You might want to consider his organizational skills as well, which are frequently a deficit in ADHD. And, beyond clinical observations, there are actual tests for attentional dysregulation, impulsivity, cognitive flexibility, etc. (usually computer-based), which should be accessible to most neuropsychologists, especially hospital-based ones. Notably, the Conners CPT & CATA.

...pronounced like the long vowel and first letter of the alphabet...