Back in April, my mum who was late 60's had a UTI and this brought the same symptoms. She went from being totally self-caring and mentally alert to confused, agressive, violent (biting the A&E staff) and paranoid within about 4 hours. as she was admitted straight from home, it was hard for me 250 miles away to explain to the staff how abrupt and marked the change was as they assumed that she had some level of dementia already. Once I had explained that, more significant events like a CVA were explored but it turned out to be a simple UTI. Quite impressive and changed my view of them.