ADHD in children and youth: Part 1-Etiology, diagnosis, and comorbidity.

Attention-deficit hyperactivity disorder (ADHD) is a chronic neurodevelopmental disorder. Three position statements have been developed by the Canadian Paediatric Society, following systematic literature reviews. Statement objectives are to: 1) Summarize the current clinical evidence regarding ADHD,2) Establish a standard for ADHD care, and3) Assist Canadian clinicians in making well-informed, evidence-based decisions to enhance care of children and youth with this condition. Specific topics reviewed in Part 1, which focuses on diagnosis, include: prevalence, genetics, pathophysiology, differential diagnosis and comorbid psychiatric disorders and developmental disorders. In addition to database searches, the most recent guidelines of the American Academy of Pediatrics, the American Academy of Child and Adolescent Psychiatry, the National Institute for Health and Clinical Excellence, the Scottish Intercollegiate Guidelines Network, and the Eunethydis European ADHD Guidelines Group, were reviewed. Because ADHD is a heterogeneous disorder, comprehensive medical assessment for ADHD should always include a complete history, a physical examination, and a thorough consideration of differential diagnosis and related comorbidities. Specific recommendations for information gathering, testing, and referral are offered.