When my Dad is alone he is constantly talking to himself. Is this normal?

My mom, who is 95 and still going strong, talks to herself all of the time. I came in on her a couple of days ago and she was getting dressed to go downstairs to get a package. She was just chattering away about being 95 and how getting dressed was a pain, etc. I think it's perfectly fine...as long as your dad isn't having delusions or hallucinations that he's talking about. I'm single and occasionally talk to myself. I'm sure the older I get, the more I will do it too. :)

What does he say? Is he just muttering to himself or does he seem to be talking to invisible friends? Does he seem disturbed or angry?

I don't have dementia. I've liked talking to myself for many years. Once I was talking to myself (outloud,unfortunately) as I pursued a shelf in a grocery store. I realized a gentleman near me was giving me funny looks. I turned to him, smiled, and said, "Just pretend I'm on my cell phone." He smiled, and probably concluded that I wasn't dangerous.

Sometimes I recite my to-do list outloud, as an aid to my memory. Sometimes I talk to inanimate objects. "Okay scissors, where are you hiding? I last saw you in the kitchen drawer. Did someone move you?"

So, maybe I'm not the best person to ask about what is "normal." :)

I'd mention this the next time you see his doctor. But if he doesn't seem disturbed or distressed or anxious while he is talking, I think I wouldn't be too concerned about it.