What I learned gathering nootropic ratings (2022)

The tl;dr is:

1. Apart from ADHD medications, which are very powerful, most drugs and weird obscure supplements have little effect (there are some intriguing but noisy results about peptides).

2. Exercise— especially weightlifting and HIIT— is also very powerful. There's evidence of a dose-response curve where light exercise is good but intense is better.

Arguably this is pretty unsurprising, from an evolutionary perspective. It would be strange if our brains had "one weird trick" to perform a lot better with no downsides, since if it existed evolution should've found it. But being in good shape confers large benefits.

So regular exercise (lifting, HIIT, and light cardio outdoors) is literally that one weird trick. It's hard to identify any downsides but the upsides are tremendous. It's amazing that people will go out ingesting all sorts of questionable substances just to avoid getting in shape.