It is unlikely that meditation is the cure for brainfog IMO, I have read these forums for years and brainfog is one of those purely physiology-based symptoms.
You should be able to find a couple of interesting discussions of sufferers in this and other forums. I have stumbled across them sometimes and they are interesting re what people have tried and what worked. For me brainfog isnt a problem, mostly because I have worse problems and also because it feels like I have had it all my life so I am used to be "a mess".