How can it be that children born in a certain month are much more likely to be diagnosed with ADHD than other children? Was it the weather in the month of their birth? Was it their astrological sign? Was it just bad luck?  And why did it happen in only some states and not in others?

The answer lies in knowing the kids.

 In a study, released in November 2018, Harvard Medical School researchers examined data from 18 states in which children who turn five by September 1 are enrolled in kindergarten. Children, therefore, born in August are almost a year younger than their classmates who were born the previous September.  The study concluded that a significant number of August babies were  being diagnosed with ADHD and put on medication for it simply because they were younger than their classmates.

The results, published in the New England Journal of Medicine, showed that students born in August had a 34 percent higher rate of ADHD diagnosis than their older classmates born in September.

Essentially, that means the youngest children in school are more likely to be diagnosed with ADHD.

Furthermore, younger students are more prone to receiving longer, more intensive medical treatments for ADHD than older classmates. That especially surprised the study’s main author, Timothy Layton, an assistant professor of Health Care Policy at Harvard Medical School.

“Our assumption was that, for those cases, there would be fewer prescriptions and less intensive treatment,” Layton said. “We found the opposite. They’re not getting mild diagnosis and treatment for ADHD. They’re being treated intensively, which is more concerning.”

According to a 2016 CDC report, nearly one in 10 children between 2 and 17 years of age — over 6.1 million total — have been diagnosed with ADHD across the nation. And the rates of ADHD diagnosis have increased by more than 40 percent over the past two decades.

But Layton believes normal maturity differences between younger students versus their older classmates are being overlooked as a factor in ADHD diagnoses, especially among young students.

“The difference in normal behavior between a 5-year-old and a 6-year-old is actually quite large,” Layton explained. “But that’s probably not something [teachers] are really thinking about. They just observe that they have a class of children who are about the same age, and they may attribute frequent misbehavior to ADHD rather than to normal variation in child behavior based on age.”

“Our work definitely shows that the diagnosis of ADHD is far from an exact science,” he says. “We have more objective ways to diagnose this condition especially because this condition is so often tied to drug treatment.”

Layton hoped this data will encourage doctors, parents and teachers to view child behaviors with more context.

“My hope is that when parents come in and say ‘my kid’s teacher says he has symptoms condition consistent with ADHD,’ that the physician pauses,” Layton said. “And if that child had a summer birthday, they say, ‘Wait a minute. Let’s consider the child’s age relative to their cohort.'”

This is a serious situation for those August babies who are being misdiagnosed with ADHD and put on intense medication for their childhood years. It is also a serious situation for all children who are younger than others in their grade if they are being judged by behavioral and intellectual standards for children a year older than they are. The younger students can develop a negative self-image as learners and thinkers if they are made to feel less adequate than their older classmates who can sit still longer and have greater focus than they do.

One size does not fit all. Context matters. And for children in the beginning years of school, age is a vital part of their context. Recognizing that as parents and educators is our job.