A new study suggests that nearly one million American children may have been misdiagnosed with attention deficit hyperactivity disorder (ADHD) simply because they were the youngest ones in their school class, not because they have behavioral problems.
The Michigan State University study found that children who are the youngest in their school grades are 60 percent more likely to be diagnosed with ADHD than the oldest children, USA Today reported.
Another study by researchers at North Carolina State University and elsewhere yielded similar findings. Both studies are scheduled for publication in the Journal of Health Economics.
Misdiagnosis of ADHD can have long-term effects, said Todd Elder, an assistant professor of economics and author of the Michigan study. It also found that the youngest children in the fifth and eighth grade were more than twice as likely as older classmates to use Ritalin, a stimulant drug commonly prescribed for ADHD, USA Today reported.