About 1.6 million cases of attention deficit hyperactivity disorder (ADHD) have been diagnosed in American elementary school children, according to the Centers for Disease Control and Prevention (CDC).

In a new report the CDC said that about half of the children in whom the disorder was diagnosed had also been identified as having a learning disability. “This report serves as a snapshot of a condition that has important consequences for the development of school age children,” said the CDC's acting director, David Fleming. “However, much more needs to be learned about ADHD and about the spectrum …