Consensus paper of the WFSBP task force on cannabis, cannabinoids and psychosis

Kynurenine amplifies tetrahydrocannabinol-induced sensorimotor impairment and classic "tetrad" effects in mice

BACKGROUND

L-kynurenine (KYN), a kynurenine pathway (KP) metabolite, is the main precursor for the neuroactive metabolite kynurenic acid (KYNA). Several studies suggest a patho-physiologically relevant association between increased brain KYNA levels and cognitive dysfunctions in individuals with schizophrenia. Δ9-tetrahydrocannabinol (Δ9-THC; i.e. the main psychoactive compound of cannabis) can worse schizophrenia-related psychosis, often leads to the development of cannabis use disorder in individuals with schizophrenia, and increases the risk of earlier onset of schizophrenia symptoms in those with a genetic predisposition. A role of KP alterations and, specifically, increased brain KYNA levels in Δ9-THC-induced psychotic symptoms has been previously proposed. The aim of the study was to investigate on the possible involvement of KP alterations in Δ9-THC-induced sensorimotor and "tetrad" responses in mice.

METHODS

Adult male CD-1 mice were treated with Δ9-THC (30 mg/ kg; i.p.) and KYN (20 mg/kg; i.p.), alone or in combination, and body temperature, acute mechanical and thermal analgesia, motor activity and sensorimotor responses were evaluated. Furthermore, brain KYNA levels as well as plasma Δ9-THC and its metabolites concentrations after the treatments were also evaluated.

RESULTS

Brain KYNA levels were significantly increased 1 h, but not 4 h, after KYN and KYN + Δ9-THC administration. KYN administration amplified the Δ9-THC-induced impairment of sensorimotor responses (visual placing, acoustic and tactile responses). Furthermore, KYN significantly increased Δ9-THC-induced motor activity impairment (bar test, drag test and rotarod test) and hypothermia (core and surface body temperature), but not Δ9-THC-induced analgesia. Finally, 1 h after Δ9-THC administration, Δ9-THC and its psychoactive metabolite 11-OH-THC plasma levels were higher in mice pretreated with KYN than in control mice.

CONCLUSIONS

The present data indicate for the first time that KYN amplifies the THC-induced sensorimotor impairment and classic "tetrad" response possibly through a pharmacokinetic interaction.

Randomized Laboratory Study of Single-Dose Cannabis, Dronabinol, and Placebo in Patients With Schizophrenia and Cannabis Use Disorder

BACKGROUND AND HYPOTHESIS

Up to 43% of people with schizophrenia have a lifetime cannabis use disorder (CUD). Tetrahydrocannabinol (THC) has been shown to exacerbate psychosis in a dose-dependent manner, but little research has assessed its effects on schizophrenia and co-occurring CUD (SCZ-CUD). In this double-dummy, placebo-controlled trial (total n = 130), we hypothesized that a modest dose of THC would worsen cognitive function but not psychosis.

STUDY DESIGN

Effects of single-dose oral THC (15 mg dronabinol) or smoked 3.5% THC cigarettes vs placebo in SCZ-CUD or CUD-only on positive and negative symptoms of schizophrenia (only for SCZ-CUD), cognition, and drug experiences assessed several hours after drug administration. SCZ-only and healthy control participants were also assessed.

STUDY RESULTS

Drug liking was higher in THC groups vs placebo. Neither smoked THC nor oral dronabinol predicted positive or negative symptom subscale scores 2 and 5 h, respectively, after drug exposure in SCZ-CUD participants. The oral dronabinol SCZ-CUD group, but not smoked THC SCZ-CUD group, performed worse than placebo on verbal learning (B = -9.89; 95% CI: -16.06, -3.18; P = .004) and attention (B = -0.61; 95% CI: -1.00, -0.23; P = .002). Every 10-point increment in serum THC + THCC ng/ml was associated with increased negative symptoms (0.40 points; 95% CI: 0.15, 0.65; P = .001; subscale ranges 7-49) and trends were observed for worse positive symptoms and performance in verbal learning, delayed recall, and working memory.

CONCLUSIONS

In people with SCZ-CUD, a modest single dose of oral THC was associated with worse cognitive functioning without symptom exacerbation several hours after administration, and a THC dose-response effect was seen for negative symptoms.

Cannabis Use Cessation and the Risk of Psychotic Disorders: A Case-Control Analysis from the First Episode Case-Control EU-GEI WP2 Study: L'arrêt de l'utilisation du cannabis et le risque de troubles psychotiques: Une analyse cas-témoins tirée de l'étude cas-témoins EU-GEI WP2 centrée sur les premiers épisodes psychotiques

OBJECTIVES

To establish whether the risk of psychotic disorders in cannabis users changes with time following cannabis cessation using data from the European Network of National Networks studying Gene-Environment Interactions in Schizophrenia (EU-GEI) case-control study.

METHODS

The EU-GEI case-control study collected data from first episode psychosis patients and population controls across sites in Europe and Brazil between May 2010 and April 2015. Adjusted logistic regressions were applied to examine whether the odd of psychosis case status changed: (1) with time following cannabis cessation and (2) across different cannabis use groups.

RESULTS

Psychosis risk declined following cessation of cannabis use (β = -0.002; 95% CI -0.004 to 0.000; P = 0.067). When accounting for duration of use, this effect remained (β = -0.003; 95% CI -0.005 to -0.001; P = 0.013). However, in models adjusting for frequency and potency of use the result was not significant. Analysis of different cannabis use groups indicated that ex-users who stopped 1 to 4 weeks previously had the highest risk for psychotic disorder compared to never users (OR = 6.89; 95% CI 3.91-12.14; P < 0.001); risk declined for those who stopped 5 to 12 weeks previously (OR = 2.70; 95% CI 1.73-4.21; P < 0.001) and 13 to 36 weeks previously (OR = 1.53; 95% CI 1.00-2.33; P = 0.050). Ex-users who stopped 37 to 96 weeks (OR = 1.01; 95% CI 0.66-1.57; P = 0.949), 97 to 180 weeks (OR = 0.73; 95% CI 0.45-1.19; P = 0.204), and 181 weeks previously or more (OR = 1.18; 95% CI 0.76-1.83; P = 0.456) had similar psychosis risk to those who had never-used cannabis.

CONCLUSION

Risk of psychotic disorder appears to decline with time following cannabis cessation, receding to that of those who have never used cannabis after 37 weeks or more of abstinence. Although, preliminary results suggest that frequent users of high potency types of cannabis might maintain an elevated risk compared to never users even when abstaining for longer than 181 weeks.

Characteristics and effects of cannabis advertisements with appeal to youth in California

BACKGROUND

California boasts the largest regulated cannabis market in the world, but it is increasingly exposing youth to cannabis marketing, and the state's definition of content appealing to youth is vague. We aimed to identify the specific features of California cannabis ads that increase interest in cannabis use among adolescents to inform reasonably restrictive marketing policy.

METHODS

Participants consisted of 409 youth (age 16-20 years) susceptible to using cannabis in the future and living in California. Using an online experiment, participants were randomly assigned to view cannabis ads with and without features previously shown to be appealing to adolescents, followed by questions about attitudes toward the ad and their interest in using the advertised cannabis product or service. Multivariable regressions tested associations of content features with these outcomes.

RESULTS

Several features were significantly associated with increasing youth interest in cannabis use and attitudes toward the ad following ad exposure, including illustration, clear product descriptions, food or flavor references, depictions of positive sensations, adventure, psychoactive effects, and references to heavy consumption.

CONCLUSION

California cannabis ads contain features that appeal to youth and that are not restricted in California or other U.S. states with legal cannabis retail.

The adverse public health effects of non-medical cannabis legalisation in Canada and the USA

Cannabis consumption is legally prohibited in most countries in the world. Several countries are legalising cannabis for adult consumption. It is important to monitor the public health effects of these policy changes. In this paper, we summarise the evidence to date on the legalisation of adult non-medical cannabis use in Canada and the USA. We describe regulatory models for cannabis legalisation, changes in cannabis products and pricing, effects on the illicit cannabis market, changes in cannabis use, and changes in cannabis-related physical and mental health harms. We discuss the challenges in assessing the effects of cannabis legalisation on public health outcomes and emphasise the importance of continuous and rigorous monitoring of adverse health effects to inform the design of public health policies and regulations.

A Computational Account of the Development and Evolution of Psychotic Symptoms

The mechanisms of psychotic symptoms such as hallucinations and delusions are often investigated in fully formed illness, well after symptoms emerge. These investigations have yielded key insights but are not well positioned to reveal the dynamic forces underlying symptom formation itself. Understanding symptom development over time would allow us to identify steps in the pathophysiological process leading to psychosis, shifting the focus of psychiatric intervention from symptom alleviation to prevention. We propose a model for understanding the emergence of psychotic symptoms within the context of an adaptive, developing neural system. We make the case for a pathophysiological process that begins with cortical hyperexcitability and bottom-up noise transmission, which engenders inappropriate belief formation via aberrant prediction error signaling. We argue that this bottom-up noise drives learning about the (im)precision of new incoming sensory information because of diminished signal-to-noise ratio, causing a compensatory relative overreliance on prior beliefs. This overreliance on priors predisposes to hallucinations and covaries with hallucination severity. An overreliance on priors may also lead to increased conviction in the beliefs generated by bottom-up noise and drive movement toward conversion to psychosis. We identify predictions of our model at each stage, examine evidence to support or refute those predictions, and propose experiments that could falsify or help select between alternative elements of the overall model. Nesting computational abnormalities within longitudinal development allows us to account for hidden dynamics among the mechanisms driving symptom formation and to view established symptoms as a point of equilibrium among competing biological forces.

Changes in Cannabis Use Patterns in Psychiatric Populations Pre- and Post-Legalization of Recreational Cannabis Use in Canada: A Repeated Cross-Sectional Survey

Objective

Since the federal Canadian government legalized cannabis in 2018, cannabis use in the general population has slightly increased. However, little is known about the impact of cannabis legalization on pattens of cannabis use in psychiatric populations.

Method

We studied changes in daily/almost daily and average 30-day cannabis use amongst individuals currently using cannabis who reported past 12-month experiences of specific mental health disorders and among those without past 12-month experiences of any mental health disorder before and after Canadian legalization of recreational cannabis use (N = 13,527). Data came from Canadian respondents in Wave 1 (August-October 2018), Wave 2 (September-October 2019), and Wave 3 (September-November 2020) of the International Cannabis Policy Study (ICPS).

Results

After adjustment for covariates, among individuals currently using cannabis, the odds of using cannabis daily/almost daily increased only in individuals with schizophrenia between Wave 1 and Waves 3 (aOR = 9.19, 95% CI: 2.46 - 34.37). Similarly, significant increases in average 30-day cannabis use between Wave 1 (M = 12.80, SE = 1.65) and Wave 3 (M = 18.07, SE = 1.03) were observed only among individuals with schizophrenia, F (1,2) = 4.58, p < .05. No significant changes in daily/almost daily or average past 30-day cannabis use were observed in those without mental health problems or those reporting anxiety, depression, PTSD, bipolar disorder, or substance use disorders.

Conclusions

Since legalization, cannabis use has significantly increased only among people with schizophrenia, highlighting the need for targeted public health prevention programs.

A proof-of-concept analysis of data from the first NHS clinic for young adults with comorbid cannabis use and psychotic disorders

BACKGROUND

Cannabis use severely affects the outcome of people with psychotic disorders, yet there is a lack of treatments. To address this, in 2019 the National Health Service (NHS) Cannabis Clinic for Psychosis (CCP) was developed to support adults suffering from psychosis to reduce and/or stop their cannabis use.

AIMS

Examine outcome data from the first 46 individuals to complete the CCP's intervention.

METHOD

The sample (N = 46) consisted of adults (aged ≥ 18) with psychosis under the care of the South London and Maudsley NHS Foundation Trust, referred to the CCP between January 2020 and February 2023, who completed their intervention by September 2023. Clinical and functional measures were collected before (T0) and after (T1) the CCP intervention (one-to-one sessions and peer group attendance). Primary outcomes were changes in the Cannabis Use Disorders Identification Test-Revised (CUDIT-R) score and pattern of cannabis use. Secondary outcomes included T0-T1 changes in measures of delusions, paranoia, depression, anxiety and functioning.

RESULTS

A reduction in the mean CUDIT-R score was observed between T0 (mean difference = 17.10, 95% CI = 15.54-18.67) and T1, with 73.91% of participants achieving abstinence and 26.09% reducing the frequency and potency of their use. Significant improvements in all clinical and functional outcomes were observed, with 90.70% being in work or education at T1 compared with 8.70% at T0. The variance in CUDIT-R scores explained between 34 and 64% of the variance in our secondary measures.

CONCLUSIONS

The CCP intervention is a feasible strategy to support cannabis use cessation/reduction and improve clinical and functional outcomes of people with psychotic disorders.

The impact of schizophrenia genetic load and heavy cannabis use on the risk of psychotic disorder in the EU-GEI case-control and UK Biobank studies

BACKGROUND

The association between cannabis and psychosis is established, but the role of underlying genetics is unclear. We used data from the EU-GEI case-control study and UK Biobank to examine the independent and combined effect of heavy cannabis use and schizophrenia polygenic risk score (PRS) on risk for psychosis.

METHODS

Genome-wide association study summary statistics from the Psychiatric Genomics Consortium and the Genomic Psychiatry Cohort were used to calculate schizophrenia and cannabis use disorder (CUD) PRS for 1098 participants from the EU-GEI study and 143600 from the UK Biobank. Both datasets had information on cannabis use.

RESULTS

In both samples, schizophrenia PRS and cannabis use independently increased risk of psychosis. Schizophrenia PRS was not associated with patterns of cannabis use in the EU-GEI cases or controls or UK Biobank cases. It was associated with lifetime and daily cannabis use among UK Biobank participants without psychosis, but the effect was substantially reduced when CUD PRS was included in the model. In the EU-GEI sample, regular users of high-potency cannabis had the highest odds of being a case independently of schizophrenia PRS (OR daily use high-potency cannabis adjusted for PRS = 5.09, 95% CI 3.08-8.43, p = 3.21 × 10-10). We found no evidence of interaction between schizophrenia PRS and patterns of cannabis use.

CONCLUSIONS

Regular use of high-potency cannabis remains a strong predictor of psychotic disorder independently of schizophrenia PRS, which does not seem to be associated with heavy cannabis use. These are important findings at a time of increasing use and potency of cannabis worldwide.

Psychiatric hospitalizations among adolescents during the pandemic in Italy: a retrospective study

OBJECTIVES

The COVID-19 pandemic has negatively impacted child and adolescent mental health. The study outcome was the evaluation of the pandemic impact on adolescents' hospitalizations in an acute psychiatric ward.

METHODS

With an observational and retrospective design, we collected selected variables among adolescents hospitalized in an acute psychiatric ward from 01/07/2017 to 30/06/2022. Data were statistically processed.

RESULTS

Our sample consisted of 118 minors with an average age of 15.7 ± 1.2 SD, mostly represented by females (61 %) and Italians (60.2 %), who made 204 hospitalizations in the study period. The admissions by years drastically decreased in 2020 concomitantly with the lockdown and increased in the first half of 2022. The admission rate was higher in winter and spring, except in 2020 when all admissions decreased (p=0.000). Females more frequently were hospitalized for suicidal behavior and acute anxiety (p=0.000) and were discharged with acute stress reactions, eating disorders, and mood disorder diagnoses (p=0.000). Differently, males more frequently were hospitalized for aggressive behavior (p=0.000) and discharged with ADHD diagnosis (p=0.000). At multiple linear regression, the duration of hospitalization (dependent variable) was negatively associated with "the pandemic period" (p=0.017) and "absent aggressive behavior" (p=0.003), and positively with "autism" diagnosis (p=0.000).

CONCLUSIONS

We highlighted the more stressful impact of COVID-19 pandemic on female adolescents, who required more frequently psychiatric hospitalizations due to suicidal behavior, anxiety and mood disorders.

Lifestyle, Environment, and Dietary Measures Impacting Cognitive Impairment: The Evidence Base for Cognitive Subtypes

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Cognition includes all phases of valid functions and processes, e.g., sensitivity, judgment, assessment, and decision-making. Thinking is also a cognitive procedure since it involves considering potential opportunities. There are various types of cognition. Hot cognition involves mental procedures where emotion plays a role, while cold cognition includes mental processes that do not include feelings or emotions. Cognitive memories of various types include sensor memory, sensing touch, smell, and sight; short-term memory allows one to recall, e.g., what one had for lunch a few days ago; working memory includes remembering telephone numbers or directions to a destination; and long-term memory comprises of major milestones in life and recalling one’s childhood events. These are further classified as episodic, e.g., the first day in primary school, and semantic memories, such as recalling the capital city of a country and filling out crossword puzzles. Declarative memories include remembering significant past events, such as global information. Cognition is affected by factors, such as nutrition, aging, addiction, environment, mental health, physical activity, smoking, and keeping the brain active. Consumption of plant- based foods plays a prominent role in the prevention of cognitive memory. Playing games and instruments, reading books, and being socially active make life more satisfying, thus assisting in the preservation of mental function and slowing mental decline.

Schizophrenia, a disease of impaired dynamic metabolic flexibility: A new mechanistic framework

Schizophrenia is a chronic, neurodevelopmental disorder with unknown aetiology and pathophysiology that emphasises the role of neurotransmitter imbalance and abnormalities in synaptic plasticity. The currently used pharmacological approach, the antipsychotic drugs, which have limited efficacy and an array of side-effects, have been developed based on the neurotransmitter hypothesis. Recent research has uncovered systemic and brain abnormalities in glucose and energy metabolism, focusing on altered glycolysis and mitochondrial oxidative phosphorylation. These findings call for a re-conceptualisation of schizophrenia pathophysiology as a progressing bioenergetics failure. In this review, we provide an overview of the fundamentals of brain bioenergetics and the changes identified in schizophrenia. We then propose a new explanatory framework positing that schizophrenia is a disease of impaired dynamic metabolic flexibility, which also reconciles findings of abnormal glucose and energy metabolism in the periphery and in the brain along the course of the disease. This evidence-based framework and testable hypothesis has the potential to transform the way we conceptualise this debilitating condition and to develop novel treatment approaches.

Cannabis Vape Product Sales in California Following CDC's Initial Advisory About Lung Injuries

Introduction: The 2019 outbreak of e-cigarette or vaping product use-associated lung injury (EVALI) is believed to have been caused by vitamin E acetate, an additive used in some cannabis vaporizer products. Previous studies have primarily focused on changes in sales of electronic nicotine delivery systems following the initial advisory issued by the Centers for Disease Control (CDC) on August 17, 2019. The present study is intended to examine variation by age groups in sales of regulated cannabis vape products in the state of California before, during, and after the outbreak. Methods: Weekly sales revenue of cannabis vape products (from January 1, 2018, to December 31, 2020) was obtained from a sample of recreational cannabis retailers licensed in California. An interrupted time series analysis, using AutoRegressive, Integrated, Moving Average methods, was employed to estimate changes in the sales and market share of cannabis vape products in the weeks following the CDC advisory. Results: The total volume of regulated cannabis vape product sales increased substantially over the 3-year study period (2018-2020). Sales and market share of cannabis vape products, however, declined in both young and older adults immediately following the advisory, rebounding to pre-EVALI levels only for the young adults. For sales, the potential EVALI effect following the CDC's advisory equates to an 8.0% and 2.2% decline below expected levels in the older and young adults, respectively. Conclusions: The differential age effect on sales may reflect concerns regarding health effects of cannabis vaping products and greater awareness of the outbreak among older adults. Findings highlight the importance of informing consumers about health risks associated with using cannabis vape products acquired from regulated versus illicit sources.

Psychotomimetic compensation versus sensitization

It is a paradox that psychotomimetic drugs can relieve symptoms that increase risk of and cooccur with psychosis, such as attention and motivational deficits (e.g., amphetamines), pain (e.g., cannabis) and symptoms of depression (e.g., psychedelics, dissociatives). We introduce the ideas of psychotomimetic compensation and psychotomimetic sensitization to explain this paradox. Psychotomimetic compensation refers to a short-term stressor or drug-induced compensation against stress that is facilitated by engagement of neurotransmitter/modulator systems (endocannabinoid, serotonergic, glutamatergic and dopaminergic) that mediate the effects of common psychotomimetic drugs. Psychotomimetic sensitization occurs after repeated exposure to stress and/or drugs and is evidenced by the gradual intensification and increase of psychotic-like experiences over time. Theoretical and practical implications of this model are discussed.

Characterization of substance use in homeless patients with mental disorders

BACKGROUND

In Denmark, 42% of homeless people suffer from dual diagnosis, i.e. the co-occurrence of a substance use of alcohol and/or illegal substances and another psychiatric disorder. Dual diagnosis homeless patients often cause differential diagnostic difficulties and fail to receive effective treatment. A solid grasp of the role of substance use in these patients may inform the diagnostic decision and contribute to improve their treatment. Today, knowledge of these issues remains scarce. The purpose of this study was to explore substance use in homeless patients with mental disorders and their subjective perspectives on their substance use.

METHODS

44 homeless dual diagnosis patients were included in the study. They were examined in interviews focusing on their substance use and their subjective perspective on their substance use.

RESULTS

The most frequently used substances were cannabinoids (70.5%) and alcohol (45.5%), followed by cocaine, sedative/hypnotics, and amphetamine. The finding suggests that substance use in dual diagnosis homeless patients is a complex phenomenon with most patients (56.8%) using multiple substances. While substance use seems to contribute to keep the patients homeless, substance use was also reported to play an important role in coping with life on the streets by offering social contact and some relief from a desperate situation.

CONCLUSION

Substance use, mental disorder, and homelessness seem to be closely entangled, reinforcing each other and making it difficult to help these vulnerable patients. Diagnostic overshadowing may cause delays in adequate diagnosis and treatment of this group of patients.

A critical assessment of the abuse, dependence and associated safety risks of naturally occurring and synthetic cannabinoids

Various countries and US States have legalized cannabis, and the use of the psychoactive1 and non-psychoactive cannabinoids is steadily increasing. In this review, we have collated evidence from published non-clinical and clinical sources to evaluate the abuse, dependence and associated safety risks of the individual cannabinoids present in cannabis. As context, we also evaluated various synthetic cannabinoids. The evidence shows that delta-9 tetrahydrocannabinol (Δ9-THC) and other psychoactive cannabinoids in cannabis have moderate reinforcing effects. Although they rapidly induce pharmacological tolerance, the withdrawal syndrome produced by the psychoactive cannabinoids in cannabis is of moderate severity and lasts from 2 to 6 days. The evidence overwhelmingly shows that non-psychoactive cannabinoids do not produce intoxicating, cognitive or rewarding properties in humans. There has been much speculation whether cannabidiol (CBD) influences the psychoactive and potentially harmful effects of Δ9-THC. Although most non-clinical and clinical investigations have shown that CBD does not attenuate the CNS effects of Δ9-THC or synthetic psychoactive cannabinoids, there is sufficient uncertainty to warrant further research. Based on the analysis, our assessment is cannabis has moderate levels of abuse and dependence risk. While the risks and harms are substantially lower than those posed by many illegal and legal substances of abuse, including tobacco and alcohol, they are far from negligible. In contrast, potent synthetic cannabinoid (CB1/CB2) receptor agonists are more reinforcing and highly intoxicating and pose a substantial risk for abuse and harm. 1 "Psychoactive" is defined as a substance that when taken or administered affects mental processes, e.g., perception, consciousness, cognition or mood and emotions.

The predictive effect of family genetic risk scores as an indirect measure of causal effects of one disorder on another

BACKGROUND

One potential cause of comorbidity is the direct causal effect of one disorder - A - on risk for subsequent onset of disorder B. Could genetic risk scores be utilized to test for such an effect? If disorder A causally impacts on risk for disorder B, then genetic risk for disorder A should be lower in cases of disorder A with v. without a prior onset of B.

METHODS

In all individuals (n = 905 736) born in Sweden from 1980 to 1990, from six psychiatric and drug use disorders (major depression, anxiety disorders, alcohol use disorder, drug use disorder, bipolar disorder, and schizophrenia), we formed 14 pairs of disorders A and B. In these pairs, we compared, using Cox proportional hazards models, the predictive effect of the familial-genetic risk score (FGRS) for disorder B in those who had v. had not had a prior onset of disorder A.

RESULTS

In all pairs, the impact of the FGRS for disorder B was significantly stronger in cases without v. with a prior history of disorder A. These effects were similar across sex, stable across levels of FGRS and not likely due to clinician bias. In many of our disorder pairs, previous clinical studies suggest a mechanism for a causal effect of disorder A on B.

CONCLUSIONS

Our findings provide indirect evidence that the occurrence of one psychiatric or substance use disorder often has a causal effect on risk for subsequent disorders. This mechanism may substantially contribute to the widespread comorbidity among psychiatric conditions.

The Developmental Trajectory to Cannabis Use Disorder

The increase of cannabis use, particularly with the evolution of high potency products, and of cannabis use disorder (CUD) are a growing healthcare concern. While the harms of adult use and potential medicinal properties of cannabis continue to be debated, it is becoming evident that adolescent cannabis use is a critical window for CUD risk with potential lifelong mental health implications. Herein, we discuss mental health consequences of adolescent cannabis use, factors that contribute to the risk of developing CUD, and what remains unclear in the changing legal landscape of cannabis use. We also discuss the importance of preclinical models to provide translational insight about the causal relationship of cannabis to CUD-related phenotypes and conclude with highlighting opportunities for clinicians and allied professionals to engage in addressing adolescent cannabis use.

Cannabidiol, but Not Δ9-Tetrahydrocannabinol, Has Strain- and Genotype-Specific Effects in Models of Psychosis

Introduction: Cannabis use has been associated with an increased incidence of psychiatric disorders, yet the underlying neurobiological processes mediating these associations are poorly understood. Whereas exposure to Δ9-tetrahydrocannabinol (THC) has been associated with the development or exacerbation of psychosis, treatment with cannabidiol (CBD) has been associated with amelioration of psychosis. In this study, we demonstrate a complex effect of CBD in mouse models of psychosis, based on factors, including dose, strain, and genotype. Methods: Adult GluN1 knockdown (GluN1KD) and dopamine transporter knockout (DATKO) mice (almost equally balanced for male/female) were acutely treated with vehicle, THC (4 mg/kg), CBD (60, 120 mg/kg), or THC:CBD (1:15, 4:60 mg/kg) and tested in behavioral assays. Results: GluN1KD and DATKO mice displayed hyperactivity, impaired habituation, and sensorimotor gating, along with increased stereotypy and vertical activity. THC, alone and in combination with CBD, produced a robust "dampening" effect on the exploratory behavior regardless of strain or genotype. CBD exhibited a more complex profile. At 60 mg/kg, CBD had minimal effects on horizontal activity, but the effects varied in terms of directionality (increase vs. decrease) in other parameters; effects on stereotypic behaviors differ by genotype, while effects on vertical exploration differ by strain×genotype. CBD at 120 mg/kg had a "dampening" effect on exploration overall, except in GluN1KD mice, where no effect was observed. In terms of sensorimotor gating, both THC and CBD had minimal effects, except for 120 mg/kg CBD, which exacerbated the acoustic startle response. Conclusions: Here, we present a study that highlights the complex mechanism of phytocannabinoids, particularly CBD, in models of psychosis-like behavior. These data require careful interpretation, as agonism of the cannabinoid receptor 1 (CB1) resulting in a decrease in locomotion can be misinterpreted as "antipsychotic-like" activity in murine behavioral outputs of psychosis. Importantly, the THC-mediated decrease in hyperexploratory behavior observed in our models (alone or in combination) was not specific to the genetic mutants, but rather was observed regardless of strain or genotype. Furthermore, CBD treatment, when comparing mutants with their wild-type littermate controls, showed little to no "antipsychotic-like" activity in our models. Therefore, it is not only important to consider dose when designing/interpreting therapeutically driven phytocannabinoid studies, but also effects of strain or genetic vulnerability respective to the general population.

Unhealthy behaviors associated with mental health disorders: a systematic comparative review of diet quality, sedentary behavior, and cannabis and tobacco use

Background

There are well-established literatures documenting the associations between mental disorders and unhealthy behaviors such as poor diet quality, sedentary behavior, and cannabis and tobacco use. Few studies have attempted to understand the respective findings in light of each other, however.

Objective

The purpose of this review was to assemble comparable data for each behavior-disorder association and assess the associations in terms of their overall strength. The review aimed to include a representative, but not exhaustive, range of studies that would allow for explorative comparisons.

Methods

Eligible studies were identified via Pubmed searches and citation searching, restricted to publications no older than 2015 written in English. To obtain comparable data, only studies that reported findings as odds ratios were included, and risk of bias related to study samples, behavioral measurement disparities, and control variables was assessed via sensitivity analyses. Findings for each disorder were compared on the basis of different measures of central tendency.

Results

From 3,682 records, 294 studies were included. The review found evidence of associations between each of the four unhealthy behaviors and psychosis, depression, anxiety, bipolar disorder, attention-deficit/hyperactivity disorder (ADHD), and post-traumatic stress disorder (PTSD), while personality disorder was only investigated in relation to cannabis and tobacco use. In overall comparison, the associations were generally of similar strength, and only the association between cannabis use and personality disorder was exceptional in terms of being significantly stronger than its counterparts across disorders and across behaviors. Analyses of bias risk identified some influence from behavioral measurement disparities and lack of adequate statistical control, but findings were generally robust across a range of sensitivity analyses.

Conclusion

This explorative and comparative review found that poor diet quality, sedentary behavior, and cannabis and tobacco use are about equally strongly associated with a range of different mental disorders. Given the general nature of these associations, we should probably understand them to reflect a general and shared etiology. However, the findings in this review should be regarded as tentative until confirmed by more comprehensive investigations.

Assessing evidence supporting cannabis harm reduction practices for adolescents at clinical high-risk for psychosis: a review and clinical implementation tool

Cannabis use is consistently associated with both increased incidence of frank psychotic disorders and acute exacerbations of psychotic symptoms in healthy individuals and people with psychosis spectrum disorders. Although there is uncertainty around causality, cannabis use may be one of a few modifiable risk factors for conversion to psychotic disorders in individuals with Clinical High Risk for Psychosis (CHR-P) syndromes, characterized by functionally impairing and distressing subthreshold psychotic symptoms. To date, few recommendations beyond abstinence to reduce adverse psychiatric events associated with cannabis use have been made. This narrative review synthesizes existing scientific literature on cannabis' acute psychotomimetic effects and epidemiological associations with psychotic disorders in both CHR-P and healthy individuals to bridge the gap between scientific knowledge and practical mental health intervention. There is compelling evidence for cannabis acutely exacerbating psychotic symptoms in CHR-P, but its impact on conversion to psychotic disorder is unclear. Current evidence supports a harm reduction approach in reducing frequency of acute psychotic-like experiences, though whether such interventions decrease CHR-P individuals' risk of conversion to psychotic disorder remains unknown. Specific recommendations include reducing frequency of use, lowering delta-9-tetrahydrocannabinol content in favor of cannabidiol-only products, avoiding products with inconsistent potency like edibles, enhancing patient-provider communication about cannabis use and psychotic-like experiences, and utilizing a collaborative and individualized therapeutic approach. Despite uncertainty surrounding cannabis' causal association with psychotic disorders, cautious attempts to reduce acute psychosis risk may benefit CHR-P individuals uninterested in abstinence. Further research is needed to clarify practices associated with minimization of cannabis-related psychosis risk.

Multi-ancestry genome-wide association study of cannabis use disorder yields insight into disease biology and public health implications

As recreational use of cannabis is being decriminalized in many places and medical use widely sanctioned, there are growing concerns about increases in cannabis use disorder (CanUD), which is associated with numerous medical comorbidities. Here we performed a genome-wide association study of CanUD in the Million Veteran Program (MVP), followed by meta-analysis in 1,054,365 individuals (ncases = 64,314) from four broad ancestries designated by the reference panel used for assignment (European n = 886,025, African n = 123,208, admixed American n = 38,289 and East Asian n = 6,843). Population-specific methods were applied to calculate single nucleotide polymorphism-based heritability within each ancestry. Statistically significant single nucleotide polymorphism-based heritability for CanUD was observed in all but the smallest population (East Asian). We discovered genome-wide significant loci unique to each ancestry: 22 in European, 2 each in African and East Asian, and 1 in admixed American ancestries. A genetically informed causal relationship analysis indicated a possible effect of genetic liability for CanUD on lung cancer risk, suggesting potential unanticipated future medical and psychiatric public health consequences that require further study to disentangle from other known risk factors such as cigarette smoking.

Circulating Endocannabinoids and N-Acylethanolamines in Individuals with Cannabis Use Disorder-Preliminary Findings

BACKGROUND

Endocannabinoids and related N-acylethanolamines (NAEs) are bioactive lipids with important physiological functions and putative roles in mental health and addictions. Although chronic cannabis use is associated with endocannabinoid system changes, the status of circulating endocannabinoids and related NAEs in people with cannabis use disorder (CUD) is uncertain.

METHODS

Eleven individuals with CUD and 54 healthy non-cannabis using control participants (HC) provided plasma for measurement by high-performance liquid chromatography-mass spectrometry of endocannabinoids (2-arachidonoylglycerol (2-AG) and N-arachidonoylethanolamine (AEA)) and related NAE fatty acids (N-docosahexaenoylethanolamine (DHEA) and N-oleoylethanolamine (OEA)). Participants were genotyped for the functional gene variant of FAAH (rs324420, C385A) which may affect concentrations of AEA as well as other NAEs (OEA, DHEA).

RESULTS

In overnight abstinent CUD, AEA, OEA and DHEA concentrations were significantly higher (31-40%; p < 0.05) and concentrations of the endocannabinoid 2-AG were marginally elevated (55%, p = 0.13) relative to HC. There were no significant correlations between endocannabinoids/NAE concentrations and cannabis analytes, self-reported cannabis use frequency or withdrawal symptoms. DHEA concentration was inversely related with marijuana craving (r = -0.86; p = 0.001). Genotype had no significant effect on plasma endocannabinoids/NAE concentrations.

CONCLUSIONS

Our preliminary findings, requiring replication, might suggest that activity of the endocannabinoid system is elevated in chronic cannabis users. It is unclear whether this elevation is a compensatory response or a predating state. Studies examining endocannabinoids and NAEs during prolonged abstinence as well as the potential role of DHEA in craving are warranted.

Systematic review and rationale of using psychedelics in the treatment of cannabis use disorder

Introduction

Cannabis use disorder (CUD) is prevalent in ~2-5% of adults in the United States and is anticipated to increase as restrictions to cannabis decrease and tetrahydrocannabinol (THC) content in cannabis products increase. No FDA-approved medications for CUD are currently available, despite trials of dozens of re-purposed and novel drugs. Psychedelics have garnered interest as a therapeutic class in other substance use disorders, and self-report surveys suggest they may result in positive outcomes for CUD. Herein, we review the existing literature pertaining to psychedelic use in persons with or at risk for CUD and consider the potential rationale underpinning psychedelics as a treatment for CUD.

Methods

A systematic search was performed in several databases. Inclusion criteria were primary research reporting use of psychedelics or related substances and CUD for treatment in human subjects. Exclusion criteria were results including psychedelics or related substances without changes in cannabis use or risks associated with CUD.

Results

Three hundred and five unique results were returned. One article was identified using the non-classical psychedelic ketamine in CUD; three articles were identified as topically relevant based on their secondary data or consideration of mechanism. Additional articles were reviewed for purposes of background, review of safety considerations, and formulating rationale.

Conclusion

Limited data and reporting are available on the use of psychedelics in persons with CUD, and more research is needed given the anticipated increase in CUD incidence and increasing interest in psychedelic use. While psychedelics, broadly, have a high therapeutic index with infrequent serious adverse effects, particular adverse effects at risk in the CUD population, such as psychosis and cardiovascular events, should be considered. Possible mechanisms by which psychedelics have therapeutic potential in CUD are explored.

Medicinal cannabis for psychiatry-related conditions: an overview of current Australian prescribing

Objective: Evidence is accumulating that components of the Cannabis sativa plant may have therapeutic potential in treating psychiatric disorders. Medicinal cannabis (MC) products are legally available for prescription in Australia, primarily through the Therapeutic Goods Administration (TGA) Special Access Scheme B (SAS-B). Here we investigated recent prescribing practices for psychiatric indications under SAS-B by Australian doctors. Methods: The dataset, obtained from the TGA, included information on MC applications made by doctors through the SAS-B process between 1st November 2016 and 30th September 2022 inclusive. Details included the primary conditions treated, patient demographics, prescriber location, product type (e.g., oil, flower or capsule) and the general cannabinoid content of products. The conditions treated were categorized according to the Diagnostic and Statistical Manual of Mental Disorders, 5th edition, text revision (DSM-5-TR). Trends in prescribing for conditions over time were analyzed via polynomial regression, and relationships between categorical variables determined via correspondence analyses. Results: Approximately 300,000 SAS-B approvals to prescribe MC had been issued in the time period under investigation. This included approvals for 38 different DSM-5-TR defined psychiatric conditions (33.9% of total approvals). The majority of approvals were for anxiety disorders (66.7% of psychiatry-related prescribing), sleep-wake disorders (18.2%), trauma- and stressor-related disorders (5.8%), and neurodevelopmental disorders (4.4%). Oil products were most prescribed (53.0%), followed by flower (31.2%) and other inhaled products (12.4%). CBD-dominant products comprised around 20% of total prescribing and were particularly prevalent in the treatment of autism spectrum disorder. The largest proportion of approvals was for patients aged 25-39 years (46.2% of approvals). Recent dramatic increases in prescribing for attention deficit hyperactivity disorder were identified. Conclusion: A significant proportion of MC prescribing in Australia is for psychiatry-related indications. This prescribing often appears somewhat "experimental", given it involves conditions (e.g., ADHD, depression) for which definitive clinical evidence of MC efficacy is lacking. The high prevalence of THC-containing products being prescribed is of possible concern given the psychiatric problems associated with this drug. Evidence-based clinical guidance around the use of MC products in psychiatry is lacking and would clearly be of benefit to prescribers.

Recommendations for Reducing the Risk of Cannabis Use-Related Adverse Psychosis Outcomes: A Public Mental Health-Oriented Evidence Review

Objective: Cannabis use is increasingly normalized; psychosis is a major adverse health outcome. We reviewed evidence on cannabis use-related risk factors for psychosis outcomes at different stages toward recommendations for risk reduction by individuals involved in cannabis use. Methods: We searched primary databases for pertinent literature/data 2016 onward, principally relying on reviews and high-quality studies which were narratively summarized and quality-graded; recommendations were developed by international expert consensus. Results: Genetic risks, and mental health/substance use problem histories elevate the risks for cannabis-related psychosis. Early age-of-use-onset, frequency-of-use, product composition (i.e., THC potency), use mode and other substance co-use all influence psychosis risks; the protective effects of CBD are uncertain. Continuous cannabis use may adversely affect psychosis-related treatment and medication effects. Risk factor combinations further amplify the odds of adverse psychosis outcomes. Conclusions: Reductions in the identified cannabis-related risks factors-short of abstinence-may decrease risks of related adverse psychosis outcomes, and thereby protect cannabis users' health.

Neurocognitive moderation of repetitive transcranial magnetic stimulation (rTMS) effects on cannabis use in schizophrenia: a preliminary analysis

Repetitive transcranial magnetic stimulation (rTMS) is a promising treatment for cannabis use disorder in schizophrenia; however, gaps in the literature remain as to the potential role of neurocognitive functioning in treatment response. We evaluated the moderating role of select cognitive functions including baseline executive functioning, verbal memory, and sustained attention, and we explore the mediating role of changes in task performance on changes in cannabis use in both active and sham rTMS groups. Participants underwent high-frequency (20 Hz) rTMS applied to the bilateral dorsolateral prefrontal cortex 5x/week for 4 weeks. Weekly self-report of cannabis use and semi-quantitative urinary carboxy-tetrahydrocannabinol levels were recorded. A neurocognitive battery assessing verbal memory, visuospatial working memory, verbal working memory, sustained attention, delayed discounting, and complex planning was administered pre- and post-treatment. Better baseline performance on tasks assessing sustained attention, delayed discounting, and complex planning moderated the extent to which participants in the active group reduced cannabis use. There were no significant indirect pathways between treatment, changes in neuropsychological performance, and changes in cannabis use; however, active rTMS improved complex planning and sustained attention. These preliminary findings suggest that there is a moderating role of sustained attention, delayed discounting, and complex planning on the effects of rTMS on cannabis use. Further, mediation models suggest rTMS may exert direct effects on cannabis use independent of its effects on cognitive functioning in people with SCZ. Trial Registration: clinicaltrials.gov: NCT03189810.

Cannabis and Intentional Self-injury: a Narrative Review

Purpose of Review

Observational studies assessing the association of cannabis use with subsequent intentional self-injury have reported mixed findings. Longitudinal studies examining the association of cannabis use with subsequent suicide death are notably rare. Our objective was to review longitudinal studies examining cannabis use and subsequent self-harm, suicide attempt, or suicide death.

Recent Findings

Few population-based studies have focused on self-harm with considerable variability across studies in how this outcome has been operationalized. Studies assessing the association between cannabis use and suicide attempt are equivocal in their conclusions and heterogenous in terms of samples utilized and assessment of confounding bias. The results of one meta-analysis were suggestive of dose dependency. For suicide death, the findings are inconsistent, and there is reason for concern of selection bias.

Summary

The existing evidence base on these associations is not yet rigorous enough to allow drawing conclusions on causality. However, cannabis might be seen as an adverse prognostic marker for intentional self-injury.

[Inhaled marijuana and the lung, a toxic cocktail?]

Unlike the well-documented effects of tobacco smoke on the lung, the effects of cannabis smoke remain controversial, the main bias consisting in co-consumption of tobacco. That said, the composition of joint smoke is close to that of cigarettes, containing many compounds that are carcinogenic and/or alter the respiratory epithelium. Confirmed respiratory effects in chronic cannabis smokers include aggravated chronic bronchitis symptoms, a cumulative effect with tobacco on COPD and emphysema occurrence, an increased risk of bullous emphysema, and pneumothorax with heightened risk of recurrence after pleural symphysis. Recent prospective studies have shown a negative impact on lung function, with not only damage to the airways, but also DLCO alteration and an accelerated drop in FEV1. Finally, cannabis smoking is very common among young patients with lung cancer. Its consumption could lead to a different lung cancer profile, potentially more undifferentiated and less accessible to targeted therapy. Questioning about cannabis consumption must be systematic and targeted medical care should be offered.