alt Hacker NewsI know this is a joke, but I'd be careful about assuming: I had a trained therapist diagnose me with ADHD ... incorrectly.
It turns out, there are other conditions out there that can appear to be be ADHD. If a trained therapist can confuse them, outside observers certainly can too, so it is possible that "very ADHD-acting" person you know might not have it.
(Or, especially for females, the reverse can be true, as not everyone with ADHD manifests with the same trademark hyperactivity.)
I understand this is your personal medical info, but could you drop any hints as to the nature of the misdiagnosis? I've learned late in life that I am neurospicy and learning from other's experiences in this domain has been quite helpful.