In the very good film, "The Help," the main antagonist's mother is portrayed by Sissy Spacek. She plays a character who is clearly not operating with an entirely full deck, neither is she completely out of it. In fact it's her lively sense of humor and sense of fair play that incite her vengeful daughter to send her to live in a nursing home seemingly prematurely.
As I watched the film I was thinking "she's meant to have dementia," but I did not recognize it as Alzheimer's because she was not at all apathetic. Just somewhat uninhibited and inappropriate (in the context of norms for white women in Mississippi circa early 60s. I made the ethnic distinction because the root of the conflict in the film is inequality at the dawn of the civil rights movement.)
Have not seen the film, but my sister will be 90 next week and badly senile--absolutely & thankfully not AD. I think she's maybe had some TIA's and it might be vascular dementia. Her son has arranged for a 'companion' to be with her most days, she's alone at night, doesn't show any signs that she'd wander. She can eat what her companion prepares, shower, dress (what companion tells her to wear), phone me, but she repeats the same story ten times in as many minutes, is confused about her special birthday, worries about Thanksgiving, gets ideas about people that are wholly made up, cannot handle money, etc, but frequently appears quite normal. If she did not have her companion and her son keeping such a close eye on her, she would have to be in a care facility. At this point, I could not care for her myself. Unlike a vengeful daughter, every effort is being made to keep her in her home and as her sister, I agree it's the best for her & grateful her son does it.
I was thinking the same thing about Sissy Spacek, and the character she played. Imagine being placed in a nursing home with such mild symptoms-----the early 60s was a different time. I recall that Sissy Spacek played a woman with dementia in a made for TV movie. She was very good in that, too.