My mother is an interesting challenge. She has short term memory problems. She can't remember things that happened more than about ten minutes ago. Despite that, she is surprisingly with it. She tells stories, play games, holds her part of a conversation. Here is challenge-- when she forgets where she is and what's happening, she confabulates. She makes up something and runs with it. She doesn't even realize she's doing it.

Example-- suppose we go out for dinner at a restaurant. At some point mom will need to use the restroom. Nothing unusual about that. By the time mom has finished in with the restroom, she'll have forgot where she was sitting and who she is with. She'll just wander off. We could loose her unless we watch the bathroom door.

Another example. Mom and dad are at home. Dad goes out to do some chores. After a while mom will forget this. Perhaps she'll decide that dad is getting their truck ready. She'll get dressed to go out, then wait by the garage or him. Or perhaps she'll wander around to try and find him.

All by the way of saying, someone needs to be there for mom all the time. This is tricky as Mom is an independent woman. She will figure out when she's being watched and will become angry if you imply she can't be alone. 

Dad needs to run a few errands while I am in town. He is having cataract surgery. Practically mom can't join him, nor can she be left alone for the day. So we tell her little white lies. Dad 'needs' her to stay at home because there will be an important call about her scans.  I will work from their home for that day just because I enjoy it there.