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Are the neurocognitive deficits associated with 3,4-methylenedioxymethamphetamine caused by statistical deficits in ecstasy research? A systematic review

Timothy Amoroso

Drug Science, Policy and Law 2018 DOI: 10.1177/2050324518789214 (opens in new tab)

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Study at a glance

AI-extracted from the abstract
Characteristics Systematic review Peer reviewed
Population Ecstasy (MDMA) users across 19 reviewed studies comparing light and heavy users
Topics MDMA
Key findings Argues that research linking MDMA to neurocognitive deficits is undermined by inconsistent and unjustified criteria for defining light versus heavy ecstasy users. Across 19 studies, nine unique dichotomization points were found, and most studies (11) did not explain their choice of criterion. The authors contend that such methodological flexibility may have produced significant findings where no relationship exists.

Abstract

There is growing concern that the majority of modern research may be comprised of false findings, which is partly attributed to unacceptable flexibility in data analyses. Here this issue is considered in the literature suggesting that MDMA (3,4-methylenedioxymethamphetamine) may be associated with neurocognitive deficits. Research suggests that increased exposure to ecstasy is associated with decreased performance on some neuropsychological tests. This claim is supported by the fact that “heavier” users often perform worse than “light” users on neurocognitive tests. However, most studies use different criteria for defining what is considered a “light” or “heavy” ecstasy user. Here the literature was systematically reviewed to compare the criteria used across studies which compare light and heavy ecstasy users. Out of the 19 studies reviewed nine unique points of dichotomization were found. In many cases, heavy users in one study would have been considered light users in another study and vice versa. Most studies ( n = 11) did not explain how or justify why a particular criterion was chosen. Only eight studies provided justifications for why they chose a particular criterion and the reasons were often misleading. There are many methodological issues which bring into question the validity of research suggesting MDMA is the cause of neurocognitive deficits. Methodologists have demonstrated that it is unacceptably easy for researchers to report significant findings where no relationship exists, which may have been the case in some studies reporting on the neurocognitive deficits found in ecstasy users.

Comparable studies

Other systematic reviews and meta-analyses on MDMA, most cited first.

Study Year Design Participants
A review of the acute subjective effects of MDMA/ecstasy 2006 Systematic review
Adverse events in clinical treatments with serotonergic psychedelics and MDMA: A mixed-methods systematic review Patients in clinical trials with MDMA or serotonergic psychedelics 2022 Systematic review n = 598
Treating posttraumatic stress disorder with MDMA-assisted psychotherapy: A preliminary meta-analysis and comparison to prolonged exposure therapy Patients with PTSD 2016 Meta-analysis
The neuropsychology of ecstasy (MDMA) use: a quantitative review MDMA users 2007 Meta-analysis
Drug-drug interactions between psychiatric medications and MDMA or psilocybin: a systematic review 2022 Systematic review

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