If you read the transcript of the interview, it's pretty difficult to conclude that Trump isn't mentally deranged, if not actually just completely lacking in basic intelligence.  He is totally incoherent, jumping from one topic to another and contradicting himself numerous times on NATO, China, North Korea, and even which television programs he watches, saying first that he watches CNN, but it was so hard to stop watching CNN and he doesn't watch it. He brags about his own television audience when he gives a speech as if it is somehow a measure of his success as president. He says that being president is different from business because as president you have to have a heart, but in business it's better not to have one. Think about that for a minute in relation to working people etc. 
Of course none of his supporters will find a single syllable out of place, but like Trump, they tend to avoid reality in favour of blind partisanship.
https://apnews.com/c810d7de280a47e88848b0ac74690c83