Yeah, "rambling Ronnie" as they used to call him was the object of cruel British satire even at the time: https://www.youtube.com/watch?v=ZGibwOlMuSE (and plenty more where that came from, even to the point where he is being led about by caregivers who say "time for your morning crap Mr President," "My fellow Americans . . . " "Not that kind of crap Mr President . . .".). As I recall, one day he gave a speech and then gave it again from the top, and at that moment they realised something was definitely amiss. Might have been after he was president. Can't find a reference on line but I think I read it in a book somewhere.