To fully remediate my brain fog, I found properly engineered brainwave entrainment really helped.
It’s a type of audio sound therapy. Made a massive difference for me just by sitting back and listening with a pair of headphones.
Have a look at this site which made all the difference for me:
One of the tracks called Neural Advantage seemed to clear up my brain fog after about a month or so.
Various nutrients such as high quality fish oil (at least 500 mg of DHA) and bio-active b vitamins (eg Thorne Research) can also make a difference. And regular power-walking each day.