Chronic use of cannabis and poor neural efficiency in verbal memory ability

Robert A. Battisti, Steven Roodenrys, Stuart J. Johnstone, Colleen Respondek, Daniel F. Hermens, Nadia Solowij

Research output: Contribution to journalArticlepeer-review

31 Citations (Scopus)

Abstract

Introduction The endogenous cannabinoid system is sensitive to the introduction of exogenous cannabinoids such as delta-9-tetrahydrocannabinol, which are known to impact upon, memory functioning. We sought to examine the impact of chronic cannabis use upon memory-related brain function via examination of the subsequent memory effect (SME) of the event-related potential (ERP). Methods The SME is predictive of recall, outcome and originates in structures that are dense with cannabinoid receptors (hippocampus and parahippocampus). The SME and performance on a verbal memory task were compared between 24 cannabis users (mean 17 years of near daily use) in the unintoxicated state and 24 non-using controls. The task involved the presentation of word lists, each with a short delay before recall. ERPs were recorded during encoding and later averaged by outcome (correctly recalled/ not recalled). Results Cannabis users showed poorer recall and altered patterns of SME activation: specifically, attenuation of the negative N4 and an increase in the late positive component. Duration of cannabis use and age of initial use correlated significantly with SME amplitudes. A longer history of use also correlated with greater recall, that was related to N4 expression. Discussion The results indicate that relative to non-using controls, chronic users of cannabis have altered memoryrelated brain activation in the form of dysfunctional SME production and/or poorer neural efficiency, which is associated with deficits in memory recall. Greater alteration was associated with a longer history of cannabis use and an earlier onset of use. Neuroadaptation to the effects of chronic exposure may additionally play a role.

Original languageEnglish
Pages (from-to)319-330
Number of pages12
JournalPsychopharmacology
Volume209
Issue number4
DOIs
Publication statusPublished - May 2010
Externally publishedYes

Keywords

  • Cannabis
  • ERP
  • N4
  • Neural efficiency
  • Neuroadaptation
  • Subsequent memory effect

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