A recent Canadian study showed that the youngest children in each grade (born in the earliest month of the Canadian grade cutoff: December) were 30% more likely to be diagnosed with ADHD than the oldest children (born in January). For girls, who overall have a lower incidence of ADHD, the difference was even more pronounced: 70%.
Interestingly, the overall rate of ADHD diagnosis in the sampling of children from this Canadian study (900,000 children) was 6.9% for boys and 2.2% for girls. Rates of diagnosis here in the United States are much higher, creeping up on 10% of all children.
What does all of this mean? Well, you can look at this data many different ways, depending on your point of view and feelings about ADHD, but it stresses to me what seems to be common sense: many factors play into our expectations of what normal behavior should be. It is often the school which prompts parents to have their child evaluated for attention problems and this comes from a comparison to other children in the class. A six year old may be significantly less mature or able to stay on task than a seven year old. Likewise, boys tend to have more trouble with the expectations of the school environment than girls in the younger grades.
Both of these groups, boys, and the younger ones in class are diagnosed and treated for ADHD at higher rates. I have ambivalent feelings on the matter. Medications are not without their side effects but most parents see an improvement in behavior with minimal negative effects. If these compounds work, if they create better students, what difference does it make what groups have higher rates of diagnosis and treatment?
I don’t know if it makes any difference, provided the medications are safe and effective. There is still, however, some part of me that questions the introduction of a medication to a mind that is still maturing, unless it is absolutely necessary. Is there a “natural process” for the creation of self control in the brain? Are we creating a reliance on an artificial substance, or missing some environmental piece of the puzzle, like sleep? I simply do not know.
Most clinicians and experts would argue ADHD is like any other organic disease. You do not choose not to treat diabetes. If that is the right way of looking at it, I think this study tells us we need to be more careful about how we choose who is selected for this diagnosis, at the very least.
Matthew Toohey is a pediatrician who blogs at The Pediatrician Next Door.
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