It does appear that is one of the molecules that will help stimulate production [1] but to what degree I can not tell. This might make for some fun reading on PubMed. I take half of those things they list but have no way to measure it.
I would avoid commenting on the people down-voting you, that typically just makes it worse.
No idea. I really do not have a good way to measure this. I am also quite skeptical of things like IQ tests as a means for measuring such things. I've had some in depth discussions with a friend that is a psychoanalyst about these tests and have read up on them myself. My limited understanding is that they are mostly useful for putting a person into a range but getting exact numbers is not feasible, meaning that the tests giving a specific number is really just an approximation in a range and that also varies by which of the two standard tests is used.
If I could get something that could measure exact interaction response times of synapses then perhaps that might be a starting point. The equipment exists but doubt I could even afford the grey-market gear nor do I have a place to put it.
One might ask why I take these molecules if I can not measure efficacy. For me it's simple. They are relatively cheap and there are enough studied benefits that even if the gains are marginal I will find that an acceptable net gain in the big picture of my overall health.
I got some Lion's Mane capsules from Amazon (though I'm not sure how pure they are; for all I know they crushed up some whitecaps and put those in there). I started with 1/3 the recommended daily dose and started having slight headaches. That was the end of that experiment. :-(
I would avoid commenting on the people down-voting you, that typically just makes it worse.
[1] - https://www.neomed-clinic.com/the-best-nerve-growth-factor-s...