Even if they don't remember where that person lives, what their name is or what relation they are?
My 84 year old mother is in mid to late mid-stage dementia. She has suddenly started writing letters that claim that she misses my brother terribly (we live 1,000 miles apart). Thing is, she can't ever remember WHO it is that she's writing these letters to. Example: Last pm in the throes of one of these letters she asks me "what's the name of my relative that lives in Pittsburgh?" You don't have any relatives in Pittsburgh anymore. "Yes, I do. Oh...it's a male...a cousin, I think." Nope. No relatives in Pittsburgh & your only cousin is a female in NC. "No. He works in the meat department...as a butcher." Sorry, Mom, not sure who you mean. "Yes, you do. His last name starts with an 'R'." Do you mean Randy? "IDK...maybe." Well, he doesn't live in Pittsburgh, he's her son, not her cousin, he works in insurance not as a butcher & his first name starts with the 'R' not the last name. If she basically doesn't remember any details about my brother, is she REALLY missing him? I can't just take her back for a visit because it's a 17 hr drive and, mostly, I have no one to care for my livestock & farm while we're gone. I also fear from some of the things she has said lately that she is reliving a neighborhood where she & Dad lived in the late 50's & early 60's. I can't help but wonder if she's still gonna be unhappy even if we make the trip because it's not gonna to be the "right" neighborhood.
Just my amateur opinion, but events, people, places and similar markers are part of the positive aspects that are stored in our brains, and perhaps drawn upon when life becomes too challenging to otherwise face.
I think even though they are confused in the details they do remember bits and pieces of the past and it's this scattering of memories that makes it so hard for them. My Mom would like to go back and visit the farm but we won't be making that trip. It's 1500 miles and physically she would have a hard time and once there I doubt if she would even recognize it as the farm has changed so much over the years. Better to live with her happy memories of the place.