Event related potential (ERP) evidence for selective impairment of verbal recollection in abstinent recreational methylenedioxymethamphetamine (“Ecstasy”)/polydrug users
Adrian P. Burgess, Louise Venables, Helena Jones, Rhiannon Edwards, Andrew C. Parrott
Psychopharmacology August 1, 2011 Peer reviewed DOI: 10.1007/s00213-011-2249-9 via Springer Nature
Summary
Ecstasy users exhibit a lasting abnormality in a brain activity pattern linked to recollection, despite similar memory performance compared to cannabis and non-drug users. Specifically, the late positivity component over left parietal areas was reduced in 15 Ecstasy/polydrug users during word recognition tasks. This finding aligns with previous evidence suggesting that the serotonergic system may impact cognitive functions more heavily in the left hemisphere.
Study at a glance
| Sample size | 42 |
|---|---|
| Population | 15 Ecstasy/polydrug users, 14 cannabis users, and 13 non-illicit drug users |
| Key finding | Ecstasy/polydrug users showed an attenuated late positivity ERP component associated with recollection during word recognition tasks. |
Abstract
Objectives Ecstasy is a recreational drug whose active ingredient, 3,4-methylenedioxymethamphetamine (MDMA), acts predominantly on the serotonergic system. Although MDMA is known to be neurotoxic in animals, the long-term effects of recreational Ecstasy use in humans remain controversial but one commonly reported consequence is mild cognitive impairment particularly affecting verbal episodic memory. Although event-related potentials (ERPs) have made significant contributions to our understanding of human memory processes, until now they have not been applied to study the long-term effects of Ecstasy. The aim of this study was to examine the effects of past Ecstasy use on recognition memory for both verbal and non-verbal stimuli using ERPs. Methods We compared the ERPs of 15 Ecstasy/polydrug users with those of 14 cannabis users and 13 non-illicit drug users as controls. Results Despite equivalent memory performance, Ecstasy/polydrug users showed an attenuated late positivity over left parietal scalp sites, a component associated with the specific memory process of recollection. Conlusions This effect was only found in the word recognition task which is consistent with evidence that left hemisphere cognitive functions are disproportionately affected by Ecstasy, probably because the serotonergic system is laterally asymmetrical. Experimentally, decreasing central serotonergic activity through acute tryptophan depletion also selectively impairs recollection, and this too suggests the importance of the serotonergic system. Overall, our results suggest that Ecstasy users, who also use a wide range of other drugs, show a durable abnormality in a specific ERP component thought to be associated with recollection.