ADHD Diagnosis and Age

Is ADHD being over diagnosed?

A study conducted over 11 years by the University of British Columbia and published in the Canadian Medical Association Journal finds that the youngest children in a classroom are more likely to be diagnosed with ADHD. Funding for the UBC study was provided by the Canadian Institutes of Health research and the B.C. Ministry of Health.

The study reflects similar findings from US researchers [I blogged about Todd Elder  in the Journal of Health Economics (Elder et al. The importance of relative standards in ADHD diagnoses: Evidence based on exact birth dates. Journal of Health Economics, 2010; DOI: 10.1016/ j.jhealeco.2010.06.003)].  US researchers performed meta-analysis, i.e. studied data from other studies and found that younger students are more frequently diagnosed as ADHD compared to their older classmates.

The Canadian researchers followed 937,943 students ages six to 12 years old between Dec. 1, 1997, and Nov. 30, 2008. They were located in a province where the cutoff age for entry to school is Dec. 31. They found children born in December were 39 per cent greater probability to be diagnosed and 48 per cent more likely to be treated with medication for ADHD, compared to children with a January birthday. This, of course, raises concerns that many schoolchildren are wrongly being diagnosed and prescribed medication.

In an interview with CBC news, the study’s lead author, Richard Morrow said, “The relative maturity of children is affecting the diagnosis, so in other words, the lack of maturity in younger children is making them more likely to get the diagnosis, and we can interpret that as the fact that sometimes a lack of maturity is being misinterpreted as symptoms of a neurobehavioural disorder of ADHD.” Morrow is health research analyst with the Therapeutics Initiative at the University of British Columbia.

In a news release, Morrow said: “Our study suggests younger, less mature children are inappropriately being labelled and treated. It is important not to expose children to potential harms from unnecessary diagnosis and use of medications.”

The ramifications are extensive. Long term use of medication by children that don’t need it has not been studied. Less mature children who have been labelled with ADHD are often treated differently by teachers and parents which could lead to ineffective teaching and parenting. It could also contribute to negative self-perception and social issues.

The researchers recommend that an ADHD assessment should include a comparison of the child’s age to that of his classmates. Parenting and  behavior outside school should also be considered.

Funding for the UBC study was provided by the Canadian Institutes of Health research and the B.C. Ministry of Health.

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