We think my mother has alzheimers but it's hard to say. The main symptom with her is severe memory loss except her personality is still there and she can chat and laugh at a joke. I suppose it affects people in different ways.
I was going to suggest that you try music, especially the sort that he enjoyed and was popular when he was young. Depending on the patient it can be very soothing, and might be for your mother as well. Maybe set up a simple music player.