Still, no study, to our knowledge, has addressed the unique and joint contribution of COMT Val158Met genetic variation and antecedent family adversity factors, including accumulation SES-risk and negative parenting during infancy, to the development of ADHD across childhood, in a large high-risk sample of children and families living in predominantly low-income and non-urban communities. Here, COMT is linked to attention deficit-hyperactivity disorder.