FRIDAY, June 7, 2024 (HealthDay News) -- If your child is among the youngest in their school grade, it's more likely they'll be mistakenly identified by teachers as having ADHD or autism, a new study confirms.

"Adults involved in identifying or raising concerns over a child’s behavior -- such as parents and teachers -- may be inadvertently misattributing relative immaturity as symptoms of ADHD," explained senior study author Kapil Sayal, a professor of child and adolescent psychiatry at the University of Nottingham, in England.

"The child’s age in relation to their classmates [their ‘relative’ age] needs to considered when making this kind of diagnosis," he said in a university news release.

It's a phenomenon that's been picked up on in prior studies. This time, Sayal's team conducted what's known as a "meta-analysis," combining the collected data on the issue from 32 studies conducted worldwide.

They found that "children who are younger relative to their peers within the same school year are 38% more likely to receive an ADHD diagnosis and 28% more likely to be prescribed ADHD medications," compared to older kids in the same class.

When it came to autism spectrum disorders (ASDs), similar trends emerged. In two "high-quality" studies conducted in Taiwan, "children who were the youngest in their school year were more likely to be diagnosed with ASD than those who were the eldest," Sayal and colleagues found.

The meta-analysis was published recently in the journal European Child & Adolescent Psychiatry.

Teachers were more apt to make a misdiagnosis of ADHD or an ASD based on a child's relative age than parents were.

“Teachers play an important role in identifying ADHD symptoms in children," said study lead author Dr Eleni Frisira, from the university's School of Medicine. "Our findings suggest that they can be more likely to rate younger students in a class as having ADHD symptoms than their older classmates. It is important teachers are supported in considering the relative age of a child in a classroom when ADHD is being queried.”

The researchers said the trend is a stubborn one, even though specialists have long understood there's an "age bias" issue in diagnosis.

“This phenomenon has been shown in research for over a decade, but knowing about it does not seem to be changing practice," noted study co-author Dr. Josephine Holland, a clinical assistant professor of child and adolescent psychiatry at Nottingham.

More information

There's guidance on recognizing the signs of ADHD at the American Academy of Pediatrics.

SOURCE: University of Nottingham, news release, June 6, 2024