Non-human primate studies suggest MDMA may not be as neurotoxic as rodent studies indicate.

“the primate studies or I should say the non-human primate studies which are the sorts of animal studies that most closely mimic what one expects to see in the human brain because after all mice and the effects of these drugs and mice do translate to humans but it's thought that non-human primates provide a model that's far more similar to humans there the data start to get kind of complicated in a way that suggests that MDMA might not be as neurotoxic as is thought based on the rodent studies”