President Trump, in his inimitable fashion, has pushed back against one of the central themes of Michael Wolff's breathless work of gossip, Fire and Fury: Inside the Trump White House. The theme -- fanciful, false, 'fake' or not -- is that Trump's White House was staffed with more than a few folks who view the man in the Oval Office as unfit for the job, lacking the qualities of mind that one should expect.
This is not a new theme.
Here is an article in Statnews last year that tried (and failed?) to 'measure' a difference between a younger and older Trump's vocabulary and fluency.
Research has shown that changes in speaking style can result from cognitive decline. STAT therefore asked experts in neurolinguistics and cognitive assessment, as well as psychologists and psychiatrists, to compare Trump’s speech from decades ago to that in 2017; they all agreed there had been a deterioration, and some said it could reflect changes in the health of Trump’s brain.
The author of the Statnews May 2017 article helpfully includes several brief video excerpts -- from 1987 and 1991, and from a more recent video of the President speaking extemporaneously.
... the decline of Grand Supreme Hoopla ...
We're still better off with Trump than Clinton