Anne Fleur Kortekaas-Rijlaarsdam

57 MPH EFFECTS ON MATH PERFORMANCE: INFLUENCE OF BEHAVIOR 3 I N T RODUC T I ON Attention-Deficit Hyperactivity Disorder (ADHD) is a common developmental disorder characterized by attentional problems, hyperactivity and impulsivity (DSM-V). In primary school, most children with ADHD experience mild to severe academic problems including problems with reading, spelling and math (DuPaul, 2007). These problems may be related to both their behavioral symptoms and cognitive problems (Daley & Birchwood, 2010; Polderman et al., 2010). Malfunctioning in school is one of the primary reasons for parents or teachers to seek professional help and start medication treatment (Wright et al., 2015). Stimulant medication is the most commonly prescribed treatment for ADHD with effect sizes ranging from 0.5-1.83 (SMD) in reducing behavioral ADHD symptoms both at home and in school (Antshel et al., 2011; Faraone, Biederman, Spencer, 2006; MTA-group, 1999b; Van der Oord et al., 2008). Besides behavioral improvements, improvements in cognitive functioning with stimulant medication are common (Coghill, Seth, et al., 2014). Because of the behavioral and cognitive improvements, positive effects of stimulants on academic performance are often assumed. A recent meta-analysis of the literature on the immediate effects of stimulant medication on academic performance of children aged 4-16 years indicates that stimulant medication improves classroom behavior and schoolwork productivity (Prasad et al., 2013). Results of this meta-analysis indicate stronger effects for higher doses regardless of whether immediate or extended release stimulants were used. The strongest results were found for mathematics compared to reading and spelling (Froehlich et al., 2014; Prasad et al., 2013), which may be the result of greater underperformance in math than in reading or spelling, in children with ADHD when compared to typically developing peers (Frazier et al., 2007; Loe & Feldman, 2007). In contrast to the positive effects of methylphenidate on classroom behavior and academic productivity of children with ADHD, evidence for increased schoolwork quality is scarce. Many studies included in the meta-analysis by Prasad and colleagues only report on the number of items correct, a measure that might be confounded by the number of items attempted (task productivity), rather than accuracy, a measure that incorporates the number of items attempted. Of those studies reporting on accuracy, only few report significant improvements with methylphenidate and improvements are apparent only with higher dosages (Baweja et al., 2015; Prasad et al., 2013). For all academic measures, effects sizes reported for accuracy are much smaller than effect sizes reported for behavioral improvements within the classroom