What do you say to someone who is struggling with dementia?

You always want to connect with your doctor about behavior changes. Things like a urinary tract infection, problems with medications, vitamin deficiencies, thyroid issues, a lot of healthcare factors could be causing things to get worse. 

Also, so many people with dementia have depression and anxiety. Most people I know who have had dementia have taken medication for one or both. It helps. Sometimes they don't have the capacity to do things they used to do to get over things, like talk to friends in depth, they just don't have the insight to be able to do that anymore. 

Also, look at whether there is something in their environment that is causing that for them. And can you change or improve that? 

Then, if they're sad and crying, can you just offer comfort? Just give them your attention fully and say, "I'm sorry you're sad".