Millions of American kids with attention-deficit/hyperactivity disorder, or ADHD, may have a genetic vulnerability to the disease, a new study suggests.

A growing number of U.S. children are being diagnosed with attention-deficit/hyperactivity disorder.

A growing number of U.S. children are being diagnosed with attention-deficit/hyperactivity disorder.

The number of ADHD diagnoses among children has risen dramatically in the past two decades, going from 6 percent to 10 percent, a new report shows.