On the other hand, what is the chess doping? If science had invented a pill that would allow one get smarter, there would be long queues at the drug stores.
When we started to work with WADA, the biggest problem was to determine what is doping. What does improve the mental performance? We have adopted the entire dope list made for the athletes. More than 20 cups of coffee is a dope. Alcohol is also a dope.
It is no secret that in the past some outstanding chess players would not start playing without a glass of brandy. That acted as a stimulus. However, there is variety of drugs that are considered a dope today.