...there's ADHD-PI ("primarily inattentive") that lacks the highly visible hyperactivity signs you find in TV-stereotipical ADHD.
It's even worse when masked by high-IQ and good coping behaviors, because when life hits you hard with trouble, it flares up and gets amplified a zillion time, and you go from 'genius' to 'retarded' instantly!
(Couple the frustration of this with some testosterone and some bad habits and you can get pretty close to "stupid and violent criminal" levels and at that point society loses all sympathy for you. I got close to this but stopped, but I imagine that most of the clever-and-ultra-violent-criminals that fill up the prisons worldwide are mostly "my kind of people" but they just lacked some special "stabilizing component" that my brain happened to have and theirs didn't.)
Most "clever and ultra violent" criminals by far are in fact sociopaths. Sociopathy does correlate with a severe lack in executive function, but the causal mechanism is very likely different from what we see in ADHD - it's probably a sort of "callousness towards oneself" stemming from the sociopath's exceedingly-poor emotional palette, that also leads to their callous behavior and lack of empathy towards others.
It's even worse when masked by high-IQ and good coping behaviors, because when life hits you hard with trouble, it flares up and gets amplified a zillion time, and you go from 'genius' to 'retarded' instantly!
(Couple the frustration of this with some testosterone and some bad habits and you can get pretty close to "stupid and violent criminal" levels and at that point society loses all sympathy for you. I got close to this but stopped, but I imagine that most of the clever-and-ultra-violent-criminals that fill up the prisons worldwide are mostly "my kind of people" but they just lacked some special "stabilizing component" that my brain happened to have and theirs didn't.)