Δ9-Tetrahydrocannabinol During Encoding Impairs Perceptual Details yet Spares Context Effects on Episodic Memory.
Manoj K. Doss, Jessica Weafer, David A Gallo, Harriet de Wit
Biological Psychiatry: Cognitive Neuroscience and Neuroimaging 2020 DOI: 10.1016/j.bpsc.2019.08.007 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Double-blind, placebo-controlled, within-subjects experiment Peer reviewed |
|---|---|
| Sample size | 24 |
| Population | Healthy infrequent cannabis users |
| Interventions | Δ9-tetrahydrocannabinol (THC) placebo |
| Dose | 15 mg |
| Duration | Two-day interval between encoding and test |
| Topics | Cannabis |
| Keywords | Context reinstatement Episodic memory False memory Memory illusion |
| Key findings | THC impaired memory for perceptual details of objects compared with placebo, and context reinstatement increased both correct and false recognition, with THC magnifying the context illusion for semantically congruent objects and abolishing it for incongruent objects. |
Abstract
With the growing acceptance of cannabis use, it is crucial to understand the drug's effects on episodic memory accuracy and distortion. We investigated the impact of the administration of Δ9-tetrahydrocannabinol (THC), the main psychoactive constituent of cannabis, on a context-based memory illusion. In a double-blind, placebo-controlled, within-subjects design, healthy infrequent cannabis users (N = 24) memorized object pictures that were superimposed over scenes (e.g., gray cat on beach) after pretreatment with placebo or THC (15 mg oral). Two days later under sober conditions, memory for the object pictures was tested by asking participants to discriminate between previously seen objects or perceptually similar lures (e.g., different gray cat). Context reinstatement was manipulated by presenting objects on their original or different scenes (e.g., beach or forest). THC impaired memory for perceptual details of objects compared with placebo, and the context illusion was obtained in each condition: context reinstatement increased high-confidence false recognition along with correct recognition of previously seen objects. Although THC did not interact with these context effects overall, post hoc analyses showed that THC magnified the context illusion when objects were semantically congruent with their encoding contexts but abolished the context illusion when objects were incongruent with their encoding contexts. These results are consistent with the hypothesis that THC impairs the encoding of specific object information more than item-context associations. As a result, THC may spare the distorting effects of context reinstatement on memory. In fact, THC may increase these distorting effects under conditions when objects are semantically congruent with context.
Comparable studies
Other randomized controlled trials on cannabis, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| Cannabidiol inhibits THC-elicited paranoid symptoms and hippocampal-dependent memory impairment Healthy participants | 2012 | Randomized controlled trial | n = 48 |
| Distinct Effects of Δ9-Tetrahydrocannabinol and Cannabidiol on Neural Activation During Emotional Processing Healthy, English-native, right-handed men who had used cannabis 15 times or less in... | 2009 | Double-blind, randomized, placebo-controlled crossover trial | n = 15 |
| Acute Effects of a Single, Oral dose of d9-tetrahydrocannabinol (THC) and Cannabidiol (CBD) Administration in Healthy Volunteers Healthy male subjects | 2012 | Randomized controlled trial | n = 16 |
| Modulation of Mediotemporal and Ventrostriatal Function in Humans by Δ9-Tetrahydrocannabinol Healthy, native English-speaking, right-handed men of white race/ethnicity who had used... | 2009 | Randomized controlled trial | n = 15 |
| Cannabidiol (CBD) content in vaporized cannabis does not prevent tetrahydrocannabinol (THC)-induced impairment of driving and cognition Healthy volunteers with a history of light cannabis use | 2019 | Randomized, double-blind, within-subjects crossover | n = 14 |
Citations in the library
Cited by 7
- The acute effects of psychoactive drugs on emotional episodic memory encoding, consolidation, and retrieval: A comprehensive review. Neuroscience & Biobehavioral Reviews July 1, 2023
- Virtual Reality as a Moderator of Psychedelic-Assisted Psychotherapy Frontiers in Psychology March 4, 2022
- Not Just a Pot: Visual Episodic Memory in Cannabis Users and Polydrug Cannabis Users: ROC and ERP Preliminary Investigation Frontiers in Human Neuroscience June 11, 2021
- Ayahuasca enhances the formation of hippocampal-dependent episodic memory without impacting false memory susceptibility in experienced ayahuasca users: An observational study. Journal of Psychopharmacology April 1, 2025
- Δ9-Tetrahydrocannabinol (THC) impairs visual working memory performance: a randomized crossover trial. Neuropsychopharmacology October 1, 2020
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