Language loss in stage 6 dementia?

Last summer I went to visit my dad in his (and my aunts') continuing care apartment. It was obvious he was in stage 6D. At Thanksgiving my dad was put on the waiting list for the memory care unit.

My question: I talk to my dad every evening. He sundowns a lot. He was very articulate when he told me he had been kidnapped was being held for ransom (he had be a politician in DC).

Recently when I talk to him, it's more like read stream of consciousness monologue. I told him about eating out at our local taco truck (the only one in my VERY rural county) and it went from "what did you eat" to "things will settle down and they will get the shooters" I suspect that news was on the TV. Also our conversations have gone from 15 minutes a night last May to 7 minutes a night. He use to be about to do the politician thing of asking questions about subjects he didn't know about (_boar taint_ sounds like a difficult problem to cost effectively over come, how did you decide your course of action? fill in underlined area with your choice of problem) to "uh huh, that sounds interesting" Is this what language loss is? Or is this just sundowning and will get better as the days get longer?