Do you think it has anything to do with one learning the effects to look for? For instance, back when I was prescribed Adderall, at first, and even at some comparatively high doses, I swore to myself that it may as well have been a placebo. Turns out that Adderall just affected me in a very subtle way. It took me a long time to "figure out" what it was I was looking for, but after not much time I felt it pretty acutely. Though, I well admit this this may have had a lot to do with merely becoming dependent on it and alleviating any withdrawal symptoms that may have come about between doses (granted, I never reached a dose higher than 40mg and never abused it, but the withdrawals symptoms were very real). Still though. There should still be something that accounts for why I thought I was feeling nothing from it at first. For something as potent as Adderall that doesn't seem to make any sense. Then again, all of our neuropharmacological makeups are different so there really is no catch-all answer to any question.

Regardless, I still am curious if a similar phenomenon is at play for kava and what people interpret as reverse tolerance.