Follow CBSPHILLY Facebook  | Twitter

PHILADELPHIA (CBS) — Children who enter elementary school a year younger than their peers are 30 percent more likely to be diagnosed with attention deficit disorder.

Boil Water Advisory Issued For Residents In Yardley Due To High Turbidity Levels

That’s according to a study at Harvard Medical School that looked at children in states with a September enrollment cutoff.

Credit: CBS3

Researchers found children with August birthdays were often a full year younger than classmates and had a harder time sitting still.

Pennsylvania Among States With Highest Overdose Death Rates In US, CDC Reports

They say factoring in a child’s age when assessing behavior is key.