If you don't sleep 8+ hours a day every single day, exercise regularly, live in a place with clean air, eat clean food, don't drink alcohol, etc. you're losing your time, no amount of supplement will make up for our modern way of life, you're going to optimise the 0.1% while missing the 99.9% that matters

There's (minimal) research on psilocybin doing just that. One of the tragedies of prohibition is that we just weren't able to study these psychedelic compounds easily for 50+ years.

Cardiovascular exercise and strength training. Both are thought to contribute to neurogenesis, even in healthy people

Supposedly NGF eye drops https://www.independent.co.uk/news/science/is-this-the-secre...

Noopept

https://en.wikipedia.org/wiki/Omberacetam

Alpha-GPC and Uridine Monophosphate appear to have some effect, though minor. Also not exactly neurogenesis, but adjacent stuff. Evidence is complicated, there seems to be a signal but it's a weak effect.

Of note, cautionary tale is too much neurogenesis is brain cancer...

I've read online that "Bacopa Monnieri" is a particularly strong and researched herbal supplement for cognitive maintenance, enhancement and neuroprotection, with the potential of supporting neurogenesis.

I've not tried that stuff since money is hard to come by these days. There have been a few human studies.

You can find more info here:

https://pubmed.ncbi.nlm.nih.gov/?term=bacopa+monnieri+cognit...

and here:

https://www.nccih.nih.gov/health/bacopa-monnieri

Nicotine is the only psychoactive substance proven to increase intellectual function. Rote neurogenisis does not - much in the same way height isn’t a proxy for IQ. Stimulants like Adderall, Caffiene, etc are Dunning-Kruger by proxy.