Magnetic Resonance Spectroscopic and Diffusion Tensor Imaging of Adolescents with Autism Spectrum Disorders

Inclusion Criteria * Male or female participants between 6 and 17 years of age. * Fulfills diagnosis of autism spectrum disorders by meeting DSM-IV-TR PDD diagnostic criteria for autistic disorder, Asperger's disorder, or PDD-NOS as established by clinical interview. * Subjects and their legal representative must have a level of understanding sufficient to communicate intelligently with the investigator and study coordinator, and to cooperate with all tests and examinations required by the protocol. * Subjects and their legal representative must be considered reliable reporters. * Each subject and his/her authorized legal representative must understand the nature of the study. The subject's authorized legal representative and the subject must sign an IRB approved informed consent and assent document respectively. * Participants with disruptive behavior disorders, mood and anxiety disorders will be allowed to participate in the study provided they do not meet any exclusionary criteria. Exclusion Criteria * IQ \< 85. * DSM-IV-TR PDD diagnoses of Rett's disorder, or childhood disintegrative disorder. * Current diagnosis of a psychotic disorder or unstable bipolar disorder. * History of recent or current (past 30 days) clinically significant depressive or anxiety disorder that warrants treatment. * History of substance use (except nicotine or caffeine) within past 3 months or urine drug screen positive for substances of abuse. * Clinically unstable psychiatric conditions or judged to be at serious safety risk to self (suicidal risk) or others. * Subjects with a medical condition or treatment that will either jeopardize subject safety or affect the scientific merit of the study. * Organic brain disorders. * History of non-febrile seizures without a clear and resolved etiology in last 1 month. * Pregnant or nursing females. * Left hand dominant subjects. * History of claustrophobia or fear of enclosed places. * Presence of metal or surgical devices (aneurysm clips, metal plates, cochlear implants, neurostimulators, braces, and other items). * Investigator and his/her immediate family; defined as the investigator's spouse, parent, child, grandparent, or grandchild.