My MIL lives in AL facility. When I visit she seems very lucid. When she is at a Dr appt she is always very mentally with it. My Husband and sibs all see a different side. Even the AL caregivers see a dementia side. Time of day doesn't matter. I can hear her rants on the phone when she calls my hubby. So I know he's not making it up. And his sibs have similar stories. How can she be two different people depending on who is around?
Its not something she does consciously.
Here are threads from others on the same topic. See the link below.
It is very common.
The trick is to help your husband learn techniques like those taught by Teepa Snow to help manage the dementia outbursts.(look for her on YouTube).
At the doctors office write notes to the doctor of what’s going on. position yourself behind her. When he asks a question where she gives false info, you shake your head.
Try to find her a geriatric primary who won’t be easily fooled.
https://www.agingcare.com/search?term=Showtiming
The ones that they don't want to see the bad and ugly get the very best they can muster, the ones that know the good, bad and ugly tend to get the brunt of things.
So she is pretending with you and the doctors. Very common with dementia in the earlier to middle stages.
Why it happens is beyond me. Sometimes she is tired, sometimes she truly is not aware of what is happening, or of who you even are.
I'm not involved in her day to day, or even her month to month. When I DO see her, I see a noticeable difference in her ability to remember things and to make decisions. She's almost 90, so it's not a big shock, it's just that she needs to be handled differently now.