Can doping increase/decrease a player's level of play? The reason I ask this is because according to this article, Magnus Carlsen is going to participate in FIDE's pilot project on doping test.  FIDE says the reason behind it is that the organization wants to be considered as an Olympic sport by the IOC in the future, with anti-doping program set as a prerequisite.

I personally don't see how doping can increase the level of play, but I can see how it would decrease the level of play, but then there would be no point in doping. Also, is this a result of there has to be some anti-doping test for every Olympic sport regardless if doping has an effect or not?
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.