Effects of ∆(9)-tetrahydrocannabinol on aversive memories and anxiety: a review from human studies

Psychedelics: A review of their effects on recalled aversive memories and fear/anxiety expression in rodents

Threatening events and stressful experiences can lead to maladaptive memories and related behaviors. Existing treatments often fail to address these issues linked to anxiety/stress-related disorders effectively. This review identifies dose ranges associated with specific actions across various psychedelics. We examined psilocybin/psilocin, lysergic acid diethylamide (LSD), N,N-dimethyltryptamine (DMT), mescaline, 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT), serotonin 2 A/2 C agonists (e.g., DOI) and 3,4-methylenedioxymethamphetamine (MDMA) on aversive memory extinction and reconsolidation, learned fear, anxiety, and locomotion in rodents. Nearly 400 studies published since 1957 were reviewed. Psychedelics often show biphasic effects on locomotion at doses that enhance extinction learning/retention, impair memory reconsolidation, or reduce learned fear and anxiety. Emerging evidence suggests a dissociation between their prospective benefits and locomotor effects. Under-explored aspects include sex differences, susceptibility to interference as memories age and generalize, repeated treatments, and immediate vs. delayed changes. Validating findings in traumatic-like memory and maladaptive fear/anxiety models is essential. Understanding how psychedelics modulate threat responses and post-retrieval memory processes in rodents may inform drug development and human studies, improving therapeutic approaches for related psychiatric conditions.

RETRACTED: Left hemisphere lateralization of the limbic system and frontoparietal network (FPN) correlates with positive and negative symptom improvement following cannabidiol (CBD) administration in psychosis and ultra-high risk (UHR) populations: A voxel-wise meta-analysis

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the authors when they discovered and reported to the editors that articles containing population samples drawn from similar cohorts of healthy participants without psychosis were erroneously included in the psychosis subgroup of the meta-analysis. This error in the systematic review processes ultimately affects the findings in the meta-analysis. The authors deeply apologize for this error.

Effects of cannabidiol, with and without ∆9-tetrahydrocannabinol, on anxiety-like behavior following alcohol withdrawal in mice

Introduction

Alcohol use disorder (AUD) is commonly associated with anxiety disorders and enhanced stress-sensitivity; symptoms that can worsen during withdrawal to perpetuate continued alcohol use. Alcohol increases neuroimmune activity in the brain. Our recent evidence indicates that alcohol directly modulates neuroimmune function in the central amygdala (CeA), a key brain region regulating anxiety and alcohol intake, to alter neurotransmitter signaling. We hypothesized that cannabinoids, such as cannabidiol (CBD) and ∆9-tetrahydrocannabinol (THC), which are thought to reduce neuroinflammation and anxiety, may have potential utility to alleviate alcohol withdrawal-induced stress-sensitivity and anxiety-like behaviors via modulation of CeA neuroimmune function.

Methods

We tested the effects of CBD and CBD:THC (3:1 ratio) on anxiety-like behaviors and neuroimmune function in the CeA of mice undergoing acute (4-h) and short-term (24-h) withdrawal from chronic intermittent alcohol vapor exposure (CIE). We further examined the impact of CBD and CBD:THC on alcohol withdrawal behaviors in the presence of an additional stressor.

Results

We found that CBD and 3:1 CBD:THC increased anxiety-like behaviors at 4-h withdrawal. At 24-h withdrawal, CBD alone reduced anxiety-like behaviors while CBD:THC had mixed effects, showing increased center time indicating reduced anxiety-like behaviors, but increased immobility time that may indicate increased anxiety-like behaviors. These mixed effects may be due to altered metabolism of CBD and THC during alcohol withdrawal. Immunohistochemical analysis showed decreased S100β and Iba1 cell counts in the CeA at 4-h withdrawal, but not at 24-h withdrawal, with CBD and CBD:THC reversing alcohol withdrawal effects..

Discussion

These results suggest that the use of cannabinoids during alcohol withdrawal may lead to exacerbated anxiety depending on timing of use, which may be related to neuroimmune cell function in the CeA.

Greater vulnerability to cannabis dependence among heavy cannabis user French women

BACKGROUND AND OBJECTIVES

Between 1990 and the mid-2010s, France registered a sharp rise in the spread and consumption of cannabis. At the same time, there has been an increase in the concentration of Δ9-tetrahydrocannabinol contained in cannabis. The aims of our study are to measure addictive and psychiatric comorbidities in cannabis users in France, and to compare characteristics between women and men.

METHODS

Three hundred and forty-two heavy cannabis users seen in a cannabis clinic between 2004 and 2014 were assessed during a 2-h clinical interview (DSM-IV, MINI).

RESULTS

83.2% of users are currently cannabis dependent, 10.6% alcohol dependent, and 2.1% cocaine/crack dependent. 37.8% have a current mood disorder, 47.6% have a current anxiety disorder, and 8.8% are psychotic. Women suffer significantly more often than men from major depressive episodes, dysthymia, agoraphobia, social phobia, generalized anxiety disorder and posttraumatic stress disorder (PTSD), both current and lifetime. Logistic regression shows that women have a significantly higher risk than men of suffering from PTSD over their lifetime (odds ratio [OR] = 5.48; p < 10-3). The vast majority of women suffering from PTSD report having been sexually assaulted in the course of their lives. In addition, women are at greater risk of cannabis dependence (OR = 3.87; p < .05) for lower cannabis consumption (grams smoked per week) (OR = 0.96; p < .05).

DISCUSSION AND CONCLUSIONS

French women heavy cannabis users are particularly at risk of PTSD and are more likely than men to be dependent despite consuming fewer.

SCIENTIFIC SIGNIFICANCE

Further studies are needed to clinically quantify cannabis consumption and distinguish its impact on women and men.

Impact of Dietary Fat and Oral Delivery System on Cannabigerol Pharmacokinetics in Adults

Background and Aims: Cannabigerol (CBG) is a nonintoxicating cannabinoid synthesized in the Cannabis sativa plant that is incorporated into dietary supplements. This study investigated the influence of dietary fat and an emulsified delivery vehicle on CBG pharmacokinetics (PKs) after oral ingestion by adults. Materials and Methods: Consented participants were enrolled in a double-crossover pilot study and were blinded to the delivery vehicle type (isolate or emulsification) and isocaloric meal condition (low-fat=<5 g fat/meal or high-fat [HF]=>30 g fat/meal). The concentration of CBG in human plasma was measured after a single 25 mg dose of CBG using liquid chromatography-tandem mass spectrometry (LC-MS/MS). PK parameters were calculated using noncompartmental analysis. Results: The PKs of the two delivery systems (emulsified vs. non-emulsified) were significantly impacted by the HF meal condition. Participants in the HF meal group exhibited significantly higher area under the plasma concentration time curve from time 0 to last quantifiable value, maximum concentration, and terminal half-life. Participants in the HF meal group also had a significantly lower terminal elimination rate constant and time to maximum concentration (Tmax), in addition to decreased Tmax variation. The threshold for bioequivalence between conditions was not met. An exploratory aim correlated anthropometric measures and previous day's dietary intake on PK parameters which yielded inconsistent results across dietary fat conditions. Conclusions: In aggregate, dietary fat had a greater effect on CBG PKs than the emulsified delivery vehicle. This supports accounting for dietary intake in development of therapeutics and administration guidelines for orally delivered CBG.

Assessment of the effect of cannabis use before partnered sex on women with and without orgasm difficulty

Background

Up to 41% of women face challenges achieving orgasm, a statistic unchanged for 50 years.

Aim

To evaluate the effect of cannabis use before partnered sex on women with and without difficulty achieving orgasm.

Methods

This observational study evaluated responses from female study participants relating to their demographics, sexual activities, mental well-being, cannabis usage, and orgasm-related questions from the Female Sexual Function Index (FSFI).

Outcomes

Outcomes included orgasm frequency, difficulty, and satisfaction related to cannabis use or lack of use before partnered sex, largely based on the FSFI orgasm subscale.

Results

Of the 1037 survey responses, 410 were valid and complete. Twenty-three surveys (5.6% returned) were excluded due to failure to meet the study's criteria. Of the valid surveys, most women (52%, n = 202) reported difficulty achieving orgasm during sexual activity with a partner. These women were primarily between 25 and 34 years of age (45%, n = 91); 75% identified their race as White (n = 152/202); 52% (n = 105) identified as LGBTQI+ (lesbian, gay, bisexual, transgender, queer/questioning, intersex, or other); and 82% (n = 165) were married or in a relationship. Among participants who experienced challenges in achieving orgasm, 72.8% (n = 147, P < .001) reported that cannabis use before partnered sex increased orgasm frequency, 67% stated that it improved orgasm satisfaction (n = 136, P < .001), and 71% indicated that cannabis use made orgasm easier (n = 143, P < .001). The frequency of cannabis use before partnered sex correlated with increased orgasm frequency for women who experienced difficulties achieving orgasm (n = 202, P < .001). The reasons for cannabis use before partnered sex resulted in a more positive orgasm response (n = 202, P = .22).

Clinical Implications

Cannabis may be a treatment for women with difficulty achieving orgasm during partnered sex.

Strengths and Limitations

The researchers examined the challenge of achieving orgasm and considered the covariates reported in the literature, including the FSFI orgasm subscale. The findings may not be generalizable to women who rarely or never use cannabis before sex, women who have never experienced an orgasm, or women who do not have female genitalia. Additionally, the specific type of cannabis used, its chemical composition, the quantity used, and whether or not the partner used cannabis were not assessed in this study.

Conclusion

Cannabis-related treatment appears to provide benefit to women who have female orgasm difficulties or dysfunction.

Impaired learning, memory, and extinction in posttraumatic stress disorder: translational meta-analysis of clinical and preclinical studies

Current evidence-based treatments for post-traumatic stress disorder (PTSD) are efficacious in only part of PTSD patients. Therefore, novel neurobiologically informed approaches are urgently needed. Clinical and translational neuroscience point to altered learning and memory processes as key in (models of) PTSD psychopathology. We extended this notion by clarifying at a meta-level (i) the role of information valence, i.e. neutral versus emotional/fearful, and (ii) comparability, as far as applicable, between clinical and preclinical phenotypes. We hypothesized that cross-species, neutral versus emotional/fearful information processing is, respectively, impaired and enhanced in PTSD. This preregistered meta-analysis involved a literature search on PTSD+Learning/Memory+Behavior, performed in PubMed. First, the effect of information valence was estimated with a random-effects meta-regression. The sources of variation were explored with a random forest-based analysis. The analyses included 92 clinical (N = 6732 humans) and 182 preclinical (N = 6834 animals) studies. A general impairment of learning, memory and extinction processes was observed in PTSD patients, regardless of information valence. Impaired neutral learning/memory and fear extinction were also present in animal models of PTSD. Yet, PTSD models enhanced fear/trauma memory in preclinical studies and PTSD impaired emotional memory in patients. Clinical data on fear/trauma memory was limited. Mnemonic phase and valence explained most variation in rodents but not humans. Impaired neutral learning/memory and fear extinction show stable cross-species PTSD phenotypes. These could be targeted for novel PTSD treatments, using information gained from neurobiological animal studies. We argue that apparent cross-species discrepancies in emotional/fearful memory deserve further in-depth study; until then, animal models targeting this phenotype should be applied with utmost care.

Ginsenoside Rg1 in neurological diseases: From bench to bedside

Ginseng has been used in China as a superior medicinal material for thousands of years that can nourish the five internal organs, calm the mind and benefit wisdom. Due to its anti-inflammatory, antioxidant and neuroprotective activities, one of the active components of ginseng, ginsenoside Rg1, has been extensively investigated in the remedy of brain disorders, especially dementia and depression. In this review, we summarized the research progress on the action mechanisms of Rg1 ameliorating depression-like behaviors, including inhibition of hyperfunction of hypothalamic-pituitary-adrenal (HPA) axis, regulation of synaptic plasticity and gut flora. Rg1 may alleviate Alzheimer's disease in the early phase, as well as in the middle-late phases through repairing dendrite, axon and microglia- and astrocyte-related inflammations. We also proposed that Rg1 could regulate memory state (the imbalance of working and aversive memory) caused by distinct stimuli. These laboratory studies would further the clinical trials on Rg1. From the prospective of drug development, we discussed the limitations of the present investigations and proposed our ideas to increase permeability and bioavailability of Rg1. Taken together, Rg1 has the potential to treat neuropsychiatric disorders, but a future in-depth investigation of the mechanisms is still required. In addition, drug development will benefit from the clinical trials in one specific neuropsychiatric disorder.

Effects of delta-9 tetrahydrocannabinol on fear memory labilization and reconsolidation: A putative role of GluN2B-NMDA receptor within the dorsal hippocampus

Cannabis preparations could be an effective reconsolidation-based treatment for post-traumatic stress disorder. However, the effects of Δ⁹-tetrahydrocannabinol (THC) in fear memory labilization, a critical condition for retrieval-induced reconsolidation, are undetermined. We sought to investigate the effect of a conventional and an ultra-low dose of THC in memory labilization of adult male Wistar rats submitted to contextual fear conditioning. Pretreatment with THC 0.002, but not THC 0.3 mg/kg, i. p., before memory retrieval, did not change memory expression during the retrieval but impaired reconsolidation. No treatment changed freezing expression in an unpaired context. Before retrieval, THC 0.3, but not THC 0.002, decreased GluN2A-NMDA expression and the GluN2A/GluN2B ratio in the dorsal hippocampus (DH) 24 h later. No changes were observed immediately after retrieval. Pretreatment with THC 0.3 abolished the reconsolidation-impairing effect of anisomycin injected into the DH, suggesting an impairment in memory labilization. This effect was associated with an increased freezing expression in the unpaired context and was not observed with the THC ultra-low dose. The GluN2B-NMDA antagonism increased fear generalization in the anisomycin-treated group but restored its reconsolidation-impairing effect and reduced fear generalization when animals were pretreated with THC 0.3. GluN2A-NMDA antagonism or inhibition of the ubiquitin-proteasome system in the DH did not interfere with the effects of THC 0.3. Our findings indicate that THC causes a bidirectional effect on fear memory labilization that depends on hippocampal GluN2B-NMDA receptors' involvement in fear memory generalization.

Cannabidiol impairs fear memory reconsolidation in female rats through dorsal hippocampus CB1 but not CB2 receptor interaction

Women present increased susceptibility to anxiety- and stress-related disorders compared to men. A potentially promising pharmacological-based strategy to regulate abnormal aversive memories disrupts their reconsolidation stage after reactivation and destabilization. Male rodent findings indicate that cannabidiol (CBD), a relatively safe and effective treatment for several mental health conditions, can impair the reconsolidation of aversive memories. However, whether and how CBD influences it in females is still unknown. The present study addressed this question in contextually fear-conditioned female rats. We report that systemically administered CBD impaired their reconsolidation, reducing freezing expression for over a week. This action was restricted to a time when the reconsolidation presumably lasted (< six hours post-retrieval) and depended on memory reactivation/destabilization. Moreover, the impairing effects of CBD on memory reconsolidation relied on the activation of cannabinoid type-1 but not type-2 receptors located in the CA1 subregion of the dorsal hippocampus. CBD applied directly to this brain area was sufficient to reproduce the effects of systemic CBD treatment. Contextual fear memories attenuated by CBD did not show reinstatement, an extinction-related feature. By demonstrating that destabilized fear memories are sensitive to CBD and how it hinders mechanisms in the DH CA1 that may restabilize them in female rats, the present findings concur that reconsolidation blockers are viable and could be effective in disrupting abnormally persistent and distressing aversive memories such as those related to posttraumatic stress disorder.

“Flower Power”: Controlled Inhalation of THC-Predominant Cannabis Flos Improves Health-Related Quality of Life and Symptoms of Chronic Pain and Anxiety in Eligible UK Patients

In November 2018, the UK’s Home Office established a legal route for eligible patients to be prescribed cannabis-based products for medicinal use in humans (CBPMs) as unlicensed medicines. These include liquid cannabis extracts for oral administration (“oils”) and dried flowers for inhalation (“flos”). Smoking of CBPMs is expressly prohibited. To date, THC-predominant cannabis flowers remain the most prescribed CBPMs in project Twenty21 (T21), the first multi-center, prospective, observational UK cannabis patient registry. This observational, prospective data review analyzes patient-reported outcome measures (PROMS) collected by T21 associated with the inhalation of KHIRON 20/1, the most prescribed CBPM in the project. PROMS collected at baseline and at subsequent 3-month follow-up included health-related quality of life (HRQoL), general mood, and sleep. Condition-specific measures of illness severity were performed with the Brief Pain Inventory Short Form (BPI-SF) and the Generalized Anxiety Disorder 7-Item Scale (GAD-7). Participants (N = 344) were mostly males (77.6%, average age = 38.3) diagnosed mainly with chronic pain (50.9%) and anxiety-related disorders (25.3%). Inhalation of KHIRON 20/1 was associated with a marked increase in self-reported HRQoL, general mood, and sleep (N = 344; p < 0.001). Condition-specific assessments showed significant improvements in pain severity (T = 6.67; p < 0.001) and interference (T = 7.19; p < 0.001) in patients using KHIRON 20/1 for chronic pain (N = 174). Similar results were found for patients diagnosed with anxiety-related disorders (N = 107; T = 12.9; p < 0.001). Our results indicate that controlled inhalation of pharmaceutical grade, THC-predominant cannabis flos is associated with a significant improvement in patient-reported pain scores, mood, anxiety, sleep disturbances and overall HRQoL in a treatment-resistant clinical population.

"Flower Power": Controlled Inhalation of THC-Predominant Cannabis Flos Improves Health-Related Quality of Life and Symptoms of Chronic Pain and Anxiety in Eligible UK Patients

In November 2018, the UK’s Home Office established a legal route for eligible patients to be prescribed cannabis-based products for medicinal use in humans (CBPMs) as unlicensed medicines. These include liquid cannabis extracts for oral administration (“oils”) and dried flowers for inhalation (“flos”). Smoking of CBPMs is expressly prohibited. To date, THC-predominant cannabis flowers remain the most prescribed CBPMs in project Twenty21 (T21), the first multi-center, prospective, observational UK cannabis patient registry. This observational, prospective data review analyzes patient-reported outcome measures (PROMS) collected by T21 associated with the inhalation of KHIRON 20/1, the most prescribed CBPM in the project. PROMS collected at baseline and at subsequent 3-month follow-up included health-related quality of life (HRQoL), general mood, and sleep. Condition-specific measures of illness severity were performed with the Brief Pain Inventory Short Form (BPI-SF) and the Generalized Anxiety Disorder 7-Item Scale (GAD-7). Participants (N = 344) were mostly males (77.6%, average age = 38.3) diagnosed mainly with chronic pain (50.9%) and anxiety-related disorders (25.3%). Inhalation of KHIRON 20/1 was associated with a marked increase in self-reported HRQoL, general mood, and sleep (N = 344; p < 0.001). Condition-specific assessments showed significant improvements in pain severity (T = 6.67; p < 0.001) and interference (T = 7.19; p < 0.001) in patients using KHIRON 20/1 for chronic pain (N = 174). Similar results were found for patients diagnosed with anxiety-related disorders (N = 107; T = 12.9; p < 0.001). Our results indicate that controlled inhalation of pharmaceutical grade, THC-predominant cannabis flos is associated with a significant improvement in patient-reported pain scores, mood, anxiety, sleep disturbances and overall HRQoL in a treatment-resistant clinical population.

Nutraceutical Interventions for Post-Traumatic Stress Disorder in Animal Models: A Focus on the Hypothalamic–Pituitary–Adrenal Axis

Post-traumatic stress disorder (PTSD) occurs after exposure to traumatic events and is characterized by overwhelming fear and anxiety. Disturbances in the hypothalamic–pituitary–adrenal (HPA) axis are involved in the pathogenesis of mood disorders, including anxiety, PTSD, and major depressive disorders. Studies have demonstrated the relationship between the HPA axis response and stress vulnerability, indicating that the HPA axis regulates the immune system, fear memory, and neurotransmission. The selective serotonin reuptake inhibitors (SSRIs), sertraline and paroxetine, are the only drugs that have been approved by the United States Food and Drug Administration for the treatment of PTSD. However, SSRIs require long treatment times and are associated with lower response and remission rates; therefore, additional pharmacological interventions are required. Complementary and alternative medicine therapies ameliorate HPA axis disturbances through regulation of gut dysbiosis, insomnia, chronic stress, and depression. We have described the cellular and molecular mechanisms through which the HPA axis is involved in PTSD pathogenesis and have evaluated the potential of herbal medicines for PTSD treatment. Herbal medicines could comprise a good therapeutic strategy for HPA axis regulation and can simultaneously improve PTSD-related symptoms. Finally, herbal medicines may lead to novel biologically driven approaches for the treatment and prevention of PTSD.

Impact of cannabidiol-rich hemp extract oil on reconsolidation disruption of naturalistic interoceptive aversive memory in humans: Protocol for a randomized clinical trial

BACKGROUND

Preclinical experiments with rodents demonstrate that cannabidiol (CBD), the non-psychotomimetic constituent of the Cannabis sativa plant, disrupts reconsolidation of aversive memories conditioned in the laboratory when administered within the memory reconsolidation window (< 6 h. post-retrieval) by indirectly activating cannabinoid type-1 (CB₁) receptors in the dorsal anterior cingulate cortex (dACC). Based on these findings, we aim to test whether administration of 300 mg CBD-rich hemp extract oil following fear reactivation of an aversive interoceptive threat memory can disrupt reconsolidation of naturalistic aversive memories in humans. More specifically, naturalistic interoceptive aversive memories, a form of transdiagnostic fear memory that contributes to the pathogenesis of fear-related disorders such as panic disorder, posttraumatic stress disorder (PTSD), and illness anxiety disorder.

METHODS

For this proof-of-concept, placebo-controlled double-blind trial, volunteers (n = 99) reporting elevated fears of somatic sensations will be stratified on biological sex and randomized to one of three intervention arms: (a). CBD-rich oil administered within the reconsolidation window, (b) Placebo oil administered within the reconsolidation window; or (c) CBD-rich oil administered outside of the reconsolidation window. Change in emotional reactivity to a 35% CO₂ challenge from baseline to two-week follow-up will serve as our primary outcome.

CONCLUSION

Study findings may contribute towards the development of a novel brief transdiagnostic intervention guided by reconsolidation theory for individuals prone to fear-related psychiatric disorders.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04726475.

Amygdalar CB2 cannabinoid receptor mediates fear extinction deficits promoted by orexin-A/hypocretin-1

Anxiety and stress disorders are often characterized by an inability to extinguish learned fear responses. Orexins/hypocretins are involved in the modulation of aversive memories, and dysregulation of this system may contribute to the aetiology of anxiety disorders characterized by pathological fear. The mechanisms by which orexins regulate fear are unknown. Here we investigated the role of the endogenous cannabinoid system in the impaired fear extinction induced by orexin-A (OXA) in male mice. The selective inhibitor of 2-arachidonoylglycerol (2-AG) biosynthesis O7460 abolished the fear extinction deficits induced by OXA. Accordingly, increased 2-AG levels were observed in the amygdala and hippocampus of mice treated with OXA that do not extinguish fear, suggesting that high levels of this endocannabinoid are related to poor extinction. Impairment of fear extinction induced by OXA was associated with increased expression of CB2 cannabinoid receptor (CB2R) in microglial cells of the basolateral amygdala. Consistently, the intra-amygdala infusion of the CB2R antagonist AM630 completely blocked the impaired extinction promoted by OXA. Microglial and CB2R expression depletion in the amygdala with PLX5622 chow also prevented these extinction deficits. These results show that overactivation of the orexin system leads to impaired fear extinction through 2-AG and amygdalar CB2R. This novel mechanism could be of relevance for the development of novel potential approaches to treat diseases associated with inappropriate retention of fear, such as post-traumatic stress disorder, panic anxiety and phobias.

The Management of Cancer Symptoms and Treatment-Induced Side Effects With Cannabis or Cannabinoids

Cannabis and cannabinoids are increasingly being accessed and used by patients with advanced cancer for various symptoms and general quality of life. Specific symptoms of pain, nausea and vomiting, loss of appetite and cachexia, anxiety, sleep disturbance, and medical trauma are among those that have prompted patients with cancer to use cannabis. This conference report from the National Cancer Institute's "Cannabis, Cannabinoid and Cancer Research Symposium" on the topic of "Cancer Symptom/Treatment Side Effect Management" is an expert perspective of cannabis intervention for cancer and cancer treatment-related symptoms. The purpose of the symposium was to identify research gaps, describe the need for high-quality randomized prospective studies of medical cannabis for palliative care in patients with cancer, and evaluate the impact of medical cannabis on cancer survivors' quality of life. Further, education of clinicians and affiliated health-care providers in guiding cancer patients in using cannabis for cancer care would benefit patients. Together, these steps will further aid in refining the use of cannabis and cannabinoids for symptom palliation and improve safety and efficacy for patients.

A review of the effects of acute and chronic cannabinoid exposure on the stress response

While cannabis has been used for centuries for its stress-alleviating properties, the effects of acute and chronic cannabinoid exposure on responses to stress remain poorly understood. This review provides an overview of studies that measured stress-related endpoints following acute or chronic cannabinoid exposure in humans and animals. Acute cannabinoid exposure increases basal concentrations of stress hormones in rodents and humans and has dose-dependent effects on stress reactivity in humans and anxiety-like behavior in rodents. Chronic cannabis exposure is associated with dampened stress reactivity, a blunted cortisol awakening response (CAR), and flattened diurnal cortisol slope in humans. Sex differences in these effects remain underexamined, with limited evidence for sex differences in effects of cannabinoids on stress reactivity in rodents. Future research is needed to better understand sex differences in the effects of cannabis on the stress response, as well as downstream impacts on mental health and stress-related disorders.

Interactions of Noradrenergic, Glucocorticoid and Endocannabinoid Systems Intensify and Generalize Fear Memory Traces

Systemic administration of drugs that activate the noradrenergic or glucocorticoid system potentiates aversive memory consolidation and reconsolidation. The opposite happens with the stimulation of endocannabinoid signaling under certain conditions. An unbalance of these interacting neurotransmitters can lead to the formation and maintenance of traumatic memories, whose strength and specificity attributes are often maladaptive. Here we aimed to investigate whether originally low-intensity and precise contextual fear memories would turn similar to traumatic ones in rats systemically administered with adrenaline, corticosterone, and/or the cannabinoid type-1 receptor antagonist/inverse agonist AM251 during consolidation or reconsolidation. The high dose of each pharmacological agent evaluated significantly increased freezing times at test in the conditioning context one and nine days later when given alone post-acquisition or post-retrieval. Their respective low dose produced no relative changes when given separately, but co-treatment of adrenaline with corticosterone or AM251 and the three drugs combined, but not corticosterone with AM251, produced results equivalent to those mentioned initially. Neither the high nor the low dose of adrenaline, corticosterone, or AM251 altered freezing times at test in a novel, neutral context two and ten days later. In contrast, animals receiving the association of their low dose exhibited significantly higher freezing times than controls. Together, the results indicate that newly acquired and destabilized threat memory traces become more intense and generalized after a combined interference acting synergistically and mimicking that reported in patients presenting stress-related psychiatric conditions.

The synthetic CB1 cannabinoid receptor selective agonists: Putative medical uses and their legalization

More than 500 molecules have been identified as components of Cannabis sativa (C. sativa), of which the most studied is Δ⁹-tetrahydrocannabinol (Δ⁹-THC). Several studies have suggested that Δ⁹-THC exerts diverse biological effects, ranging from fragmentation of DNA to behavioral disruptions. Currently, it is accepted that most of the pharmacological properties of Δ⁹-THC engage the activation of the cannabinoid receptors, named CB₁ and CB₂. Interestingly, multiple pieces of evidence have suggested that the cannabinoid receptors play an active role in the modulation of several diseases leading to the design of synthetic cannabinoid-like compounds. Advances in the development of synthetic CB₁ cannabinoid receptor selective agonists as therapeutical approaches are, however, limited. This review focuses on available evidence searched in PubMed regarding the synthetic CB₁ cannabinoid receptor selective agonists such as AM-1235, arachidonyl-2' chloroethylamide (ACEA), CP 50,556-1 (Levonantradol), CP-55,940, HU-210, JWH-007, JWH-018, JWH-200 (WIN 55,225), methanandamide, nabilone, O-1812, UR-144, WIN 55,212-2, nabiximols, and dronabinol. Indeed, it would be ambitious to describe all available evidence related to the synthetic CB₁ cannabinoid receptor selective agonists. However, and despite the positive evidence on the positive results of using these compounds in experimental models of health disturbances and preclinical trials, we discuss evidence in regards some concerns due to side effects.

Adolescent exposure to delta-9-tetrahydrocannabinol and ethanol heightens sensitivity to fear stimuli

Cannabis use disorder (CUD) has doubled in prevalence over the past decade as a nation-wide trend toward legalization allows for increased drug accessibility. As a result, marijuana has become the most commonly used illicit drug in the United States particularly among the adolescent population. This is especially concerning since there is greater risk for the harmful side effects of drug use during this developmental period due to ongoing brain maturation. Increasing evidence indicates that CUD often occurs along with other debilitating conditions including both alcohol use disorder (AUD) and anxiety disorders such post-traumatic stress disorder (PTSD). Additionally, exposure to cannabis, alcohol, and stress can induce alterations in glutamate regulation and homeostasis in the prefrontal cortex (PFC) that may lead to impairments in neuronal functioning and cognition. Therefore, in order to study the relationship between drug exposure and the development of PTSD, these studies utilized rodent models to determine the impact of adolescent exposure to delta-9-tetrahydrocannabinol (THC) and ethanol on responses to fear stimuli during fear conditioning and used calcium imaging to measure glutamate activity in the prelimbic cortex during this behavioral paradigm. The results from these experiments indicate that adolescent exposure to THC and ethanol leads to enhanced sensitivity to fear stimuli both behaviorally and neuronally. Additionally, these effects were attenuated when animals were treated with the glutamatergic modulator N-acetylcysteine (NAC). In summary, these studies support the hypothesis that adolescent exposure to THC and ethanol leads to alterations in fear stimuli processing through glutamatergic reliant modifications in PFC signaling.

Impact of Acute and Chronic Cannabis Use on Stress Response Regulation: Challenging the Belief That Cannabis Is an Effective Method for Coping

Although research has only recently started to examine the impact of cannabis use on stress response, there is some evidence that indicates acute and chronic impacts of cannabis on these processes. In this paper, we review processes involved in regulating the stress response and we review the influence of acute and chronic exposure to cannabis on patterns and regulation of the stress response. We also highlight the role of stress as a risk factor for initiation and maintenance of cannabis use. In this context, we examine moderating variables, including sex and life adversity. In light of recent observations indicating increasing prevalence of cannabis use during pregnancy, we provide additional focus on cannabis use in this vulnerable population, including how acute and chronic stress may predispose some individuals to use cannabis during pregnancy. While this line of research is in its infancy, we review available articles that focus on the perinatal period and that examined the association between cannabis use and various life stressors, including partner violence, job loss, and lack of housing. We also review psychiatric co-morbidities (e.g., post-traumatic stress disorder, anxiety). A better understanding of the way stress and cannabis use relate within the general population, as well as within certain subgroups that may be at a greater risk of using and/or at greater risk for adverse outcomes of use, may lead to the development of novel prevention and intervention approaches.

Female but not male rats show biphasic effects of low doses of Δ9-tetrahydrocannabinol on anxiety: can cannabidiol interfere with these effects?

Δ⁹-tetrahydrocannabinol (THC) is the main phytocannabinoid present in the Cannabis sativa. It can produce dose-dependent anxiolytic or anxiogenic effects in males. THC effects on anxiety have scarcely been studied in females, despite their higher prevalence of anxiety disorders. Cannabidiol, another phytocannabinoid, has been reported to attenuate anxiety and some THC-induced effects. The present study aimed to investigate the behavioral and neurochemical effects of THC administered alone or combined with CBD in naturally cycling female rats tested in the elevated plus-maze. Systemically administered THC produced biphasic effects in females, anxiolytic at low doses (0.075 or 0.1 mg/kg) and anxiogenic at a higher dose (1.0 mg/kg). No anxiety changes were observed in males treated with the same THC dose range. The anxiogenic effect of THC was prevented by co-administration of CBD (1.0 or 3.0 mg/kg). CBD (3.0 mg/kg) caused an anxiolytic effect. At a lower dose (1.0 mg/kg), it facilitated the anxiolytic effect of the low THC dose. The anxiogenic effect of THC was accompanied by increased dopamine levels in the medial prefrontal cortex (mPFC) and nucleus accumbens (NAc). In contrast, its anxiolytic effect was associated with increased mPFC serotonin concentrations. The anxiolytic effect of CBD was accompanied by increased mPFC serotonin turnover. Together, these results indicate that female rats are susceptible to the biphasic effects of low THC doses on anxiety. These effects could depend on mPFC and NAc dopaminergic and serotoninergic neurotransmissions. CBD could minimize potential THC high-dose side effects whereas enhancing the anxiolytic action of its low doses in females.

Biopsychosocial Model Social Anxiety and Substance Use Revised

PURPOSE OF REVIEW

To review data published in the past 5 years to evaluate the utility of our biopsychosocial model of social anxiety's relation to substance misuse to evaluate the model's utility and update it.

RECENT FINDINGS

Data support the utility of our revised model-e.g., socially anxious persons report using substances to manage subjective anxiety, despite evidence that some substances may not have a direct effect on physiological responding. Other factors with promise include social influence, cognitive processes (e.g., post-event processing), and avoidance. Data highlight the importance of context as socially anxious persons use some substances more in some high-risk situations, despite lack of relation between social anxiety and use generally. Sociocultural factors remain understudied. This updated model is a theory- and data-driven model of the relations between social anxiety and substance misuse that can inform future work to improve substance-related outcomes among this especially vulnerable group.

Endocannabinoid System as Therapeutic Target of PTSD: A Systematic Review

Post-Traumatic Stress Disorder (PTSD) is a complex disorder involving dysregulation of stress-related hormones and neurotransmitter systems. Research focused on the endocannabinoid system (eCBS) for anxiety and stress regulation, cognitive and emotional responses modulation and aversive memories extinction, leading to the hypothesis that it could represent a possible alternative treatment target for PTSD. In this systematic review, we summarize evidence about the efficacy and safety of medicinal cannabidiol (CBD), Δ⁹-tetrahydrocannabinol (Δ⁹-THC), and nabilone in PTSD treatment. The PRISMA statement guidelines were followed. A systematic literature search was conducted in MEDLINE/PubMed, Scopus and Web of Science by two independent researchers, who also performed data extraction and quality assessment. Among the initial 495 papers, 234 were screened for eligibility and 10 were included. Studies suggested that different medicinal cannabinoids at distinct doses and formulations could represent promising treatment strategies for the improvement of overall PTSD symptomatology as well as specific symptom domains (e.g., sleep disorders, arousal disturbances, suicidal thoughts), also influencing quality of life, pain and social impact. Although there is a robust rationale for treatment with drugs that target the eCBS and the results are promising, further studies are needed to investigate the safety and efficacy profile of their prolonged use.

Endocannabinoid system in trauma and psychosis: distant guardian of mental stability

Central endocannabinoid system (eCBS) is a neuromodulatory system that inhibits potentially harmful, excessive synaptic activation. Endocannabinoid receptors are abundant among brain structures pivotal in different mental disorders development (for example, hippocampus, amygdala, medial-prefrontal cortex, hypothalamus). Here, we review eCBS function in etiology of psychosis, emphasizing its role in dealing with environmental pressures such as traumatic life events. Moreover, we explore eCBS as a guard against hypothalamic-pituitary-adrenal axis over-activation, and discuss its possible role in etiology of different psychopathologies. Additionally, we review eCBS function in creating adaptive behavioral patterns, as we explore its involvement in the memory formation process, extinction learning and emotional response. We discuss eCBS in the context of possible biomarkers of trauma, and in preclinical psychiatric conditions, such as at-risk mental states and clinical high risk states for psychosis. Finally, we describe the role of eCBS in the cannabinoid self-medication-theory and extinction learning.