Younger kids in the class may be overdiagnosed with ADHD

TORONTO – The youngest kids in the classroom are more likely to be diagnosed with attention deficit disorder compared to their peers, a new large-scale Canadian study suggests.

While children may appear to have symptoms of attention-deficit/hyperactivity disorder (ADHD), researchers at the University of British Columbia say the medical community may be overdiagnosing the condition and that young kids may be “inappropriately labelled.”

UBC scientists studied a large cohort of 937,943 children between six and 12 years old during their 11-year study conducted from Dec. 1, 1997 to Nov. 30, 2008, in the West Coast province.

The cut-off birth date for entry to school is the last calendar day of the year, Dec. 31, so children born in December are the youngest in their class while their peers born in January could be almost a year older.

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“We sought to determine the influence of relative age within a grade on the diagnosis and pharmacologic treatment of ADHD in children,” the researchers said in their report published Monday in the Canadian Medical Association Journal (CMAJ).

Results showed that kids were 39 per cent more likely to be diagnosed and 48 per cent more likely to be treated with ADHD medication if they were born in December compared to January.

December baby boys were 30 per cent more likely to be diagnosed with ADHD than their male peers born in January. Girls were 70 per cent more likely to be diagnosed with attention deficit issues if they were born in December compared to those born in January, results showed.

“The relative age of children is influencing whether they are diagnosed and treated for ADHD. Our study suggests younger, less mature children are inappropriately being labelled and treated,” lead author Rich Morrow said.

“It is important not to expose children to potential harms from unnecessary diagnosis and use of medications,” he said.

The Canadian study adds to mounting research that points to a link between ADHD diagnosis and age.

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Two recent American studies that analyzed survey data and private health plan information also showed that one’s date of birth was a predictor of diagnosis and treatment of ADHD based on the age at which a respondent started school. The pattern even existed across states.

ADHD is the most commonly diagnosed behavioural disorder in children. The B.C. researchers say there are significant health and social repercussions of diagnosing a child with the condition if he or she doesn’t have it. It’s often treated with prescribed medicine that has side effects from sleep disruption, increased risk of cardiovascular discomfort and slower growth rates.

Kids who have been diagnosed with ADHD could also be treated differently by teachers and parents, the study notes.

Jane Garland, study coauthor and psychiatrist at the B.C. Children’s Hospital, says that doctors, teachers and parents need to consider what needs to change in diagnosis.

“The potential harms of overdiagnosis and overprescribing and the lack of an objective test for ADHD strongly suggest caution be taken in assessing children for this disorder and providing treatment,” the authors conclude.

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