BACKGROUND AND SIGNIFICANCE Attention-Deficit/Hyperactivity Disorder (ADHD) is among the most common impairing neuropsychiatric disorder worldwide among children and adolescents with the prevalence of DSM-IV ADHD in the range of 5-10% in Western countries (Faraone et al., 2003) and 7.5% in Taiwan (Gau et al., 2005) with the ratio of boys to girls as 3-8:1. The significance of ADHD in clinical practice and research is not only in its high prevalence but also in the impairments it brings about in neurocognitive function, academic performance, and social adjustment.