A 9-year-old boy who received a diagnosis of attention deficit- hyperactivity disorder (ADHD) at 7 years of age is brought to your office by his parents for a follow-up visit. He had had behavioral problems since preschool, including excessive fidgeting and difficulty following directions and taking turns with peers. Parent and teacher ratings of behavior confirmed elevated levels of inattention, hyperactivity, and impulsivity that were associated with poor grades, disruptions of classroom activities, and poor peer relationships. He was treated with sustained-release methylphenidate. Although parent and teacher rating scales after treatment showed reduced symptoms, he still makes many careless mistakes and has poor grades and no friends. What would you advise?