I can tell you almost first hand Biden has dementia. I'd like them to ask Biden what day it is, simple things, such as his age, the month and season. He has a problem with numbers and current, those are strong signs of dementia.
I know a guy with a high IQ since hit with dementia many years ago. He can still maintain an intelligent conversation assuming where he's at in the moment, but generally speaking, the topics of discussion are always the same assuming he's controlling the conversation. You know, like Biden, "you're racist, you caused COVID deaths, you're reason for recession, blah blah blah". He's a Colonel, masters in writing/political science. He's still fully aware how bad the left are, though he hasn't seen how far they've declined last years, especially now.
What he doesn't have is Biden's confusion and stuttering, where Biden immediately forgets where he's at. Sure he's confused why he's in a home, it's traumatic and there's far more to it, then add COVID. In Biden's case he simply gets lost in what he's trying to say. If Biden can still make himself a sandwich good for him, but I have some doubt he can manage that.
Did you know all Americans are dead? On multiple occasions Biden has declared 200 million people have died because of Trump and COVID, and another 150 million have died from Gun deaths and the 2nd amendment.