She is 88. Most of the time she is very alert, conversed, dressed self, etc. However, she has become delusional and hallucinate, and is becoming mean and demanding. A friend suggested she get tested for dementia. She agreed until l mentioned it, she said never talk about that again. She said she would never go for a dementia test. Would checking her by a doctor really help with delusions?
I don't see any point in saying why she's seeing the doctor. IT could be check up, getting med refill prescription, etc.
I wouldn't focus on her not mentioning your previous conversation again, since, she likely has forgotten about it.
Don't tell mom about the memory test; just physical exam. Dr. can just say, "all patients over 65 are getting the test". Let doctor do the exam and then, likely he will send her to neurologist for follow up. She doesn't have to know what for -- but likely she may refuse to see neurologist -- that was my experience.
Primary care can at least assess the stage of dementia. Frankly, to me it didn't matter. He put mom on Namenda and aricept, which she didn't like, took erratically, and finally gave up. I saw no improvement. I tried to prepare by understanding disease and tried to encourage mom to let me help on finances, bills, getting assistance in help (she refused all) and we went down a long 7-8 yr path of decline. Mom just went into much needed memory care this year.
ONce you have diagnosis - that is small part. You will likely have to decide path forward and prepare. Getting the diagnosis is easy; getting a doctor to sign that mom is incompetent so you can invoke DPOA and make decisions for mom (if she refuses assistance or to move) is the hard part. I couldn't make that happen. Every dr, geriatric psychiatrist, neurologist would just kick the can down the road and refuse to write such a letter on legal grounds. My experience was a nightmare, but an imminent event finally occurred and we were able to get dr to sign.
Dr. may prescribe meds to help with anxiety, delusions, etc. But sometimes these meds can make things worse and they have to be managed -- she has to take at regular intervals, monitor for other interactions, adjust dose, etc. not to mention unpleasant side affects (nausea, dizziness, diarrhea).
Educate yourself, talk to others and try to make a plan for long term.