What is ADHD? Attention Deficit Hyperactivity Disorder is a neurological disorder that is characterized by developmentally inappropriate hyperactivity, inattention, or impulsivity. It is believed that children with ADHD have an impairment in the brain’s executive functions which affect the way they learn, store, and retrieve information. ADHD is suspected when a child’s behavior in class is problematic. In this article, we will discuss the symptoms of ADHD.