And your initial comment sounded to me like you were taking it for granted that such drugs do indeed enhance cognitive performance - which I don't think is a given.
I had the same confusion. I would have then said "New Study Finds Evidence for Cognitive Performance-Enhancing Drugs: They Help with Chess" or something. The way "for Chess" is tacked on the end makes it seem like the most important detail: I would argue just reading this title would make one go "oh, I guess we already had these for other tasks, but this is the first one for Chess". In fact, as worded, my second option was "what they really mean is that people are using them in the wild and they are what is making or breaking tournements", not "we have just discovered it is possible".
In that case, my fault for not being clear. You're right, I do lean towards the conclusion that some of those drugs enhance cognitive performance (particularly the ones that are used for treatment of ADHD), but you're also right that currently, there isn't sufficient evidence to treat that as a given.
