BACKGROUND: While neighborhood conditions have previously been shown to have substantial effects on later occupational, educational and health outcomes, this is the first study to examine the relation between neighborhood factors and attention-deficit/hyperactivity disorder (ADHD) symptoms in children with autism and developmental delays. METHODS: Children from the CHARGE (Childhood Autism Risks from Genetics and the Environment) Study were evaluated at ages 2-5 years and then later in the ReCHARGE (follow-up) Study at ages 8-20 years (mid-childhood/adolescence). Using linear regression, we assessed associations between the Child Opportunity Index 2.0 (COI) at birth, a multidimensional neighborhood measure of childhood opportunity, and ADHD symptoms on the Aberrant Behavior Checklist at mid-childhood/adolescence. RESULTS: Participants included a total of 524 youth (401 males
123 females), composed of 246 autistic children (AUT), 85 children with Developmental Delays (DD) without autism, and 193 Typically Developing (TD) children. Mean age was 3.8 years ( CONCLUSIONS: Among autistic, but not TD or DD youth, poorer neighborhood conditions at birth predict greater ADHD symptoms in later development. These findings have important clinical implications and highlight the need for increased and improved resources in poorer neighborhoods to reduce existing disparities in ADHD, a common neurodevelopmental impairment.