Prospective memory deficits in illicit polydrug users are associated with the average long term typical dose of ecstasy typically consumed in a single session

Abstract

Rationale Neuroimaging evidence suggests that ecstasy-related reductions in SERT densities relate more closely to the number of tablets typically consumed per session rather than estimated total lifetime use. In order to better understand the basis of drug related deficits in prospective memory (PM) we explored the association between PM and average long-term typical dose and long-term frequency of use. Method Study 1: Sixty five ecstasy/polydrug users and 85 non-ecstasy users completed an event based, a short-term and a long-term time based PM task. Study 2: Study 1 data were merged with outcomes on the same PM measures from a previous study creating a combined sample of 103 ecstasy/polydrug users, 38 cannabis-only users and 65 nonusers of illicit drugs. Results Study 1: Ecstasy/polydrug users had significant impairments on all PM outcomes compared to non-ecstasy users. Study 2: Ecstasy/polydrug users were impaired in event based PM compared to both other groups and in long-term time based PM compared to non illicit drug users. Both drug using groups did worse on the short-term time based PM task compared to nonusers. Higher long-term average typical dose of ecstasy was associated with poorer performance on the event and short-term time based PM tasks and accounted for unique variance in the two PM measures over and above the variance associated with cannabis and cocaine use. Conclusions The typical ecstasy dose consumed in a single session is an important predictor of PM impairments with higher doses reflecting increasing tolerance giving rise to greater PM impairment.