My Mom takes Canada Drugs glutathione for brain fog and fortunately, it works for her. From what I read, glutathione plays a crucial role in protecting the brain from oxidative stress which can contribute to the development of mental health conditions (not only brain fog but also other neurological disorders).
However, it has to be noted, that not only meds can help. Changing a diet, getting more sleep, spending less time on the computer or phone, regularly exercising, avoiding alcohol and smoking, etc. are additional ways to solve the problem.