I've noticed that grandpa goes through "talking jags" the same way that some people have "crying jags."  During this time, he will talk non-stop, regardless of what's going on, about almost anything.  It seems to be predicated by some sort of strange conspiracy idea that he's come up with.  Wow, he comes up with some doozies. 

 I get concerned, sometimes, that he's going to act on some of his ideas, because he could really damage some of his relationships beyond repair.  I'd hate to see that happen, but it's useless to try and argue with him.  He's beyond reason; beyond logic.  The sad thing is that not everyone is as understanding of his condition, so people tend to treat him like he's serious, when, although he is serious at the time, he's actually impaired and doesn't realize what he's saying.