According to the Centers for Disease Control, about 5 percent of American children are diagnosed with Attention Deficit Hyperactivity Disorder (ADHD), a neurodevelopmental disorder characterized by patterns of inattention and hyperactivity-impulsivity. However, a new study of hundreds of thousands of Taiwanese children, published in the Journal of Pediatrics, suggests that some children may be overdiagnosed and overprescribed when, in fact, they are just more immature than their classmates, the BBC reports.

The study looked at 378,881 children in Taiwan between the ages 4 and 17 over a 14-year period to determine if there was a correlation between age and diagnosis. They discovered a trend between the date of a student's birthday, the birthday-cutoff for the school year (August 31), and an ADHD diagnosis. Children born in August (the youngest) were more likely than the children born in September (the oldest) to be diagnosed with ADHD and prescribed medication. The authors write that the younger students in a given grade are the “most developmentally immature” relative to their peers, which may “play a crucial role in the risk of being diagnosed with ADHD and receiving ADHD medication among children and adolescents.”

Chairman of ADHD Foundation, Kuben Naidoo, told The Telegraph that the study “highlights the importance of ensuring the assessment for ADHD is rigorous and relies on a variety of sources of information,” but added that “the issue is not as simple as assuming that age, as an indicator of neurocognitive maturity, influences ADHD symptoms.”

Visit the National Institute of Mental Health (NIMH) to learn more about the disorder as well as how it is diagnosed and treated.

[h/t The BBC]