My Grandmother, who has Vascular Dementia, is consistent in asking us where "Little Tina" is. Tina is her now 40 year old daughter. She speaks to "Adult Tina" normally, asking her normal, relevant, life questions, but she will also ask her where Tina is. She has never not recognized my aunt or asked who she is. She calls her by name and introduces her as her daughter, but still every day insists on knowing the location of her small daughter. (She often uses her hand to show us the height of the girl.) When we explain that Tina is here and is grown up, she demands that she knows this, but needs to know where "Little Tina" is. We calm her by telling her that "Little Tina" is safe at home with her father, but I would still like to know her thought process in thinking that both young Tina and grown-up Tina exist at the same time.
He also went back and forth between thinking I was his daughter to thinking I was a helper or healthcare worker. As he got worse, I became a helper/health worker more often and a daughter less.
My mother has dementia and she has no problem remembering people. She forgets times and events. She also tends to cast me in an adversarial role even when I'm trying to help. There is no explaining it. We can predict what people with dementia will do usually, but can't understand the why of it. The brain is just not working in the same plane as people without dementia.