One way to think about this - if there was no societal stigma or legality surrounding the issue, would the use of stimulants improve one's chess game?
A while back, there was a thread around this topic on chess.com, though be warned that a lot of it is just noise.
Seems like an interesting choice that has to be made - short-term increase in concentration (there are drugs for that: taking Adderall, Ritalin or caffeine) versus stimulants that enhance right-brain thinking that help one see increased connections.
When I read Jonah Lehrer's book "Imagine" I thought of possible connections to chess. The book covers this at some length, especially as it relates to Bob Dylan's creativity. This NYPost article covers it well:
Stimulants increase the flow of dopamine, creating a state in which
“the world is suddenly saturated with interesting ideas,” Lehrer says.
“Dopamine makes even the most tedious details too interesting to
ignore.”
So it is arguable that these dopamine stimulating drugs can make players see connections and become a better player, at least for a period of time. For concentration improving stimulants, with a lot of immediate incentives riding on it, a player might opt for the short-term gain, even knowing the long term deterioration.
...a study done in Leipzig, East Germany, before the reunification, showed that Chess players who were trained physically, like other athletes, were better enabled to deal with the dreaded “last hour syndrome” which afflicts International players at the worst possible time.– xaisoft Dec 5 '12 at 19:23