Tetrahydrocannabinol (THC) impairs encoding but not retrieval of verbal information.
Mohini Ranganathan, Rajiv Radhakrishnan, Peter H. Addy, Ashley M. Schnakenberg Martin, Ashley H Williams, Michelle Carbuto, Jacqueline Elander, Brian Pittman, R Andrew Sewell, Patrick D. Skosnik, Deepak Cyril D'Souza
Progress in neuro-psychopharmacology & biological psychiatry October 3, 2017 DOI: 10.1016/j.pnpbp.2017.06.019 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Randomized controlled trial Placebo-controlled Double-blind Peer reviewed |
|---|---|
| Sample size | 95 |
| Population | Healthy subjects recruited from the community |
| Intervention | THC |
| Measures | Rey-Auditory Verbal Learning Test (RAVLT) |
| Topics | Cannabis |
| Keywords | Cannabinoids Encoding Learning Memory Retrieval |
| Registration | NCT00708994 NCT00678730 |
| Key findings | THC acutely impairs encoding of verbal memory but does not impair retrieval. Total immediate recall, short delayed recall, and long delayed recall were reduced only when the RAVLT was administered under the influence of THC, not when administered beforehand. |
Abstract
Cannabis and agonists of the brain cannabinoid receptor (CB1R) produce acute memory impairments in humans. However, the extent to which cannabinoids impair the component processes of encoding and retrieval has not been established in humans. The objective of this analysis was to determine whether the administration of Δ9-Tetrahydrocannabinol (THC), the principal psychoactive constituent of cannabis, impairs encoding and/or retrieval of verbal information. Healthy subjects were recruited from the community. Subjects were administered the Rey-Auditory Verbal Learning Test (RAVLT) either before administration of THC (experiment #1) (n=38) or while under the influence of THC (experiment #2) (n=57). Immediate and delayed recall on the RAVLT was compared. Subjects received intravenous THC, in a placebo-controlled, double-blind, randomized manner at doses known to produce behavioral and subjective effects consistent with cannabis intoxication. Total immediate recall, short delayed recall, and long delayed recall were reduced in a statistically significant manner only when the RAVLT was administered to subjects while they were under the influence of THC (experiment #2) and not when the RAVLT was administered prior. THC acutely interferes with encoding of verbal memory without interfering with retrieval. These data suggest that learning information prior to the use of cannabis or cannabinoids is not likely to disrupt recall of that information. Future studies will be necessary to determine whether THC impairs encoding of non-verbal information, to what extent THC impairs memory consolidation, and the role of other cannabinoids in the memory-impairing effects of cannabis. Cannabinoids, Neural Synchrony, and Information Processing (THC-Gamma) http://clinicaltrials.gov/ct2/show/study/NCT00708994 NCT00708994 Pharmacogenetics of Cannabinoid Response http://clinicaltrials.gov/ct2/show/NCT00678730 NCT00678730.