Visuospatial memory impairments in users of MDMA ('ecstasy').

RATIONALE

Previous studies have presented conflicting findings regarding visuospatial span deficits in MDMA ('ecstasy') users, possibly attributable to a lack of distinction between simple visuospatial span and visuospatial working memory span. Both draw upon central executive processing, while the latter also involves concurrent goal-orientated visuospatial processing.

OBJECTIVES

This study compared visuospatial working memory span for MDMA users and controls. An additional concurrent task also loading on the central executive tested for inter-group differences related to central executive workload.

METHOD

MDMA user group (25 current users, 10 previous users and 18 non-users) was between-participants, and dual task condition (concurrent alphabetic generation, random letter generation, and no dual task) was within-participants. The visuospatial working memory task required participants to serially recall a spatial sequence while simultaneously completing a visual judgement task, and was completed on its own and under dual task conditions.

RESULTS

Overall, non-users performed significantly better than both MDMA user groups. However, contrary to expectation, the performance decrement among users was no worse with concurrent random generation than under control conditions. Analyses controlling for background variables and the use of other drugs in the previous 3 months showed that the main effect of MDMA remained significant following control for intelligence, alcohol, amphetamines and cocaine, among other potential confounds. Unclear results were found following control for cannabis use.

CONCLUSIONS

The MDMA users experienced deficits in visuospatial working memory span. The lack of interaction between dual task condition and user group may be due to inter-group differences in central executive utilisation under different task conditions.