Role of the endocannabinoid system in brain functions relevant for schizophrenia: an overview of human challenge studies with cannabis or ∆9-tetrahydrocannabinol (THC)

Endocannabinoid levels in plasma and neurotransmitters in the brain: a preliminary report on patients with a psychotic disorder and healthy individuals

BACKGROUND

Interactions between the endocannabinoid system (ECS) and neurotransmitter systems might mediate the risk of developing a schizophrenia spectrum disorder (SSD). Consequently, we investigated in patients with SSD and healthy controls (HC) the relations between (1) plasma concentrations of two prototypical endocannabinoids (N-arachidonoylethanolamine [anandamide] and 2-arachidonoylglycerol [2-AG]) and (2) striatal dopamine synthesis capacity (DSC), and glutamate and y-aminobutyric acid (GABA) levels in the anterior cingulate cortex (ACC). As anandamide and 2-AG might reduce the activity of these neurotransmitters, we hypothesized negative correlations between their plasma levels and the abovementioned neurotransmitters in both groups.

METHODS

Blood samples were obtained from 18 patients and 16 HC to measure anandamide and 2-AG plasma concentrations. For all subjects, we acquired proton magnetic resonance spectroscopy scans to assess Glx (i.e. glutamate plus glutamine) and GABA + (i.e. GABA plus macromolecules) concentrations in the ACC. Ten patients and 14 HC also underwent [18F]F-DOPA positron emission tomography for assessment of striatal DSC. Multiple linear regression analyses were used to investigate the relations between the outcome measures.

RESULTS

A negative association between 2-AG plasma concentration and ACC Glx concentration was found in patients (p = 0.008). We found no evidence of other significant relationships between 2-AG or anandamide plasma concentrations and dopaminergic, glutamatergic, or GABAergic measures in either group.

CONCLUSIONS

Our preliminary results suggest an association between peripheral 2-AG and ACC Glx levels in patients.

Acute effects of Δ9-tetrahydrocannabinol (THC) on resting state connectivity networks and impact of COMT genotype: A multi-site pharmacological fMRI study

BACKGROUND

Cannabis produces various acute psychotropic effects, with marked individual differences. Cannabis use is a risk factor for developing psychotic disorders. The main component responsible for these effects is Δ9-tetrahydrocannabinol (THC). Here we investigated the neural basis of acute THC effects and its modulation by catechol-methyl-transferase (COMT) Val158Met genotype.

METHODS

Resting state functional MRI data of healthy occasional cannabis users were combined and re-analyzed from three double-blind, placebo-controlled, within-subject pharmacological functional magnetic resonance imaging studies (total N=87). Functional connectivity after placebo and THC was compared in three functional networks (salience, executive and default mode network) and a network implicated in psychosis (the hippocampus-midbrain-striatum network). COMT genotype modulation of subjective effects and connectivity was examined.

RESULTS

THC reduced connectivity in the salience network, specifically from the right insula to both the left insula and anterior cingulate cortex. We found a trend towards decreased connectivity in the hippocampus-midbrain-striatum network after THC. COMT genotype modulated subjective effects of THC, with strongest dysphoric reactions in Met/Met individuals. In addition, reduced connectivity after THC was demonstrated in the hippocampus-midbrain-striatum network of Met/Met individuals only.

CONCLUSIONS

In this large multisite study we found that THC robustly decreases connectivity in the salience network, involved in processing awareness and salient information. Connectivity changes in the hippocampus-midbrain-striatum network may reflect the acute psychotic-like effects of THC. COMT genotype modulation of THC's impact on subjective effects and functional connectivity provides further evidence for involvement of prefrontal dopamine levels in the acute effects of cannabis.

The interaction between first-episode drug-naïve schizophrenia and age based on gray matter volume and its molecular analysis: a multimodal magnetic resonance imaging study

OBJECTIVES

Schizophrenia is a neurodevelopmental disorder characterized by progressive and widespread gray matter (GM) atrophy. Studies have shown that normal brain development has an impact on schizophrenia-induced GM alterations. However, the neuropathology and underlying molecular mechanisms of interaction between age and schizophrenia are unclear.

METHODS

This study enrolled 66/84 first-episode drug-naïve patients with early-onset/adult-onset schizophrenia ((EOS)/(AOS)) and matched normal controls (NC) (46 adolescents/73 adults), undergoing T1-weighted high-resolution magnetic resonance imaging. Gray matter volume (GMV) in four groups was detected using 2-way analyses of variance with diagnosis and age as factors. Then, factors-related volume maps and neurotransmitter maps were spatially correlated using JuSpace to determine the relationship to molecular structure.

RESULTS

Compared to AOS, EOS and adult NC had larger GMV in right middle frontal gyrus. Compared to adolescent NC, EOS and adult NC had smaller GMV in right lingual gyrus, right fusiform gyrus, and right cerebellum_6. Disease-induced GMV reductions were mainly distributed in frontal, parietal, thalamus, visual, motor cortex, and medial temporal lobe structures. Age-induced GMV alterations were mainly distributed in visual and motor cortex. The changed GMV induced by schizophrenia, age, and their interaction was related to dopaminergic and serotonergic receptors. Age is also related to glutamate receptors, and schizophrenia is also associated with GABAaergic and noradrenergic receptors.

CONCLUSIONS

Our results revealed the multimodal neural mechanism of interaction between disease and age. We emphasized age-related GM abnormalities of ventral stream of visual perceptual pathways and high-level cognitive brain in EOS, which may be affected by imbalance of excitatory and inhibitory neurotransmitters.

The association between cannabis use and facial emotion recognition in schizophrenia, siblings, and healthy controls: Results from the EUGEI study

Schizophrenia is frequently accompanied with social cognitive disturbances. Cannabis represents one established environmental factor associated with the onset and progression of schizophrenia. The present cross-sectional study aimed to investigate the association of facial emotion recognition (FER) performance with cannabis use in 2039 patients with schizophrenia, 2141 siblings, and 2049 healthy controls (HC). FER performance was measured using the Degraded Facial Affect Recognition Task (DFAR). Better FER performance as indicated by higher DFAR-total scores was associated with lifetime regular cannabis use in schizophrenia (B = 1.36, 95% CI 0.02 to 2.69), siblings (B = 2.17, 95% CI 0.79 to 3.56), and HC (B = 3.10, 95% CI 1.14 to 5.06). No associations were found between DFAR-total and current cannabis use. Patients with schizophrenia who started to use cannabis after the age of 16 showed better FER performance than patients who started earlier (B = 2.50, 95% CI 0.15 to 4.84) and non-users (B = 3.72, 95 CI 1.96 to 5.49). Better FER performance was found also in siblings who started to use cannabis after 16 compared to non-users (B = 2.37, 95% CI 0.58 to 4.16), while HC using cannabis performed better than non-users at DFAR-total regardless of the age at onset. Our findings suggest that lifetime regular cannabis use may be associated with better FER regardless of the psychosis risk, but that FER might be moderated by age at first use in people with higher genetic risk. Longitudinal studies may clarify whether there is a cause-and-effect relationship between cannabis use and FER performance in psychotic and non-psychotic samples.

A scoping review of the use of cannabidiol in psychiatric disorders

Cannabidiol (CBD) has become a fast-growing avenue for research in psychiatry, and clinicians are challenged with understanding the implications of CBD for treating mental health disorders. The goal of this review is to serve as a guide for mental health professionals by providing an overview of CBD and a synthesis the current evidence within major psychiatric disorders. PubMed and PsycINFO were searched for articles containing the terms "cannabidiol" in addition to major psychiatric disorders and symptoms, yielding 2952 articles. Only randomized controlled trials or within-subject studies investigating CBD as a treatment option for psychiatric disorders (N = 16) were included in the review. Studies were reviewed for psychotic disorders (n = 6), anxiety disorders (n = 3), substance use disorders (tobacco n = 3, cannabis n = 2, opioid n = 1), and insomnia (n = 1). There were no published studies that met inclusion criteria for alcohol or stimulant use disorder, PTSD, ADHD, autism spectrum disorder, or mood disorders. Synthesis of the CBD literature indicates it is generally safe and well tolerated. The most promising preliminary findings are related to the use of CBD in psychotic symptoms and anxiety. There is currently not enough high-quality evidence to suggest the clinical use of CBD for any psychiatric disorder.

Delta-9-tetrahydrocannabinol reduces willingness to exert effort in women

BACKGROUND

The use of cannabis has been clinically associated with decreased motivation to engage in normally rewarding activities. However, evidence from previous controlled studies is mixed.

METHOD

In this study, we examined the effects of acute delta-9-tetrahydrocannabinol (THC) versus placebo on a task measuring willingness to exert effort for rewards. This is a secondary analysis of a larger study examining interactions between ovarian hormones and THC. In this within-subjects study, oral THC and placebo were administered under double-blind conditions in counterbalanced order to healthy young adult (M age = 24 years) women with previous cannabis experience who were not regular users. Forty subjects completed three 4-h sessions with PL, 7.5 and 15 mg THC, while an additional 18 completed only PL and 15 mg THC sessions (design abridged due to pandemic). At each session, they completed a task consisting of making repeated choices between a hard and an easy task, which were worth varying amounts of money at varying probabilities.

RESULTS

THC dose-dependently decreased hard task choices (drug effect, b =  - 0.79, SE = 0.29, z =  - 2.67, p < 0.01), especially at moderate to high expected values of reward (drug × probability × amount interaction, b = 0.77, SE = 0.38, z = 1.99, p = 0.04). THC also slowed task performance (drug effect, b = 0.01, SE = 0.005, t(5.24) = 2.11, p = 0.04), but the effect of THC on choice was still significant after controlling for this psychomotor slowing.

CONCLUSIONS

These findings support the idea that cannabis acutely reduces motivation to earn non-drug rewards. Still to be determined are the neurochemical mechanisms underlying this effect.

Cannabidiol (CBD) and cognition in epilepsy

Anecdotal reports of the benefits of cannabis and its components in the treatment of epilepsy have been reported for millennia. However, only recently randomized controlled trial data in support of cannabidiol (CBD) became available resulting in its FDA approval for the treatment of seizures and epilepsy. One of the most common and debilitating comorbidities of epilepsy is cognitive impairment. This impairment has a multifactorial etiology including network dysfunction due to seizures, negative cognitive side effects from anti-seizure medications (ASMs), and mood disturbances. Knowing the effects of a particular ASM (either positive or negative) is vital for providers to counsel patients on expected side effects, and may result in choosing a particular regimen over the other if the patient already suffers from significant cognitive deficits. Unlike most other ASMs and other well-studied cannabinoids such as Δ9-tetrahydrocannabinol, CBD has been shown to have additional mechanisms of action (MOA) that result in neuroprotective, anti-inflammatory, anti-oxidant, and neurogenesis effects. These additional MOAs suggest that the use of CBD could lead to other actions including positive effects on cognition that may be independent of seizure control. This targeted review discusses the currently available data on CBD's effects on cognition in epilepsy. First, we review the proposed mechanisms by which CBD could exert effects on cognition. Then, we present the pre-clinical/animal data investigating cognitive effects of CBD in seizure/epilepsy models. Finally, we discuss the available human data, including the studies in people with epilepsy that included cognitive evaluations pre- and on-CBD, and studies investigating if CBD has any effects on brain structure or function in areas pertinent to memory and cognitive functions.

Repetitive transcranial magnetic stimulation as a potential treatment approach for cannabis use disorder

The expanding legalization of cannabis across the United States is associated with increases in cannabis use, and accordingly, an increase in the number and severity of individuals with cannabis use disorder (CUD). The lack of FDA-approved pharmacotherapies and modest efficacy of psychotherapeutic interventions means that many of those who seek treatment for CUD relapse within the first few months. Consequently, there is a pressing need for innovative, evidence-based treatment development for CUD. Preliminary evidence suggests that repetitive transcranial magnetic stimulation (rTMS) may be a novel, non-invasive therapeutic neuromodulation tool for the treatment of a variety of substance use disorders (SUDs), including recently receiving FDA clearance (August 2020) for use as a smoking cessation aid in tobacco cigarette smokers. However, the potential of rTMS for CUD has not yet been reviewed. This paper provides a primer on therapeutic neuromodulation techniques for SUDs, with a particular focus on reviewing the current status of rTMS research in people who use cannabis. Lastly, future directions are proposed for rTMS treatment development in CUD, with suggestions for study design parameters and clinical endpoints based on current gold-standard practices for therapeutic neuromodulation research.

Cannabidiol modulation of hippocampal glutamate in early psychosis

BACKGROUND

Emerging evidence supports the antipsychotic effect of cannabidiol, a non-intoxicating component of cannabis, in people with psychosis. Preclinical findings suggest that this antipsychotic effect may be related to cannabidiol modulating glutamatergic signalling in the brain.

AIM

The purpose of this study was to investigate the effects of cannabidiol on the neurochemical mechanisms underlying psychosis.

METHODS

We investigated the effects of a single oral dose of cannabidiol (600 mg) in patients with psychosis, using a double-blind, randomised, placebo-controlled, repeated-measures, within-subject cross-over design. After drug administration, 13 patients were scanned using proton magnetic resonance spectroscopy to measure left hippocampal glutamate levels. Symptom severity was rated using the Positive and Negative Syndrome Scale 60 min before drug administration (pre-scan), and 270 min after drug administration (post-scan). Effects of cannabidiol on hippocampal glutamate levels, symptom severity, and correlations between hippocampal glutamate and symptoms were investigated.

RESULTS

Compared to placebo, there was a significant increase in hippocampal glutamate (p=0.035), and a significantly greater decrease in symptom severity (p=0.032) in the psychosis patients under cannabidiol treatment. There was also a significant negative relationship between post-treatment total Positive and Negative Syndrome Scale score and hippocampal glutamate (p=0.047), when baseline Positive and Negative Syndrome Scale score, treatment (cannabidiol vs placebo), and interaction between treatment and glutamate levels were controlled for.

CONCLUSIONS

These findings may suggest a link between the increase in glutamate levels and concomitant decrease in symptom severity under cannabidiol treatment observed in psychosis patients. Furthermore, the findings provide novel insight into the potential neurochemical mechanisms underlying the antipsychotic effects of cannabidiol.

The Yin and Yang of Cannabis: A Systematic Review of Human Neuroimaging Evidence of the Differential Effects of Δ9-Tetrahydrocannabinol and Cannabidiol

Cannabidiol (CBD) and Δ9-tetrahydrocannabinol (THC) have been the most investigated cannabinoids at the human and preclinical levels, although the neurobiological mechanisms underlying their effects remain unclear. Human experimental evidence complemented by observational studies suggests that THC may have psychotogenic effects while CBD may have antipsychotic effects. However, whether their effects on brain function are consistent with their opposing behavioral effects remains unclear. To address this, here we synthesize neuroimaging evidence investigating the acute effects of THC and CBD on human brain function using a range of neuroimaging techniques, with an aim to identify the key brain substrates where THC and CBD have opposing effects. After a systematic search, a review of the available studies indicated marked heterogeneity. However, an overall pattern of opposite effect profiles of the two cannabinoids was evident with some degree of consistency, primarily attributed to the head-to-head challenge studies of THC and CBD. While head-to-head comparisons are relatively few, collectively the evidence suggests that opposite effects of THC and CBD may be present in the striatum, parahippocampus, anterior cingulate/medial prefrontal cortex, and amygdala, with opposite effects less consistently identified in other regions. Broadly, THC seems to increase brain activation and blood flow, whereas CBD seems to decrease brain activation and blood flow. Given the sparse evidence, there is a particular need to understand the mechanisms underlying their opposite behavioral effects because it may not only offer insights into the underlying pathophysiological mechanisms of psychotic disorders but also suggest potentially novel targets and biomarkers for drug discovery.

Imaging Brain Fatty Acid Amide Hydrolase in Untreated Patients With Psychosis

BACKGROUND

The brain's endocannabinoid system, the primary target of cannabis, has been implicated in psychosis. The endocannabinoid anandamide is elevated in cerebrospinal fluid of patients with schizophrenia. Fatty acid amide hydrolase (FAAH) controls brain anandamide levels; however, it is unknown if FAAH is altered in vivo in psychosis or related to positive psychotic symptoms.

METHODS

Twenty-seven patients with schizophrenia spectrum disorders and 36 healthy control subjects completed high-resolution positron emission tomography scans with the novel FAAH radioligand [¹¹C]CURB and structural magnetic resonance imaging. Data were analyzed using the validated irreversible 2-tissue compartment model with a metabolite-corrected arterial input function.

RESULTS

FAAH did not differ significantly between patients with psychotic disorders and healthy control subjects (F_1,62.85 = 0.48, p = .49). In contrast, lower FAAH predicted greater positive psychotic symptom severity, with the strongest effect observed for the positive symptom dimension, which includes suspiciousness, delusions, unusual thought content, and hallucinations (F_1,26.69 = 12.42, p = .002; Cohen's f = 0.42, large effect). Shorter duration of illness (F_1,26.95 = 13.78, p = .001; Cohen's f = 0.39, medium to large effect) and duration of untreated psychosis predicted lower FAAH (F_1,26.95 = 6.03, p = .021, Cohen's f = 0.27, medium effect). These results were not explained by past cannabis exposure or current intake of antipsychotic medications. FAAH exhibited marked differences across brain regions (F_7,112.62 = 175.85, p < 1 × 10^-56; Cohen's f > 1). Overall, FAAH was higher in female subjects than in male subjects (F_1,62.84 = 10.05, p = .002; Cohen's f = 0.37).

CONCLUSIONS

This first study of brain FAAH in psychosis indicates that FAAH may represent a biomarker of disease state of potential utility for clinical studies targeting psychotic symptoms or as a novel target for interventions to treat psychotic symptoms.

Peripheral Endogenous Cannabinoid Levels Are Increased in Schizophrenia Patients Evaluated in a Psychiatric Emergency Setting

BACKGROUND

The endogenous cannabinoid system mediates the psychoactive effects of cannabis in the brain. It has been argued that this system may play a key role in the pathophysiology of schizophrenia. While some studies have consistently shown that the levels of anandamide, an endogenous cannabinoid ligand, are increased in the cerebrospinal fluid of schizophrenia patients, inconsistent results have been observed in studies measuring anandamide levels in the periphery. Here, we sought to determine if the assessment of peripheral anandamide levels in patients evaluated in a psychiatric emergency setting would show robust increases.

METHODS

One hundred seven patients with a schizophrenia-spectrum disorder from the psychiatric emergency settings of the Institut Universitaire en Santé Mentale de Montréal and 36 healthy volunteers were included in the study. A subsample of thirty patients were assessed at two time points: at the emergency and at their discharge from the hospital. Anxious and depressive symptoms, sleep and substance use were assessed using self-report questionnaires. In addition to anandamide, the levels of oleoylethanolamide (OEA), an anorexigenic fatty-acid ethanolamide, were also measured, since the prevalence of the metabolic syndrome is increased in schizophrenia. Plasma levels of anandamide and OEA were measured using liquid chromatography and mass spectrometry.

RESULTS

Plasma anandamide and OEA levels were significantly increased in schizophrenia patients, relative to controls (Cohen's d=1.0 and 0.5, respectively). Between-group differences remained significant after controlling for metabolic measures. No differences were observed between schizophrenia patients with and without a comorbid substance use disorder at baseline. Importantly, the levels of both endocannabinoids significantly decreased after discharge from the emergency setting.

CONCLUSION

The current results add to the growing body of evidence of endocannabinoid alterations in schizophrenia. The strong elevation of plasma anandamide levels in schizophrenia patients assessed in the psychiatric emergency setting suggests that anandamide and OEA area potential biomarkers of the psychological turmoil associated with this context.

Comparison of Male and Female Patients in Louisiana Medical Marijuana Dispensaries

Relatively little is known in terms of patient demographics, indications, previous cannabis use, or the forms and dosages of medical marijuana (MM) dispensed for patients at MM dispensaries. Even less is known in terms of how male and female patients may differ in each of these aspects. The goal of the current study was to examine each of these variables using a retrospective analysis of deidentified patient data from MM dispensaries in Louisiana. Deidentified data were analyzed from web-based pharmacist-patient consultations at MM dispensaries throughout Louisiana. Data were collected during the first 6 months following the initiation of the MM dispensing program in Louisiana. A total of 1195 MM patients (598 male/597 female) were included in the analyses. The average age of the sample was 51.9 years (±14.8) and it was composed primarily of white patients (86.7%). Males and females were nearly identical in terms of average age, race, previous cannabis use, indication profile, and MM recommendations. Differences between males and females were observed in terms of opioid use, history of psychosis, presence of more than one indication, and the duration of previous cannabis use. Our data indicate that, in MM dispensaries of the Deep South state, there are numerous similarities-and some potentially important differences-between male and female MM patients. The importance of these differences, and the importance of continued data collection/analysis, for improving MM dispensing are discussed.

Maternal immune activation is associated with a lower number of dopamine receptor 3-expressing granulocytes with no alterations in cocaine reward, resistance to extinction or cue-induced reinstatement

There is evidence for increased rates of drug use among schizophrenic patients. However, the causality in this relationship remains unclear. In the present work, we use a maternal immune activation model to test whether animals at high risk of developing a schizophrenia-like condition are more prone to acquire cocaine self-administration, show enhanced sensitivity to the reinforcing actions of cocaine or if they are resistant to extinction or vulnerable to relapse. Also, given that D3 and CB2 receptor expression in immune cells is altered in patients with schizophrenia, we examined the populations of immune cells expressing these receptors. Pregnant rats were daily injected with lipopolysaccharide (LPS) (2 mg/kg s.c.) or saline during pregnancy, and we tested prepulse inhibition -PPI- in the offspring. After this, one group of rats was submitted to cocaine self-administration (0.5 mg/kg) under fixed and progressive ratio schedules, dose-response testing, extinction and cue-induced drug-seeking. Another group was sacrificed to study the immune blood cells by flow cytometry. While rats born to LPS-treated mothers showed impaired PPI, there were no differences in cocaine self-administration acquisition, responsiveness to dose shifts, extinction or cue-induced reinstatement. Finally, there were fewer D3R⁺ granulocytes in the LPS-offspring and an exciting trend for CB2R⁺ lymphocytes to be more abundant in LPS-exposed rats. Our results indicate that the higher prevalence of cocaine abuse among people with schizophrenia is not due to a pre-existing pathology and suggest that D3R⁺ granulocytes and possibly CB2R⁺ lymphocytes could be potential biomarkers of schizophrenia.

Factors Moderating the Association Between Cannabis Use and Psychosis Risk: A Systematic Review

Increasing evidence indicates a relationship between cannabis use and psychosis risk. Specific factors, such as determinants of cannabis use or the genetic profile of cannabis users, appear to moderate this association. The present systematic review presents a detailed and up-to-date literature overview on factors that influence the relationship between cannabis use and psychosis risk. A systematic search was performed according to the PRISMA guidelines in MEDLINE and Embase, and 56 studies were included. The results show that, in particular, frequent cannabis use, especially daily use, and the consumption of high-potency cannabis are associated with a higher risk of developing psychosis. Moreover, several genotypes moderate the impact of cannabis use on psychosis risk, particularly those involved in the dopamine function, such as AKT1. Finally, cannabis use is associated with an earlier psychosis onset and increased risk of transition in individuals at a clinical high risk of psychosis. These findings indicate that changing cannabis use behavior could be a harm reduction strategy employed to lower the risk of developing psychosis. Future research should aim to further develop specific biomarkers and genetic profiles for psychosis, thereby contributing to the identification of individuals at the highest risk of developing a psychotic disorder.

Do the effects of cannabis on the hippocampus and striatum increase risk for psychosis?

Cannabis use is associated with increased risk of psychotic symptoms and in a small number of cases it can lead to psychoses. This review examines the neurobiological mechanisms that mediate the link between cannabis use and psychosis risk. We use an established preclinical model of psychosis, the methylazoxymethanol acetate (MAM) rodent model, as a framework to examine if psychosis risk in some cannabis users is mediated by the effects of cannabis on the hippocampus, and this region's role in the regulation of mesolimbic dopamine. We also examine how cannabis affects excitatory neurotransmission known to regulate hippocampal neural activity and output. Whilst there is clear evidence that cannabis/cannabinoids can affect hippocampal and medial temporal lobe function and structure, the evidence that cannabis/cannabinoids increase striatal dopamine function is less robust. There is limited evidence that cannabis use affects cortical and striatal glutamate levels, but there are currently too few studies to draw firm conclusions. Future work is needed to test the MAM model in relation to cannabis using multimodal neuroimaging approaches.

Evidence That Cannabis Exposure, Abuse, and Dependence Are Related to Glutamate Metabolism and Glial Function in the Anterior Cingulate Cortex: A 1H-Magnetic Resonance Spectroscopy Study

There is evidence that long-term cannabis use is associated with alterations to glutamate neurotransmission and glial function. In this study, 26 long-term cannabis users (males=65.4%) and 47 non-cannabis using healthy controls (males=44.6%) underwent proton magnetic resonance spectroscopy (¹H-MRS) of the anterior cingulate cortex (ACC) in order to characterize neurometabolite alterations in cannabis users and to examine associations between neurometabolites, cannabis exposure, and cannabis use behaviors. Myo-inositol, a marker of glial function, and glutamate metabolites did not differ between healthy controls and cannabis users or cannabis users who met criteria for DSM5 cannabis use disorder (n=17). Lower myo-inositol, a putative marker of glial function, was related to greater problematic drug use (F_1,22 = 11.95, p=.002; Cohen's f=0.59, large effect; Drug Abuse Screening Test) and severity of cannabis dependence (F_1,22 = 6.61, p=.17; Cohen's f=0.44, large effect). Further, past-year cannabis exposure exerted different effects on glutamate and glutamate+glutamine in males and females (glutamate: F_1,21 = 6.31, p=.02; glutamate+glutamine: F_1,21 = 7.20, p=.014), such that greater past-year cannabis exposure was related to higher concentrations of glutamate metabolites in male cannabis users (glutamate: F_1,14 = 25.94, p=.00016; Cohen's f=1.32, large effect; glutamate+glutamine: F_1,14 = 23.24, p=.00027, Cohen's f=1.24, large effect) but not in female cannabis users (glutamate: F_1,6 = 1.37, p=0.78; glutamate+glutamine: F_1,6 = 0.001, p=.97). The present results extend existing evidence of altered glial function and glutamate metabolism with cannabis use by providing evidence linking problematic drug use behaviors with glial function as measured with myo-inositol and recent chronic cannabis exposure to alterations in glutamate metabolism. This provides novel directions for the interrogation of the impact of cannabis use on brain neurochemistry.

In Vivo Imaging of Translocator Protein in Long-term Cannabis Users

IMPORTANCE

Cannabis is the most commonly used illicit drug in the world. Cannabinoids have been shown to modulate immune responses; however, the association of cannabis with neuroimmune function has never been investigated in vivo in the human brain.

OBJECTIVE

To investigate neuroimmune activation or 18-kDa translocator protein (TSPO) levels in long-term cannabis users, and to evaluate the association of brain TSPO levels with behavioral measures and inflammatory blood biomarkers.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study based in Toronto, Ontario, recruited individuals from January 1, 2015, to October 30, 2018. Participants included long-term cannabis users (n = 24) and non-cannabis-using controls (n = 27). Cannabis users were included if they had a positive urine drug screen for only cannabis and if they used cannabis at least 4 times per week for the past 12 months and/or met the criteria for cannabis use disorder. All participants underwent a positron emission tomography scan with [18F]FEPPA, or fluorine F 18-labeled N-(2-(2-fluoroethoxy)benzyl)-N-(4-phenoxypyridin-3-yl)acetamide.

MAIN OUTCOMES AND MEASURES

Total distribution volume was quantified across regions of interest. Stress and anxiety as well as peripheral measures of inflammatory cytokines and C-reactive protein levels were also measured.

RESULTS

In total, 24 long-term cannabis users (mean [SD] age, 23.1 [3.8] years; 15 men [63%]) and 27 non-cannabis-using controls (mean [SD] age, 23.6 [4.2] years; 18 women [67%]) were included and completed all study procedures. Compared with the controls, cannabis users had higher [18F]FEPPA total distribution volume (main group effect: F1,48 = 6.5 [P = .01]; ROI effect: F1,200 = 28.4 [P < .001]; Cohen d = 0.6; 23.3% higher), with a more prominent implication for the cannabis use disorder subgroup (n = 15; main group effect: F1,39 = 8.5 [P = .006]; ROI effect: F1,164 = 19.3 [P < .001]; Cohen d = 0.8; 31.5% higher). Greater TSPO levels in the brain were associated with stress and anxiety and with higher circulating C-reactive protein levels in cannabis users.

CONCLUSIONS AND RELEVANCE

The results of this study suggest that TSPO levels in cannabis users, particularly in those with cannabis use disorder, are higher than those in non-cannabis-using controls. The findings emphasize the need for more complementary preclinical systems for a better understanding of the role of cannabinoids and TSPO in neuroimmune signaling.

How does cannabidiol (CBD) influence the acute effects of delta-9-tetrahydrocannabinol (THC) in humans? A systematic review

The recent liberalisation of cannabis regulation has increased public and scientific debate about its potential benefits and risks. A key focus has been the extent to which cannabidiol (CBD) might influence the acute effects of delta-9-tetrahydrocannabinol (THC), but this has never been reviewed systematically. In this systematic review of how CBD influences the acute effects of THC we identified 16 studies involving 466 participants. Ten studies were judged at low risk of bias. The findings were mixed, although CBD was found to reduce the effects of THC in several studies. Some studies found that CBD reduced intense experiences of anxiety or psychosis-like effects of THC and blunted some of the impairments on emotion and reward processing. However, CBD did not consistently influence the effects of THC across all studies and outcomes. There was considerable heterogeneity in dose, route of administration and THC:CBD ratio across studies and no clear dose-response profile emerged. Although findings were mixed, this review suggests that CBD may interact with some acute effects of THC.

The Potential of Cannabidiol as a Treatment for Psychosis and Addiction: Who Benefits Most? A Systematic Review

The endogenous cannabinoid (eCB) system plays an important role in the pathophysiology of both psychotic disorders and substance use disorders (SUDs). The non-psychoactive cannabinoid compound, cannabidiol (CBD) is a highly promising tool in the treatment of both disorders. Here we review human clinical studies that investigated the efficacy of CBD treatment for schizophrenia, substance use disorders, and their comorbidity. In particular, we examined possible profiles of patients who may benefit the most from CBD treatment. CBD, either as monotherapy or added to regular antipsychotic medication, improved symptoms in patients with schizophrenia, with particularly promising effects in the early stages of illness. A potential biomarker is the level of anandamide in blood. CBD and THC mixtures showed positive effects in reducing short-term withdrawal and craving in cannabis use disorders. Studies on schizophrenia and comorbid substance use are lacking. Future studies should focus on the effects of CBD on psychotic disorders in different stages of illness, together with the effects on comorbid substance use. These studies should use standardized measures to assess cannabis use. In addition, future efforts should be taken to study the relationship between the eCB system, GABA/glutamate, and the immune system to reveal the underlying neurobiology of the effects of CBD.

Acute effects of ∆9-tetrahydrocannabinol (THC) on resting state brain function and their modulation by COMT genotype

Cannabis produces a broad range of acute, dose-dependent psychotropic effects. Only a limited number of neuroimaging studies have mapped these effects by examining the impact of cannabis on resting state brain neurophysiology. Moreover, how genetic variation influences the acute effects of cannabis on resting state brain function is unknown. Here we investigated the acute effects of ∆9-tetrahydrocannabinol (THC), the main psychoactive constituent of cannabis, on resting state brain neurophysiology, and their modulation by catechol-methyl-transferase (COMT) Val158Met genotype. Thirty-nine healthy volunteers participated in a pharmacological MRI study, where we applied Arterial Spin Labelling (ASL) to measure perfusion and functional MRI to assess resting state connectivity. THC increased perfusion in bilateral insula, medial superior frontal cortex, and left middle orbital frontal gyrus. This latter brain area showed significantly decreased connectivity with the precuneus after THC administration. THC effects on perfusion in the left insula were significantly related to subjective changes in perception and relaxation. These findings indicate that THC enhances metabolism and thus neural activity in the salience network. Furthermore, results suggest that recruitment of brain areas within this network is involved in the acute effects of THC. Resting state perfusion was modulated by COMT genotype, indicated by a significant interaction effect between drug and genotype on perfusion in the executive network, with increased perfusion after THC in Val/Met heterozygotes only. This finding suggests that prefrontal dopamine levels are involved in the susceptibility to acute effects of cannabis.

Cannabidiol as a potential treatment for psychosis

Psychotic disorders such as schizophrenia are heterogeneous and often debilitating conditions that contribute substantially to the global burden of disease. The introduction of dopamine D2 receptor antagonists in the 1950s revolutionised the treatment of psychotic disorders and they remain the mainstay of our treatment arsenal for psychosis. However, traditional antipsychotics are associated with a number of side effects and a significant proportion of patients do not achieve an adequate remission of symptoms. There is therefore a need for novel interventions, particularly those with a non-D2 antagonist mechanism of action. Cannabidiol (CBD), a non-intoxicating constituent of the cannabis plant, has emerged as a potential novel class of antipsychotic with a unique mechanism of action. In this review, we set out the prospects of CBD as a potential novel treatment for psychotic disorders. We first review the evidence from the perspective of preclinical work and human experimental and neuroimaging studies. We then synthesise the current evidence regarding the clinical efficacy of CBD in terms of positive, negative and cognitive symptoms, safety and tolerability, and potential mechanisms by which CBD may have antipsychotic effects.

Prenatal immune activation potentiates endocannabinoid-related plasticity of inhibitory synapses in the hippocampus of adolescent rat offspring

There is strong evidence that immune activation from prenatal infection increases the risk for offspring to develop schizophrenia. The endocannabinoid (eCB) system has been implicated in the pathophysiology of schizophrenia while models of cortical dysfunction postulate an imbalance between neuronal excitation and inhibition in the disorder. The current study examined the impact of prenatal immune activation on eCB-mediated inhibitory mechanisms. We compared two forms of eCB-related plasticity of evoked inhibitory postsynaptic currents, namely depolarization-induced suppression of inhibition (DSI) and metabotropic glutamate receptor-induced long term depression (mGluR-iLTD), in both the dorsal and ventral hippocampus between adolescent offspring from rat dams that received either saline or bacterial lipopolysaccharide (LPS) during pregnancy. Compared to prenatal saline offspring, prenatal LPS offspring displayed prolonged DSI and stronger mGluR-iLTD in the dorsal and ventral hippocampus, respectively. The sensitivity of mGluR-iLTD to the CB1 receptor antagonist AM251 was also lower in the dorsal hippocampus of prenatal LPS compared to prenatal saline offspring. Testing whether changes in eCB receptor signaling or levels could contribute to these changes in inhibitory transmission, we found region specific increases in 2-arachidonoylglycerol-stimulated signaling and in basal and mGluR-induced levels of anandamide in prenatal LPS offspring when compared to prenatal saline offspring. Our findings indicate that prenatal immune activation can lead to long-term changes in eCB-related plasticity of hippocampal inhibitory synaptic transmission in adolescent rat offspring. Perturbation of the eCB system resulting from prenatal immune activation could represent a mechanism linking early life immune events to the development of psychopathology in adolescence.

The effects of cannabis use on salience attribution: a systematic review

OBJECTIVE

The relationship between cannabis use and the onset of psychosis is well established. Aberrant salience processing is widely thought to underpin many of these symptoms. Literature explicitly investigating the relationship between aberrant salience processing and cannabis use is scarce; with those few studies finding that acute tetrahydrocannabinol (THC) administration (the main psychoactive component of cannabis) can result in abnormal salience processing in healthy cohorts, mirroring that observed in psychosis. Nevertheless, the extent of and mechanisms through which cannabis has a modulatory effect on aberrant salience, following both acute and chronic use, remain unclear.

METHODS

Here, we systematically review recent findings on the effects of cannabis use - either through acute THC administration or in chronic users - on brain regions associated with salience processing (through functional MRI data); and performance in cognitive tasks that could be used as either direct or indirect measures of salience processing. We identified 13 studies either directly or indirectly exploring salience processing. Three types of salience were identified and discussed - incentive/motivational, emotional/affective, and attentional salience.

RESULTS

The results demonstrated an impairment of immediate salience processing, following acute THC administration. Amongst the long-term cannabis users, normal salience performance appeared to be underpinned by abnormal neural processes.

CONCLUSIONS

Overall, the lack of research specifically exploring the effects of cannabis use on salience processing, weaken any conclusions drawn. Additional research explicitly focussed on salience processing and cannabis use is required to advance our understanding of the neurocognitive mechanisms underlying the association between cannabis use and development of psychosis.

The Potential of Cannabidiol Treatment for Cannabis Users With Recent-Onset Psychosis

A major factor associated with poor prognostic outcome after a first psychotic break is cannabis misuse, which is prevalent in schizophrenia and particularly common in individuals with recent-onset psychosis. Behavioral interventions aimed at reducing cannabis use have been unsuccessful in this population. Cannabidiol (CBD) is a phytocannabinoid found in cannabis, although at low concentrations in modern-day strains. CBD has a broad pharmacological profile, but contrary to ∆9-tetrahydrocannabinol (THC), CBD does not activate CB1 or CB2 receptors and has at most subtle subjective effects. Growing evidence indicates that CBD acts as an antipsychotic and anxiolytic, and several reports suggest neuroprotective effects. Moreover, CBD attenuates THC's detrimental effects, both acutely and chronically, including psychotogenic, anxiogenic, and deleterious cognitive effects. This suggests that CBD may improve the disease trajectory of individuals with early psychosis and comorbid cannabis misuse in particular-a population with currently poor prognostic outcome and no specialized effective intervention.

Cannabinoids and Vanilloids in Schizophrenia: Neurophysiological Evidence and Directions for Basic Research

Much of our knowledge of the endocannabinoid system in schizophrenia comes from behavioral measures in rodents, like prepulse inhibition of the acoustic startle and open-field locomotion, which are commonly used along with neurochemical approaches or drug challenge designs. Such methods continue to map fundamental mechanisms of sensorimotor gating, hyperlocomotion, social interaction, and underlying monoaminergic, glutamatergic, and GABAergic disturbances. These strategies will require, however, a greater use of neurophysiological tools to better inform clinical research. In this sense, electrophysiology and viral vector-based circuit dissection, like optogenetics, can further elucidate how exogenous cannabinoids worsen (e.g., tetrahydrocannabinol, THC) or ameliorate (e.g., cannabidiol, CBD) schizophrenia symptoms, like hallucinations, delusions, and cognitive deficits. Also, recent studies point to a complex endocannabinoid-endovanilloid interplay, including the influence of anandamide (endogenous CB₁ and TRPV₁ agonist) on cognitive variables, such as aversive memory extinction. In fact, growing interest has been devoted to TRPV₁ receptors as promising therapeutic targets. Here, these issues are reviewed with an emphasis on the neurophysiological evidence. First, we contextualize imaging and electrographic findings in humans. Then, we present a comprehensive review on rodent electrophysiology. Finally, we discuss how basic research will benefit from further combining psychopharmacological and neurophysiological tools.

Simvastatin and Bezafibrate ameliorate Emotional disorder Induced by High fat diet in C57BL/6 mice

High fat diet (HFD)-induced metabolic disorders may lead to emotional disorders. This study aimed to explore the effect of simvastatin (SMV) and bezafibrate (BZ) on improving HFD-induced emotional changes, and tried to identify their different mechanisms. The intraperitoneal glucose tolerance test (IPGTT) was used to evaluate glucose control ability; and behavior tests including open field tests (OFT), forced swimming tests (FST), tail suspension tests (TST) and sucrose preference (SPT), were then performed to evaluate emotional changes. Serum samples were collected for the LC-MS based metabolomics analysis to explore the emotional-related differential compounds; we then evaluated the effect of the drugs. The abnormal serum metabolic profiling and emotional changes caused by HFD in mice was alleviated by SMV treatment, whereas BZ only affected the emotional disorder. The improvement of cannabinoid analogues and then produced influences on the endocannabinoid system, which may be a potential mechanism SMV action. BZ promoted tryptophan-serotonin pathway and inhibited tryptophan-kynurenine pathway, which may be its mechanism of action. Here, we proposed a shed light on the biological mechanisms underlying the observed effects, and identified an important drug candidate for the treatment of emotional disorders induced by HFD.

Neuroimaging studies towards understanding the central effects of pharmacological cannabis products on patients with epilepsy

Recent interest for the use of cannabis-derived products as therapeutic agents in the treatment of epilepsies has necessitated a reevaluation of their effects on brain and behavior. Overall, prolonged cannabis use is thought to result in functional and structural brain alterations. These effects may be dependent on a number of factors: e.g., which phytocannabinoid is used (e.g., cannabidiol (CBD) vs. tetrahyrocannabinol (THC)), the frequency of use (occasional vs. heavy), and at what age (prenatal, childhood, adulthood) the use began. However, due to the fact that there are over seven hundred constituents that make up the Cannabis sativa plant, it is difficult to determine which compound or combination of compounds is responsible for specific effects when studying recreational users. Therefore, this review focuses only on the functional MRI studies investigating the effects of specific pharmacological preparations of cannabis compounds, specifically THC, tetrahydrocannabivarin (THCV), and CBD, on brain function in healthy individuals and persons with epilepsy with references to non-epilepsy studies only to underline the gaps in research that need to be filled before cannabis-derived products are considered for a wide use in the treatment of epilepsy. This article is part of a Special Issue entitled "Cannabinoids and Epilepsy".

Mechanisms contributing to cognitive deficits in cannabis users

Studies from preclinical animal models indicate that sustained activation of CB1 receptor signaling is a major contributing factor for the onset of cognitive deficits associated to chronic cannabis use, in particular within the working memory and decision-making domains. Yet, very few studies have been designed to directly assess the role of CB1 receptors in mediating the effects of cannabis on human brain function. This perspective review article provides an overview of current state of knowledge on possible neurobiological mechanisms accounting for the detrimental effects of chronic cannabis use on cognition and related changes in brain structure and functional connectivity. This article is part of the Special Issue entitled "A New Dawn in Cannabinoid Neurobiology".

Cannabinoids as hippocampal network administrators

Extensive pioneering studies performed in the hippocampus have greatly contributed to our knowledge of an endogenous cannabinoid system comprised of the molecular machinery necessary to process endocannabinoid lipid messengers and their associated cannabinoid receptors. Moreover, a foundation of knowledge regarding the function of hippocampal circuits, and its role in supporting synaptic plasticity has facilitated our understanding of the roles cannabinoids play in the diverse behaviors in which the hippocampus participates, in both normal and pathological states. In this review, we present an historical overview of research pertaining to the hippocampal cannabinoid system to provide context in which to understand the participation of the hippocampus in cognition, behavior, and epilepsy. We also examine potential roles for the hippocampal formation in mediating dysfunctional behavior, and assert that these phenomena reflect disordered physiological activity within the hippocampus and its interactions with other brain regions after exposure to synthetic cannabinoids, and the phytocannabinoids found in marijuana, such as Δ⁹-THC and cannabidiol. In this regard, we examine contemporary hypotheses concerning the hippocampal endocannabinoid system's participation in psychotic disorders, schizophrenia, and epilepsy, and examine cannabinoid-sensitive cellular mechanisms contributing to coherent network oscillations as potential contributors to these disorders. This article is part of the Special Issue entitled "A New Dawn in Cannabinoid Neurobiology".

Characterization of peripheral cannabinoid receptor expression and clinical correlates in schizophrenia

The relationship between cannabinoid receptor signaling and psychosis vulnerability requires further exploration. The endocannabinoid signaling system is extensive, with receptors exerting regulatory functions in both immune and central nervous systems. In the brain, cannabinoid receptors (CBR) directly modulate neurotransmitter systems. In the peripheral lymphocyte, CBRs mediate cytokine release, with dysregulated cytokine levels demonstrated in schizophrenia. mRNA levels of CBRs were measured in human peripheral blood mononuclear cells (PBMCs) obtained from 70 participants (35 non-clinical controls, 35 participants with schizophrenia), who were recruited for the absence of marijuana use/abuse by self-report. Changes in mRNA expression were measured using qRT-PCR. Clinical measurements collected included the MATRICS Cognitive Battery and the Positive and Negative Syndrome Scale. Levels of CB1R and CB2R mRNA in PBMCs were significantly higher in participants with schizophrenia compared to the non-clinical controls. Additionally, CB1R and CB2R mRNA levels correlated with impairments in cognitive processing and clinical symptom severity in multiple domains. These results continue to support dysregulation of particular aspects of the endocannabinoid signaling system in participants with schizophrenia selected for the self-reported absence of marijuana abuse/dependence.

Annual Research Review: On the developmental neuropsychology of substance use disorders

BACKGROUND

Adolescence represents a period of development during which critical biological, as well as social and cognitive, changes occur that are necessary for the transition into adulthood. A number of researchers have suggested that the pattern of normative brain changes that occurs during this period not only predisposes adolescents to engage in risk behaviours, such as experimentation with drugs, but that they additionally make the adolescent brain more vulnerable to the direct pharmacological impact of substances of abuse. The neural circuits that we examine in this review involve cortico-basal-ganglia/limbic networks implicated in the processing of rewards, emotion regulation, and the control of behaviour, emotion and cognition.

FINDINGS AND CONCLUSIONS

We identify certain neurocognitive and personality/comorbidity-based risk factors for the onset of substance misuse during adolescence, and summarise the evidence suggesting that these risk factors may be further impacted by the direct effect of drugs on the underlying neural circuits implicated in substance misuse vulnerability.

The CCDC55 couples cannabinoid receptor CNR1 to a putative DISC1 schizophrenia pathway

PURPOSE

Our previous study suggested that the coiled coil domain-containing 55 gene (CCDC55), also named as NSRP1 (nuclear speckle splicing regulatory protein 1 (NSRP1)), was encompassed in a haplotype block spanning over the serotonin transporter (5-HTT) gene in patients with schizophrenia (SCZ). However, the neurobiological function of CCDC55 gene remains unknown. This study aims to uncover the potential role of CCDC55 in SCZ-associated molecular pathways.

EXPERIMENTAL DESIGN

Using molecular cloning, sequencing and immune blotting to identify basic properties, yeast two-hybrid screening and glutathione S-transferase (GST) pull-down assay to test protein-protein interaction, and confocal laser scanning microscopy (CSLM) to show intracellular interaction of proteins.

PRINCIPAL FINDINGS

(i) CCDC55 is expressed as a nuclear protein in human neuronal cells; (ii) Protein-protein interaction analyses showed CCDC55 physically interacted with Ran binding protein 9 (RanBP9) and disrupted in schizophrenia 1 (DISC1); (iii) CCDC55 and RanBP9 co-localized in the nucleus of human neuronal cells; (iv) CCDC55 also interacted with the cannabinoid receptor 1 (CNR1), and with the brain cannabinoid receptor-interacting protein 1a (CNRIP1a); (v) CNR1 activation in differentiated human neuronal cells resulted in an altered RanBP9 localization.

CONCLUSION

CCDC55 may be involved in a functional bridging between the CNR1 activation and the DISC1/RanBP9-associated pathways.

A systematic review of the antipsychotic properties of cannabidiol in humans

Despite extensive study over the past decades, available treatments for schizophrenia are only modestly effective and cause serious metabolic and neurological side effects. Therefore, there is an urgent need for novel therapeutic targets for the treatment of schizophrenia. A highly promising new pharmacological target in the context of schizophrenia is the endocannabinoid system. Modulation of this system by the main psychoactive component in cannabis, Δ9-tetrahydrocannabinol (THC), induces acute psychotic effects and cognitive impairment. However, the non-psychotropic, plant-derived cannabinoid agent cannabidiol (CBD) may have antipsychotic properties, and thus may be a promising new agent in the treatment of schizophrenia. Here we review studies that investigated the antipsychotic properties of CBD in human subjects. Results show the ability of CBD to counteract psychotic symptoms and cognitive impairment associated with cannabis use as well as with acute THC administration. In addition, CBD may lower the risk for developing psychosis that is related to cannabis use. These effects are possibly mediated by opposite effects of CBD and THC on brain activity patterns in key regions implicated in the pathophysiology of schizophrenia, such as the striatum, hippocampus and prefrontal cortex. The first small-scale clinical studies with CBD treatment of patients with psychotic symptoms further confirm the potential of CBD as an effective, safe and well-tolerated antipsychotic compound, although large randomised clinical trials will be needed before this novel therapy can be introduced into clinical practice.

Impact of Cannabis Use on the Development of Psychotic Disorders

The link between cannabis use and psychosis comprises three distinct relationships: acute psychosis associated with cannabis intoxication, acute psychosis that lasts beyond the period of acute intoxication, and persistent psychosis not time-locked to exposure. Experimental studies reveal that cannabis, tetrahydrocannabinol (THC) and synthetic cannabinoids reliably produce transient positive, negative, and cognitive symptoms in healthy volunteers. Case-studies indicate that cannabinoids can induce acute psychosis which lasts beyond the period of acute intoxication but resolves within a month. Exposure to cannabis in adolescence is associated with a risk for later psychotic disorder in adulthood; this association is consistent, temporally related, shows a dose-response, and is biologically plausible. However, cannabis is neither necessary nor sufficient to cause a persistent psychotic disorder. More likely it is a component cause that interacts with other factors to result in psychosis. The link between cannabis and psychosis is moderated by age at onset of cannabis use, childhood abuse and genetic vulnerability. While more research is needed to better characterize the relationship between cannabinoid use and the onset and persistence of psychosis, clinicians should be mindful of the potential risk of psychosis especially in vulnerable populations, including adolescents and those with a psychosis diathesis.