ADHD Diagnosis Is More Common For Youngest Students In Class : Shots - Health News Harvard University researchers probed the way ADHD is assessed by taking advantage of a quirk found in many U.S. school systems that means some kids are a year younger their classmates.

Youngest Children In A Class Are Most Likely To Get ADHD Diagnosis

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Sometimes children might get diagnosed with attention deficit and hyperactivity disorder simply because they are younger than their peers and not because of a medical condition. That's one way to interpret a study published online today in The New England Journal of Medicine. NPR's Richard Harris reports.

RICHARD HARRIS, BYLINE: Attention deficit hyperactivity disorder is on the rise in the United States and is being diagnosed even in preschool children. Anupam Jena and his colleagues at Harvard Medical School decided to follow up on studies suggesting that the youngest children in a class were more likely to get an ADHD diagnosis than their relatively mature classmates.

ANUPAM JENA: ADHD is a condition which a lot of people think might be overdiagnosed, and you could certainly imagine a scenario in which two kids who were in a class who are different in age by almost a year could be viewed very differently by a teacher or school personnel who's evaluating them.

HARRIS: The researchers relied on a quirk of school enrollment in order to identify the youngest and oldest children in a class. Many states have a cutoff that says children born after September 1 have to wait a year to enroll in kindergarten. The children with August birth dates come in just under the wire, so they're almost a year younger than the oldest kids in the class.

JENA: A year of age difference in the 5-year-old, 6-year-old is huge.

HARRIS: Jena and his colleagues had a huge database of health insurance claims. They sorted kids by their birth month, then asked a simple question - whether the youngest kids were more likely to be diagnosed and treated for ADHD when compared with the oldest kids in the class. Looking at children ages 4 through 7, they conclude the answer was yes.

JENA: The kids who were born in August have about a 35 percent higher rate of diagnosis and medical treatment compared to the children who were born in September.

HARRIS: This makes a big difference to the individual children diagnosed with ADHD, but it has only a small effect on the overall number of ADHD diagnoses nationwide, Jena says. It's even a relatively small effect for the youngest children in a class, those born in August.

JENA: It could be the case that as much as a quarter of the diagnoses that are occurring in August may be inappropriate.

HARRIS: Jeffrey Newcorn, a psychiatrist and pediatrician who runs the ADHD division at Mount Sinai in New York, finds the results intriguing, but he interprets the study cautiously.

JEFFREY NEWCORN: I don't think it says anything about overdiagnosis.

HARRIS: In his view, this says a lot more about identifying kids with ADHD.

NEWCORN: Maybe you're going to be more inclined to call that younger kid ADHD when you wouldn't if you put them in a younger grade, but maybe in a year or two, you would anyway.

HARRIS: Newcorn says, in any event, he considers whether a child is among the youngest or the oldest in class when evaluating someone for ADHD. This whole conversation highlights the challenge of making a diagnosis, which is based on a lot of input from teachers and parents, not any kind of medical test. Meredith Bergey, a sociologist at Villanova University, says the new study underscores the need for a careful evaluation of signs and symptoms in the doctor's office.

MEREDITH BERGEY: What if the teacher were actually there in that conversation with the physicians, with the parents? And there needs to be a lot more, I would argue, conversation across stakeholders who are involved in making an ADHD diagnosis and dealing with ADHD treatment.

HARRIS: ADHD is increasingly diagnosed in very young children and is diagnosed far more often in the United States than elsewhere. So social context matters a lot. And that's why she finds the study that highlights differences of diagnosis based on relative age intriguing. Richard Harris, NPR News.

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