A portrait of the grifter as an old man
By 
Trump was slurring words today in the context of giving a very brief prepared statement to the media. (ETA: better video here, also what’s with the sniffing again, as Calvin Klein probably said at Studio 54 once upon a time and a very good time it was).
This is just the latest pebble in a mountain of evidence that he is suffering some pronounced and fairly rapid cognitive decline
Trump’s old, he has terrible health habits — no exercise (golf [eta: the way Trump plays it, i.e., no walking, not even onto the green] doesn’t really count), lots of KFC, and who knows what other mind-altering substances — and he’s not used to doing any real work, which is something that’s not possible to avoid completely when you’re president of the United States, though he’s certainly doing his worst to test that generalization.
People talk about the 25th amendment as if invoking it in Trump’s case would be nothing but a legal fig leaf for a de facto coup, but the chances that it may come into play in a much more straightforward and legitimate way are far from negligible.