glutamine, especially between meals. A dear friend found that glutamine plus a healthy snack between meals helped her think more clearly and have better mood.
Mine is so much better than it was 15 yrs ago. The brain fog is so much better.
We also went through Cutler protocol heavy metal detox. I don't know how much of the improvement was due to detox but I suspect it was only partially responsible. Maybe I'm not 100% finished with detox.