Just read this artical in the paper local to my town. A elderly subject with dementia had an eposide and stabbed his caretaker in the face. She exited the car and he followed her until he snapped out of the episide in which case he started to help her.
Had you been driving down the road and seen a women with a bloody face and a guy following her with a knife, how would you have reacted? Read the artical above to get a better idea of the situation.