Summary: A new study reveals the youngest children in a class are more likely than their older peers to be diagnosed with ADHD. Researchers say the problem may lie with some teachers mistakenly believing a child’s immaturity compared to older classmates is actually ADHD.
Source: University of Adelaide.
A new global study involving the University of Adelaide has found that children who are the youngest in their classroom are more likely to be diagnosed with Attention Deficit Hyperactivity Disorder (ADHD) than their older classmates.
The research, led by Curtin University and published in the Journal of Child Psychology and Psychiatry, systematically reviewed studies that examine the relationship between a child’s age relative to their classmates and their chances of being diagnosed with, or medicated for, ADHD.
Seventeen studies covering more than 14 million children – five in the USA, two in Spain and one each in Canada, Finland, Germany, Netherlands, Iceland, Israel, Norway, Sweden, Taiwan and Australia – found it was more common for the youngest children in a classroom to be diagnosed with ADHD and medicated.
Co-author Professor Jon Jureidini, a Child and Adolescent Psychiatrist from the University of Adelaide, said the findings highlighted the importance of teachers, doctors and parents being aware of the impact of relative age and giving the youngest children in class the extra time they need to mature.
“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,” Professor Jureidini said.
“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.”
Lead author Dr Martin Whitely, Research Fellow at the John Curtin Institute of Public Policy based at Curtin University, said there are no biological markers or physical tests for ADHD and the diagnosis is based in large part on teacher reports of a child’s behaviour.
“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,” Dr Whitely said.
“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.”
Dr Whitely explained that only two studies, both in Denmark, demonstrated a weak or non-existent late birth-date effect, with the majority of late-born Danish boys held back a year, which makes it unclear whether 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,” Dr Whitely said.
The research was co-authored by researchers from the John Curtin Institute of Public Policy at Curtin University, University of Adelaide, including international researchers Professor Sami Timimi from Lincolnshire Partnership NHS Foundation Trust, Dr Jonathan Leo from Lincoln Memorial University in the US, Dr Joanna Moncrieff from University College London, and Patrick Landman MD, leading psychiatrist from France.
Source: Jon Jureidini – University of Adelaide
Publisher: Organized by NeuroscienceNews.com.
Image Source: NeuroscienceNews.com image is in the public domain.
Original Research: Open access research for “Attention deficit hyperactivity disorder late birthdate effect common in both high and low prescribing international jurisdictions: systematic review” by Martin Whitely, Melissa Raven, Sami Timimi, Jon Jureidini, John Phillimore, Jonathan Leo, Joanna Moncrieff, and Patrick Landman in Journal of Child Psychology and Psychiatry. Published October 14 2018.
doi:10.1111/jcpp.12991
[cbtabs][cbtab title=”MLA”]University of Adelaide”Youngest in Class More Likely to be Diagnosed with ADHD.” NeuroscienceNews. NeuroscienceNews, 15 October 2018.
<https://neurosciencenews.com/adhd-youngest-class-10024/>.[/cbtab][cbtab title=”APA”]University of Adelaide(2018, October 15). Youngest in Class More Likely to be Diagnosed with ADHD. NeuroscienceNews. Retrieved October 15, 2018 from https://neurosciencenews.com/adhd-youngest-class-10024/[/cbtab][cbtab title=”Chicago”]University of Adelaide”Youngest in Class More Likely to be Diagnosed with ADHD.” https://neurosciencenews.com/adhd-youngest-class-10024/ (accessed October 15, 2018).[/cbtab][/cbtabs]
Abstract
Attention deficit hyperactivity disorder late birthdate effect common in both high and low prescribing international jurisdictions: systematic review
Background
Multiple studies have found that the youngest children in a classroom are at elevated risk of being diagnosed with, or medicated for, ADHD. This systematic review was conducted to investigate whether this late birthdate effect is the norm and whether the strength of effect is related to the absolute risk of being diagnosed/medicated.
Methods
A literature search of the PubMed and ERIC databases and snowball and grey literature searching were conducted.
Results
A total of 19 studies in 13 countries covering over 15.4 million children investigating this relationship were identified. Three other studies exploring related topics were identified. The diversity of methodologies prevented a meta‐analysis. Instead a systematic review of the 22 studies was conducted.
A total of 17 of the 19 studies found that the youngest children in a school year were considerably more likely to be diagnosed and/or medicated than their older classmates. Two Danish studies found either a weak or no late birth date effect. There was no consistent relationship between per‐capita diagnosis or medication rates and the strength of the relative age effect, with strong effects reported in most jurisdictions with comparatively low rates.
Conclusions
It is the norm internationally for the youngest children in a classroom to be at increased risk of being medicated for ADHD, even in jurisdictions with relatively low prescribing rates. A lack of a strong effect in Denmark may be accounted for by the common practice of academic ‘redshirting’, where children judged by parents as immature have a delayed school start. Redshirting may prevent and/or disguise late birthdate effects and further research is warranted. The evidence of strong late birthdate effects in jurisdictions with comparatively low diagnosis/medication rates challenges the notion that low rates indicate sound diagnostic practices.
