Can a UTI cause confusion of a elderly?

yeah thats what she has the doctor said she has had it for a while and that it was bad

My Aunt E lived to be 100. The only time she was confused at all was when she had a uti, in her late 80s.

Most definitely! I have seen people admitted to the hospital with suspicion of stroke that turned out to have a UTI. A few days on antibiotics and they were back their normal selves.

Yes, it could. Here's a really good article from AgingCare.

https://www.agingcare.com/articles/urinary-tract-infections-elderly-146026.htm