Nearly 1 in 5 high-school-age boys in the United States and 11 percent of school-age children overall have received a medical diagnosis of attention deficit hyperactivity disorder, according to new data from the federal Centers for Disease Control and Prevention.These rates reflect a marked rise over the past decade and could fuel growing concern among many doctors that the ADHD diagnosis and its medication are overused in American children.The figures showed that an estimated 6.4 million children ages 4 through 17 had received an ADHD diagnosis at some point in their lives, a 16 percent increase since 2007 and a 53 percent rise in the past decade. About two-thirds of those with a current diagnosis receive prescriptions for stimulants like Ritalin or Adderall, which can drastically improve the lives of those with ADHD but can also lead to addiction, anxiety and occasionally psychosis."Those are astronomical numbers. I'm floored," said Dr. William Graf, a pediatric neurologist in New Haven and a professor at the Yale School of Medicine. He added, "Mild symptoms are being diagnosed so readily."Use of stimulantsAnd even more teenagers are likely to be prescribed medication in the near future, because the American Psychological Association plans to change the definition of ADHD to allow more people to receive the diagnosis and treatment. ADHD is described by most experts as resulting from abnormal chemical levels in the brain that impair impulse control and attention skills.While some patient advocates have welcomed rising diagnosis rates as evidence that the disorder is being better recognized and accepted, others said the new rates suggest that millions of children may be taking medication merely to calm behavior or to do better in school.Fifteen percent of school-age boys have received an ADHD diagnosis, the data showed; the rate for girls was 7 percent. Diagnoses among those of high-school age -- 14 to 17 -- were particularly high, 10 percent for girls and 19 percent for boys. About one in 10 high-school boys currently takes ADHD medication, the data showed.Rates by state are less precise but vary widely. Southern states, like Arkansas, Kentucky, Louisiana, South Carolina and Tennessee, showed about 23 percent of school-age boys receiving an ADHD diagnosis. The rates in Colorado and Nevada were less than 10 percent.The medications often afford those with severe ADHD the concentration and impulse control to lead relatively normal lives. Because the pills can vastly improve focus and drive among those with perhaps only traces of the disorder, an ADHD diagnosis has become a popular shortcut to better grades, some experts said.Sales of stimulants to treat ADHD have more than doubled to $9 billion in 2012 from $4 billion in 2007, according to healthcare information company IMS Health.Given that severe ADHD that goes untreated has been shown to increase a child's risk for academic failure and substance abuse, doctors have historically focused on raising awareness of the disorder and reducing fears surrounding stimulant medication.A leading voice has been Dr. Ned Hallowell, a child psychiatrist and author of bestselling books on the disorder. But in a recent interview, Hallowell said that the new CDC data, combined with recent news reports of young people abusing stimulants, left him assessing his role.Whereas Hallowell for years would reassure skeptical parents by telling them that Adderall and other stimulants were "safer than aspirin," he said last week, "I regret the analogy" and that he "won't be saying that again."