I have heard & read that dementia and Alzheimer’s patients have real quick tempers and some can be very mean.
I know at age 81, I have a lot shorter fuse than I did just a few years ago. I am also pretty much always armed, so tread lightly :)
My grandfather was a very calm pleasant man until he began to change in his eighties. It was pretty quick going from happy pleasant fellow to fits of anger and downright rage.