MDMA ("ecstasy") is widely used as a recreational drug, although there has been some debate about its neurotoxic effects in humans. However, most studies have investigated subjects with heavy use patterns, and the effects of transient MDMA use are unclear. In this review, we therefore focus on subjects with moderate use patterns, in order to assess the evidence for harmful effects. We searched for studies applying neuroimaging techniques in man. Studies were included if they provided at least one group with an average of <50 lifetime episodes of ecstasy use or an average lifetime consumption of <100 ecstasy tablets. All studies published before July 2015 were included. Of the 250 studies identified in the database search, 19 were included. There is no convincing evidence that moderate MDMA use is associated with structural or functional brain alterations in neuroimaging measures. The lack of significant results was associated with high methodological heterogeneity in terms of dosages and co-consumption of other drugs, low quality of studies and small sample sizes.

5. Conclusions

In summary, studies in this field exhibit a variety of differences and report highly heterogeneous results. Additionally, they suffer from problems that are inherent to the observational designs or due to other reasons. While some problems, like imprecise data on actual consumed doses, are unlikely to be solved, others should be carefully accounted for, for example appropriately matched control groups, including the consumption of the legal drugs nicotine and alcohol; moreover, such controls might be difficult to recruit. In the moderate dose range investigated in this review, we found no clear evidence from neuroimaging techniques that MDMA induces changes in the human brain. This also implies that there is currently no clear evidence from neuroimaging that the use of MDMA as an additive in psychotherapy should be regarded as dangerous per se. On the other hand, our systematic review does not allow the conclusion that MDMA is not neurotoxic in moderate use, as possible alterations caused by MDMA might not be detectable with the techniques used, some of the included studies were not specifically designed to investigate neurotoxic effects of MDMA in moderate users and several studies were of rather poor quality.

PMID: 26746590 [PubMed - in process] Free full text
http://www.ncbi.nlm.nih.gov/pubmed/26746590