Letters in Science. An exchange of letters about MDMA dopaminergic neurotoxicity between the MAPS MDMA/PTSD team and the NIDA-funded research team of Ricaurte et al. appeared in the journal Science, June 6, 2003, Vol. 300, p. 1503-4. MAPS has already submitted to Science a request for a correction to a misleading statement in the Ricaurte et al. letter, in which only one of the primates was claimed to have died from the doses of MDMA administered, as compared to two primates reported to have died in the initial paper. For details, see MAPS’ discussion of the Ricaurte et al. study.
MAPS is in the process of preparing a response to the Ricaurte et al. letter for the MAPS website and Forum. In brief, Ricaurte et al. state that dopaminergic deficits will only be found in binge users, but then discount all the studies in heavy MDMA users that found no dopaminergic changes by saying that they contained no or only a few binge users. This raises the obvious question of just how “common” is this binge use pattern, since they allege in the title of their paper that the doses they administered to the primates represented a “common recreational dose regimen.” Ricaurte conclude their letter by saying that “we remain of the opinion that there are not sufficient data to conclude that clinical MDMA research can be conducted without running the risk of monoaminergic brain neural injury.” First, it’s impossible to ever prove that there is no risk. Nevertheless, by Ricaurte et al.’s own admission that binge use isn’t even the same as heavy use, it is possible to conclude that there is no evidence that the clinical use of MDMA will in any way cause dopaminergic neurotoxicity or lead to Parkinson’s. Note also that Ricaurte et al. conclude with a general statement about both serotonergic and dopaminergic risk, and dismiss as being unpublished evidence from Dr. Franz Vollenweider’s PET scan study that showed no evidence of serotonin changes in MDMA-naive subjects administered doses of MDMA in the therapeutic range.