ADHD to Disclose or Not in Personal Statement

Hi:
My son has ADHD ( diagnosed in 3rd grade & medicated since ) He is not sure whether to add personal statement/ explanation of grades essay on the Common App. His grades in 9th & 10th were mostly C’s in his core classes. A’s & B’s in elective classes. In 11th grade he earned all A’s & B’s in all classes. Current GPA unweighted 3.0 / Weighted 3.5 - ACT 29.
We have been given conflicting advice from a few trusted sources. Some say disclose in secondary essay, others say leave it out.
He is applying mostly to Universities that have ADHD support ( U Denver, U Connecticut, Northeastern and a few others )
Any advice appreciated.