Procedures

Infants and their families participated in clinic visits at ages 6, 12, and 24 months, and were scanned using MRI at 12-months. Assessments at 24 months included the Autism Diagnostic Observation Schedule (ADOS) and Autism Diagnostic Interview- Revised (46, 47). Clinical-best estimate diagnoses were made by experienced, licensed clinicians using DSM-IV-TR criteria for Autistic Disorder (ASD) or Pervasive Developmental Disorder-Not Otherwise Specified (PDD-NOS). See Estes and colleagues (10) for a full description of the assessment and diagnostic procedures.