Dr. James Perrin, the director of the division of general pediatrics at the Mass General Hospital for Children in Boston, says it takes more than one doctor's visit to get an ADHD diagnosis right. (Perrin helped write guidelines for diagnosing ADHD in general practice or family practice settings, which were published in 2000, but did not participate in Garland's study).

CNN: Youngest kids in class more likely to be diagnosed with ADHD