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Study breakdown

Cannabinoids consistently facilitate extinction of traumatic memories in animal and human studies

ReviewStrong evidence
The takeaway

Activating CB1 receptors, either directly or by boosting endocannabinoids, facilitates the extinction of aversive memories with large effect sizes, offering therapeutic potential for PTSD.

PTSD researchers, trauma therapists, psychiatrists, and veterans or trauma survivors exploring cannabinoid options.

Cohen's d >= 1.0 effect sizes

What the researchers found

Direct or indirect CB1 receptor activation consistently facilitated extinction of aversive/traumatic memories across animal and human studies. Effect sizes were large (Cohen's d >= 1.0) in most cases. Key brain areas involved include the medial prefrontal cortex, amygdala, and hippocampus. Timing of administration (around memory formation or reminders) influenced outcomes.

Why it matters

PTSD is fundamentally a disorder of aversive memory that resists extinction. If cannabinoids reliably facilitate this extinction process, they could enhance exposure-based therapies that are the current gold standard for PTSD treatment.

The numbers in context

Effect sizes were large (Cohen's d >= 1.0) in most studies. Effects observed in medial prefrontal cortex, amygdala, and hippocampus. Both CB1 activation and endocannabinoid augmentation were effective.

How the study worked

Comprehensive review of animal and human studies on cannabinoid interventions for aversive memory extinction, with effect size calculations for each intervention.

What this study cannot tell us

Most data comes from animal studies with relatively simple fear conditioning paradigms. Human PTSD involves more complex memory processing. Few clinical trials have tested cannabinoid augmentation of PTSD therapy.

How to read the evidence

Strong: consistent findings across multiple animal and human studies with quantified large effect sizes.

When this study was published

Published in 2019.

The bigger picture

The endocannabinoid system appears to be a natural mechanism for updating threat memories. Enhancing this system pharmacologically could make existing trauma therapies more effective rather than requiring entirely new treatment approaches.

Questions still open

  • Could cannabinoids be used as adjuncts to exposure therapy for PTSD? What is the optimal timing of cannabinoid administration relative to trauma memory reactivation?

Common questions

How might cannabinoids help with PTSD?
They appear to facilitate extinction of traumatic memories, the same process targeted by exposure therapy. By boosting the endocannabinoid system, they may help the brain update threat memories more effectively.
Is there human evidence for this?
Some human studies confirm cannabinoid facilitation of fear extinction, though clinical trials specifically testing cannabinoid-augmented PTSD therapy remain limited.

Read the original research

Tempering aversive/traumatic memories with cannabinoids: a review of evidence from animal and human studies.

Psychopharmacology, 236(1), 201-226

Citation

Lisboa, Sabrina F; Vila-Verde, C; Rosa, J; Uliana, D L; Stern, C A J; Bertoglio, L J; Resstel, L B; Guimaraes, F S. (2019). Tempering aversive/traumatic memories with cannabinoids: a review of evidence from animal and human studies.. Psychopharmacology, 236(1), 201-226. https://doi.org/10.1007/s00213-018-5127-x

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