Recreational use of 3,4-methylenedioxymethamphetamine (MDMA) or ‘ecstasy’: evidence for cognitive impairment

Recreational users of MDMA (ecstasy) show impaired verbal memory and verbal fluency compared to non-users, while visual memory and working memory remain unaffected. In a study comparing 80 participants divided into non-users, novice users, regular users, and currently abstinent users, all three MDMA-using groups performed significantly worse on tests of immediate and delayed prose recall and verbal fluency. The deficits were not explained by differences in general intelligence or cannabis use. Days since last use and total lifetime consumption of MDMA each independently contributed to the variance in recall scores, together accounting for nearly half the variance in delayed recall. The findings suggest that verbal memory impairments in MDMA users combine reversible acute effects that resolve over two to three weeks with longer-term changes linked to lifetime exposure.

Study at a glance

Abstract

Background. It has recently been shown that 3,4-methylenedioxymethamphetamine (MDMA) or ‘ecstasy’ causes long-lasting alterations to brain structure and function in animals, and there is mounting evidence that recreational users of the drug show impairments in some aspects of cognitive functioning including memory for verbal information. The present study investigates possible effects on other cognitive functions and explores the temporal course of development and resolution of these impairments by comparing novice, regular and abstaining users with a matched group of non-users. Methods. Eighty participants categorized as non-users, novice users, regular users or currently abstinent users of MDMA were assessed on tests of verbal IQ, reversed digit span, immediate and delayed recall of a prose passage and of a complex geometric figure and verbal fluency. Results. The four groups were well-matched for verbal IQ and on demographic variables. They differed in frequency of cannabis use over the last month, but this did not correlate with any cognitive test scores. All three groups of MDMA users showed significantly poorer verbal fluency and immediate and delayed prose recall than non-users. Days since last use and total lifetime consumption of MDMA made separate contributions to the variance in recall scores, accounting jointly for almost half of the variance in delayed recall. By contrast, the groups did not differ on either visual recall or reversed digit span. Conclusions. The observed deficits provide further evidence of impairments of verbal but not visual memory in MDMA users, and indicate that the deficits are not attributable either to differences in general reasoning ability or to impairment of working memory. The data further suggest that the observed impairments may be attributable to a combination of reversible acute effects of MDMA resolving over a period of 2–3 weeks and more long-term changes associated with extent of lifetime consumption.