Attention-deficit hyperactivity disorder (ADHD) is a neurobehavioral disorder generally characterized by the following symptoms:
Types of ADHD
ADHD is classified into three subtypes:
- Predominantly Hyperactive-Impulsive Type. Behavior marked by hyperactivity and impulsivity, but not inattentiveness
- Predominantly Inattentive Type. Behavior marked by inattentiveness, but not hyperactivity and impulsivity
- Combination Type. A combination of hyperactivity/impulsivity and inattentive symptoms. This is the most common type of ADHD.
In the United States, about 5.3 million children ages 3 - 17 have been diagnosed at some point with ADHD. This accounts for 8.6% of all American children in this age range. Symptoms of ADHD usually become apparent around age 7.
Review Date: 01/27/2011
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.