I wrote about this topic previously in several SharePosts listed below, but I still think it's a skill that caregivers - especially those who are new to careing for loved ones who have dementia - need to learn how to develop. Learning how to respond in a loving way to comments that aren't based in reality can help you keep your own peace of mind as well as that of your loved one who has Alzheimer's.
Other Shareposts on this Topic:

10 Ways to Protect Your Brain Against Alzheimer’s
10 Signs of Alzheimer's
10 Things to Do After an Alzheimer's Diagnosis
Seven Facts You Should Know About Alzheimer's Disease