With increasing numbers of children being diagnosed with attention deficit hyperactivity disorder, parents have questions about why this is happening, whether their child's diagnosis is accurate and whether or not they need to be medicated. Now, a new study may have some answers, including why children who are the youngest in their class tend to be diagnosed more frequently than their older classmates.
The authors of the study, published in the Journal of Child Psychology and Psychiatry, reviewed data from multiple studies involving a total of more than 14 million children in 12 countries and found it was more common for the youngest children in a classroom to be diagnosed with ADHD and put on medication to treat it.
But why is this the case? According to the study's lead author, Dr. Martin Whitely, a research fellow at the John Curtin Institute of Public Policy based at Curtin University in Australia, there are no biological markers or physical tests for ADHD, so in most cases, the diagnosis is based primarily on teacher reports of a child’s behavior in the classroom.
“It appears that across the globe some teachers are mistaking the immaturity of the youngest children in their class for ADHD. Although teachers don’t diagnose it, they are often the first to suggest a child may have ADHD,” Whitely said in a statement. “Our research shows that the ADHD late-birthday effect occurs in both high prescribing countries, like the USA, Canada and Iceland, and in countries where ADHD is far less common, like Finland, Sweden and Taiwan. Our findings challenge the notion that misdiagnosis only happens in countries where there is a high rate of prescriptions for ADHD.”
Of the 17 studies that were reviewed as part of this research, only two — both conducted in Denmark — didn't show this correlation. However, a majority of Danish boys who would be the younger students in class are held back a year, so the authors of this study note that it's unclear whether this this prevents or just disguises the effect.
“Further research could help us determine whether allowing parents to decide if their child is ready to begin school helps reduce this and other late birthday effects. It could be that it helps the delayed-entry child but other children suffer,” Whitely said in the statement.
But there may be a way to more accurately diagnose children with ADHD. According to the study's coauthor, professor Jon Jureidini, a child and adolescent psychiatrist from the University of Adelaide, the findings of this research emphasized the need for parents, teachers and physicians to be aware of the potential impact of relative age in a classroom on diagnoses.
“Mistaking perfectly normal age-related immaturity for ADHD is just one of many problems with the label. Children who are sleep deprived, bullied, have suffered abuse or have a host of other problems, often get labelled ADHD,” Jureidini said in the statement. “Not only does this result in them getting potentially harmful drugs they don’t need, but their real problems don’t get identified and addressed.”