 Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition DSM-IV defined ADHD. The DSM-IV diagnosis of ADHD will be based on the Parent Diagnostic Interview for Children and Adolescents in participants 18 years or age and younger and the Schedule for the Diagnosis of DSM Disorders for participants above 18 years of age. For those of school age, an additional inclusion criterion is the Conners Teacher Hyperactivity rating greater than 1.5 standard deviations above age- and sex-specific means. ADHD is rarely found in isolation and comorbidity is common. Thus the protocol will include individuals with ADHD and the 