Introduction

Attention-deficit hyperactivity disorder (ADHD) is a neurobehavioral disorder generally characterized by the following symptoms:

• Inattention
• Distractibility
• Impulsivity
• Hyperactivity

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.

Childhood 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.

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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.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)