New Harvard Medical School research shows that the youngest children in a grade are 34% more likely to receive an A.D.H.D. diagnosis than their classmates.
It makes sense that developmentally less mature children, often younger by almost an entire year, would have trouble paying attention and remaining still when asked.
Having an earlier cut-off date for first grade may be beneficial for the youngest students, especially boys. Many believe this research also strengthens the case for starting school and academics at a later age.