Having experienced my Mother's dementia/Alzheimer's, up close n personal.... One moment, I was her son. The next moment, I was her taxi driver. The next moment, her dad. The next moment, her college student. The next moment, she wanted to visit her Aunt Virginia (deceased for a decade +). I could ramble on, in terms of who I "was," in my Mother's eyes. One more. She often assumed, that her husband of 63 year's, was a stranger in our home.
Nutshell, given Gene's Advanced Alzheimer state, NOTHING surprising here.
My Mother is in a much better, here off-earth-place. So is Gene and wife.