Mother-in-law (88) often refuses to take her medicine and is mad if we dole it out.

jeannegibbs and JessieBelle- Thank you so much for your comments. I was not
aware of Capgras Syndrome, but it corresponds to MIL's behavior. Susan

jeanne gave some excellent guidance and I would add only one thing. If the behavior came on quickly, let your MIL's doctor know about it. Some physical problems, e.g. urinary tract infections, can create psychological symptoms that come on fast. It would be nice if this is what it is, so the symptoms would get better when the infection cleared.

I don't know if this will be of any comfort to you, but the delusion that known people are imposters is common enough to have its own name and theories about it. It is called Capgras Syndrome. Now that you know that you can research it on the Internet and discuss it with her doctor.

I'm not sure if that is related to the refusal of pills. Perhaps since she thinks you are imposters she is worried that she can't trust you to give her her meds.

My heart goes out to you. Dealing with the various aspects of dementia is challenging, frustrating, and heartbreaking.