In my experience... it can cause confusion in a normaly heathy otherwise a-symptomatic person... but it is usually in the elder. Not sure if these are a-symtomatic (early stages) of cognitive decline or not. But the cognitive side of the UTI seems to be limited to the older/cognitively impaired set.
It can take a day, two, three, to show marked signs of improvement after the antibiotics takes effect. You also have to have the right antibiotic to treat the specific bacteria or the UTI will usually reoccur... and sometimes it does anyway... so follow up test are needed to be sure it is gone and not just better. Mom suffered from chronic recurring UTI for 18 months. It would flare up, antibiotics given, there was some improvement, then it would flare up again... repeatedly. She was on the wrong antibiotic for the infection. Just have them double check and culture to be sure it is gone