Stimulant vs. Non-stimulant Treatments and Reward Processing in Drug-naive Youth at SUD Risk

Inclusion Criteria: * Pre-pubertal (e.g. Tanner stage 1 or 2) * Age 7-12 inclusive * Signed consent/assent * Parent communicates sufficiently in English to provide informed consent and complete assessment instruments; * ADHD as determined by computerized DISC (C-DISC) parent interview * ADHD-Rating Scale-5 total score (interview with parent ) * SNAP ADHD total score (teacher) of 1.5 SD \> age/sex norms * CD or severe ODD: CD or ODD + 2 symptoms of CD on C-DISC * SNAP ODD/CD subscale (parent and teacher) 1.5 SD \> age/sex norms 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)75 score \<75 * Prior or current treatment with stimulants (prior or current treatment with non-stimulants is permitted, but participants must be off medication for 2 weeks at baseline) * Current or past alcohol/drug use (DISC 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 (e.g., braces, metal plate) * Visual disturbances that may impair task performance * Precocious puberty (e.g. Tanner stage \>2) or pregnancy Notes: * History of SUD in a 1st degree relative is permitted, and is expected in \~1/2 of the subjects * Ongoing psychosocial treatment is allowed but should not be initiated during the study