Attention-Deficit/Hyperactivity Disorder (ADHD) is a behavior disorder, usually first diagnosed in childhood, which is characterized by persistent problems with inattention and/or impulsivity and hyperactivity. These difficulties must be present in two or more settings (e.g., home, school, work, social), and must occur with sufficient frequency and severity as to interfere with the person's ability to function in an age-appropriate manner.
The symptoms of hyperactivity and impulsivity, when present, are almost always apparent by the age of 7 and may be apparent in very young preschoolers. These symptoms often interfere with the child's ability to interact appropriately with peers, siblings, and adults; to follow rules and instructions; and to not engage in behaviors which may be physically dangerous. In contrast, the symptoms of inattention are often not evident until a child faces the demands and expectations of elementary school.