Brain Indices of Stimulant Treatment in Drug-Naive Youth at Risk for Substance Use Disorder

Inclusion Criteria: * General: pre-pubertal (e.g. Tanner stage 1 or 2) * age 7-12 inclusive * signed consent/assent * parent communicates sufficiently in English * Has ADHD as determined by parent interview * ADHD-Rating Scale-5 total score (interview with parent) of 1.5 SD \> age/sex norms * Youth with CD or severe ODD: CD or ODD + 2 symptoms of CD Exclusion Criteria: * major neurological/medical illness * history of head injury * fetal exposure to alcohol/drugs; * diagnosis of major psychiatric disorder (e.g., schizophrenia, bipolar disorder, major depression, generalized anxiety, social phobia, Tourette's Disorder, PTSD, autism spectrum disorder) current suicidal ideation or past history of suicide attempt * Wechsler Abbreviated Scale of Intelligence (WASI) score \<75; 7) * current treatment with stimulants (prior or current treatment with non-stimulants is permitted, but participants must be off medication for 2 weeks at baseline; youth who had a past, brief stimulant medication exposure of no more than about a month, and not within the past 6 months may be included .) * current or past alcohol/drug use (interview; urine toxicology) * psychological or medical condition which precludes being in the scanner (e.g., claustrophobia, morbid obesity) * metal in the body that cannot be removed * visual disturbances that may impair task performance * precocious puberty (e.g. Tanner stage \>2).