I mean... Maybe? But he still seems pretty capable to me. Plus it makes him ultra entertaining to watch. In all seriousness, this is an interesting opinion, and I'd like to know more about what evidence the OP has that Biden has dementia. As for myself, I've met a man with dementia before. Biden doesn't remind me of him. But I'll have to research more about dementia and watch more footage of Biden before I can form a solid opinion. And even then, I feel like it's impossible to see true signs of dementia unless you know the person intimately, or know enough about how they've always been throughout their life to know when they are starting to deteriorate.

If you are talking about the way he speaks, Biden has a stutter. That is not something that goes away. It can be managed, but it's something that is there for life.

Republicans (and some Bernie-esque Democrats) found Biden's speech impediment to be a good device to portray Biden as Trumps equialvent, whereby the 2020 election was viewed by many as a referendum on Trump and his general disposition as a power-hungry right-winger, it became necessary for people against Biden to come up with a similar notion to apply to Biden. It would be politicly naive to cast Biden as anything worth calling a referendum over, due to his mild political temperament that works in tandem with a mild manner, so therefore his stutter became a good attack line in an attempt to make voters think, "Vote Trump as to avoid Biden", rather than vice versa.

Obviously.