Cannabinoid facilitation of fear extinction memory recall in humans
ABSTRACT 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'.
- SourceAvailable from: Margaret Haney
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- "The next day, participants were treated with placebo or dronabinol 2 h prior to an extinction session. Those treated with dronabinol had less reinstatement of fear responding 24 h later relative to the placebo group (Rabinek et al, 2013). "
ABSTRACT: There have been extensive policy shifts in the legality of recreational and therapeutic use of cannabis in the US, as well as a steady increase in the number of people using the drug on a regular basis. Given these rapid societal changes, defining what is known scientifically about the consequences of cannabis use on mental health takes on added public health significance. The purpose of this Circumspectives piece is to discuss evidence of cannabis' effects on two psychiatric conditions: post-traumatic stress disorder (PTSD) and psychotic disorders. Dr Haney and Dr Evins will discuss two viewpoints regarding the benefit and harm of cannabis use for these conditions, while outlining what remains unproven and requires further testing in order to move the field forward.Neuropsychopharmacology accepted article preview online, 19 August 2015. doi:10.1038/npp.2015.251.Neuropsychopharmacology: official publication of the American College of Neuropsychopharmacology 08/2015; DOI:10.1038/npp.2015.251 · 7.05 Impact Factor
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- "The primary psychoactive ingredient in cannabis, Δ 9 tetrahydrocannabinol (THC), binds to CB 1 receptors in the brain and produces a variety of acute effects, including subjective feelings of sedation and euphoria (Johns, 2001). Consistent with the role of the endogenous cannabinoid system in the regulation of anxiety and fear learning (Chhatwal and Ressler, 2007), THC and other CB 1 agonists have also been shown to modulate subjective anxiety (Wachtel et al., 2002) and facilitate the extinction of fear responses (Rabinak et al., 2013). The effects of THC on anxiety and fear may be due to changes in amygdala reactivity. "
ABSTRACT: Δ(9)-tetrahydrocannabinol (THC) has been shown to modulate anxiety and facilitate the extinction of fear by inhibiting amygdala reactivity. Since functional coupling between the amygdala and prefrontal cortex (PFC) is implicated in affective processes, it is possible that THC affects amygdala-PFC functional connectivity, in ways that differ across amygdala subregions: basolateral (AMYG-BL), centromedial (AMYG-CM), and superficial (AMYG-SF). The aim of the study was to examine the effects of THC on functional connectivity between amygdala subregions and the PFC during socio-emotional threat in healthy adults using a double-blind, placebo-controlled, within-subjects design. Sixteen subjects completed a functional magnetic resonance imaging (fMRI) task designed to probe amygdala responses to social threat. Amygdala subregion-PFC functional connectivity was compared between THC and placebo using generalized psychophysiological interaction (gPPI) analyses. Findings indicated that THC enhanced AMYG-BL and AMYG-SF connectivity to the rostral anterior cingulate/medial PFC. These effects, including THC's potential ability to reduce threat perception or enhance socio-emotional regulation, may help understand the neurocircuitry of affect. Published by Oxford University Press on behalf of CINP 2014. This work is written by (a) US Government employee(s) and is in the public domain in the US.The International Journal of Neuropsychopharmacology 12/2014; 18(3). DOI:10.1093/ijnp/pyu104 · 4.01 Impact Factor
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- "Recently, several pharmacological agents have been proposed as boosters of exposure therapy (Bentz, Michael, de Quervain, & Wilhelm, 2010; Vervliet, 2008). These new therapeutic approaches are based on the idea that the pharmacological agents facilitate the learning processes underlying the success of exposure therapy (Hofmann, Pollack, & Otto, 2006; Otto, Basden, Leyro, McHugh, & Hofmann, 2007; Rabinak et al., 2013). One agent that has been suggested to improve exposure therapy is cortisol. "
ABSTRACT: Previous research in patients with phobia showed that the administration of glucocorticoids reduces fear in phobic situations and enhances exposure therapy. Glucocorticoids underlie a daily cycle with a peak in the morning and low levels during the evening and night. The aim of the present study was to investigate whether exposure is more effective when conducted in the morning when endogenous cortisol levels are high. Sixty patients meeting DSM IV criteria for specific phobia (animal type) were randomly assigned to one-session exposure treatment either at 08.00 a.m. (high cortisol group) or at 06.00 p.m. (low cortisol group). Participants returned for a posttreatment assessment one week after therapy and a follow-up assessment three months after therapy. Both groups showed good outcome, but patients treated in the morning exhibited significantly less fear of spiders in the behavioral approach test (BAT) and a trend for lower scores on the Fear of Spiders Questionnaire (FSQ) than patients treated in the evening. This effect was present at posttreatment and follow-up. Our findings indicate that exposure therapy is more effective in the morning than in the evening. We suggest that this may be due to higher endogenous cortisol levels in the morning group that enhance extinction memory.Behaviour Research and Therapy 09/2014; 60. DOI:10.1016/j.brat.2014.06.009 · 3.85 Impact Factor