Anne Fleur Kortekaas-Rijlaarsdam

125 EFFECTS OF MPH AND REWARD ON MATH PERFORMANCE 6 Entry Level Entry level was significantly lower for the ADHD group (placebo condition) than for the TD group ( t (128)=-3.06, p =.003, d =.54). Further, entry level within the ADHD group was higher when treated with MPH compared to placebo ( t (62)=2.12, p =.038, d =.27). When treated with MPH, performance of children with ADHD no longer differed from TD children ( t (128)=1.66, p =.099). Therefore, entry level was included as a covariate in the GLMM analyses for group and treatment effects. Group Effects GLMM analysis showed that the main effect of condition was significant ( t (128)=2.14, p =.034, d =.17), showing better performance in the motivational condition compared to neutral condition. With rewarded feedback, math performance of children with ADHD normalized to the level of TD controls ( t (128)=1.72, p =.088). The main effect of group was not significant ( t (192.4)=-1.23, p =.219) indicating that the achieved math level of children with ADHD is comparable to that of TD children, when entry level was taken into account. There was no significant group*condition interaction ( t (128)=.76, p =.445) when entry level was taken into account, indicating that math performance of children with ADHD and TD children profited equally from the motivational condition. On average, all children performed better at the end of the task compared to entry level, irrespective of condition, indicating learning during the task ( t (192)=3.72, p <.001, d =.27 and t (192)=8.26, p <.001, d =.59 for the neutral and the motivation condition, respectively). Table 6.3 Group comparisons and MPH effects on math performance with and without feedback ADHD TD ADHD v TD MPH v PLA PLA MPH t t N M SD M SD N M SD Entry level 63 6.62 2.11 7.19 1.96 67 7.81 2.24 -3.06** 2.12* Achieved math level + neutral condition 63 7.00 2.55 7.60 2.28 67 8.33 2.35 Achieved math level + motivation condition 63 7.59 2.29 8.03 2.12 67 8.72 2.39 Condition effect (achieved level difference scores, motivation - neutral condition) 63 .59 1.51 .43** 1.51 67 .39* 1.46 -1.23 1.04 Note . ADHD Attention-deficit hyperactivity disorder; TD Typically developing controls; PLA placebo; MPH methylphenidate; + Math level ranged from 1-12. Asterisks for the difference scores indicate significance of the main effect of condition in the comparisons ADHD with placebo versus TD and ADHD with placebo versus MPH. * p<.05; **p<.01