Cloudscape

The reason MDMA only sometimes causes brain damage (The Guardian: Ecstasy does not wreck the mind, study claims) may be that it causes brain damage in much the same way as seizures do, through overstimulation, which could be why MDMA at raves sometimes causes seizures, as in rarer cases may raves themselves. Without the overstimulation of raves, studies will therefore find no brain damage. This could also be why THC prevents brain damage from MDMA (Plos One: THC Prevents MDMA Neurotoxicity in Mice), as it could counterbalance this overstimulation.