Member-only story
Your ADHD Diagnosis May Depend on Your Birthday
Imagine you were conceived and born a month earlier than you actually were. As long as you’re not a believer in astrological signs, you would probably expect to be the same person you are today, just a month older. That’s a very reasonable assumption because you would have the same genes, parents, and general childhood environment. But there is one thing about your early life that could change rather dramatically: your starting age at school.
If you were born in August, you probably started school almost a whole year earlier than your age-matched peers born in September. You were separated by a grade throughout your early educational life. This might not seem like a big deal but it does make a meaningful difference. Because of the way the school calendar is arranged in countries like the US and UK, August-borns are the youngest in their class while September-borns are the oldest in their class. In adulthood, an 11-month age difference relative to a colleague does not substantially affect mental ability or developmental characteristics. But in childhood, the experiences and behaviors of kids aged 8 vary from those of kids aged 7. And as they grow and compete in the same class, that conflict can have notable consequences.
I’ve previously highlighted many of these consequences in another article, but more recently, researchers have looked…
