Background: It is well established that the main psychoactive constituent of cannabis, Δ9-tetrahydrocannabinol (THC), impairs episodic memory encoding and modulates emotional processing, but little is known about the impact of THC during the retrieval of emotional episodic memories. With the rise of cannabis to treat medical conditions, including those characterized by emotional and episodic memory disturbances, there is an urgent need to determine the effects of THC on memory accuracy and distortion. Here, we report the first study investigating the effects of THC during retrieval of neutral and emotional episodic memories. Methods: Using a double-blind, placebo-controlled, within-subjects design, healthy volunteers (N = 23) viewed negative, neutral, and positive pictures (emotional memory task) and lists of semantically related words (false memory task). Forty-eight hours later, participants ingested a capsule containing either THC (15 mg) or placebo and completed tasks to test their memories for the previously studied pictures and words. Results: THC during retrieval did not reduce the number of correct responses to studied items. Instead, it robustly increased false recollection on both the emotional memory and false memory tasks. This effect was found for both neutral and emotional items. Conclusions: These findings show that THC has adverse effects during memory retrieval, distorting both neutral and emotional memories. Coupled with THC's known effects during encoding, these new retrieval findings are important in light of the spreading acceptance of cannabis.
|Number of pages
|Published - Nov 15 2018
Bibliographical noteFunding Information:
HdW has received a GRAND research award from Pfizer, donation of a study drug from Indivior, support for a research study from Insys Therapeutics, and consulting fees from Bristol-Myers-Squibb, Jazz Pharmaceuticals, Marinus, and Organon. None of these were related to the research presented here. The other authors report no biomedical financial interests or potential conflicts of interest.
This project was supported by Grant No. DA02812 (to HdW). We thank lab personnel who recruited and screened participants and Royce Lee, M.D., for medical oversight. HdW has received a GRAND research award from Pfizer, donation of a study drug from Indivior, support for a research study from Insys Therapeutics, and consulting fees from Bristol-Myers-Squibb, Jazz Pharmaceuticals, Marinus, and Organon. None of these were related to the research presented here. The other authors report no biomedical financial interests or potential conflicts of interest. ClinicalTrials.gov: Effects of THC on Emotional Memory Retrieval; https://clinicaltrials.gov/ct2/show/NCT03471585; NCT03471585.
© 2018 Society of Biological Psychiatry
Copyright 2018 Elsevier B.V., All rights reserved.
- Emotional memory
- Episodic memory
- False memory
- False recollection
ASJC Scopus subject areas
- Biological Psychiatry