Attention Deficit Hyperactivity Disorder (ADHD) is a condition that can make it hard for a person to sit still, control behavior and pay attention. These difficulties usually begin before the person is 7 years old. However, these behaviors may be noticed earlier or may not be noticed until the child is older.

Doctors do not know just what causes ADHD. However, researchers who study the brain are coming closer to understanding what may cause ADHD. They believe that some people with ADHD do not have enough of certain chemicals (called neurotransmitters) in their brain. These chemicals help the brain control behavior.

As many as 5 out of every 100 children in school may have ADHD. Boys are three times more likely than girls to have ADHD.

There are three main signs, or symptoms, of ADHD. These are:

problems with paying attention,
being very active (called hyperactivity), and
acting before thinking (called impulsivity).

Based on these symptoms, three types of ADHD have been identified:

inattentive type, where the person can't seem to get focused or stay focused on a task or activity;
hyperactive-impulsive type, where the person is very active and often acts without thinking; and
combined type, where the person is inattentive, impulsive, and too active.

When a child shows signs of ADHD, he or she needs to be evaluated by a trained professional. A complete evaluation is the only way to know for sure if the child has ADHD.

Examples, Subsets and Synonyms for Attention Deficit Disorders (minimal brain dysfunction, hyperkinetic syndrome)

Attention Deficit Hyperactivity Disorder (ADHD)

Inattentive Type
Hyperactive Type
Combined Type

Related Marcus Autism Center Clinical Programs

Pediatric Neurodevelopmental Center

Additional Resources

Attention Deficit Disorder Association
(www.add.org)

Children and Adults with ADD
(www.chadd.org)

Learning Disabilities Online
(www.ldonline.org)