Unlike nearly all previous research on the issue of potential long-term effects of Ecstasy use, the Netherlands XTC Toxicity team used a prospective study design, assessing people before and after they decided to take Ecstasy. It is precisely because Schilt and colleagues1 are engaged in conducting one of the most ambitious and carefully thought out programs of research that seeks to overcome the problems of retrospective study designs that we remark on the serious problems with this report. Schilt and colleagues overstate the findings of their nonrandomized study when they conclude that their data show that “even a first low cumulative dose of Ecstasy is associated with decline in verbal memory.”1(p728) All 12 cognitive test scores in both groups were within the normal range, and no decreases were demonstrated in the Ecstasy group over time.
Krebs TS, Johansen P. No Evidence of Decrease in Cognitive Function in Users of Low-Dose Ecstasy. Arch Gen Psychiatry. 2008;65(2):236. doi:10.1001/archgenpsychiatry.2007.36