Stage II: All subjects enrolled into stage one will be followed for the next 6 months. Medication for ADHD treatment may be used to these subjects based on investigators' clinical judgments. Subjects will visit clinics in week-24 (Visit 2). The same assessments at Visit 1 will be performed at Visit 2. In addition, the adherence to treatment, adverse events, overall satisfaction to treatment, and academic performances during these 6 months will be recorded.