The Relationship Between Age and ADHD Diagnoses in Young Kids

In states with the September 1 cut off, there was no significant difference in ADHD diagnosis rates between kids in the same class born in July versus August or September versus October. In states without a September 1 cut-off, there wasn't a significant difference between August and September born kids. Taken together, it bolstered our initial hypothesis: The relative age effect and ADHD diagnosis of young kids was real.