Does anyone suffer of brain-fog too?

Does anyone suffer of brain-fog too? In my opinion, for someone who stutters it's mandatory for us to keep one's mind full of knowledge. We need to have thoughts about possible everything, because that would solves 50% of the problem,. It helps us to focus 100% on your stutter only. That's why i believe that most of us are smarter than 80-90% of those around us. But somehow I got brain-fog i don't know how .. i just know that whenever I have to think or to focus on something I simply CAN'T. So does anyone had the same problem and how did you overcome it?