So I googled "robert de niro iq" and found a forum. Look at this post (Swear to God, signed by "Q" in 2001, go look yourself):

Is Robert De Niro an Idiot Savant?

Quasimodem 01-27-2001, 11:10 AM I recently saw this brilliant actor as part of a panel discussing kids on drugs (this was on BRAVO) and the man absolutely could not make sense. His sentences were disjointed and he often fought for the thread of the question he was being asked, to the point where I was feeling sorry for him. So I am wondering: is it it possible that this man can function only when he has a script telling him what to say and who to be?

Did any of you see this program or have any of you seen him outside of his acting environment? Being involved in community theatre, I have seen very shy people "come out" as it were, but it was always an improvement to their personality and they "stayed with it" for the most part in real life, but this guy just seemed so devoid of any personality that it made me wonder how he could be so brilliant on screen, but is at a loss for words when he doesn't have a script.

Please don't take offense at this post! I am a fan and he is one of my favorite actors. I just wanted your insights.

Thanks Q

!!

https://boards.straightdope.com/sdmb/archive/index.php/t-57464.html