The study published in the Journal of the American Academy of Child and Adolescent Psychiatry (JAACAP) found that an estimated two million more children in the United States (U.S.) have been diagnosed with attention-deficit/hyperactivity disorder (ADHD) between 2003-04 and 2011-12. One million more U.S. children were taking medication for ADHD between 2003-04 and 2011-12. According to the study conducted by the Centers for Disease Control and Prevention (CDC):

* 6.4 million children in the U.S. (11 percent of 4-17 year olds) were reported by their parents to have received an ADHD diagnosis from a healthcare provider, a 42 percent increase from 2003-04 to 2011-12.

* Over 3.5 million children in the U.S. (6 percent of 4-17 year olds) were reported by their parents to be taking medication for ADHD, a 28 percent increase from 2007-08 to 2011-12.

Attention-deficit/hyperactivity disorder (ADHD) is one of the most common neurobehavioral disorders of childhood. It often persists into adulthood. Children with ADHD may have trouble paying attention and/or controlling impulsive behaviors. Effective treatments for ADHD include medication, mental health treatment, or a combination of the two. When children diagnosed with ADHD receive proper treatment, they have the best chance of thriving at home, doing well at school, and making and keeping friends.

According to CDC scientists, children are commonly being diagnosed at a young age. Parents report that half of children diagnosed with ADHD were diagnosed by 6 years of age, but children with more severe ADHD tended to be diagnosed earlier, about half of them by the age of 4.

"This finding suggests that there are a large number of young children who could benefit from the early initiation of behavioral therapy, which is recommended as the first-line treatment for preschool children with ADHD," said Susanna Visser, of the Centers for Disease Control and Prevention, lead author of the study.

The study increases our knowledge of ADHD treatment. Nearly 1 in 5 or 18 percent of children with ADHD did not receive mental health counseling or medication in 2011-2012. Of these children, one-third were reported to have moderate or severe ADHD.

"This finding raises concerns about whether these children and their families are receiving needed services," said Dr. Michael Lu, Senior Administrator, Health Resources and Service Administration (HRSA).

The study also found that:

* Seven in 10 children (69 percent) with a current diagnosis of ADHD were taking medication to treat the disorder.

* Medication treatment is most common among children with more severe ADHD, according to parent reports.

* States vary widely in terms of the percentage of their child population diagnosed and treated with medication for ADHD. The percentage of children with a history of an ADHD diagnosis ranges from 15 percent in Arkansas and Kentucky to 4 percent in Nevada.

Nearly one in five high school boys and one in 11 high school girls in the U.S. were reported by their parents as having been diagnosed with ADHD by a healthcare provider. For this study, data from the 2011-2012 National Survey of Children's Health (NSCH) were used to calculate estimates of the number of children in the U.S. ages 4-17 that, according to a parent, had received a diagnosis of ADHD by a healthcare provider and were currently taking medication for ADHD. The NSCH is conducted in collaboration between HRSA and CDC.