in re Trump and dementia - certainly wouldn't be surprising, but impossible to diagnose from afar, esp as "dementia" is a collection of symptoms rather than a specific diagnosis
whether or not he has some form of dementia, one easily observable thing is how completely Donald Trump media persona has eclipsed Donald Trump the person
he's always been massively self-aggrandizing etc but as people have said up until maybe 15-20 years ago he comes much differently - like a hugely exaggerated version of a super-rich asshole, but still a human being. unlike this grotesque, completely delusional clown we have now.
I think the real turning point is The Apprentice - it boosted his fame to household name level, especially with Americans too young to remember the 80s, and it marks the point where he becomes a caricature of himself, like you can almost see the exact point when the character "Donald Trump" unhinges its swollen jaws and swallows Donald Trump, shady NY real estate mogul and Page 6 fixture.
not that Twitter is unimportant, but it seems more like amplification of an already ongoing process than the cause itself