Anne Fleur Kortekaas-Rijlaarsdam

59 MPH EFFECTS ON MATH PERFORMANCE: INFLUENCE OF BEHAVIOR 3 efficacy in improving academic performance. Differences in academic improvements with methylphenidate may be explained by differences in behavioral treatment response. For example, improvements in academic productivity are often accompanied by large teacher-rated improvements in behavior in the classroom (Baweja et al., 2015). In line with this, a mediating role for on-task behavior (a proxy for ADHD symptoms within the classroom) on the effects of methylphenidate on math productivity was recently shown (Froehlich et al., 2014): Methylphenidate improved time-on task, which in turn improved math productivity. Only one study investigated the moderating effects of comorbid learning disorders and found comparable efficacy of methylphenidate in improving academic functioning in children with ADHD with and without comorbid learning disorders (Williamson et al., 2014). The current study was set up to investigate the impact of clinically titrated dosages of long-acting methylphenidate on academic performance using a double blinded, placebo-controlled cross-over design with a large group of carefully screened and diagnosed primary school children with ADHD. Children with ADHD were compared to typically developing (TD) children to assess whether medication normalized academic performance in math, reading and spelling using well-validated measures in naturalistic school settings. Prior studies into acute effects of methylphenidate (effects of treatment during one week or less) on standardized tests of school performance showed improvements in math, reading and spelling (Bental & Tirosh, 2008; Robb et al., 2014; Wigal et al., 2014). Effects of medication shown in trials with relative short durations (less than a week) are comparable in (medium) size to effects shown in trials with a longer duration (e.g. 21 days), e.g. (Gorman et al., 2006; Lufi & Gai, 2007) versus (Quinn et al., 2004). Medication treatment was expected to improve academic productivity especially for mathematics (Prasad et al., 2013). No improvements in accuracy were expected (Froehlich et al., 2014; Prasad et al., 2013), and academic performance of children with ADHD was not expected to normalize in comparison with TD children when treated with medication (Langberg & Becker, 2012). We expected that improvements in academic performance would be related to reductions in parent- and teacher-rated ADHD symptoms (Baweja et al., 2015; Froehlich et al., 2014). Finally, we expected that the presence of learning problems and higher number of ADHD symptoms would moderate an increased efficacy of methylphenidate in improving academic performance.