My sainted FDR-liberal grandma was afflicted with Alzheimer’s, and did not recognize me for the last few years of her life. It is a very unpleasant disease, although I can’t say she ever really suffered. She was no more than a shell of a human being by the end, but she was comfortable and pain-free and surrounded by people who loved her even if she didn’t know who they were.
We lost my dad just over 6 months ago; he also had dementia, but his was more age-related brain atrophy stuff (age 94).
This disease is one of nature's cruel little tricks. I'm still not quite right with God -- but maybe I better fix it, because of my gene pool....sigh