Many studies have demonstrated the efficacy of stimulants in treating ADHD. Among them, methylphenidate (MPH) was the widely used and has been rigorously studied (eg. Spencer et al., 2005; Stein et al., 2005; Wilens et al., 2005). MPH is also the only stimulant medication for the treatment of ADHD in Taiwan; it has been proved to reduce significantly the symptoms of ADHD, and to increase self regulation, learning motivation, academic performance, and interpersonal ability. Meanwhile, its efficacy was also observed in the significant improvement of neuropsychological functioning (e.g., Konrad et al., 2004).