Almost all children have times when their behavior veers out of control. They may speed about in constant motion, make noise nonstop, refuse to wait their turn, and crash into everything around them. At other times they may drift as if in a daydream, failing to pay attention or finish what they start.

However, for some children, these kinds of behaviors are more than an occasional problem. Children with attention-deficit/hyperactivity disorder (ADHD), have behavior problems that are so frequent and severe that they interfere with their ability to live normal lives.

These children often have trouble getting along with siblings and other children at school, at home and in other settings. Those who have trouble paying attention usually have trouble learning. An impulsive nature may put them in actual physical danger. Because children with ADHD have difficulty controlling this behavior, they may be labeled "bad kids" or "space cadets."

ADHD is a condition of the brain that makes it difficult for children to control their behavior. It is one of the most common chronic conditions of childhood. It affects 4 percent to 12 percent of school-aged children. About three times more boys than girls are diagnosed with ADHD.

Left untreated, more severe forms of ADHD can lead to serious, lifelong problems such as poor grades in school, run-ins with the law, failed relationships, and the inability to keep a job.