Event related potential (ERP) evidence for selective impairment of verbal recollection in abstinent recreational methylenedioxymethamphetamine (“Ecstasy”)/polydrug users

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.

The development of Cannabidiol as a psychiatric therapeutic:a review of its antipsychotic efficacy and possible underlying pharmacodynamic mechanisms

Cannabidiol (CBD), a once-considered inert cannabis constituent, is one of two primary constituents of cannabis, alongside delta-9-tetrahydrocannabinol (?9-THC/THC). In the last 30 years, CBD has become implicated with a range of pharmaceutical mechanisms of great therapeutic interest and utility. This review details the literature speculating CBD’s attenuation of psychotic symptoms, particularly in light of a marked elevation in mean THC concentrations, and a concomitant decline in CBD concentrations in the prevalent U.K street market cannabis derivatives since c. 2000. CBD is purported to exhibit pharmacology akin to established atypical antipsychotics, whilst THC has been implicated with the precipitation of psychosis, and the induction of associated symptoms. The aim of the review was to clarify the conjecture surrounding CBD’s antipsychotic efficacy, before going on to detail prominent theories about its associated pharmacodynamics. Were CBD’s antipsychotic efficacy established, then there is potential for major latent anthropological repercussions to manifest, such as significant elevations in psychosis manifestations in the U.K. The review found a largely affirmative body of evidence asserting CBD’s antipsychotic efficacy. CBD exhibited capacity to attenuate natural and artificially induced psychoses in both animal and human cohorts, the latter of which included individuals considered resistant to conventional treatment. CBD also shows promising potential for use as an antipsychotic drug for Parkinson’s disease (PD) patients with psychosis, owing to its low rate of extra-pyramidal side-effect induction. A range of potential pharmacological mechanisms behind CBD’s neuroleptic pharmacology are outlined, with particular emphasis on its prevention of the hydrolysis and reuptake of the endogenous cannabinoid, anandamide. However, given the nebular aetiological basis for psychoses, explicit conclusions on how CBD attenuates psychotic symptoms remains to be determined.