One thing it’s called is the body closing down and end of life. To check for other signs, click on Care Topics at the top right hand side of the screen, scroll down the alphabetic list that comes up till you get to ‘end of life signs’. Have courage!
I don't know but I remember my aunt had it in the late stages of Alzheimer's. I remember my cousin telling me about it. Very scary because this was a woman I had admired as a kid for her sharp, quick witt. If it could happen to her, it could happen to anyone.