I take it to lower cortisol, but it can be pretty expensive to run for the long term.
But I find that Gycline works just as well, 5g each meal, and it's a hell of a lot cheaper then PS.
CT recommends 400-800mg PWO to lower cortisol. But he also has recommended it for people with high cortisol issues to use 400-800mg with each meal (or 5g Glycine each meal, depending which one you have).
As for the cognitive benefits, I know that lower cortisol levels and lead to better memory, but PS or Glycine does not directly effect cognitive ability as far as I know. I could be wrong about that though.