Dose Response Effects of Quillivant XR in Children With ADHD and Autism: A Pilot Study

Inclusion Criteria: * A clinical diagnosis of Autistic disorder or Asperger's disorder by DSM-IV or Autism Spectrum Disorder by DSM-V. * A DSM-V diagnosis of ADHD based upon the K-SADS-P. * Clinical Global Impressions - Severity for ADHD (CGI-S-ADHD) rating \> 4. * Findings on physical exam, labs and ECG are judged to be normal for age with pulse and blood pressure within 95% of age and gender mean. * Informed consent by a parent or legal guardian, and assent for children with developmental age 7 years or older. * At least one parent fluent in English Exclusion Criteria: * History of Seizure disorder (Febrile seizures are non-exclusionary). * History of Intellectual Disability (IQ\< 70) * Treatment with MAO Inhibitor (or within 14 days following discontinuation of MAO Inhibitor). * Other psychotropic medication other than stable dose of Selective Serotonin Reuptake Inhibitors, which is permitted) * Known to be hypersensitive to methylphenidate, or other components of Quillivant XR * Cardiac or other medical contraindications for stimulant trial (e.g., family history of heart attack at age younger than 40 years, personal history of heart disease, history of fainting while exercising, structural cardiac abnormalities, cardiomyopathy, serious cardiac arrhythmias, coronary artery disease, or other serious cardiac problems. If any doubt, children will be referred to a cardiologist for a cardiac clearance. * Raynaud's disease * Pregnancy or Breast-feeding.