Researchers at Harvard suggest that many children who are being diagnosed with ADHD might actually just be inappropriately placed in school.

A press release from Harvard University asks, “Could a child’s birthday put them at risk for an ADHD misdiagnosis?

The answer appears to be yes, at least among children born in August who start school in states with a September 1 cutoff enrollment date.” In the paper, published last year in the New England Journal of Medicine, lead researcher Timothy Layton, assistant professor of health care policy at Harvard Medical School, writes, “Our findings suggest the possibility that large numbers of kids are being over-diagnosed and over treated for ADHD because they happen to be relatively immature compared to their older classmates in the early years of elementary school.”

The researchers compared the records of more than 400,000 elementary school children to see if there was a difference between those diagnosed with ADHD who had an August birthday versus children who were born in September (and therefore were among the oldest in the class). They report, “85 out of 10,000 students born in August were either diagnosed with or treated for ADHD, compared with 64 students per 10,000 born in September.”

Many states have a cutoff date of September first, so a child who is born in August will be nearly a year younger than his classmates and could have difficulty focusing on academics. At an early age, the difference between the behavior of a six-year-old and a seven-year-old can be significant, and the immaturity of the younger child can be viewed as a disorder.