Health A-Z

Medical Content Created by the Faculty of the Harvard Medical School


What Is It?

Attention-deficit hyperactivity disorder (ADHD), usually first diagnosed in childhood, can appear in a variety of forms and has many possible causes. People with ADHD probably have an underlying genetic vulnerability to developing it, but the severity of the problem is also influenced by the environment. Conflict and stress tend to make it worse.

The main features of this disorder are found in its name. Attention problems include daydreaming, difficulty focusing and being easily distracted. Hyperactivity refers to fidgeting or restlessness. A person with the disorder may be disruptive or impulsive, may have trouble in relationships and may be accident-prone. Hyperactivity and impulsiveness often improve as a person matures, but attention problems tend to last into adulthood.

ADHD is the most common problem seen in outpatient child and adolescent mental health settings. It is estimated that ADHD affects between 5% and 10% of school-aged children. Boys are more often diagnosed with ADHD than girls. Studies suggest that the number of ADHD diagnoses has risen significantly over the years. But whether more people have the disorder or whether it is just being diagnosed more often is not clear. The definition of the disorder has changed over the past several decades and will continue to develop as the experts explain more about the biology behind it.

The activity component is less apparent in adult ADHD. Adults tend to have problems with memory and concentration and they may have trouble staying organized and meeting commitments at work or at home. The consequence of poor functioning may be anxiety, low self-esteem, or mood problems. Some people turn to substances to manage these feelings.

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From Health A-Z, Harvard Health Publications. Copyright 2007 by the President and Fellows of Harvard College. All rights reserved. Written permission is required to reproduce, in any manner, in whole or in part, the material contained herein. To make a reprint request, contact Harvard Health Publications. Used with permission of StayWell.

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