Prospective memory deficits in Ecstasy users: Effects of longer ongoing task delay interval

Abstract

Ecstasy use has been associated with neurotoxicity and neurocognitive impairment in a variety of domains, including prospective memory (ProM), which involves the delayed execution of a previously encoded intention in response to a specific cue. The present study adopted the multiprocess theory of ProM to evaluate the hypothesis that Ecstasy users would evidence differentially impaired ProM on longer versus shorter ongoing task delays. Ecstasy (n = 31) users, high-risk alcohol users (n = 21), and healthy nonusers (n = 31) completed the short (2-min) and long (15-min) delay ProM scales of the Memory for Intentions Screening Test. Results showed a significant group by ProM delay interaction, such that Ecstasy users performed comparably to the comparison groups on short-delay trials, but were impaired on long-delay ProM, particularly for time-based cues. Among the Ecstasy users, long-delay ProM was positively associated with risky decision making, but not with retrospective memory or other aspects of executive functions. These findings suggest that Ecstasy users may be particularly susceptible to deficits in strategic target monitoring and maintenance of cue–intention pairings over longer ProM delays. Findings are discussed in the context of their potential everyday functioning (e.g., academic, vocational) and treatment implications for Ecstasy users.

Keywords:

• Prospective memory
• Ecstasy
• Substance abuse
• Episodic memory
• Executive functions
• Time perception
• Cognition

Acknowledgments

This research was supported by a 2008 Research Development Scheme Award from the University of Western Australia to M.W. and National Institute of Mental Health R01-MH73419 to S.P.W. The views expressed in this article are those of the authors and do not reflect the official policy or position of the Department of the Navy, Department of Defense, or the United States Government. Aspects of these data were presented at the 2011 Mid-Year Meeting of the International Neuropsychological Society in Auckland, New Zealand. The authors extend their gratitude to Sarah Raskin for providing us with the Memory for Intentions Screening Test (MIST) and to students (Helen Shield, Simone Fernandez, Amy Hamilton, GillianWakeford, Dianna Bradley, andWhitney Swope) for their assistance with data collection and processing.

Notes

¹MIST data did not meet assumptions for parametric approaches due to a significant negative skew. As there is no nonparametric equivalent, and ANOVA-based approaches are robust to violations of normality given adequate sample sizes (e.g., Howell, 2005), the mixed-model ANOVA remained the most appropriate approach. However, results using Wilcoxon Ranked Sum Tests produced identical results.