When communicating with residents with dementia, you should:

It depends on which stage of dementia they are in

Explanation:

3rd Stage: If they are in the third stages of dementia (Where they are very progressed through the disease), it is important to not ask open ended questions and keep things to a "yes" or "no" basis, open responses could lead to confusion and could make them possibly agitated. It is also important to explain what you are going to do and what you are going to help them with, keep it short and simple but tell them all the steps and demonstrate if they still don't understand.

2nd Stage: In the second stage of dementia, she are still somewhat cognitive and understand some aspects of what you are asking them. Continue to ask questions in which they have a suggestion to choose from, such as "Would you like to eat Spaghetti for dinner or would you like Meatloaf?". It's also important to let them try to do things for themselves, like buttoning some buttons on their shirt when getting dressed, and let them try to brush their teeth on their own and whatnot. You also have to explain every step you're going to do when you are providing help or caring for them.

1st Stage: In the first stage of dementia this disease is still early, and depending on how rapidly its progressing, some individuals will be better than others. You can ask them what they used to do for their job, if they remember their house, ask them their favorite holiday, and a few other simple questions that they may know. It is also important to give them enriching activities to do, such as questionnaires that may have some information about their time. You can also let them do things on their own, and provide assistance when they need it.

(I work in a Memory Care facility, so that's all that I pretty much know though so I'm not sure if those are the answers that you wanted.