I believe this has to do with neurotransmitters. My brain fog seems to be related to dopamine depletion. I have tried using Amphetamines (Dextroamphetamine and Adderall) but they leave me in a worse fog, which makes me wonder if I am depleting my neurotransmitters at a faster rate than normal (such as after ejaculation, exercise, stress, etc.). With re-uptake I use the little I have and get more out of it, which interestingly enough seems to help get rid of some of the fog for a short period of time.
If anyone has the chance to get Ritalin prescribed or perhaps get it from a friend, I suggest you try it at small doses. I currently take 5mg once every hour, since I metabolize it fast, rather than 40mg all at once and be overstimulated. This has been the only thing that has helped my mental clarity after spending thousands of dollars on supplements, drugs, pointless doctor visits, etc.
Still a long way to go for treatment, however. Hope this can potentially help someone.