This document discusses Attention Deficit Hyperactivity Disorder (ADHD). It defines ADHD as a neurodevelopmental disorder characterized by developmentally inappropriate levels of hyperactivity, impulsivity, and inattention. The document reviews the prevalence, symptoms, diagnostic criteria, comorbid conditions, developmental course, and potential causes of ADHD. Causes discussed include genetics, neurological insults, and differences found in brain structure and function through neuroimaging studies.