Bernard,
I sympathise. My wife (with CA) appears to be suffering quite severely from dementia, but I don’t think she knows anything about it. It must be very difficult to come to terms with.
There are people who have studied similar conditions and I am going to read up on them. I do not think there is an answer, as the brain is largely unknown to us, but reading about it can help me understand what can happen.
I wish you the best of luck, and am keen to know how this goes, if you are able to share. This is a major problem for our family.