My mother is living alone and independent however she has severe nerve pain in her back and leg and has a few epidurals as well as nerve burning to no avail. She had 3 "mini" strokes about 5 years ago and has a bit of aphasia though most people would not notice anything. Fortunately. However, I do. I had her take a dementia test at the hospital and she got a score of 28/30 which absolutely rules out any dementia. But, I notice she forgets a lot of short memory stuff and has difficulty getting the words to go with her thoughts, and talks more to people as well as talking through the conversation on the phone, like she doesn't always hear me, but this is difficult to explain. I get angry when she'll ask me something and she doesn't understand what I mean and we argue. I feel like crap and like I'm going to hell in a hand-basket. I don't know what to do. I see her as fragile but trying and going to therapy both physical and mental. But, she's changed. And, she gets mad at me a lot more. She accuses me of being angry, but she sounds angry with me almost all the time.
It started with forgetting her words, personality changes, forgetfulness, not liking doing the things she ones did and she started to withdrawal. If you feel that your mom has dementia than you are probably right. Like someone stated "you know her better than anyone eles."
Get your mom a real cognitive work up.
You know her better than anyone.so your observations of her decline are valid,
Try not to argue but accept that her brain capacity is likely compromised, Perhaps find a dementia support group to attend. They can be very helpful for family. Stick around here and read how others cope. Hopefully others with respond and give you other perspectives. Good luck.