ADHD diagnosis rate higher in children born in July and August, study finds

Researchers found a higher rate of ADHD diagnosis in children born in July and August, but they also explain why this is happening and why they don’t find it surprising.

Awareness of neurodiversity is on the rise, and as more parents seek an ADHD diagnosis for their child and educators become more aware of common ADHD personality traits, this is an area of neurodiversity that is quickly gaining acceptance. However, those interested in ADHD symptoms and treatments for their child may not realize that their child’s birth month could have something to do with the condition.

To explain this phenomenon further, research has shown that children born in July and August are at least 40% more likely to be diagnosed with ADHD or receive treatment for ADHD than children born in September and October. This large-scale study analyzed anonymized data from 96,698 children born between 2002 and 2010 in July, August, September, or October.

To put this in context, children born in July and August are still very young when they start school, almost a year younger than those born in September and October. The study found that by age 15, about 1.5% of children born in July or August who started school early were receiving ADHD prescriptions, compared to just 1% of children born in September and October who started school later. That’s a 50% increase in ADHD prescriptions among children who started school early compared to those who started school later.

The study also found that by age 15, children born in July or August were 40 percent more likely to be diagnosed with ADHD. The researchers weren’t surprised by the findings, however, and believe they may be due to what they call “peer comparison bias” caused by age differences between classmates. In other words, teachers are more likely to attribute normal signs of immaturity in children to ADHD, rather than seeing them as normal for a child who starts school early.

“A discrepancy in drug treatment between children born in July-August and September-October suggests an inefficient and unfair use of medical resources.”
Dr. Joaquim Vidiella-Martin

However, study co-author Dr. Catia Nicodemo has some good news to share. She says, “The good news is that from age nine onward, there is no difference in the implementation of ADHD prescriptions between children born in July-August and September-October, meaning that the peer comparison bias disappears with age.”

Dr Joaquim Vidiella-Martin, co-author of the study, adds: “We cannot determine with certainty whether there is an overdiagnosis of children born in July-August or an underdiagnosis of children born in September-October or simply more marginal diagnoses for children born in July-August, but we can say that a gap in pharmacological treatment between children born in July-August and September-October suggests an inefficient and unfair use of medical resources.”

To combat this problem, the team behind the research suggests increasing awareness of ADHD symptoms among parents and teachers to improve diagnostic accuracy. They also believe it would be beneficial to have two school start dates throughout the year, grouping children of similar ages together, with a maximum age difference of six months.

To learn more about this topic, there is six benefits of ADHD parents need to know and Understanding the three different types of ADHD may be beneficial if your child has a diagnosis. Parents with ADHD Raising Children with ADHD each have their own set of challenges, but support is available.