Proton Magnetic Spectroscopy in Children and Adolescents With ADHD Before and After Treatment With OROS Methylphenidate

Inclusion Criteria: 1. Male or female subjects, 12-17 years of age. 2. ADHD subjects must meet study criteria for the "Prevention of Cigarette Smoking in ADHD Youth with CONCERTA Protocol"; #2003-P-001313. 3. Control subjects must not meet full DSM-IV criteria for Attention Deficit Hyperactivity Disorder, or any other current major psychiatric disorder. 4. Each subject and his/her authorized legal representative must understand the nature of this proposed study, and must sign informed consent and informed assent documents. 5. Subject and parent must have a level of understanding sufficient to communicate intelligently with the investigator and study coordinator, and to cooperate with study procedures. Exclusion Criteria: 1. Clinically significant chronic medical condition including hepatic, renal, gastroenterologic, respiratory, cardiovascular (including ischemic heart disease), endocrinologic, neurologic, immunologic, or hematologic disease. 2. Organic brain disorders or mental retardation (I.Q. \<75). 3. Contraindication to MRI including presence of metal or surgical devices (plates, implants, braces or other items). 4. Pregnancy; women of child bearing potential must be using a medically approved method of birth control. Women of child bearing potential will receive a urinary pregnancy test prior to each MR scanning session. 5. Severe phobia of being in small, enclosed spaces. 6. Investigator and his/her immediate family; defined as the investigator's spouse, parent, child, grandparent, or grandchild will not be eligible to participate in the treatment arm of the study.