My mother has some dementia, but basically has not spoken for 6 months. In early January, she took Bactrim for 7 days and started speaking the 2nd day on Bactrim. Three weeks later she was given Bactrim for 3 days and again started speaking on the 2nd day. As soon as the Bactrim is stopped, she stops speaking again. (Note: She has had oral thrush for several months also.)