Remembering Molly: Immediate and delayed false memory formation after acute MDMA exposure

Summary

A double-blind, placebo-controlled trial with 60 healthy volunteers who had previously used MDMA examined the drug's effects on false memory. Participants received 75 mg of MDMA or a placebo and were tested using a word list task and two misinformation tasks involving a virtual reality crime scene. Memory was tested immediately and one week later. MDMA caused small impairments in true memory on the word list task at both time points. It increased false memory for related but non-critical lures immediately but decreased false memory for critical lures after a week. Episodic memory in the misinformation tasks was not consistently affected. The findings suggest no heightened vulnerability to external suggestion during MDMA intoxication.

Study at a glance

Abstract

The entactogen 3,4-Methylenedioxymethamphetamine (MDMA) is increasingly being recognized for its therapeutic potential but is also widespread in nightlife settings where it may co-occur with crime. Since previous research detected impaired verbal memory during acute MDMA intoxication, understanding the drug's ramifications in an applied legal context becomes crucial. We conducted a double-blind, placebo-controlled trial to examine acute and delayed effects of MDMA (75 mg) on false memory in 60 healthy volunteers with a history of MDMA use, using three well-established false memory methods: a basic, associative word list (Deese/Roediger-McDermott (DRM)) paradigm and two applied misinformation tasks using a virtual reality crime. Memory was tested immediately (encoding and retrieval under drug influence) and 1 week later (retrieval when sober). Small MDMA-induced impairments of true memory in the word list task were detected at both time points. MDMA increased false memory for related but non-critical lures during the immediate test, and decreased false memory for critical lures after a delay. Episodic memory assessed in the misinformation tasks was not consistently affected. Findings indicate a complex memory profile but no heightened vulnerability to external suggestion in response to MDMA intoxication. Recommendations for future applied legal psychological research include adding measures of recall on top of recognition, using study designs that separate the different memory phases, and potentially testing higher doses. Further research on false memories and suggestibility using imagination procedures can also be relevant for the clinical context.