Researchers from Australia, France, the USA and the UK have come together to compile a 2019 Annual Research Review for the Journal of Child Psychology and Psychiatry on the correlation between a late birth-date (relative to the school year) and risk of attention-deficit/hyperactivity disorder (ADHD). Martin Whitely and colleagues conducted a systematic review of the literature for studies exploring the relationship between birth date and ADHD diagnosis, and found 19 studies conducted in 13 countries that covered more than 15.4 million children. In 17/19 studies, they found a higher proportion of ADHD cases in children with a late birth date.
Interestingly, the two studies that did not report this effect were conducted in Danish populations. In Denmark, it is not uncommon for children who are considered to be immature, to delay starting school — a practice known as ‘academic redshirting’. As the researchers note, this point raises an interesting question as to whether academic redshirting might indeed prevent or disguise late birth-date effects in the classroom.
Importantly, Whitely and colleagues found that the youngest children in a classroom are at an increased risk of being medicated for ADHD, even in jurisdictions with a low diagnosis and/or prescribing rate. The researchers assert that this data challenges the notion that low rates indicate sound diagnostic practices. As pointed out by Sonuga-Barke et al. in their accompanying commentary, it could be considered a positive finding if the disproportionate number of young-for-class children with ADHD, is due to a perceptual bias. To adjust this issue, teachers could simply adjust their teaching practice and judgement to account for the maturity of the child, relative to their classmates. Going forward, Whitely et al. explain that both teachers and clinicians should remain alert to the potential of age-related immaturity being misdiagnosed as ADHD.
Whitely, M., Raven, M., Timimi, S., Jureidini, J., Phillimore, J., Leo, J., Moncrieff, J. & Landman, P. (2019), Annual Research Review: Attention deficit hyperactivity disorder late birthdate effect common in both high and low prescribing international jurisdictions: a systematic review. J. Child Psychol. Psychiatr. 60: 380-391. doi: 10.111/jcpp.12991.
Sonuga-Barke, E.J.S. & Pasco Fearon, R.M. (2019), Commentary: ‘Ready of not here I come’: developmental immaturity as a driver of impairment and referral in young-for-school-grade ADHD children. A reformulation inspired by Whitely et al. (2019). 60: 392-394. https://doi.org/10.1111/jcpp.13039.
Academic redshirting: the practice of delaying the entry of an age-eligible child into school to give additional time to the child to grow emotionally, physically and cognitively.