My mother-in-law knows. She's currently trying to hide out from every person she's ever known in her life that's not my wife and me. Won't got to church, won't visit friends. Sometimes she's in denial about stuff she doesn't remember, and sometimes she admits it. Very common phrase coming from her is "I'm losin' it", of course in reference to her ability to remember. She's been losing her ability to form new memories steadily in the entire 10 years I've known her.

The last time she had a doctor's appointment, they gave her the memory test, though. And she drew the clock correctly, and remembered the three words. Scored 5 out of 5. It blew my mind, because she regularly asks the same question again and again when we visit.