Anne Fleur Kortekaas-Rijlaarsdam

CHAPTER 1 10 BACKGROUND AND A I MS O F T H I S T H E S I S Attention-Deficit/Hyperactivity Disorder Attention-Deficit/Hyperactivity Disorder (ADHD) is a highly common childhood developmental disorder characterized by attentional problems, hyperactivity and impulsivity, occurring in at least two different situations to a degree that interferes with daily functioning (American Psychiatric Association, 2013). ADHD has a prevalence of five percent in children and is two to three times more common in boys than in girls (Faraone et al., 2015; Willcutt, 2012). The current (5 th ) edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM) distinguishes between three presentations (formerly subtypes) of ADHD, representing the predominant symptom pattern: the predominantly inattentive presentation, the predominantly hyperactive-impulsive presentation and the combined presentation (American Psychiatric Association, 2013). The definition ‘presentation’ implies that symptom patterns may change over time. ADHD shows high persistence into adulthood (estimated prevalence in adulthood is 66-74%), especially for individuals with severe ADHD symptoms in childhood (Faraone et al., 2015; Karam et al., 2015; Langley et al., 2010; Uchida, Spencer, Faraone, & Biederman, 2015). Moreover, ADHD has a significant impact on children’s social, academic functioning and adult occupational outcomes (Barkley, Fischer, Smallish, & Fletcher, 2006; D. Coghill et al., 2008; Frazier, Youngstrom, Glutting, &Watkins, 2007; Loe & Feldman, 2007). ADHD is a heterogeneous disorder with large differences in symptom severity and high comorbidity with externalizing disorders (oppositional defiant disorder: ODD; conduct disorder: CD) and internalizing disorders including anxiety and depression (American Psychiatric Association, 2013). Comorbidity with learning disorders is also high (30%) and often results in worse academic outcomes than ADHD alone (Faraone et al., 2015; Faraone, Biederman, & Monuteaux, 2001; Williamson, Murray, Damaraju, Ascher, & Starr, 2014). Academic Functioning in ADHD With regard to academic functioning, children with ADHD often experience mild to severe problems, ranging from slight underperformance to the need for special education or school dropout (DuPaul, 2007; Frazier et al., 2007; Loe & Feldman, 2007). The meta-analysis by Frazier et al. (2007) combined 72 studies on academic achievement in ADHD and showed that academic achievement is lower for students with ADHD than controls, with medium-to large effects ( d =.71). Academic impairments in individuals with ADHD were most profound on standardized achievement tests for reading ( d =.73) and math ( d =.67) but also visible on longer-term outcomes of academic achievement: For example, individuals with ADHD showed lower grades and fewer