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ADHD diagnosis & your child's birthday - the correlation

Two interesting articles published in the September issue in the Journal of Health Economics shows that children who were younger than their classmates were more likely to be diagnosed with ADHD and were more likely to be medicated for ADHD. This raises some intriguing points about diagnosis and expectations that we (parents & teachers) place on children. An older child will act differently than a younger one. A child that is 10 months younger that his/her peers is probably less mature psychologically than their older counterparts, yet we expect all kids to act and behave uniformly. Perhaps we need to factor in birthdays when making these diagnoses. See references below should you wish to read the studies in its entirety.

In the book Outliers by Malcolm Gladwell, we are shown the same correlation between birth dates and hockey players. Gladwell shows that a disproportionate amount of NHL players were born in the early months. The theory being that earlier birthdays equals greater physical maturity and hence they tend to do better at sports at a younger age. A guy that hits puberty first will have a significant height and strength advantage over his less mature teammate. The 'older male' having shown greater promise at a younger age leads to more coaching and ice time, which leads to even better play and thus increases ones skill level. This pattern repeats itself from peewee hockey to the minors and leads to a greater chance of making it to the NHL. Mind boggling, isn't it how the day you're born can play such an important factor in your life. If I recall properly, I've also read papers linking your birthday to other health factors as well.

Yours in health,

Ian Koo, ND
Doctor of Naturopathic Medicine

Naturopathic Essentials Health Centre
"The care you want, the health you need"


  1. Elder TE. The importance of relative standards in ADHD diagnoses: evidence based on exact birth days. J Health Econ. 2010;29:641-656. Abstract
  2. Evans WN, Morrill MS, Parente ST. Measuring inappropriate medical diagnosis and treatment in survey data: the case of ADHD among school-age children. J Health Econ. 2010;29:657-673. Abstract

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