Most evidence points towards an interaction between the effects of reward and MPH, with higher performance on cognitive and academic tasks when these are combined (Liddle et al., 2011; Pelham et al., 1986; Rosch et al., 2016; Strand et al., 2012; Wilkison, Kircher, McMahon, & Sloane, 1995). Only one study investigated the synergy between effects of reward and medication an academic performance (Pelham et al., 1986). It is therefore important to expand these findings in order to determine the most