Published in the Medical Journal of Australia, the research suggests the youngest children in the class are more likely than their older classmates to receive medication for ADHD.
Based upon a sample of more than 300,000 children in Western Australia, researchers from Curtin University compared those that were born in the early and late months of a recommended school-intake and who received at least one prescription for an ADHD medication.
They found that among children aged six to ten, those born in June – the last month of a recommended school-year intake in Western Australia – were nearly twice as likely to have received ADHD medication than those born the previous July, the first intake month.
For children aged 11-15, the effect was less marked, but ‘still significant’.
Dr Martin Whitely, who lead the research, goes on to cite a study in Taiwan last year with similar findings, which suggested that teachers might be comparing the behaviour of more mature children to those of children who are a lot younger. He also points to an earlier North American study that indicated developmental immaturity could be being wrongly labelled as a mental disorder and unnecessarily treated with stimulant medication.
In 2013, a group of doctors warned that ADHD was being overdiagnosed. Writing in the British Medical Journal (BMJ), they argued that the definition of ADHD in doctors’ guidelines had broadened in recent years, contributing to a ‘steep rise’ in diagnosis of the disorder particularly among children. They said it could mean ‘unnecessary and possibly harmful medical treatment’ for some individuals, and went on to call for a more ‘cautious diagnostic approach’ to help reduce the risk of overdiagnosis.
Compulsory education in Australia starts at around the age of five or six years, with minor variations between the states and territories. The school year runs from January to December. Education is primarily the responsibility of the states and territories.
To help prevent misdiagnosis of ADHD, Dr Whitely of Curtin University suggests allowing parents to decide when their child is ready to start school. Delaying a child’s school start is much less common in Western Australian than it is in other states in the country.
He concludes that further research is needed on the ADHD late birthdate effect in states with greater flexibility around school starting age.
Liz Searle, consultant child and adolescent psychiatrist at the Tavistock Centre, said, 'The research raises some interesting issues.
'There can be quite a big gap between children in a year group born in July/August compared to those born in September, particularly if a younger child has learning difficulties.'
However, Dr Searle said it is very unlikely in this country that a child would be misdiagnosed for ADHD and given medication as NICE guidelines are very robust. This is in comparison to the United States, which she said has very different practices.
'If people follow the guidance in this country, it is very unlikely for a child to get misdiagnosed. When diagnosing the condition we meet with parents and the child in clicnic. We observe the child at school and speak with teachers. We also use a diagnostic tool called the Connors test.
'Medication is only given to children with ADHD if they are on the moderate to severe side. If children are on the milder end, we recommend parent groups, in which parents are given strategies to help support their child. This is also recommended for moderate to severe children.
'Giving children medication is a very serious decision. We wouldn’t consider it unless a child is getting into sufficient trouble.'