During the last months I have seen the effects of dementia - happening to my father in law. We had really good and very funny days. Not only that he cannot remember those days any more, communication can be really a challenge when everything is forgotten in less than a minute.
An interesting and important fact I learned dealing with this situation: The content of any dialog is forgotten pretty soon - but the emotions are remembered way longer!
Not in the same extreme way, but I do notice also in many other situations:
Arguments are ignored or forgotten quite easily, but the feelings, the emotions and the whole mental situation is burned into people's mind quite easily.
So in reality when communicating with other people you should pay more attention at the sensation you are creating than on the content.
You will see, people are not as rational as you believed....
Related post: Emotion and sensation, There is suffering, 6 triggers of bad actions, The wise talk less.