All of drug naïve children and adolescents who meet the DSM-5 diagnostic criteria (American Psychiatric Association, 2013) for combined ADHD were eligible. The diagnosis was made through a semistructured diagnostic interview with parents using SADS-K-PL by a child and adolescent psychiatrist. Exclusion criteria were history of severe head injury, neurological disorders, genetic disorders, psychiatric disorders other than ADHD, and intellectual disability. Children who had received psychotherapy within the past one year were also excluded. After enrolment by the evaluating psychiatrist, selected children were randomly divided into two groups by a schedule generated by RandList (Figure 1) by a nonevaluator coauthor. Recruitment started in April and ended in December 2014.