Have you ever considered brain maxxing?

?

I have been gathering some resources, if you're interested. It seems that choline is beneficial for memory without a doubt, but there are other variables that are a bit more tricky, like testosterone, which seems to be good (for lessening anxiety and depression and improving spatial reasoning and memory) except when turned into estrogen due to a variety of factors.

This is the link I refer to for the second claim: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4330791/

For alertness/concentration?

I take modafinil every now and then. Modafinil basically makes you alert with some mild stimulation, slightly above caffeine. It has some speedy effects like extreme focus and jaw clenching. Adderall is the poor man's modafinil IMO. Adderall withdrawals are just too much; not the kind of drug I'd like to be dependent on.

Another thing I do is high dose caffeine pills + beta blockers (atenolol). You get all the mental stimulation of caffeine without the jitters or high heart rate.

For (temporarily) increasing your IQ?

LSD is the only substance I've ever tried that can actually enlarge your metaphorical mental whiteboard. It makes sense since it induces synesthesia. Being on acid is like operating 30,000 feet above your normal mental processing.