1. Definition and symptoms of ADHD in children Childhood ADHD, also known as attention deficit hyperactivity disorder (ADHD), is a common neurodevelopmental disorder. It mainly manifests as three major categories of symptoms: inattention, hyperactivity and impulsive behavior. Among them, inattention is the most important symptom, which manifests as learning difficulties, forgetfulness, and inability to concentrate. Hyperactivity manifests as inability to sit still, crawling around, chattering, etc. Impulsive behavior manifests itself in the inability to wait patiently for one\’s turn to speak or do something. 2. Causes and diagnostic methods of ADHD in children 1.