Colloquium: Differential effects of long-term ecstasy use on short-term and working memory

Ecstasy is an illicit recreational drug that has been linked to impaired memory function. A meta-analysis showed that ecstasy consumption impaired short-term and working memory for both verbal and visuo-spatial material, both in comparison to drug-naïve controls and poly-drug controls. The cognitive processes responsible for the memory impairment were investigated by examining the effect of low-level long-term ecstasy consumption on behavioural performance and electrophysiological indices of memory processing (P3a and P3b) during serial recognition tasks engaging short-term and working memory for verbal and visuo-spatial material. Ecstasy users showed greater reduction in performance on the working memory than the short-term memory tasks than the poly-drug user and non-user controls. The frontally distributed P3a, presumed to index attentional capture, and the parietally distributed P3b, presumed to index updating representations in memory, were significantly smaller in the digit-backward than the digit-forward tasks in poly-drug users and non-users. There was no significant difference between the amplitude of the P3a and P3b component elicited in the digit forward and digit backward task in the ecstasy users. Hence ecstasy users do not show the reduced P3a and P3b components in the backward task that is seen in both non-using control groups. The electrophysiological results suggest the ecstasy-related working memory impairment is due to changes in attentional capture and altered allocation of cognitive resources toward updating representations in memory and engaging in processes required by working memory tasks.