Verbal Learning and Memory in Cannabis and Alcohol Users: An Event-Related Potential Investigation

Abstract

Aims: Long-term heavy use of cannabis and alcohol are known to be associated with memory impairments. In this study, we used event-related potentials to examine verbal learning and memory processing in a commonly used behavioral task.Method: We conducted two studies: first, a small pilot study of adolescent males, comprising 13 Drug-Naive Controls (DNC), 12 heavy drinkers (HD) and 8 cannabis users (CU). Second, a larger study of young adults, comprising 45 DNC (20 female), 39 HD (16 female), and 20 CU (9 female). In both studies, participants completed a modified verbal learning task (the Rey Auditory Verbal Learning Test, RAVLT) while brain electrical activity was recorded. ERPs were calculated for words which were subsequently remembered vs. those which were not remembered, and for presentations of learnt words, previously seen words, and new words in a subsequent recognition test. Pre-planned principal components analyses (PCA) were used to quantify the ERP components in these recall and recognition phases separately for each study.Results: Memory performance overall was slightly lower than published norms using the standardized RAVLT delivery, but was generally similar and showed the expected changes over trials. Few differences in performance were observed between groups; a notable exception was markedly poorer delayed recall in HD relative to DNC (Study 2). PCA identified components expected from prior research using other memory tasks. At encoding, there were no between-group differences in the usual P2 recall effect (larger for recalled than not-recalled words). However, alcohol-related differences were observed in a larger P540 (indexing recollection) in HD than DNC, and cannabis-related differences were observed in a smaller N340 (indexing familiarity) and a lack of previously seen > new words effect for P540 in Study 2.Conclusions: This study is the first examination of ERPs in the RAVLT in healthy control participants, as well as substance-using individuals, and represents an important advance in methodology. The results indicate alterations in recognition memory processing, which even if not manifesting in overt behavioral impairment, underline the potential for brain dysfunction with early exposure to alcohol and cannabis.

Electroencephalographic signatures of the binge drinking pattern during adolescence and young adulthood: A PRISMA-driven systematic review

“…females and males), suggesting that the neural abnormalities associated with inhibition presented in the previous study are common to both sexes. The other two studies conducted by this research group did not show alterations in BDs’ brain activity relative to control individuals ( Smith et al, 2015 , Smith et al, 2017a ).…”

“…The impact of BD on the behavioral performance was explored by 29 of the 31 studies (the remaining three studies analyzed the brain activity at rest). Remarkably, only seven of these 29 studies (24.1%) – four from the same research group - showed significant differences between BDs and non/low drinkers during tasks involving inhibitory control, performance monitoring and verbal episodic memory ( Kim and Kim, 2019 , Lannoy et al, 2020 , Na et al, 2019 , Smith and Mattick, 2013 , Smith et al, 2016 , Smith et al, 2017a , Smith et al, 2017b ).…”

“…BDs would need more time to adjust their behavior after a late response. Conversely, Smith et al, (2017a) used an error awareness task, where participants needed to signal the awareness of inhibitory errors on the subsequent trial. They also analyzed the Pe to explore conscious error detection and the ERN to assess early pre-conscious error detection.…”

“…According to these studies, BDs exhibited poor response inhibition ability in comparison with controls, being reflected by longer stop-signal reaction times ( Smith and Mattick, 2013 , Smith et al, 2016 ) and greater number of commission errors (to NoGo Stimuli) during an error awareness task ( Smith et al, 2017a ). Also, BDs showed poorer inhibition performance for explicit than implicit processing of alcohol-related information ( Lannoy et al, 2020 ).…”

Self-reported history and saliva analyses of recreational drug use among students in a public university in Mombasa, Kenya

“…In mid-Atlantic USA marijuana was the most commonly used drug among college students in every year of study (8) consequences, the health effects should be of concern to the administration of learning institutions. Of great concern are the effects induced by delta-9-tetrahydrocannabinol (THC) on verbal, thinking and working memory (55).…”