What is actually immaturity may be mislabeled as ADHD, according to new studies.
''It's not just how old you are when you enter kindergarten that matters," says researcher Todd Elder, PhD, a health economist at Michigan State University, East Lansing. "It's how old you are relevant to your classmates."
Likewise, if your child is the oldest in the class and doesn't have a diagnosis of ADHD, that, too could be wrong, Elder says.
Although recent headlines from his research have focused on the possibility that nearly 1 million children in the U.S. may have been misdiagnosed with ADHD, Elder tells WebMD that there may also be a substantial amount of underdiagnosis among older kids.
The research is slated to publish in the Journal of Health Economics.
Is It Really ADHD? A Closer Look
In his study, Elder looked at the differences in ADHD and medication rates between the oldest and youngest children in a grade. He used data from the Early Childhood Longitudinal Study Kindergarten Cohort, funded by the National Center for Education Statistics.
He looked at whether and how the age of a child relevant to his classmates made a difference. He also looked at which child was likely to take ADHD medications and if the patterns differed by states, which have different cutoff dates for when a child can enter kindergarten.
He found that the youngest children in kindergarten were 60% more likely to be diagnosed with ADHD than their oldest classmates, which could translate to 900,000 children potentially misdiagnosed. They were more likely to be on ADHD medications than the older kids.
What is it about the peer group that may influence a misdiagnosis of ADHD? ''I'm not entirely sure," Elder says. "Diagnoses are explicitly based on a comparison of a kid's behaviors with those of their peers."
Kids in the same grade and kids of the same age are two very different scenarios, he says.