Missing That New Car Smell
While the aged and not so aged relatives in question have not degenerated to the point of being emotionally violent and unpredictable, as can sometimes happen, there are many signs of the disease waging war against their minds.
This Conversation is On a Loop
One particular relative, seems to suffer a hard reset every 10 minutes or so. Breaks whatever thought he is in the middle of and starts over.
The silver lining (perhaps) is that you can try the same conversation a few ways until you reach an "optimal" version. That's not something you normally have the opportunity to do. It takes the resolution of the "I wish I'd said..." train of self doubt to new levels.
The Framed Memories of Yesteryear
In the fashion of certain "logic machines" you may have studied in math class, such as put 4 into the machine and get 12, input 6 and get 18, these relatives now have a very systematic approach to conversation. If I say certain words, it results in a fully detailed story; yet, in other cases 7 or 8 phrases or words all trigger the same response.
The amazing thing is that these memories seem to have calcified, there isn't any variation in the details or manner of telling the story. Yet other, less impactful memories, change and are reinvented from conversation.