Came here to pose the exact same question. I also always understood that one of the risks of repeated mdma intake is serotonin depletion. Also the effect where

Came here to pose the exact same question. I also always understood that one of the risks of repeated mdma intake is serotonin depletion. Also the effect where one feels like shit 1-3 days after an mdma trip is very real. So while it is possible serotonin is not the happy chemical, it either does play a role (possibly or even likely if you ask me in combination with other chemicals) or else all other research so far has been very much wrong.