Proportion of patients in south London with first-episode psychosis attributable to use of high potency cannabis: a case-control study

Clinical and public safety risks associated with cannabis legalization and frequency of cannabis use among forensic mental health patients

BACKGROUND

There are ongoing concerns regarding the impact of Canada's cannabis legalization and commercialization on vulnerable persons such as those with serious forms of mental illness, including persons with schizophrenia-spectrum disorders and users of forensic mental health services. The primary objective of this study was to investigate the potential harms and mental health-related impacts associated with cannabis legalization on a sample of forensic patients in Ontario (N = 187).

METHODS

Using a pseudo-prospective design, we investigated the frequency of cannabis use over a four-year period encompassing two years preceding and two years following the legislative change. We recorded clinical and public safety outcomes (i.e., mental health deterioration, length of stay in the forensic system, rates of hospital readmission, victimization and violence) over the same period to test relationships between these variables and rates of cannabis use.

RESULTS

We found that one-third of patients either self-reported or were discovered, via urine testing, to have used cannabis over the study period. Frequency of use was lower in the pre-legalization period, and then gradually and significantly increased after legalization. Compared to patients with no cannabis use, those with one or more instances of use were more likely to be readmitted to hospital and had higher rated static risk factors for violence. However, there were no observed differences in the actual rate of violence between patients using and not using cannabis, nor differences in the rate of violence over time. Over half of the patients who used cannabis experienced a worsening of their mental health status in the week following use.

CONCLUSIONS

Cannabis use among those with SMI is associated with adverse clinical outcomes. Results from this study suggest that the mental health burdens associated with cannabis use have risen in terms of delayed clinical recovery and progress through the forensic system since legalization.

Cross-ancestry genetic investigation of schizophrenia, cannabis use disorder, and tobacco smoking

Individuals with schizophrenia frequently experience co-occurring substance use, including tobacco smoking and heavy cannabis use, and substance use disorders. There is interest in understanding the extent to which these relationships are causal, and to what extent shared genetic factors play a role. We explored the relationships between schizophrenia (Scz; European ancestry N = 161,405; African ancestry N = 15,846), cannabis use disorder (CanUD; European ancestry N = 886,025; African ancestry N = 120,208), and ever-regular tobacco smoking (Smk; European ancestry N = 805,431; African ancestry N = 24,278) using the largest available genome-wide studies of these phenotypes in individuals of African and European ancestries. All three phenotypes were positively genetically correlated (rgs = 0.17-0.62). Genetic instrumental variable analyses suggested the presence of shared heritable factors, but evidence for bidirectional causal relationships was also found between all three phenotypes even after correcting for these shared genetic factors. We identified 327 pleiotropic loci with 439 lead SNPs in the European ancestry data, 150 of which were novel (i.e., not genome-wide significant in the original studies). Of these pleiotropic loci, 202 had lead variants which showed convergent effects (i.e., same direction of effect) on Scz, CanUD, and Smk. Genetic variants convergent across all three phenotypes showed strong genetic correlations with risk-taking, executive function, and several mental health conditions. Our results suggest that both shared genetic factors and causal mechanisms may play a role in the relationship between CanUD, Smk, and Scz, but longitudinal, prospective studies are needed to confirm a causal relationship.

LOTUS: Protocol for a double-blind placebo controlled randomized trial of hemp-derived cannabidiol for the treatment of cannabis use disorder

BACKGROUND

As cannabis legalization continues to spread across the United States, average Δ9-tetrahydrocannabinol concentrations in recreational products have significantly increased, and no prior study has evaluated effective treatments to reduce cannabis use among high potency cannabis users. Some research has found that the non-intoxicating cannabinoid cannabidiol reduces cannabis use and cannabis use disorder-related symptoms, such as affective disturbance and withdrawal. Results of these studies are promising but limited to synthetic or isolated forms of cannabidiol.

OBJECTIVE

Conduct a placebo-controlled randomized control trial comparing the effects of hemp-derived cannabidiol on reducing Δ9-tetrahydrocannabinol use in concentrate users with cannabis use disorder.

METHODS

Design. Double-blind, three-arm randomized placebo-controlled trial. Setting. University in the Denver-Boulder, CO, USA area. Study population. Community members who are heavy, stable cannabis concentrate users that meet criteria for at least moderate cannabis use disorder and are seeking to decrease or stop cannabis use. Data. Self-report demographics, substance use, and mental health characteristics, blood and urine based biomarkers and anthropometrics. Outcomes. Affective, physiological, and physical withdrawal symptoms, Δ9-tetrahydrocannabinol use. Analysis. Three-group ANOVAs and χ2 tests will be used to compare baseline variables between groups. Characteristics that differ between groups will be evaluated as potential covariates in subsequent analyses. A multilevel modeling framework will be used for primary outcome analysis to account for the repeated observations nested within participants over time. Pairwise post-hoc simple effects tests will be conducted to confirm patterns of differences.

TRIAL REGISTRATION

ClinicalTrials.gov NCT06107062.

Schizophrenia is associated with altered DNA methylation variance

Varying combinations of genetic and environmental risk factors are thought to underpin phenotypic heterogeneity between individuals in psychiatric conditions such as schizophrenia. While epigenome-wide association studies in schizophrenia have identified extensive alteration of mean DNA methylation levels, less is known about the location and impact of DNA methylation variance, which could contribute to phenotypic and treatment response heterogeneity. To explore this question, we conducted the largest meta-analysis of blood DNA methylation variance in schizophrenia to date, leveraging three cohorts comprising 1036 individuals with schizophrenia and 954 non-psychiatric controls. Surprisingly, only a small proportion (0.1%) of the 213 variably methylated positions (VMPs) associated with schizophrenia (Benjamini-Hochberg FDR < 0.05) were shared with differentially methylated positions (DMPs; sites with mean changes between cases and controls). These blood-derived VMPs were found to be overrepresented in genes previously associated with schizophrenia and amongst brain-enriched genes, with evidence of concordant changes at VMPs in the cerebellum, hippocampus, prefrontal cortex, or striatum. Epigenetic covariance was also observed with respect to clinically significant metrics including age of onset, cognitive deficits, and symptom severity. We also uncovered a significant VMP in individuals with first-episode psychosis (n = 644) from additional cohorts and a non-psychiatric comparison group (n = 633). Collectively, these findings suggest schizophrenia is associated with significant changes in DNA methylation variance, which may contribute to individual-to-individual heterogeneity.

Validation of the Reasons for Quitting Smoking Cannabis Scale Among People with Cannabis Use Disorder

BACKGROUND

The prevalence of cannabis use disorder (CUD) has increased in the last ten years with medicinal and recreational legalization across the United States and increasing accessibility worldwide. Estimates suggest that 8-18% of individuals who use cannabis meet diagnostic criteria for CUD, leading to significant impairments across functioning. However, there are currently no measures that assess the reasons for quitting smoking cannabis to use in treatments with validation evidence in those with CUD.

METHOD

We validated the Reasons for Quitting Smoking Cannabis Scale (RQSCS) in adults (n = 133) who meet the diagnostic criteria for CUD as part of a laboratory-based clinical trial on transdermal nicotine patches for cannabis withdrawal symptoms (R01DA031006). We conducted standard psychometric testing, including exploratory factor analyses, estimating internal consistencies, exploring demographic variation, and testing construct validity.

RESULTS

The RQSCS demonstrated a four-factor structure, including: (1) cognitive health, (2) social functioning, (3) health problems, (4) reputation, and a single item that assesses experimental incentive; λs > .410), with acceptable to high internal consistencies for each subscale (αs > .725). The scale demonstrated strong construct validity and minor demographic variation. Finally, all subscales were sensitive to detecting reasons for quitting cannabis and differentially predicted cannabis use 31 days after the study.

CONCLUSION

The RQSCS is a psychometrically robust, timely instrument for assessing the reasons for quitting smoking cannabis in individuals with CUD. The scale has the potential to provide useful information for clinicians attempting to help those with CUD reduce or cease their cannabis use, informing individualized treatment plans and enhancing motivation for change.

Sex effects on DNA methylation affect discovery in epigenome-wide association study of schizophrenia

Sex differences in the epidemiology and clinical characteristics of schizophrenia are well-known; however, the molecular mechanisms underlying these differences remain unclear. Further, the potential advantages of sex-stratified meta-analyses of epigenome-wide association studies (EWAS) of schizophrenia have not been investigated. Here, we performed sex-stratified EWAS meta-analyses to investigate whether sex stratification improves discovery, and to identify differentially methylated regions (DMRs) in schizophrenia. Peripheral blood-derived DNA methylation data from 1519 cases of schizophrenia (male n = 989, female n = 530) and 1723 controls (male n = 997, female n = 726) from three publicly available datasets, and the TOP cohort were meta-analyzed to compare sex-specific, sex-stratified, and sex-adjusted EWAS. The predictive power of each model was assessed by polymethylation score (PMS). The number of schizophrenia-associated differentially methylated positions identified was higher for the sex-stratified model than for the sex-adjusted one. We identified 20 schizophrenia-associated DMRs in the sex-stratified analysis. PMS from sex-stratified analysis outperformed that from sex-adjusted analysis in predicting schizophrenia. Notably, PMSs from the sex-stratified and female-only analyses, but not those from sex-adjusted or the male-only analyses, significantly predicted schizophrenia in males. The findings suggest that sex-stratified EWAS meta-analyses improve the identification of schizophrenia-associated epigenetic changes and highlight an interaction between sex and schizophrenia status on DNA methylation. Sex-specific DNA methylation may have potential implications for precision psychiatry and the development of stratified treatments for schizophrenia.

Neurological Complications of Cannabinoids

Cannabinoid use, particularly for recreational purposes, is increasing exponentially across all age groups, especially in younger populations, due to its perceived low risk and legalization. While cannabinoids may be largely considered as safe, there is mounting evidence of increased risk of systemic and neurological complications through their interaction with the poorly understood endocannabinoid receptor network within the central nervous system and other organ systems. Acute cannabinoid exposure can cause neuropsychiatric symptoms in addition to altering cerebral blood flow, leading to cerebrovascular complications such as ischemic stroke, subarachnoid hemorrhage, and reversible cerebral vasoconstriction syndrome (RCVS). Chronic use, particularly among adolescents, may be associated with increased risk of long-term cognitive deficits, schizophrenia, and other neuropsychiatric effects. Synthetic cannabinoids have increased potency, with reports of causing profound neurological complications including coma, seizures, posterior reversible encephalopathy syndrome, and RCVS. Despite increasing evidence, the quality of literature describing neurologic complications with cannabinoids remains limited to case series and retrospective cohort studies, with significant confounding factors such as concomitant use of other illicit drugs, limiting interpretation. In this review, we summarize the effect of cannabinoids on the neurologic system and associated neurological complications.

Association between cannabis potency and mental health in adolescence

INTRODUCTION

In legal and illegal markets, high-potency cannabis (>10 % delta-9-tetrahydrocannabinol (THC)) is increasingly available. In adult samples higher-potency cannabis has been associated with mental health disorder but no studies have considered associations in adolescence.

METHODS

A population-wide study compared no, low and high potency cannabis using adolescents (aged 13-14 years) self-reported symptoms of probable depression, anxiety, and auditory hallucinations.

RESULTS

Of the 6672 participants, high-potency cannabis was used by 2.6 % (n=171) and low-potency by 0.6 % (n=38). After adjustment for sociodemographic factors, tobacco and alcohol use, in comparison to participants who had never used cannabis, people who had used high-potency but not low-potency cannabis were more likely to report symptoms of depression (odds ratio 1.59 [95 % confidence interval 1.06, 2.39), anxiety (OR 1.45, 95 % CI 0.96, 2.20), and auditory hallucinations (OR 1.56, 95 % CI 0.98, 2.47).

CONCLUSIONS

High-potency cannabis use is associated with an increased risk of probable mental health disorders. Services and programming to minimise drug harms may need to be adapted to pay more attention to cannabis potency.

Acceptability, feasibility and fidelity of the culturally adapted version of Unplugged ("Yo Se Lo Que Quiero"), a substance use preventive program among adolescents in Chile: a pilot randomized controlled study

INTRODUCTION

The consumption of alcohol, tobacco, and cannabis is a public health problem that impacts the cognitive, social, and emotional development of adolescents. Prevention strategies such as the "Unplugged" program are effective in delaying the progression of daily smoking and episodes of drunkenness among adolescents. "Yo Se Lo Que Quiero" (YSLQQ) corresponds to the adaptation of this program to the Chilean context. This study assesses the acceptability and feasibility of implementing this program to the local reality.

MATERIAL AND METHODS

This was a cluster-randomized controlled pilot study conducted on six public schools. All consented students attending 6th, 7th, and 8th grades (n = 1,180) participated in the study. The schools were randomly assigned to one of two conditions in a 1:1 ratio: (1) the "YSLQQ" intervention group (n = 526), and (2) the Control group (n = 654). The program consisted of a 12-hour class-based curriculum based on a comprehensive social-influence approach delivered by a trained facilitator. The acceptability and feasibility were assessed in the intervention group at the end of the intervention using questionnaires answered by students and facilitators. The quality and fidelity of the program were evaluated during the implementation using self-ported surveys answered by the facilitators and the assessment of video-recorded sessions rated by external observers. Finally, a pre-test and a post-test survey assessing past and current substance use and risk and protective factors were conducted before and immediately after the program's implementation.

RESULTS

A high proportion of students (49.6%) liked the sessions. 79.2% reported that the YSLQQ helped them learn about the dangers of substances, while 65.8% reported having more skills to avoid substance use in the future. Regarding students' satisfaction with YSLQQ, 62.9% reported being happy or very happy with the program. Facilitators reported implementing the intervention according to the manual in 73.9% of sessions. Regarding substance use, students who participated in the intervention groups reported a significant reduction in drunkenness in the last year and last 30-day prevalence and also a significant reduction in a lifetime and 30-day prevalence of cannabis use when compared with those students in the control group.

CONCLUSIONS

Our results suggest that YSLQQ has adequate acceptability and feasibility to be implemented in the Chilean context, and there were promising results in reducing drunkenness and cannabis use. Future research should confirm these results in a larger RCT study.

TRIAL REGISTRATION

The trial was registered in ClinicalTrials.gov, NCT04566627; registration date: 01/03/2019.

Characterization of Cannabis users and products and the experience of negative mental emotions following Cannabis use

There is a potential link between cannabis and mental disorders. Cannabis exposure involves in many cases negative mental emotions, which are unpleasant sensations or thoughts. Whereas mild cases of negative mental emotions inflict patient's quality of life, more severe cases lead to therapy discontinuations, or even hospitalizations and death. This study characterizes cannabis users who experienced negative mental emotions after cannabis exposure. The Releaf App database was utilized to evaluate the association between personal and cannabis use characteristics on reporting a negative mental emotion during cannabis exposure. This global mobile lets individuals track real-time cannabis experience use with cannabinoid-based products, containing data points such as gender, age, reasons for use, product type, cannabis composition, and feelings and emotions experienced after cannabis use. Multivariable logistic regression models were constructed, adjusting for potential confounders such as gender and previous experience with cannabis use. The study population comprised 4,435 users, and 34,279 sessions were collected from various countries, mainly from North America, and included in the primary analysis. Reporting on negative mental emotions was associated with users in the age group of 18-30 years. Using cannabis for a mental purpose was associated with a small increase in reporting on negative mental emotions (OR = 1.10, 95%CI [1.03-1.19]). Oral products were associated with reporting on negative mental emotions. THC-dominant products were associated with reporting negative mental emotions compared to balanced products (OR = 1.21, 95%CI [1.06-1.38]). This study suggests that some characteristics of cannabis use, such as young age and oral consumption are associated with negative mental emotions. Further studies should examine the interface between cannabis consumption, characteristics of consumers, and negative emotional experience or even long-term mental disorders.

Assessing rates and predictors of cannabis-associated psychotic symptoms across observational, experimental and medical research

Cannabis, one of the most widely used psychoactive substances worldwide, can give rise to acute cannabis-associated psychotic symptoms (CAPS). While distinct study designs have been used to examine CAPS, an overarching synthesis of the existing findings has not yet been carried forward. To that end, we quantitatively pooled the evidence on rates and predictors of CAPS (k = 162 studies, n = 210,283 cannabis-exposed individuals) as studied in (1) observational research, (2) experimental tetrahydrocannabinol (THC) studies, and (3) medicinal cannabis research. We found that rates of CAPS varied substantially across the study designs, given the high rates reported by observational and experimental research (19% and 21%, respectively) but not medicinal cannabis studies (2%). CAPS was predicted by THC administration (for example, single dose, Cohen's d = 0.7), mental health liabilities (for example, bipolar disorder, d = 0.8), dopamine activity (d = 0.4), younger age (d = -0.2), and female gender (d = -0.09). Neither candidate genes (for example, COMT, AKT1) nor other demographic variables (for example, education) predicted CAPS in meta-analytical models. The results reinforce the need to more closely monitor adverse cannabis-related outcomes in vulnerable individuals as these individuals may benefit most from harm-reduction efforts.

Cannabis use disorder and perioperative outcomes following complex cancer surgery

INTRODUCTION

Cannabis usage is increasing in the United States, especially among patients with cancer. We sought to evaluate whether cannabis use disorder (CUD) was associated with higher morbidity and mortality among patients undergoing complex cancer surgery.

METHODS

Patients who underwent complex cancer surgery between January 2016 and December 2019 were identified in the National Inpatient Sample database. CUD was defined according to ICD-10 codes. Propensity score matching was performed to create a 1:1 matched cohort that was well balanced with respect to covariates, which included patient comorbidities, sociodemographic factors, and procedure type. The primary composite outcome was in-hospital mortality and seven major perioperative complications (myocardial ischemia, acute kidney injury, stroke, respiratory failure, venous thromboembolism, hospital-acquired infection, and surgical procedure-related complications).

RESULTS

Among 15 014 patients who underwent a high-risk surgical procedure, a cohort of 7507 patients with CUD (median age; 43 years [IQR: 30-56 years]; n = 3078 [41.0%] female) were matched with 7507 patients who were not cannabis users (median age; 44 years [IQR: 30-58 years); n = 2997 [39.9%] female). CUD was associated with slight increased risk relative to postoperative kidney injury (CUD, 7.8% vs. no CUD, 6.1%); however, in-hospital mortality was slightly lower (CUD, 0.9% vs. no CUD, 1.6%) (both p < 0.001). On multivariable analysis, after controlling for other risk factors, CUD was not associated with higher morbidity and mortality (adjusted odds ratio: 1.06, 95% CI: 0.98-1.15; p = 0.158).

CONCLUSION

CUD was not associated with a higher risk of postoperative morbidity and mortality following complex cancer surgery.

Alcohol and cannabis use and co-use among Whites and Hispanics on and off the U.S./Mexico border in California

This paper examines self-reported rates of drinking and cannabis use and co-use among White and Hispanic adults randomly selected in four counties in California: Imperial on the border; and Kern, Tulare, and Madera in California's Central Valley. Co-use was significantly higher among the U.S. born than among those born abroad, and in the Central Valley than on the border. Co-users were heavier drinkers, had higher rates of alcohol use disorder, other alcohol problems, and a positive history of illicit drug use than drinkers only.

Applying machine learning to international drug monitoring: classifying cannabis resin collected in Europe using cannabinoid concentrations

In Europe, concentrations of ∆9-tetrahydrocannabinol (THC) in cannabis resin (also known as hash) have risen markedly in the past decade, potentially increasing risks of mental health disorders. Current approaches to international drug monitoring cannot distinguish between different types of cannabis resin which may have contrasting health effects due to THC and cannabidiol (CBD) content. Here, we compared concentrations of THC and CBD in different types of cannabis resin collected in Europe (either Moroccan-type, or Dutch-type). We then tested the ability of machine learning algorithms to classify the type of cannabis resin (either Moroccan-type, or Dutch-type) using routinely collected monitoring data on THC and CBD. Finally, we applied the optimal algorithm to new samples collected in countries where the type of cannabis resin was unknown, the UK and Denmark. Results showed that overall, Dutch-type samples had higher THC (Hedges' g = 2.39) and lower CBD (Hedges' g = 0.81) than Moroccan-type samples. A Support Vector Machine algorithm achieved classification accuracy exceeding 95%, with little variation in this estimate, good interpretability, and plausibility. It made contrasting predictions about the type of cannabis resin collected in the UK (94% Moroccan-type; 6% Dutch-type) and Denmark (36% Moroccan-type; 64% Dutch-type). In conclusion, we provide proof-of-concept evidence for the potential of machine learning to inform international drug monitoring. Our findings should not be interpreted as objective confirmatory evidence but suggest that Dutch-type cannabis resin has higher THC concentrations than Moroccan-type cannabis resin, which may contribute to variation in drug markets and health outcomes for people who use cannabis in Europe.

Understanding Pharmacy Students' Preparedness towards Counseling over Cannabis Use Disorder

The rise in cannabis use prompts significant concerns regarding pharmacy students' abilities to counsel patients over cannabis use disorder. This study aims to understand pharmacy students' preparedness to counsel patients with cannabis use disorder (CUD) and evaluate the relationship between knowledge, attitudes towards medical cannabis (MC) and recreational cannabis (RC), and behavior intention (BI) to counsel over CUD. A cross-sectional survey was administered to pharmacy students. Descriptive analyses of sample characteristics were assessed with the t-test and one-way ANOVA test. Pearson correlation and linear regression were conducted, measuring the strength and direction of relationships. The average scores for knowledge, attitudes towards MC use and RC, and behavioral intention were 81% (SD 16%), 4.13 (SD 0.75), 3.28 (0.80), and 2.74 (1.00). Significant correlations were observed between knowledge-attitudes toward MC, knowledge-attitudes towards RC, and attitudes towards RC-behavioral intentions. Linear regression indicated attitudes towards MC use and RC, academic year, awareness of MC use legality, obtained knowledge, and past patient interaction were significantly associated with behavioral intention on confidence in counseling over CUD. There is a gap in students' behavioral intention to counsel. These findings emphasize the importance of ample preparation that enables student pharmacists to address patient needs related to cannabis use confidently.

Development and initial validation of the cannabis-related psychosis risk literacy scale (CPRL): a multinational psychometric study

BACKGROUND

Public education efforts to address and reduce potential harms from cannabis use in Arab countries are either slow or inexistent, and do not follow the steadily increasing trends of cannabis use in Arab youth. Several decades of research on substance use, it can be suggested that being aware of, and knowing about, psychosis risk related to cannabis can at least limit the consumption of the substance. Motivated by a lack of measures specifically designed to measure literacy about cannabis-related psychosis risk in younger populations, and based on an extensive literature review, we aimed to create and validate a new self-report scale to assess the construct, the Cannabis-related Psychosis Risk Literacy Scale (CPRL), in the Arabic language.

METHOD

A cross-sectional study was carried-out during the period from September 2022 to June 2023, enrolling 1855 university students (mean age of 23.26 ± 4.96, 75.6% females) from three Arab countries (Egypt, Kuwait and Tunisia).

RESULTS

Starting from an initial pool of 20 items, both Exploratory Factor Analysis and Confirmatory Factor Analysis suggested that the remaining 8 items loaded into a single factor. The scale demonstrated good internal consistency, with both McDonald omega and Cronbach's alpha values exceeding 0.7 (omega = 0.85 / alpha = 0.85). The CPRL showed measurement invariance across gender and country at the configural, metric, and scalar levels. Concurrent validity of the CPRL was established by correlations with less favourable attitudes towards cannabis (r = -.14; p <.001). In addition, higher literacy levels were found in students who never used cannabis compared to lifetime users (4.18 ± 1.55 vs. 3.44 ± 1.20, t(1853) = 8.152, p <.001).

CONCLUSION

The newly developed CPRL scale offers a valid and reliable instrument for assessing and better understanding literacy about cannabis-related psychosis risk among Arabic-speaking young adults. We believe that this new scale is suitable as a screening tool of literacy, as an instrument for measuring the effect of public education interventions aimed at promoting cannabis-related psychosis risk literacy among young people, and as a research tool to facilitate future studies on the topic with a wider application.

Marijuana and E-cigarette Initiation Among Adolescents: A Survival Analysis

PURPOSE

Prior literature suggests marijuana and e-cigarette initiation among adolescents is surpassing combustible cigarette uptake. Marijuana and nicotine co-use is also a concern as these products grow in popularity. Initiation trajectories for marijuana and e-cigarette products are not well understood, let alone how the use of one product may impact initiation susceptibility for the other.

METHODS

We used national longitudinal data from the Population Assessment of Tobacco and Health study from 2013 to 2018. Eighth graders in Wave 1 made up the analytic sample (N = 2,270). We employed discrete time survival analyses to determine the likelihood of initiating marijuana and e-cigarettes between Waves 2 and 5. We used survival analyses to estimate the relationships between prior cigarette and marijuana use and subsequent e-cigarette initiation, as well as prior cigarette and e-cigarette use and subsequent marijuana initiation.

RESULTS

Previous marijuana initiation was associated with later e-cigarette initiation (odds ratio = 6.88, 95% confidence interval [4.89, 9.67]). Previous e-cigarette initiation was associated with later marijuana initiation (odds ratio = 9.28, 95% confidence interval [6.86, 12.56]). By wave 5, adolescents were more than 42% likely to initiate marijuana and e-cigarettes.

DISCUSSION

Susceptibility to marijuana and e-cigarette products starts as early as eighth grade and increases over time. The use of one product is significantly related to later initiation for the other. Rather than addressing marijuana and nicotine as separate concerns, interventions may benefit by recognizing the closely related nature of these products.

Cannabis Use in Adolescent and Young Adult Athletes: A Clinical Review

CONTEXT

Cannabis use among the general population has increased over time, in part due to decriminalization of use and greater social acceptance of cannabis use. These changes have contributed to increased availability of cannabis products, thus raising the likelihood that a subset of adolescent and young adult athletes will use cannabis. Therefore, it is imperative that clinicians and other providers working with young athletes have a thorough understanding of the impact cannabis can have on the athletic performance and overall health of a young athlete.

EVIDENCE ACQUISITION

PubMed (Medline), CINAHL, PsycINFO, and SportDiscus databases were used to perform a literature search of articles published between January 1, 2010 and December 31, 2022. Additional articles were reviewed based on references obtained from initial articles.

STUDY DESIGN

Clinical review.

LEVEL OF EVIDENCE

Level 4.

RESULTS

Survey studies suggest that up to 1 in 4 athletes have used cannabis at least once in the last year. Age, sex, race, sexual orientation, level of competition, and country of residence of an athlete all contribute to differing rates of cannabis use among athletes. The scientific literature does not support using cannabis for athletic performance, and multiple studies have demonstrated notable impairments in objective athletic performance measures. Cannabis use can also negatively impact an athlete's overall health via cardiovascular, gastrointestinal, and mental health symptoms and disorders.

CONCLUSION

Cannabis use among adolescent and young adult athletes is common, and rates of use are influenced by many different factors. Current evidence suggests that cannabis use can worsen sport performance, negatively impact an athlete's general health, and contribute to negative mental health outcomes.

The impact of recreational cannabis legalization on youth: the Colorado experience

Over the past two decades, cannabis policies have liberalized in the United States, culminating in the legalization of recreational cannabis in Colorado and Washington state in 2012. This review will focus on the impact of recreational cannabis legalization in Colorado. While the prevalence of past-year and past-month cannabis use has remained relatively steady among adolescents post-legalization, the prevalence of young adult use has continued to rise. Cannabis products with increased potency have become more prevalent and widely used. There are concerns that the use of products with increased potency will increase risk for cannabis use and comorbid mental health disorders, particularly cannabis-induced psychosis and suicidal behavior, although more research is needed to fully understand the impact of high-potency products. Since the legalization of recreational cannabis, numerous additional public health concerns have emerged: unintentional overdoses requiring acute care visits, electronic vaping-associated lung injury, increased motor vehicle collisions related to cannabis consumption, and higher rates of cannabis use during pregnancy. Lessons learned from the first decade of cannabis legalization emphasize the need for research efforts to provide evidence-based guidelines, inform prevention strategies, and implement selective interventions for at-risk populations including youth, individuals with comorbid mental health disorders, and individuals who are pregnant.

Opinions of French psychiatrists on the regulatory status of cannabis: Results from the "PsyCan - Encéphale" national online survey

OBJECTIVE

To explore the opinions of French psychiatrists toward the legalization of medical or recreational use of cannabis in France.

METHODS

Psycan was an anonymous Internet survey conducted between September 28, 2021 and March 29, 2022, among subscribers of the Encéphale Online community, i.e., approximately 4000 French psychiatrists. Participants were asked to complete a structured questionnaire, collecting their socio-demographic features, clinical experience, opinions toward cannabis legalization, and perceived impact of cannabis derivatives for psychiatric disorders. Logistic regression models were used to identify factors associated with being for or against cannabis legalization.

RESULTS

In total, 413 psychiatrists answered the survey, of whom 253 (61.3%) declared being in favour of recreational cannabis, and 349 (84.4%) of medical cannabis. Being in favour of legalization of recreational cannabis was negatively associated with being female (odd ratio [OR]=0.61; 95% confidence interval [CI]=0.41-0.93), and with the frequency of meeting patients with cannabis use disorder (OR=0.60; 95%CI=0.43-0.83). Most respondents were concerned about the development of psychotic disorders. The most frequent pro-legalization arguments were improved prevention, better control of product content, and better protection of youth, respectively. Arguments against legalization were increased societal damages, increased impact on health, including mental health.

CONCLUSIONS

A majority of French psychiatrists were in favour of the marketing of medical cannabis, and, to a lesser extent, the legalization of recreational cannabis. For recreational cannabis, the proportion of pro-legalization psychiatrists was slightly more elevated than that found in the French general population.

The Relationship between Vaping Cannabis and Frequency of Cannabis Use and Cannabis-Related Problems among Urban High School Students

Background: Vaping, including vaping cannabis, is increasing among adolescents. In this longitudinal study, we examined the relationship between vaping cannabis and frequency of cannabis use and related problems over 6 months among adolescents. Material and Methods: Data were from 233 participants (46.8% male, 93.1% African American, mean age = 16.4 years) reporting cannabis use. The Alcohol, Smoking and Substance Involvement Screening Test (ASSIST) assessed frequency of past 30-day cannabis use and cannabis-related problems at baseline, 3- and 6-months post-baseline. We used latent growth curve modeling to compare vaping to non-vaping adolescents on trends in cannabis use frequency and ASSIST cannabis scores. Results: Adolescents who vaped cannabis (11.7%) had higher past 30-day frequency (mean = 17.89 days, SD = 10.49) of cannabis use at baseline compared to adolescents who had not vaped (mean = 12.1 days, SD = 10.93), but reported a significantly sharper decline in frequency of cannabis use (b = -0.34, p = 0.017). A significantly steeper decrease existed in the mean cannabis ASSIST scores for the vaping group than for the non-vaping group (b = -0.34, p = 0.014). Mean ASSIST scores on the cannabis subscale between the two groups were significantly different at 6-month follow-up (Vape mean = 6.00, SD = 8.12 vs. Non-vape mean = 9.6, SD = 9.39; p < 0.021). Conclusions: In a sample of cannabis-using adolescents, adolescents with experience vaping cannabis, compared to adolescents without vaping experience, on average reported sharper decreases in frequency of cannabis use and cannabis-related problems such as health or social problems.

Cross-ancestry genetic investigation of schizophrenia, cannabis use disorder, and tobacco smoking

Individuals with schizophrenia frequently experience co-occurring substance use, including tobacco smoking and heavy cannabis use, and substance use disorders. There is interest in understanding the extent to which these relationships are causal, and to what extent shared genetic factors play a role. We explored the relationships between schizophrenia (Scz), cannabis use disorder (CanUD), and ever-regular tobacco smoking (Smk) using the largest available genome-wide studies of these phenotypes in individuals of African and European ancestries. All three phenotypes were positively genetically correlated (rgs = 0.17 - 0.62). Causal inference analyses suggested the presence of horizontal pleiotropy, but evidence for bidirectional causal relationships was also found between all three phenotypes even after correcting for horizontal pleiotropy. We identified 439 pleiotropic loci in the European ancestry data, 150 of which were novel (i.e., not genome-wide significant in the original studies). Of these pleiotropic loci, 202 had lead variants which showed convergent effects (i.e., same direction of effect) on Scz, CanUD, and Smk. Genetic variants convergent across all three phenotypes showed strong genetic correlations with risk-taking, executive function, and several mental health conditions. Our results suggest that both horizontal pleiotropy and causal mechanisms may play a role in the relationship between CanUD, Smk, and Scz, but longitudinal, prospective studies are needed to confirm a causal relationship.

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.

Stress, Environment and Early Psychosis

Existing literature provides extended evidence of the close relationship between stress dysregulation, environmental insults, and psychosis onset. Early stress can sensitize genetically vulnerable individuals to future stress, modifying their risk for developing psychotic phenomena. Neurobiological substrate of the aberrant stress response to hypothalamic-pituitary-adrenal axis dysregulation, disrupted inflammation processes, oxidative stress increase, gut dysbiosis, and altered brain signaling, provides mechanistic links between environmental risk factors and the development of psychotic symptoms. Early-life and later-life exposures may act directly, accumulatively, and repeatedly during critical neurodevelopmental time windows. Environmental hazards, such as pre- and perinatal complications, traumatic experiences, psychosocial stressors, and cannabis use might negatively intervene with brain developmental trajectories and disturb the balance of important stress systems, which act together with recent life events to push the individual over the threshold for the manifestation of psychosis. The current review presents the dynamic and complex relationship between stress, environment, and psychosis onset, attempting to provide an insight into potentially modifiable factors, enhancing resilience and possibly influencing individual psychosis liability.

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.

Using Task-fMRI to Explore the Relationship Between Lifetime Cannabis Use and Cognitive Control in Individuals With First-Episode Schizophrenia

While continued cannabis use and misuse in individuals with schizophrenia is associated with a variety of negative outcomes, individuals with a history of use tend to show higher cognitive performance compared to non-users. While this is replicated in the literature, few studies have used task-based functional magnetic resonance imaging (fMRI) to evaluate whether the brain networks underpinning these cognitive features are similarly impacted. Forty-eight first-episode individuals with schizophrenia (FES) with a history of cannabis use (FES + CAN), 28 FES individuals with no history of cannabis use (FES-CAN), and 59 controls (CON) performed the AX-Continuous Performance Task during fMRI. FES+CAN showed higher cognitive control performance (d'-context) compared to FES-CAN (P < .05, ηp 2 = 0.053), and both FES+CAN (P < .05, ηp 2 = 0.049) and FES-CAN (P < .001, ηp 2 = 0.216) showed lower performance compared to CON. FES+CAN (P < .05, ηp 2 = 0.055) and CON (P < 0.05, ηp 2 = 0.058) showed higher dorsolateral prefrontal cortex (DLPFC) activation during the task compared to FES-CAN, while FES+CAN and CON were not significantly different. Within the FES+CAN group, the younger age of initiation of cannabis use was associated with lower IQ and lower global functioning. More frequent use was also associated with higher reality distortion symptoms at the time of the scan. These data are consistent with previous literature suggesting that individuals with schizophrenia and a history of cannabis use have higher cognitive control performance. For the first time, we also reveal that FES+CAN have higher DLPFC brain activity during cognitive control compared to FES-CAN. Several possible explanations for these findings are discussed.

Current evidence and opportunities in child and adolescent public mental health: a research review

BACKGROUND

A public mental health lens is increasingly required to better understand the complex and multifactorial influences of interpersonal, community and institutional systems on the mental health of children and adolescents.

METHODS

This research review (1) provides an overview of public mental health and proposes a new interactional schema that can guide research and practice, (2) summarises recent evidence on public mental health interventions for children and adolescents, (3) highlights current challenges for this population that might benefit from additional attention and (4) discusses methodological and conceptual hurdles and proposes potential solutions.

RESULTS

In our evidence review, a broad range of universal, selective and indicated interventions with a variety of targets, mechanisms and settings were identified, some of which (most notably parenting programmes and various school-based interventions) have demonstrated small-to-modest positive effects. Few, however, have achieved sustained mental health improvements.

CONCLUSIONS

There is an opportunity to re-think how public mental health interventions are designed, evaluated and implemented. Deliberate design, encompassing careful consideration of the aims and population-level impacts of interventions, complemented by measurement that embraces complexity through more in-depth characterisation, or 'phenotyping', of interpersonal and environmental elements is needed. Opportunities to improve child and adolescent mental health outcomes are gaining unprecedented momentum. Innovative new methodology, heightened public awareness, institutional interest and supportive funding can enable enhanced study of public mental health that does not shy away from complexity.

Effects of the Acute and Chronic Administration of Cannabidiol on Cognition in Humans and Animals: A Systematic Review

Introduction: The effects of cannabidiol (CBD) on cognition has been investigated in recent years to determine the therapeutic potential of this cannabinoid for a broad gamut of medical conditions, including neuropsychiatric disorders. The aim of the present study was to perform a systematic review of studies that analyzed the effects of the acute and chronic administration of CBD on cognition in humans and animals both to assess the cognitive safety of CBD and to determine a beneficial potential of CBD on cognition. Methods: The PubMed, Web of Science, PsycINFO, and Scopus databases were searched in December of 2022 for relevant articles using the following combinations of keywords: ("cannabidiol" OR "CBD") AND ("cognition" OR "processing cognitive" OR "memory" OR "language" OR "attention" OR "executive function" OR "social cognition" OR "perceptual motor ability" OR "processing speed"). Results: Fifty-nine articles were included in the present review (36 preclinical and 23 clinical trials). CBD seems not to have any negative effect on cognitive processing in rats. The clinical trials confirmed these findings in humans. One study found that repeated dosing with CBD may improve cognitive in people who use cannabis heavily but not individuals with neuropsychiatric disorders. Considering the context of neuropsychiatric disorders in animal models, CBD seems to reverse the harm caused by the experimental paradigms, such that the performance of these animals becomes similar to that of control animals. Conclusions: The results demonstrate that the chronic and acute administration of CBD seems not to impair cognition in humans without neuropsychiatric disorders. In addition, preclinical studies report promising results regarding the effects of CBD on the cognitive processing of animals. Future double-blind, placebo-controlled, randomized clinical trials with larger, less selective samples, with standardized tests, and using different doses of CBD in outpatients are of particular interest to elucidate the cognitive effects of CBD.

Cannabis as a Source of Approved Drugs: A New Look at an Old Problem

Cannabis plants have been used in medicine since ancient times. They are well known for their anti-diabetic, anti-inflammatory, neuroprotective, anti-cancer, anti-oxidative, anti-microbial, anti-viral, and anti-fungal activities. A growing body of evidence indicates that targeting the endocannabinoid system and various other receptors with cannabinoid compounds holds great promise for addressing multiple medical conditions. There are two distinct avenues in the development of cannabinoid-based drugs. The first involves creating treatments directly based on the components of the cannabis plant. The second involves a singular molecule strategy, in which specific phytocannabinoids or newly discovered cannabinoids with therapeutic promise are pinpointed and synthesized for future pharmaceutical development and validation. Although the therapeutic potential of cannabis is enormous, few cannabis-related approved drugs exist, and this avenue warrants further investigation. With this in mind, we review here the medicinal properties of cannabis, its phytochemicals, approved drugs of natural and synthetic origin, pitfalls on the way to the widespread clinical use of cannabis, and additional applications of cannabis-related products.

Cannabis use and psychotic disorders in diverse settings in the Global South: findings from INTREPID II

BACKGROUND

Cannabis use has been linked to psychotic disorders but this association has been primarily observed in the Global North. This study investigates patterns of cannabis use and associations with psychoses in three Global South (regions within Latin America, Asia, Africa and Oceania) settings.

METHODS

Case-control study within the International Programme of Research on Psychotic Disorders (INTREPID) II conducted between May 2018 and September 2020. In each setting, we recruited over 200 individuals with an untreated psychosis and individually-matched controls (Kancheepuram India; Ibadan, Nigeria; northern Trinidad). Controls, with no past or current psychotic disorder, were individually-matched to cases by 5-year age group, sex and neighbourhood. Presence of psychotic disorder assessed using the Schedules for Clinical Assessment in Neuropsychiatry and cannabis exposure measured by the World Health Organisation Alcohol, Smoking and Substance Involvement Screening Test (ASSIST).

RESULTS

Cases reported higher lifetime and frequent cannabis use than controls in each setting. In Trinidad, cannabis use was associated with increased odds of psychotic disorder: lifetime cannabis use (adj. OR 1.58, 95% CI 0.99-2.53); frequent cannabis use (adj. OR 1.99, 95% CI 1.10-3.60); cannabis dependency (as measured by high ASSIST score) (adj. OR 4.70, 95% CI 1.77-12.47), early age of first use (adj. OR 1.83, 95% CI 1.03-3.27). Cannabis use in the other two settings was too rare to examine associations.

CONCLUSIONS

In line with previous studies, we found associations between cannabis use and the occurrence and age of onset of psychoses in Trinidad. These findings have implications for strategies for prevention of psychosis.

The association between reasons for first using cannabis, later pattern of use, and risk of first-episode psychosis: the EU-GEI case-control study

BACKGROUND

While cannabis use is a well-established risk factor for psychosis, little is known about any association between reasons for first using cannabis (RFUC) and later patterns of use and risk of psychosis.

METHODS

We used data from 11 sites of the multicentre European Gene-Environment Interaction (EU-GEI) case-control study. 558 first-episode psychosis patients (FEPp) and 567 population controls who had used cannabis and reported their RFUC.We ran logistic regressions to examine whether RFUC were associated with first-episode psychosis (FEP) case-control status. Path analysis then examined the relationship between RFUC, subsequent patterns of cannabis use, and case-control status.

RESULTS

Controls (86.1%) and FEPp (75.63%) were most likely to report 'because of friends' as their most common RFUC. However, 20.1% of FEPp compared to 5.8% of controls reported: 'to feel better' as their RFUC (χ2 = 50.97; p < 0.001). RFUC 'to feel better' was associated with being a FEPp (OR 1.74; 95% CI 1.03-2.95) while RFUC 'with friends' was associated with being a control (OR 0.56; 95% CI 0.37-0.83). The path model indicated an association between RFUC 'to feel better' with heavy cannabis use and with FEPp-control status.

CONCLUSIONS

Both FEPp and controls usually started using cannabis with their friends, but more patients than controls had begun to use 'to feel better'. People who reported their reason for first using cannabis to 'feel better' were more likely to progress to heavy use and develop a psychotic disorder than those reporting 'because of friends'.

A brain imaging study of dopamine receptor D2 availability in cannabis dependent users after recovery from cannabis-induced psychosis

There is increased risk of psychosis associated with cannabis use disorder and the interaction of THC with dopamine neurotransmission is complex. It is important to investigate the recovery from cannabis-induced psychosis and its effects on the brain's dopamine neurotransmission. This study was to evaluate dopamine receptor D2 availability in the striatum (caudate/putamen) in recently abstinent cannabis dependent users after recovery from psychosis in comparison with abstinent MDMA "ecstasy" abusers and healthy control participants. Participants were eight abstinent ex cannabis-dependent users who were treated for cannabis-induced psychosis with anti-psychotic medication and psychosocial support for 4 months in an inpatient treatment center for drug users. They were compared with nine abstinent ex MDMA "ecstasy" abusers who received medication and psycho-social treatment for 4 months at the same treatment facility and eight healthy control participants. All participants were scanned with bolus and constant infusion of [123I] Iodobenzamide (IBZM) in Single Photon Computed Tomography (SPECT). Cannabis abstinent users who were treated for cannabis-induced psychotic episodes showed no difference in dopamine D2 receptor availability in the caudate compared with abstinent MDMA "ecstasy" abusers and healthy control participants. This finding indicates minimal effects of cannabis-induced psychosis on dopamine reward mechanisms. There is evidence for reduced D2 receptor availability measures in the right putamen (uncorrected) which may indicate a residual effect of anti-psychotic medication.

Delta-9-Tetrahydrocannabinol, Cannabidiol, and Acute Psychotomimetic States: A Balancing Act of the Principal Phyto-Cannabinoids on Human Brain and Behavior

Background: THC and CBD are the principal phyto-cannabinoids in the cannabis plant. The differential and possibly antagonistic effects of these compounds on specific brain and behavioral responses, and the mechanisms underlying their effects have generated extensive interest in pre-clinical and clinical neuroscience investigations. Methods: In this double-blind randomized placebo-controlled counterbalanced Human Laboratory Study, we examined the effects of three different dose ratios of CBD:THC (1:1, 2:1, and 3:1) on "neural noise," an electrophysiological biomarker of psychosis known to be sensitive to cannabinoids as well as subjective and psychotomimetic effects. Healthy volunteers (n=28, 12 women) with at least one prior exposure to cannabis participated in the study. Outcomes: The lowest CBD (2.5 mg):THC (0.035 mg/kg) ratio (1:1) resulted in maximal attenuation of both THC-induced psychotomimetic effects (Positive and Negative Syndrome Scale [PANSS] positive: Anova Type Statistic [ATS]=7.83, pcorrected=0.015) and neural noise (ATS=8.83, pcorrected=0.009). Further addition of CBD did not reduce the subjective experience of THC-induced "high" (p>0.05 for all CBD doses). Interpretation: These novel results demonstrate that CBD attenuates specific THC-induced subjective and objective effects relevant to psychosis in a dose/ratio-dependent manner. Given the increasing global trend of cannabis liberalization and application for medical indications, these results assume considerable significance given the potential dose-related interactions of these key phyto-cannabinoids. Trial registration: The trial was registered in clinicaltrials.gov ID: NCT01180374.

Emerging adult perceptions of higher-risk cannabis consumption behaviours

BACKGROUND

Emerging adults have the highest cannabis consumption rates in Canada and are among the most vulnerable to cannabis-related harms. Since certain cannabis consumption behaviours carry greater risks of harm, the Lower-Risk Cannabis Use Guidelines (LRCUG) provide harm reduction strategies. To address a critical gap in the literature, the current study examined emerging adults' awareness of the guidelines and perceptions of higher-risk cannabis consumption behaviours identified within the LRCUG.

METHODS

Emerging adults (N = 653) between the ages of 18-25 years were recruited from across Canada. Participants were presented with five vignettes depicting a character's cannabis consumption behaviours. Each vignette focused on a unique aspect of the character's consumption (frequency, polysubstance use, family history of mental illness, method of consumption, and potency). Participants were randomly assigned to one of three conditions within each of the five vignettes that were altered to capture varying levels of risk (e.g. weekly, almost daily, or daily consumption). Following each vignette, participants were asked to respond to four items relating to overall risk of harm, cognitive health, physical health, and mental health.

RESULTS

Participants perceived: (1) frequent consumption to be associated with greater risks than less frequent consumption; (2) simultaneous consumption of cannabis and tobacco as being associated with higher risk of harm, yet no difference between simultaneous consumption of cannabis and alcohol or cannabis consumption alone; (3) consuming cannabis with a family history of psychosis or substance use disorder as being associated with greater overall risk than consumption with no family history; (4) smoking and vaping cannabis as associated with more risk than ingesting edibles; and (5) higher-potency THC-dominant strains as being associated with more risk than lower-potency CBD-dominant strains, yet no difference between the two higher-potency THC-dominant strains.

CONCLUSIONS

While emerging adults seemed to appreciate the risks associated with some cannabis consumption behaviours, they had difficulty identifying appropriate levels of harm of other higher-risk behaviours. Through an improved understanding of emerging adult perceptions, effective education campaigns should be designed to improve the awareness of cannabis risks and encourage the uptake of harm reduction awareness and strategies.

Influence of cannabis use on incidence of psychosis in people at clinical high risk

AIMS

Evidence for case-control studies suggests that cannabis use is a risk factor for the development of psychosis. However, there have been limited prospective studies and the direction of this association remains controversial. The primary aim of the present study was to examine the association between cannabis use and the incidence of psychotic disorders in people at clinical high risk of psychosis. Secondary aims were to assess associations between cannabis use and the persistence of psychotic symptoms, and with functional outcome.

METHODS

Current and previous cannabis use were assessed in individuals at clinical high risk of psychosis (n = 334) and healthy controls (n = 67), using a modified version of the Cannabis Experience Questionnaire. Participants were assessed at baseline and followed up for 2 years. Transition to psychosis and persistence of psychotic symptoms were assessed using the Comprehensive Assessment of At-Risk Mental States criteria. Level of functioning at follow up was assessed using the Global Assessment of Functioning disability scale.

RESULTS

During follow up, 16.2% of the clinical high-risk sample developed psychosis. Of those who did not become psychotic, 51.4% had persistent symptoms and 48.6% were in remission. There was no significant association between any measure of cannabis use at baseline and either transition to psychosis, the persistence of symptoms, or functional outcome.

CONCLUSIONS

These findings contrast with epidemiological data that suggest that cannabis use increases the risk of psychotic disorder.

Annual incidence of substance-induced psychoses in Scandinavia from 2000 to 2016

BACKGROUND

Substance-induced psychosis (SIP) is a serious condition and may predispose for schizophrenia. We know too little about SIP incidence over time and across countries, including substance-specific SIPs. We estimated annual incidence rate of SIP in Denmark, Norway, and Sweden according to substance, age, gender, and socioeconomic background.

METHODS

Data were drawn from registries covering the whole adult population in the countries. Annual incidence rate per 100 000 persons of SIPs was estimated for Denmark and Sweden from 2000 to 2016 and for Norway from 2010 to 2015.

RESULTS

The annual incidence rate of any SIP fluctuated between 9.3 and 14.1. The most commonly occurring SIPs were those induced by alcohol, cannabis, amphetamines, and multiple substances. There was a steady decrease in the incidence rate of alcohol-induced psychosis from the first to the last year of the observation period in Denmark (from 4.9 to 1.5) and Sweden (from 4.5 to 2.2). The incidence rate of cannabis-induced psychosis increased in all countries, from 2.6 to 5.6 in Denmark, from 0.8 to 2.7 in Sweden, and from 1.8 to 3.0 in Norway. Median age of any SIP decreased in Denmark (from 36 to 29 years) and Sweden (from 41 to 31 years). Incidence rates were higher in men and in individuals on disability pension, and increased more among those with high parental education.

CONCLUSIONS

We found similar and stable incidence rates of any SIP in all Scandinavian countries through the observation period. The incidence of alcohol-induced psychosis decreased. The incidence of cannabis-induced psychosis increased.

Should oncologists trust cannabinoids?

Cannabis enjoyed a "golden age" as a medicinal product in the late 19th, early 20th century, but the increased risk of overdose and abuse led to its criminalization. However, the 21st century have witnessed a resurgence of interest and a large body of literature regarding the benefits of cannabinoids have emerged. As legalization and decriminalization have spread around the world, cancer patients are increasingly interested in the potential utility of cannabinoids. Although eager to discuss cannabis use with their oncologist, patients often find them to be reluctant, mainly because clinicians are still not convinced by the existing evidence-based data to guide their treatment plans. Physicians should prescribe cannabis only if a careful explanation can be provided and follow up response evaluation ensured, making it mandatory for them to be up to date with the positive and also negative aspects of the cannabis in the case of cancer patients. Consequently, this article aims to bring some clarifications to clinicians regarding the sometimes-confusing various nomenclature under which this plant is mentioned, current legislation and the existing evidence (both preclinical and clinical) for the utility of cannabinoids in cancer patients, for either palliation of the associated symptoms or even the potential antitumor effects that cannabinoids may have.

Review of Major Social Determinants of Health in Schizophrenia-Spectrum Psychotic Disorders: III. Biology

BACKGROUND

Social determinants of health (SDoHs) are nonmedical factors that significantly impact health and longevity. We found no published reviews on the biology of SDoHs in schizophrenia-spectrum psychotic disorders (SSPD).

STUDY DESIGN

We present an overview of pathophysiological mechanisms and neurobiological processes plausibly involved in the effects of major SDoHs on clinical outcomes in SSPD.

STUDY RESULTS

This review of the biology of SDoHs focuses on early-life adversities, poverty, social disconnection, discrimination including racism, migration, disadvantaged neighborhoods, and food insecurity. These factors interact with psychological and biological factors to increase the risk and worsen the course and prognosis of schizophrenia. Published studies on the topic are limited by cross-sectional design, variable clinical and biomarker assessments, heterogeneous methods, and a lack of control for confounding variables. Drawing on preclinical and clinical studies, we propose a biological framework to consider the likely pathogenesis. Putative systemic pathophysiological processes include epigenetics, allostatic load, accelerated aging with inflammation (inflammaging), and the microbiome. These processes affect neural structures, brain function, neurochemistry, and neuroplasticity, impacting the development of psychosis, quality of life, cognitive impairment, physical comorbidities, and premature mortality. Our model provides a framework for research that could lead to developing specific strategies for prevention and treatment of the risk factors and biological processes, thereby improving the quality of life and increasing the longevity of people with SSPD.

CONCLUSIONS

Biology of SDoHs in SSPD is an exciting area of research that points to innovative multidisciplinary team science for improving the course and prognosis of these serious psychiatric disorders.

Risk-thresholds for the association between frequency of cannabis use and the development of psychosis: a systematic review and meta-analysis

BACKGROUND

Epidemiological studies show a dose-response association between cannabis use and the risk of psychosis. This review aimed to determine whether there are identifiable risk-thresholds between the frequency of cannabis use and psychosis development.

METHODS

Systematic search of Embase, MEDLINE, PsycINFO, CINAHL, and Web of Science for relevant studies (1 January 2010-26 April 2021). Case-control or cohort studies that investigated the relationship between cannabis use and the risk of psychosis development that reported effect estimates [odds ratios (OR), hazard ratios (HR), risk ratios (RR)] or the raw data to calculate them, with information on the frequency of cannabis consumption were included. Effect estimates were extracted from individual studies and converted to RR. Two-stage dose-response multivariable meta-analytic models were utilized and sensitivity analyses conducted. The Newcastle Ottawa Scale was used to assess the risk of bias of included studies.

RESULTS

Ten original (three cohorts, seven case-control) studies were included, including 7390 participants with an age range of 12-65 years. Random-effect model meta-analyses showed a significant log-linear dose-response association between cannabis use frequency and psychosis development. A restricted cubic-splines model provided the best fit for the data, with the risk of psychosis significantly increasing for weekly or more frequent cannabis use [RR = 1.01, 95% confidence interval (CI) 0.93-1.11 yearly; RR = 1.10, 95% CI 0.97-1.25 monthly; RR = 1.35, 95% CI 1.19-1.52 weekly; RR = 1.76, 95% CI 1.47-2.12 daily].

CONCLUSION

Individuals using cannabis frequently are at increased risk of psychosis, with no significant risk associated with less frequent use. Public health prevention messages should convey these risk-thresholds, which should be refined through further work.

Transition From Substance-Induced Psychosis to Schizophrenia Spectrum Disorder or Bipolar Disorder

Objective: The authors investigated transitions to schizophrenia spectrum or bipolar disorder following different types of substance-induced psychosis and the impact of gender, age, number of emergency admissions related to substance-induced psychosis, and type of substance-induced psychosis on such transitions. Methods: All patients in the Norwegian Patient Registry with a diagnosis of substance-induced psychosis from 2010 to 2015 were included (N=3,187). The Kaplan-Meier method was used to estimate cumulative transition rates from substance-induced psychosis to either schizophrenia spectrum disorder or bipolar disorder. Cox proportional hazard regression was used to estimate hazard ratios for transitions to schizophrenia spectrum or bipolar disorders associated with gender, age, number of emergency admissions, and type of substance-induced psychosis. Results: The 6-year cumulative transition rate from substance-induced psychosis to schizophrenia spectrum disorder was 27.6% (95% CI=25.6–29.7). For men, the risk of transition was higher among younger individuals and those with either cannabis-induced psychosis or psychosis induced by multiple substances; for both genders, the risk of transition was higher among those with repeated emergency admissions related to substance-induced psychosis. The cumulative transition rate from substance-induced psychosis to bipolar disorder was 4.5% (95% CI=3.6–5.5), and the risk of this transition was higher for women than for men. Conclusions: Transition rates from substance-induced psychosis to schizophrenia spectrum disorder were six times higher than transition rates to bipolar disorder. Gender, age, number of emergency admissions, and type of substance-induced psychosis affected the risk of transition.

Associations Between Cannabis Use, Polygenic Liability for Schizophrenia, and Cannabis-related Experiences in a Sample of Cannabis Users

BACKGROUND AND HYPOTHESIS

Risk for cannabis use and schizophrenia is influenced in part by genetic factors, and there is evidence that genetic risk for schizophrenia is associated with subclinical psychotic-like experiences (PLEs). Few studies to date have examined whether genetic risk for schizophrenia is associated with cannabis-related PLEs.

STUDY DESIGN

We tested whether measures of cannabis involvement and polygenic risk scores (PRS) for schizophrenia were associated with self-reported cannabis-related experiences in a sample ascertained for alcohol use disorders (AUDs), the Collaborative Study on the Genetics of Alcoholism (COGA). We analyzed 4832 subjects (3128 of European ancestry and 1704 of African ancestry; 42% female; 74% meeting lifetime criteria for an AUD).

STUDY RESULTS

Cannabis use disorder (CUD) was prevalent in this analytic sample (70%), with 40% classified as mild, 25% as moderate, and 35% as severe. Polygenic risk for schizophrenia was positively associated with cannabis-related paranoia, feeling depressed or anhedonia, social withdrawal, and cognitive difficulties, even when controlling for duration of daily cannabis use, CUD, and age at first cannabis use. The schizophrenia PRS was most robustly associated with cannabis-related cognitive difficulties (β = 0.22, SE = 0.04, P = 5.2e-7). In an independent replication sample (N = 1446), associations between the schizophrenia PRS and cannabis-related experiences were in the expected direction and not statistically different in magnitude from those in the COGA sample.

CONCLUSIONS

Among individuals who regularly use cannabis, genetic liability for schizophrenia-even in those without clinical features-may increase the likelihood of reporting unusual experiences related to cannabis use.

Adult use of highly-potent Δ9-THC cannabis concentrate products by U.S. state cannabis legalization status, 2021

BACKGROUND

Compared to plant/flower cannabis products, cannabis concentrates have higher average potency of delta-9-tetrahydrocannabinol (Δ9-THC), which may be associated with greater likelihood of cannabis-related harms. Information on factors associated with use of cannabis concentrates is needed.

METHODS

Respondents were 4,328 adult past-7-day cannabis users from all 50 U.S. states and Washington DC (DC) who participated in an online 2021 survey. Using logistic regression to generate adjusted odds ratios (aOR), we investigated whether participants in states that enacted recreational cannabis laws (RCL, 12 states plus DC [treated as a state], n = 1,236) or medical cannabis laws (MCL-only, 23 states, n = 2,030) by December 31, 2020 were more likely than those in states without cannabis laws (no-CL, 15 states, n = 1,062) to use cannabis concentrate products in the prior 7 days.

RESULTS

Most participants (92.4%) used plant material in the prior 7 days; 57.0% used cannabis concentrates. In RCL, MCL and no-CL states, concentrate use was reported by 61.5%, 56.6%, and 52.5%, respectively. Compared to participants in no-CL states, odds of using cannabis concentrate products were greater among those in RCL states (aOR = 1.47; CI = 1.17-1.84) and MCL-only states (aOR = 1.29; CI = 1.08-1.55). Whether states had legally-authorized dispensaries had little effect on results.

CONCLUSION

Results suggest that individuals in MCL-only and RCL states are more likely to use cannabis concentrate products. Determining mechanisms underlying these results, e.g., commercialization, could provide important information for prevention. Clinicians should be alert to patient use of concentrates, especially in MCL-only and RCL states. Continued monitoring is warranted as additional states legalize cannabis use.

High potency cannabis use, mental health symptoms and cannabis dependence: Triangulating the evidence

BACKGROUND

Cannabis potency (concentration of Δ-9-Tetrahydrocannabinol) has been associated with risks of adverse mental health outcomes and addiction but no studies have triangulated evidence from self-report and objective measures of cannabis potency. We hypothesised that users of high potency cannabis would have higher levels of (a) anxiety, (b) depression and (c) psychosis-like symptoms (d) cannabis dependence than users of lower potency cannabis.

METHODS

A cross-sectional study of 410 participants donated a sample of cannabis for analysis of THC concentration and reported their cannabis potency preference. These two exposure measures were investigated for their association with cannabis dependence, depression, anxiety, and psychosis-like symptoms in separate linear/logistic regression models.

RESULTS

High potency cannabis preference was associated with a slight increased risk of cannabis dependence after adjusting for confounding, with the exception of cannabis use frequency (OR = 1.16, 95% CI 1.04-1.28). No association was found between THC concentration in cannabis and cannabis dependence. There was weak evidence of a small association between cannabis potency and depression and anxiety. There was no association between high potency cannabis preference or THC concentration in cannabis and psychosis-like symptoms.

CONCLUSIONS

Users of cannabis who preferred high potency types might be at increased risk of problematic cannabis use. This should be considered with caution as we were not able to triangulate these results with an objective measure of cannabis potency. More research is needed to understand the association between high potency cannabis use and depression and anxiety.

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.

From heavy cannabis use to psychosis: is it time to take action?

Cannabis is one of the most widely used recreational drugs among people with clinical psychosis, after nicotine and alcohol. There has been a debate in psychiatry about whether or not we can infer a cause-and-effect relationship between the use of cannabis and psychotic disorders. In this editorial, we first present and critically discuss the evidence to date of the association between heavy cannabis use and psychosis. We argue that while the biological mechanisms underlying individual susceptibility to develop a psychotic disorder following heavy cannabis use are still unknown, heavy cannabis use remains the most modifiable risk factor for the onset of psychotic disorders and for its clinical and functional outcome. This demands a clear move towards both primary and secondary prevention intervention to reduce the impact of heavy cannabis use on the incidence and prevalence of psychotic disorders.

Social Media Marketing Practices of Illinois Recreational Cannabis Dispensaries in the First Year of Legal Sales: Product Promotions, Branding, and Price Promotions

Research from tobacco suggests that the recreational cannabis industry will use aggressive tactics, including product innovation and mass-marketing and advertising, to increase demand for their products. The purpose of this study is to examine product promotions, branding, and promotional pricing on recreational dispensary social media pages in the state of Illinois in the first year of legal sales. Data were collected from all recreational cannabis dispensary Facebook and Twitter accounts and a quantitative content analysis was used to analyze the data. Differences in marketing practices were assessed by neighborhood race/ethnicity and income and dispensary type. Results of the study revealed that flower and edibles were the two most heavily promoted products; promotions for vaporizers and concentrates were also promoted frequently. Posts with branded promotions and price promotions increased substantially over the year. Research suggests that this trend in marketing practices will lead to greater initiation and intensity of cannabis use.

First episode psychosis with and without the use of cannabis and synthetic cannabinoids: Psychopathology, global functioning and suicidal ideation and antipsychotic effectiveness

BACKGROUND

Natural Cannabis (NC) and Synthetic Cannabinoids (SCs) use can increase the risk of developing psychotic disorders and exacerbate their course.

AIMS

To examine the differences between psychoses not associated with cannabis use and those associated with NC and SCs use, evaluating psychotic symptoms, global functioning, dissociative symptoms and suicidal ideation.

METHODS

The sample of 61 patients with First Episode Psychosis (FEP) was divided into 3 groups: non-Cannabis users (non-users, N = 20); NC users (THC-users, N = 21); SCs users (SPICE-users, N = 20). Each group was assessed at FEP and after 3 and 9 months through specific psychopathological scales.

RESULTS

THC-users, and even more SPICE-users, displayed much more severe positive symptoms than non-users. Negative symptoms were higher among non-users. After 9 months the non-users had recovered significantly better than SPICE-users in their global functioning. Dissociative symptoms were significantly greater in substance users. Finally, suicidal ideation was higher in SPICE-users than in both THC-users and non-users.

DISCUSSION

The psychoses induced by NC and SCs showed different symptomatic pictures and outcomes from each other and when compared to the psychoses not associated with the use of substances; such knowledge could be relevant in identifying a specific drug treatment.

How are young people's mental health related to their sexual health and substance use? A systematic review of UK literature

OBJECTIVES

The transition from childhood to adulthood is complex and presents challenges to young people's mental health. Mental health impacts and is impacted by a range of contextual and personal factors. Adolescence and young adulthood also coincide with increased experimentation with sex, sexuality and substance use. Addressing the mental health, sexual health and substance-use challenges experienced by young people therefore necessitates an understanding of how these elements relate to one another. By collecting and analysing existing literature, this review aims to identify associations between young people's mental health and sexual health, their mental health and substance use and any resulting gaps-in-knowledge.

CONTENT

Seven electronic databases were searched between March and May 2021 and updated in May 2022 with terms collated under the categories of "young people", "mental health", "sexual health" and "substance use". English-language articles, presenting data from the UK & Ireland, on young people aged 16-24 years inclusive were screened and subjected to a selection process in accordance with PRISMA guidelines (preregistered on PROSPERO, ref. number CRD42021245096). The quality of the resulting articles were assessed using the Mixed Methods Appraisal Tool (MMAT) and findings were tabulated through a data extraction process.

SUMMARY

27 articles were included in the review. Various mental health indices such as depression, anxiety, self-harm, psychotic-like experiences, hypomanic symptoms and binge-purge type eating disorders were found to be associated with higher use of substances such as alcohol, cannabis, ecstasy and generalised drug use. Additionally, mental health indices such as depression, anxiety and self-harm were found to be associated with sex before age 16 and/or unprotected sex at age 16, positive Chlamydia infection and higher levels of sexual activity at a younger age. Overall, cross-sectional associations were stronger than the longitudinal associations presented in the articles.

OUTLOOK

This review into the specific relations between young people's mental health, sexual health and substance use has revealed the complex and bi-directional nature of these associations, with some conditions and substances having been more extensively investigated (e.g., alcohol and depression/anxiety) as opposed to the relations between young people's sexual health and mental health which is lacking in the UK and Irish context. The findings can help inform mental health related policies and service provisions targeted at young people in the UK and Ireland. Areas for future work are suggested.