Stages of dementia?

My father has been talking about people dying and funerals lately. He never says who has died, but he talks about death. He has not been officially diagnosed with dementia, but he is showing all of the symptoms. He is 89 and was a minister for 48 years, before his dementia symptoms showed up. He has started sleeping more as well. Not sure if this is a sign of anything, just wondering, what I need to do when he talks about this.