False memory formation in cannabis users: a field study

Lilian Kloft,Alicja Garbaciak,Henry Otgaar,Arjan Blokland,Johannes G Ramaekers,Lauren A Monds

doi:10.1007/s00213-019-05309-w

Lilian Kloft, Alicja Garbaciak + Show 4 more

Open Access

https://doi.org/10.1007/s00213-019-05309-w

Copy DOI

Abstract

RationaleCannabis use is widespread and has previously been associated with memory impairments. However, the role of cannabis in relation to false memory production, i.e., memories of events that were not experienced, is less well-understood.ObjectiveThe aim of the current field study was to examine the impact of cannabis use on false memory production.MethodsThe Deese/Roediger-McDermott (DRM) paradigm was used to induce false memories. In this paradigm, participants study word lists that are associatively related to a non-presented word, termed the critical lure. In a later memory test, true recognition rates and false alarm rates toward critical lures and unrelated items are assessed. Memory performance was compared between three groups: regular cannabis consumers who were acutely intoxicated (n = 53), regular cannabis consumers who were sober (n = 50), and cannabis-naïve controls (n = 53). The participants were approached in Dutch coffee shops (cannabis outlets) and cafes and asked to participate in our study. After collecting general information on their cannabis use, they were subjected to the DRM procedure.ResultsAlthough false memory rates for critical lures did not statistically differ between groups, both intoxicated and sober cannabis consumers falsely recognized more unrelated items than control participants. Also, individuals without a history of cannabis use demonstrated higher memory accuracy compared with the intoxicated group.ConclusionIt is concluded that cannabis intoxication and history of cannabis use induce a liberal response criterion for newly presented words for which the level of association with previously learned words is low and uncertainty is high.

Highlights

Cannabis is the world’s most widely used “illicit” drug, with an estimated global prevalence of 2.7–4.9% and a lifetime use of 78% (United Nation Office on Drugs and Crime 2017; Winstock et al 2017)
Groups differed statistically significantly with regard to sex distribution. This variable was entered as a covariate in a multivariate general linear model analysis with all four DRM parameters as dependent variables (DVs) and group as a fixed factor
Sex was found to be statistically significantly associated with one of the DRM parameters; this factor was further investigated in an exploratory analysis

Summary

Introduction

Cannabis is the world’s most widely used “illicit” drug, with an estimated global prevalence of 2.7–4.9% and a lifetime use of 78% (United Nation Office on Drugs and Crime 2017; Winstock et al 2017). Cannabis appears to have potential for medical use such as pain relief (Urits et al 2019), cannabis may induce cognitive impairment, in the domain of memory (Broyd et al 2016). Cannabis use has been associated with memory impairments both during acute intoxication (Ranganathan and D’Souza 2006) and during abstinence in long-term users (Solowij and Battisti 2008). According to the majority of Psychopharmacology (2019) 236:3439–3450 the research on this topic, cannabis use appears to primarily impair memory in the domains of verbal learning and declarative memory (Broyd et al 2016; Schoeler and Bhattacharyya 2013; Theunissen et al 2014). The primary active cannabinoid tetrahydrocannabinol (THC) acutely elicits reliable, dose-dependent impairments in immediate and delayed verbal memory performance, most often measured using word list learning tasks testing both recall and recognition memory ( recognition memory is less consistently affected, e.g., Broyd et al 2016; Hart et al 2010)

Methods

Results

Conclusion