Oh I so understand this! Mum's descent into dementia was quite catastrophic. She was bumbling along at home, a bit dodgy but managing independently (undiagnosed). Then she fell getting off a bus and ended up in hospital. I visited and she'd dropped straight to the 'where are my parents? I didn't know you had children! Why am I on this ship? The men came in the night and took all the money!' stageThanks. I needed this. I keep chopping and changing my mind about care home type- just had a conversation on phone with mother who has been moved out of her covid ward now, 10 days apparently up. She seemed so "with it" on the phone just now. Other days, other times of day I do not seem to be able to get her to understand anything and communication is so poor. Just have to let the next rehab step come, when it happens, whilst continuing with my research, visiting and familiarisation of care homes.
There was no way she could go home (I lived miles away) so I moved her to a care home near me. But.... although her cognition took a dive, she still looked like a thriving well-dressed/well-kempt 'with-it' older lady with excellent mobility, etc. and - unless she was talking nonsense - you could have a perfectly 'normal' conversation with her. So when I first went to visit I was shocked how she could 'flip-flop' between the seemingly rational mum and the crazy version. I'd find myself talking normally to her, maybe explaining something and she'd reply appropriately, only to throw me a curved ball a few minutes later. e.g. 'Did you hear about the chef? They chopped him up and fed him to the pigs...' Then I'd be totally flummoxed, not knowing where to go with that and wondering if any of what I'd just told her had actually been understood.
I gradually realised that mum could in fact hold a complete conversation on auto-pilot. (Habit of a lifetime I suppose - a lot of automatic responses.) But she retained very little of what was said and often got things back to front. So if I said I'd ask the doctor about something, she might think the doctor was waiting to talk to me or had already been. Mum was able to do hostess mode like a good 'un for a long time! Even after I got wise to it, she continued to fool professionals and family who she only saw occasionally.
So I would say this: whatever you think she understands, she probably only understands half of that. And half of what she does remember will be incorrect. Each visit you'll need to start from scratch....