hum,not sure it is, does she forget alot, does she have trouble everyday living. thoses are things you look for. does it run in her family. i my mom is scared of the dark and of someone coming into her house and getting her , and yes she sees people in her house that has been dead for 50 years . you could take her to dr have them test her and see whats going on with her. prayers are she dont have it.
No, although it does represent a typical psychiatric symptom. This may or may not co-exist with dementia, but many younger people develop such delusions.
Square one is to insure good nutrition, to include a daily multi-vitamin, and B-12 with folic acid, as well as co-enzyme Q-10 every day. Next is to ensure daily hydration. It goes without saying bloodwork is necessary, specifically to detect anemia.
Only then would I consider a psychiatric consult, and would not consider medications unless the delusions became severe enough to interfere with daily activities.