How do I persuade Mother to talk to her doctor about cognitive issues, if the only hope is that it's NOT dementia? Does treatment help?

She might be taking too much medicine without eating enough food to regulate her thinking. If she is taking glipperzide (diabetic medicine--?) and metformin, the combination can be problematic if her glucose is not checked regularly. There is also a test for dementia that a specialist can give but i would check the medicines first as they can cause this to happen. Forgetfulness is normal for her age. Add your name to everything she has and get a power of attorney and medical proxy to help her through the process. She need your support without yelling or using accusatory language. she still feels very independent, so work with that notion and you will get a lot more done (use sweetness, everyone loves a compliment).

Her insurance is through my late father's employer. My brother tried the subtle approach and got frozen out, and then I was blunt with her, so she's resistant again. She blames not wearing her hearing aids enough, having stress over the money (caused because she got paranoid and forgot that the bills were on autopay), telling me that I'm silly, etc.
I'm starting to think that I'll have to wait till she's bad enough for APS to be called, because living with her (when she was competent) was very traumatic for me, and much more so for my spouse. I'm not going through that again.

When my mother developed dementia, we took her to have a complete workup. It turns out her dementia is one that is often treatable, NPH (normal pressure hydrocephalus). Unfortunately she turned out to not be a good candidate for treatment. But many people are and i have heard multiple first person accounts about how it was life change to have the treatment (surgery to install a shunt).

That's just one example of why you want to get a complete diagnosis. There are other reasons also, but that was our experience.

I will note that this was not caught by her PCP, nor did he suggest the complete workup. We did that due to my reading here that it was a good idea. We used the Memory and Brain Wellness center at our large local university.

Really, there is no cure. Slowing down...my opinion...just prolongs the inevitable.

Mom needs an eval. People on forum have suggested telling LOs Medicare needs them to get a checkup.

The virtue of an assessment is that it is always better to know what you're dealing with.

If your mother's difficulties are caused by something other than dementia, then as you say it may be possible to offer her all kinds of options. And if it is dementia, not knowing won't stop it happening.

What's more, if it is, then there will be all kinds of possibilities for supporting her quality of life for longer. Forewarned is forearmed. If you Google "living well with dementia" you'll find lots of ideas for adaptations and strategies that both support people at home and also enable a well-informed choice when the time comes, if it ever does, to find the right kind of facility.

It's a scary thing to face, but it's an even scarier thing to fear in the dark. So I should tackle the conversation from an "it REALLY won't help not to know" angle.

I don’t know of anyone who would be happy about a diagnoses of Alzheimer’s/dementia, so your mother’s hesitancy to speak with her doctor is understandable. But if it is, ignoring it won’t make it go away. Before you go to the doctor, you and Mom do some research on what to expect. This site is an excellent place to start. Knowing what to expect does a lot to allay fears.

There are many medicarions for dementia. There is unfortunately no cure, but medications can help. Above all, assure her you’ll be there for her to help her.