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Birth month may impact ADHD diagnosis :

April 19, 2016

The youngest children in a grade are more likely to be diagnosed with attention-deficit/hyperactivity disorder (ADHD) than the oldest children, according to a new study.

“Our findings emphasize the importance of considering the age of a child within a grade when diagnosing ADHD and prescribing medication to treat ADHD,” the authors said.

ADHD affects roughly 7% of children worldwide and 15% of those in the U.S., according to the study.

Researchers looked at ADHD rates for 378,881 children ages 4-17 in Taiwan where the cutoff birthday for school enrollment is Aug. 31, making students born in that month the youngest in their class and those born in September the oldest.

They found 1.8% of students born in September received an ADHD diagnosis compared to 2.9% of those born in August. Roughly 1.2% of those born in September received ADHD medication compared to 2.1% of those born in August.

The findings held true for both girls and boys. However, broken down by age, preschool and elementary schoolchildren were at higher risk of an ADHD diagnosis based on their birth month, but adolescents were not.

The findings were consistent with other studies in the U.S. and Canada and showed “relative age, as an indicator of neurocognitive maturity, may play a crucial role in the risk of being diagnosed with ADHD and receiving ADHD medication,” the authors said.

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