Youngest Children In Class More Likely To Be Diagnosed With ADHD

According to a new paper, published in the Journal of Pediatrics, children born late in their school year are more likely to be diagnosed with ADHD, and/or receive medication, than those born earlier. The study was performed on data from more than 378,000 children in Taiwan aged 4 to 17 years old from 1997 to 2011, where the cut-off date for enrollment at school is August 31.

Of the 32,394 children born in August (the youngest children), 2.9 percent were diagnosed with ADHD. The lowest was September (the oldest children), with 1.8 percent of the 33,607 children diagnosed with ADHD. And there was a sliding scale between the two extremes. The full results are available in Table 1 of the paper.

"Our findings emphasize the importance of considering the age of a child within a grade when diagnosing ADHD and prescribing medication for treating ADHD," the researchers wrote.

Interestingly enough, this was only found in pre-school and elementary school children, and not adolescent. The uniformity in ADHD in teenagers might imply that increasing age (and hence maturity) could reduce the impact of birth month on ADHD.

This is not the first time these types of correlations have been found. A study on 1.7 million New Yorkers between 1985 and 2013 showed that ADHD diagnoses peaked in November, which was the cut-off month (November 30, specifically) for enrollment in schools.

In the U.S. alone, over 10 percent of children aged 4 to 17 are diagnosed with ADHD, and researchers are yet to fully understand how ADHD manifests and how to best help children diagnosed with it. ADHD is a developmental disorder with a single diagnostic label, but individual children who are struggling with it might experience significant differences between each other.