Higher ADHD diagnosis for kids born in July and August, says study - but why?

Researchers found higher diagnosis of ADHD in children born in July and August, but also explain the reason for this and why they don't find it surprising. 

Neurodiversity awareness is on the rise, and as more parents seek an ADHD diagnosis for their child and educators become more aware of the common ADHD personality traits, this is one area of the neurodiversity umbrella gaining rapid acceptance. However, those looking into ADHD symptoms, and treatments for their child, might not realise their birth month could have something to do with their child having the condition.  

To explain this further, research found children born in July and August are at least 40% more likely to be diagnosed with, or have medication for ADHD than children born in September and October. The large scale study involved analysing anonymised data from 96,698 children born between 2002 and 2010 in either July, August, September or October. 

For context, children born in July and August are still very young when they start school, almost a year younger than those born on September and October. The study found that by age 15, around 1.5 per cent of early school starters - those born in July or August - were receiving prescriptions for ADHD, compared to just 1 per cent of late starters born in September and October. This is an increase of 50 per cent in ADHD prescriptions for early school starters compared to late starters. 

The study also found that by age 15, children are 40 per cent more likely to be diagnosed with ADHD if born in July and August. Researchers however, were unsurprised by the findings and believe they can be explained by what they term a 'peer-comparison bias' caused by the differences in ages among classmates. In other words, teachers are more likely to attribute normal signs of immaturity in children to ADHD, rather than viewing them as normal for an early school starter.

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

Fellow co-author Dr Joaquim Vidiella-Martin, adds "We can’t definitively identify whether there is an over-diagnosis of children born in July-August or an under-diagnosis of children born in September-October or just more marginal diagnoses for July-August born, but we can say that a gap in pharmacological treatment between between children born in July-August and in September-October suggests an inefficient and unfair use of medical resources."

To combat the issue, the team behind the research suggest parents and teachers more are made more aware of ADHD symptoms to improve accurate diagnosis. They also believe it would be beneficial to have two school start dates throughout the year, grouping children close in age together, with a maximum of six months difference between them.

For more on this subject, there are six upsides to ADHD parents need to know about, and understanding the three different types of ADHD can be beneficial if your child has a diagnosis. Parents with ADHD raising children with ADHD have their own set of challenges, but there is support available.