[Hickfang]

https://adhd-institute.com/burden-of-adhd/epidemiology/gende...

“Evidence suggests that the prevalence of attention-deficit hyperactivity disorder (ADHD), or hyperkinetic disorder (HKD), is greater in males than females.”

A more plausible explanation is that those doing the diagnosing are female teachers who perceive the more naturally boisterous play of young males as symptomatic of a mental disorder.