Remedies for brain fog is a long one, but to keep it really short, alkalizing is the basic as alkalization dilates the capillaries, which includes the brain.
Certain infections, yeast, candida can initiate a brain fog too, as much as mycoplasma, mycobacterium and other microbial overload. The one interesting aspect of alkalization is these microorganism don't survive well in alkaline and high oxygen environments.
There are certain other supplements that have high anti fungals (which causes brain fogs), and heavy metal accumulation can also lead to brain fog (when you take antibiotics, heavy metal accumulates), and even in event of vaccination (mycoplasma they are living, exist causing brain fog, but also the mercury and the aluminum they added). Therefore, molybdenum and boron (from borax) have antifungal properties too. Molybdenum is a well know antioxidant, at least for me, which exists in superoxide dismutase along with copper and zinc also.
Regarding the use of boron (antifungal), I posted several information on that already. However, apple cider deserves a special mention because of the malic acid content (eating apples helps) removes aluminum build up and that can help the brain fog as well.
One particular less known remedies of brain fog is the magnesium where I read an article concerning heavy metal toxicity were reduced and hence brain fog, if the body's magnesium level is sufficient since magnesium is protective against heavy metal toxicity, so despite higher than average level of heavy metal, the effects can be minimized with magnesium supplements such as magnesium citrate.
I attached below a link to other information sources regarding the use of molybdenum. I used it myself to help with night vision problem, along with vitamin A when taking them, but I don't take them that frequently, just as needed basis. Molybdenum can also help with brain fog due to its anti candida properties.