Anne Fleur Kortekaas-Rijlaarsdam

CHAPTER 7 140 A puzzling finding in this mediator analysis is that these mediational effects were limited to parent-ratings of symptom improvements and self-perceived competence. In our RCT, parents reported larger reductions in ADHD symptoms than teachers and only parent-ratings of MPH-related increases in perceived competence were significant. The difference between parent- and teacher-ratings of ADHD symptoms and self- perceived competence may be because parents generally spend more time with their child and observe their child in different settings, compared to teachers who often work part-time. As a result, parents may be better in detecting changes in their child’s behavior than teachers (Shemmassian & Lee, 2012) an may be more reliable judges of symptom improvements . However, although the difference between parent- and teacher ratings of ADHD symptoms is also observed in the literature, studies also stress the importance of using multiple informants for the identification of the full range of ADHD symptoms (Mitsis, Mckay, Schulz, Newcorn, & Halperin, 2000). This supports our approach in investigating multiple (parent-, teacher- and sometimes child-) perspectives on our proposed mediators. Concerning the second mediator, self- perceived competence, it might be argued that parents are a reliable source of information here as children with ADHD often give extremely positive reports of their own competence, i.e. they show an illusory bias (Owens, Goldfine, Evangelista, Hoza, & Kaiser, 2007). Figure 7.1 In this thesis we proposed that MPH-related improvements in academic performance could be partly explained by (1) reductions in ADHD symptoms; (2) improvements in cognition (attention, working memory, interference control and processing speed); (3) increases in academic motivation and self-perceived competence. Our results do not support this model. Results from our RCT suggest a mediating role for parent-rated improvements in ADHD symptoms and parent-rated increases in their child’s self-perceived competence.