This concerns a character who was not close to his family before his onset of AD. He always had an unpredictable temper and was difficult to be around. He has been a widower for years. His grown children, who are also well-off, are not really malicious, but they do not want to be involved in his daily life. They want to "do the best they can," and then put it out of mind.
At that time, nursing homes were horror stories, and I don't know if there was another dignified option besides home care. It seems most likely to me that this man would be kept in an in-law apartment, restricted to a small area of the property, so that is what I have been going with.
I have used the Google terms "history of Alzheimer's," "Alzheimer's care 1980s," and others, and reviewed the WP article, together with "The Experience and Management of Temporality in Five Cases of Dementia" (Scandinavian Journal of Occupational Therapy 2001:8:85) (look, it came up). Personally, I did have a great-grandmother with AD during the 1980s, and she was well looked after, but we weren't wealthy and there was not a lot to observe about it. All I remember is that she sat in her chair in the den all day, and nodded, and rocked.