My grandmother was getting that way toward the end of her life. She lived to be 104. More precisely, she thought she lived to 104. She died a week short of her birthday, but she thought it was her birthday. We were told she cried in the morning because her family had forgotten her birthday -- we lived in the area and would have come over. Then she didn't make it to the end of the day. This story has me wondering whether mistaking the date contributed to her death.

Maybe she has a subconscious conviction that she will live a long time even though she doesnt want to? The mind is a tricky thing..

Nope, everyone (including her) though she'd be dead within a week of her husband passing, but it's been a few years now. Married for like 75 years, since they were really young, but no kids or grandkids or anything. No one had her lasting this long.