I don't know about the financial supervision, but I can speak to the medical. 1poormom had dementia. It was progressing slowly enough that I didn't really notice. In hindsight, I should have. It had gotten pretty bad by the time I noticed "hey, there's a problem" (e.g. she thought her computer was malfunctioning when the "lines" screensaver started). However, the neurologist noticed it immediately. I'll spare you the story. The neurologist runs a series of tests for cognition, and the results are pretty unambiguous.

So I would recommend seeing a neurologist 1x per year (for each of you). You can't really rely on your own ability to see your dementia, and possibly not your spouse's. But the neurologist will see it.

I think 1poormom had moments when she realized she had a problem, but the rest of the time it was others, not her. "Stupid people!" She said that a lot, even though she was the one who couldn't remember things, was remembering things that never happened, etc. It's probably more merciful that you don't realize your have dementia.