Attention Deficit and Hyperactivity Disorder (ADHD) is a neurodevelopmental disorder defined by impairing levels of inattention, disorganization, and/or hyperactivity-impulsivity.

Inattention and disorganization entail inability to stay on task, seeming not to listen, and losing materials necessary for tasks, at levels that are inconsistent with age or developmental level.

Hyperactivity-impulsivity entails over activity, fidgeting, inability to stay seated, intruding into other people’s activities, and inability to wait—symptoms that are excessive for age or developmental level.

In childhood, ADHD frequently overlaps with disorders that are often considered to be “externalizing disorders,” such as oppositional defiant disorder and conduct disorder. ADHD often persists into adulthood, with resultant impairments of social, academic, and occupational functioning.