Trump wasnt always so linguistically challenged. What could explain the change?

It was the kind of utterance that makes professional transcribers question their career choice:

“ … there is no collusion between certainly myself and my campaign, but I can always speak for myself — and the Russians, zero.”

When President Trump offered that response to a question at a press conference last week, it was the latest example of his tortured syntax, mid-thought changes of subject, and apparent trouble formulating complete sentences, let alone a coherent paragraph, in unscripted speech.

Now, Trump’s vocabulary is simpler. He repeats himself over and over, and lurches from one subject to an unrelated one, as in this answer during an interview with the Associated Press last month:

“People want the border wall. My base definitely wants the border wall, my base really wants it — you’ve been to many of the rallies. OK, the thing they want more than anything is the wall. My base, which is a big base; I think my base is 45 percent. You know, it’s funny. The Democrats, they have a big advantage in the Electoral College. Big, big, big advantage. … The Electoral College is very difficult for a Republican to win, and I will tell you, the people want to see it. They want to see the wall.”