Clinical Studies and Case Reports

On this site you will find clinical studies with cannabis or single cannabinoids in different diseases and case reports on the use of cannabis by patients.
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Title Cannabinoid facilitation of fear extinction memory recall in humans.
Author(s)Rabinak CA, Angstadt M, Sripada CS, Abelson JL, Liberzon I, Milad MR, Phan KL.
Journal, Volume, IssueNeuropharmacology. 2012 Jul 13. [Epub ahead of print]
Major outcome(s)THC prevented the recovery of fear in this experiment of extinction learning.
IndicationAnxiety;Posttraumatic stress disorderAbstract
MedicationDelta-9-THC

A first-line approach to treat anxiety disorders is exposure-based therapy, which
relies on extinction processes such as repeatedly exposing the patient to stimuli
(conditioned stimuli; CS) associated with the traumatic, fear-related memory.
However, a significant number of patients fail to maintain their gains, partly
attributed to the fact that this inhibitory learning and its maintenance is
temporary and conditioned fear responses can return. Animal studies have shown
that activation of the cannabinoid system during extinction learning enhances
fear extinction and its retention. Specifically, CB1 receptor agonists, such as
Δ9-tetrahydrocannibinol (THC), can facilitate extinction recall by preventing
recovery of extinguished fear in rats. However, this phenomenon has not been
investigated in humans. We conducted a study using a randomized, double-blind,
placebo-controlled, between-subjects design, coupling a standard Pavlovian fear
extinction paradigm and simultaneous skin conductance response (SCR) recording
with an acute pharmacological challenge with oral dronabinol (synthetic THC) or
placebo (PBO) 2 h prior to extinction learning in 29 healthy adult volunteers
(THC = 14; PBO = 15) and tested extinction retention 24 h after extinction
learning. Compared to subjects that received PBO, subjects that received THC
showed low SCR to a previously extinguished CS when extinction memory recall was
tested 24 h after extinction learning, suggesting that THC prevented the recovery
of fear. These results provide the first evidence that pharmacological
enhancement of extinction learning is feasible in humans using cannabinoid system
modulators, which may thus warrant further development and clinical testing. This
article is part of a Special Issue entitled 'Cognitive Enhancers'.

Route(s)Oral
Dose(s)
Duration (days)2
Participants29 healthy subjects
DesignControlled study
Type of publicationMedical journal
Address of author(s)Department of Psychiatry, University of Michigan, Ann Arbor, MI, USA.
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