I have had some kind of decent results with oral nicotine for brain fog. Lots of long covid people on twitter were taking some to cure their brainfog (like 14mg doses) but not everyone benefitted from it, some reported it made the symptoms worse. Some saw great improvement but the caveat is that nicotine is not really a good long term solution, its got diminishing returns.

Still, I also discovered that adhders apparently take it for executive dysfunction (along with caffeine which it is synergistic with) same caveat applies : diminished effects when taken too often.

I take 2-4mg in gum form once in a while when I need to get something done. Never more than 3 days in a row, and usually not every week. Maybe once or twice a month or so. Also helps headaches and has mild pain relief, appetite suppressant, anti anxiety effects.

I would recommend studying its effects to be well informed, and proceed with caution if its something you feel would negatively impact your quality of life.

As well as following the advice that people have already posted, this is how I deal with my brain fog.