Attention deficit hyperactivity disorder (ADHD) is a disorder that affects behavior. It can cause hyperactive and impulsive behavior, and/or make it difficult to pay attention. Most people have some of these behavioral issues at some time. However with ADHD, these behavioral problems continue over a long period of time. To be considered ADHD, these behaviors must last for at least six months and be present in two environments (home, work, or school). ADHD affects children, adolescents, and adults.

There are three types of ADHD:

  • Inattentive (classic "ADD")
  • Hyperactive-impulsive
  • Combined—the most common type

The cause of ADHD is unknown. It most likely is caused by a chemical imbalance in the brain. There also appears to be a genetic factor since ADHD can run in families.

Child's Brain
Child Brain
A chemical imbalance in the brain may be responsible for ADHD.
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