Does the paranoia and suspicion fade as the disease progresses?

I always wonder how far along we are in the disease progression. How long is left? Mum manages her personal care (after I finally had to tell her that she must shower weekly AND wash her hair) but is losing the ability to care for her cat and is unable to do any other tasks. She's 86 years old; I moved her to assisted living 2 and 1/2 years ago.
She has become convinced that I take her identification and bank card; she loses these items and her keys every couple of days, then becomes distraught and calls old neighbors and church members, weeping and sobbing and wanting them to come over immediately. Recently I went out of town to visit my grandchildren for a few days. Mum called my brother to tell him that she had bad news, that I had 'ABSCONDED' and she had no identification or access to her bank account or money. She weeps and wails, and says she's lost everything. And I guess she pretty much has.

She does have pleasant hallucinations that my younger brother, who died a couple of years ago, has come to comfort her. She had vivid unpleasant dreams about 6 months ago but doesn't mention them anymore. She's sometimes astonished to hear from me because she's certain I've died.

Her health is pretty good beyond Alzheimer's and vascular dementia - she has a 47% blockage in one intracranial carotid artery and has severe delirium with any bladder infection or hospital stays.

How long will this go on?