The gender of dementia.
I once saw a man who scored 3 out of 30 on his cognitive screening test, with a wife and daughter who initially denied that there were any problems with his memory. This man spent his days walking his dog around his local streets (or perhaps the dog was walking him); his wife did everything else for him. His role in the family was to be served by women, so the family had simply continued to serve him. I see whole families who have rearranged their lives around a man with advanced dementia, ensuring that he’s constantly supported, helping him wash and eat, without ever seeking a formal diagnosis.