People who have dementia or other forms of neurological disorders oftentimes behave aggressively.  When my dad was diagnosed with Parkinson's Disease the neurologist told my mom that one day, years down the road, she could wake up with my dad standing over her with a butcher knife. He said neurological diseases will transform your loved one into someone you don't recognize.  After watching Parkinson's slowly consume my dad for the better part of 30 years now, he has change in profound ways. His personality can be aggressive and he most certainly isn't the man he used to be.  He says and does things now that I would have never thought he'd ever say or do years ago.  It's so very sad, scary and frustrating.