Increasing potency and price of cannabis in Europe, 2006-16

Incident psychotic experiences following self-reported use of high-potency cannabis: Results from a longitudinal cohort study

BACKGROUND AND AIMS

High-potency cannabis has been associated with increased risk of psychosis, but a lack of prospective data hinders understanding of causality in this relationship. This study aimed to combine prospective report of cannabis use with retrospective report of potency to infer the potency of cannabis used in adolescence and explore whether use of cannabis, and the use of high-potency cannabis, in adolescence is associated with incident psychotic experiences.

DESIGN

Population-based birth cohort study.

SETTING

United Kingdom.

PARTICIPANTS

n = 5570 participants who reported on any cannabis use (yes/no) age 16 and 18 years, and n = 1560 participants from this group who also retrospectively reported on cannabis potency.

MEASUREMENTS

In questionnaires at ages 16 and 18, individuals self-reported lifetime cannabis use, and at age 24, participants reported the type of cannabis they most commonly used in the whole time since first using cannabis. Psychotic experiences were assessed at age 24 years using the semi-structured Psychosis-Like Symptom Interview, with incident defined as new-onset occurring between ages 19 and 24 years.

FINDINGS

Use of high-potency cannabis at age 16 or 18 was associated with twice the likelihood of experiencing incident psychotic experiences from age 19-24 (Odds Ratio 2.15, 95% Confidence Intervals 1.13-4.06). There was less evidence for an effect of any cannabis use on incident psychotic experiences (Odds Ratio 1.45, 95% Confidence Intervals 0.94-2.12).

CONCLUSIONS

Use of high-potency cannabis appears to be associated with increased likelihood of psychotic experiences.

Daily Cannabidiol Administration for 10 Weeks Modulates Hippocampal and Amygdalar Resting-State Functional Connectivity in Cannabis Users: A Functional Magnetic Resonance Imaging Open-Label Clinical Trial

Introduction: Cannabis use is associated with brain functional changes in regions implicated in prominent neuroscientific theories of addiction. Emerging evidence suggests that cannabidiol (CBD) is neuroprotective and may reverse structural brain changes associated with prolonged heavy cannabis use. In this study, we examine how an ∼10-week exposure of CBD in cannabis users affected resting-state functional connectivity in brain regions functionally altered by cannabis use. Materials and Methods: Eighteen people who use cannabis took part in a ∼10 weeks open-label pragmatic trial of self-administered daily 200 mg CBD in capsules. They were not required to change their cannabis exposure patterns. Participants were assessed at baseline and post-CBD exposure with structural magnetic resonance imaging (MRI) and a functional MRI resting-state task (eyes closed). Seed-based connectivity analyses were run to examine changes in the functional connectivity of a priori regions-the hippocampus and the amygdala. We explored if connectivity changes were associated with cannabinoid exposure (i.e., cumulative cannabis dosage over trial, and plasma CBD concentrations and Δ9-tetrahydrocannabinol (THC) plasma metabolites postexposure), and mental health (i.e., severity of anxiety, depression, and positive psychotic symptom scores), accounting for cigarette exposure in the past month, alcohol standard drinks in the past month and cumulative CBD dose during the trial. Results: Functional connectivity significantly decreased pre-to-post the CBD trial between the anterior hippocampus and precentral gyrus, with a strong effect size (d=1.73). Functional connectivity increased between the amygdala and the lingual gyrus pre-to-post the CBD trial, with a strong effect size (d=1.19). There were no correlations with cannabinoids or mental health symptom scores. Discussion: Prolonged CBD exposure may restore/reduce functional connectivity differences reported in cannabis users. These new findings warrant replication in a larger sample, using robust methodologies-double-blind and placebo-controlled-and in the most vulnerable people who use cannabis, including those with more severe forms of Cannabis Use Disorder and experiencing worse mental health outcomes (e.g., psychosis, depression).

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.

Brain reward function in people who use cannabis: a systematic review

Rationale

Cannabis is one of the most widely used psychoactive substances globally. Cannabis use can be associated with alterations of reward processing, including affective flattening, apathy, anhedonia, and lower sensitivity to natural rewards in conjunction with higher sensitivity to cannabis-related rewards. Such alterations have been posited to be driven by changes in underlying brain reward pathways, as per prominent neuroscientific theories of addiction. Functional neuroimaging (fMRI) studies have examined brain reward function in cannabis users via the monetary incentive delay (MID) fMRI task; however, this evidence is yet to be systematically synthesised.

Objectives

We aimed to systematically integrate the evidence on brain reward function in cannabis users examined by the MID fMRI task; and in relation to metrics of cannabis exposure (e.g., dosage, frequency) and other behavioural variables.

Method

We pre-registered the review in PROSPERO and reported it using PRISMA guidelines. Literature searches were conducted in PsycINFO, PubMed, Medline, CINAHL, and Scopus.

Results

Nine studies were included, comprising 534 people with mean ages 16-to-28 years, of which 255 were people who use cannabis daily or almost daily, and 279 were controls. The fMRI literature to date led to largely non-significant group differences. A few studies reported group differences in the ventral striatum while participants anticipated rewards and losses; and in the caudate while participants received neutral outcomes. A few studies examined correlations between brain function and withdrawal, dosage, and age of onset; and reported inconsistent findings.

Conclusions

There is emerging but inconsistent evidence of altered brain reward function in cannabis users examined with the MID fMRI task. Future fMRI studies are required to confirm if the brain reward system is altered in vulnerable cannabis users who experience a Cannabis Use Disorder, as postulated by prominent neuroscientific theories of addiction.

Potency trends of cannabis in Jamaica during the period of 2014 to 2020

Reports suggest that cannabis potency has dramatically increased over the last decade in the USA and Europe. Cannabinoids are the terpeno-phenolic compounds found in the cannabis plant and are responsible for its pharmacological activity. The two most prominent cannabinoids are delta-9-tetrahydrocannabinol (Δ9 THC) and cannabidiol (CBD). Cannabis potency is measured not only by the Δ9 THC levels but also by the ratio of Δ9 THC to other non-psychoactive cannabinoids, namely, CBD. Cannabis use was decriminalized in Jamaica in 2015, which opened the gates for the creation of a regulated medical cannabis industry in the country. To date, there is no information available on the potency of cannabis in Jamaica. In this study, the cannabinoid content of Jamaican-grown cannabis was examined over the period 2014-2020. Two hundred ninety-nine herbal cannabis samples were received from 12 parishes across the island, and the levels of the major cannabinoids were determined using gas chromatography-mass spectrometry. There was a significant increase (p < 0.05) in the median total THC levels of cannabis samples tested between 2014 (1.1%) and 2020 (10.2%). The highest median THC was detected in the central parish of Manchester (21.1%). During the period, THC/CBD ratios increased from 2.1 (2014) to 194.1 (2020), and there was a corresponding increase in the percent freshness of samples (CBN/THC ratios <0.013). The data show that a significant increase in the potency of locally grown cannabis has occurred in Jamaica during the last decade.

Phytocannabinoids: Pharmacological effects, biomedical applications, and worldwide prospection

Scientific evidence exists about the association between neurological diseases (i.e., Parkinson's disease, Alzheimer's disease, amyotrophic lateral sclerosis (ALS), multiple sclerosis, depression, and memory loss) and oxidative damage. The increasing worldwide incidence of such diseases is attracting the attention of researchers to find palliative medications to reduce the symptoms and promote quality of life, in particular, in developing countries, e.g., South America and Africa. Among potential alternatives, extracts of Cannabis Sativa L. are suitable for people who have neurological disorders, spasticity, and pain, nausea, resulting from diseases such as cancer and arthritis. In this review, we discuss the latest developments in the use of Cannabis, its subtypes and constituents, extraction methods, and relevant pharmacological effects. Biomedical applications, marketed products, and prospects for the worldwide use of Cannabis Sativa L. extracts are also discussed, providing the bibliometric maps of scientific literature published in representative countries from South America (i.e., Brazil) and Africa (i.e., South Africa). A lack of evidence on the effectiveness and safety of Cannabis, besides the concerns about addiction and other adverse events, has led many countries to act with caution before changing Cannabis-related regulations. Recent findings are expected to increase the social acceptance of Cannabis, while new technologies seem to boost the global cannabis market because the benefits of (-)-trans-delta-9-tetrahydrocannabinol (Δ9-THC) and cannabidiol (CBD) use have been proven in several studies in addition to the potential to general new employment.

Association between cannabis use disorder and schizophrenia stronger in young males than in females

BACKGROUND

Previous research suggests an increase in schizophrenia population attributable risk fraction (PARF) for cannabis use disorder (CUD). However, sex and age variations in CUD and schizophrenia suggest the importance of examining differences in PARFs in sex and age subgroups.

METHODS

We conducted a nationwide Danish register-based cohort study including all individuals aged 16-49 at some point during 1972-2021. CUD and schizophrenia status was obtained from the registers. Hazard ratios (HR), incidence risk ratios (IRR), and PARFs were estimated. Joinpoint analyses were applied to sex-specific PARFs.

RESULTS

We examined 6 907 859 individuals with 45 327 cases of incident schizophrenia during follow-up across 129 521 260 person-years. The overall adjusted HR (aHR) for CUD on schizophrenia was slightly higher among males (aHR = 2.42, 95% CI 2.33-2.52) than females (aHR = 2.02, 95% CI 1.89-2.17); however, among 16-20-year-olds, the adjusted IRR (aIRR) for males was more than twice that for females (males: aIRR = 3.84, 95% CI 3.43-4.29; females: aIRR = 1.81, 95% CI 1.53-2.15). During 1972-2021, the annual average percentage change in PARFs for CUD in schizophrenia incidence was 4.8 among males (95% CI 4.3-5.3; p < 0.0001) and 3.2 among females (95% CI 2.5-3.8; p < 0.0001). In 2021, among males, PARF was 15%; among females, it was around 4%.

CONCLUSIONS

Young males might be particularly susceptible to the effects of cannabis on schizophrenia. At a population level, assuming causality, one-fifth of cases of schizophrenia among young males might be prevented by averting CUD. Results highlight the importance of early detection and treatment of CUD and policy decisions regarding cannabis use and access, particularly for 16-25-year-olds.

Prevention of hazardous use of alcohol among high school students: a study protocol for the randomized controlled trial 'Our choice'

BACKGROUND

Adolescent hazardous alcohol use is prevalent and has serious short- and long-term consequences. The trial 'Our Choice' examines efficacy, feasibility and acceptability of prevention interventions targeting school, parent, and student levels at Danish high schools. We hypothesize that students in a structural intervention (school and parent levels) reduce hazardous alcohol use and related health behaviors compared to students in an assessment only control group 12 months post baseline; and that adding group-based Motivational Interviewing (group MI) yields further improvements. The study examines the efficacy of interventions targeting multiple levels with the aim of providing novel insights into prevention of adolescent hazardous alcohol use and related health outcomes.

METHOD

The study employs a parallel group cluster randomized controlled trial design with three conditions: (1) structural condition targeting school and parent levels, (2) structural condition combined with group MI which also targets the student level, and (3) assessment-only control condition. A participatory approach is used to adapt and develop interventions. Sixteen high schools in Denmark and about N = 3100 first-year students (15-18 years) enrolled in high school in August 2023 will be recruited. Data will be collected via online questionnaires pre-interventions (baseline), 2, 6, 9 and 12 month post baseline and analyzed with generalized linear mixed models. The primary outcome is past month high intensity drinking; secondary outcomes are alcohol use, alcohol-related consequences, well-being, tobacco, and illegal substance use. Feasibility and acceptability will be assessed via surveys (students) and interviews (high school staff) to inform future implementation.

DISCUSSION

'Our Choice' is the first trial to compare the efficacy of a structural intervention targeting school- and parent levels to an intervention targeting these levels and the student level via group MI - on hazardous drinking and related health outcomes among students. Preventing and reducing hazardous alcohol use during adolescence is crucial due to the short- and long-term negative consequences. The tested interventions can be implemented at low cost. The study has significant implications for adolescent health and well-being and has potential to inform evidence-based decisions on alcohol prevention policy, education, and health professions.

TRIAL REGISTRATION NUMBER

The trial was retrospectively registered at ClinicalTrials.gov on August 24th, 2023.

TRIAL REGISTRATION NUMBER

ID NCT06018389.

Trends in Illicit Cannabis Potency based on the Analysis of Law Enforcement Seizures in the Southern Area of Rome

Cannabis remains the most illicitly produced and consumed substance worldwide, and the average trans-Δ9-tetrahydrocannabinol (THC) content in cannabis products (marijuana, hashish) has increased over time. This paper presents data about THC concentration in cannabis resin samples seized by law enforcement from 2015 to 2022 in the southern area of Rome (Italy). From 2015 to 2022, more than 1000 hashish samples were analyzed; the average THC content was 18.0% and dramatically increased from 13.7% (2015) to 27.1% (2022). The potency of THC in some samples characterized by unusual shape and color was higher than 24% and, in a few cases, higher than 40%. The age group most involved in seizures of cannabis resin concerned males aged between 15 and 36 years old. The spread of this phenomenon increases the risk of adverse health outcomes. Many observational studies compare the increased cannabis potency with the onset of psychosis, depression, anxiety and cannabis use disorders (CUDs), mainly in young adults. THC-potency monitoring provides data that can be helpful to create a network of communication and interaction between universities, and legislative and public health institutions to support education, awareness and surveillance related to cannabis abuse.

Characterization of Some "Hashish" Samples in the Egyptian Illicit Trafficking Market Using a Thermal Separation Probe and Gas Chromatography-Mass Spectrometry

Drugs that are illegal have long been a part of Egyptian society. The most widely misused form of narcotic is marijuana, also known as "bango", and other cannabis-related products like "hashish". The chemical profile of some available "hashish" in the local Egyptian illegal market and its possible country of origin are investigated using a gas chromatography-mass spectrometry technique in conjunction with a thermal separation probe (TSP/GC/MS). The TSP/GC/MS method reveals the presence of 23 different terpenes, of which caryophylla-4(12),8(13)-dien-5α-ol, isoaromadendrene epoxide, caryophyllene, and alloaromadendrene oxide-(1) are detected in high relative proportions. Ten cannabinoid components are also detected. These are cannabiorcochromene (CBC-C1), tetrahydrocannabivarin (THCV), delta-8-tetrahydrocannabinol (delta-8-THC), exo-THC, cannabichromene, cannabidiol (CBD), cannabielsoin (CBE), dronabinol (delta-9-THC), cannabigerol (CBG), and cannabinol (CBN). Phenotypic index (THC % + CBN %)/CBD %) is measured for the test samples to identify both the nature of the samples (fiber- or drug-type cannabis) and the country of origin.

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.

Early-onset smoking and vaping of cannabis: Prevalence, correlates and trends in New Zealand 14-15-year-olds

INTRODUCTION

Initiating cannabis use at an early age elevates risk of harm. Cannabis vaping is an emerging issue, and it is unknown whether the patterning and correlates of early-onset cannabis vaping differ from those of cannabis smoking.

METHODS

We used repeat cross-sectional data from a nationally representative biennial survey (2012-2018) of students aged 14-15 years in New Zealand (N = 11,405), response rate 65% (2012), 64% (2014-2016) and 59% (2018).

RESULTS

Between 2012 and 2018 lifetime cannabis use decreased, but regular use (past month, weekly, daily) was stable. Prevalence of past month, weekly and daily use in 2016-2018 (pooled) was 8.6%, 3.4% and 1.5%, respectively. Cannabis vaping was reported by 24% of past month cannabis users. The demographic profile of early-onset cannabis smokers and vapers was similar, with elevated use of both modes among Māori (Indigenous), same- or both-sex attracted students and those in low decile (high-deprivation) schools. Correlates were similar for both modes. Cannabis use was strongly associated with tobacco and alcohol use. The next strongest associations (after adjustment) were exposure to second-hand smoke at home, student income >$50/week and low parental monitoring of whereabouts. Past week social media use, psychological distress and low parental monitoring of spending were also associated with both modes.

DISCUSSION AND CONCLUSIONS

Early-onset cannabis use is much higher in structurally disadvantaged groups, and among those who use tobacco and alcohol. Comprehensive multisubstance approaches to prevention are indicated in this age group. Efforts to reduce socio-economic inequity and exposure to other risk factors may reduce cannabis-related harm.

Effects of cannabinoids on resting state functional brain connectivity: A systematic review

Cannabis products are widely used for medical and non-medical reasons worldwide and vary in content of cannabinoids such as delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD). Resting state functional connectivity offers a powerful tool to investigate the effects of cannabinoids on the human brain. We systematically reviewed functional neuroimaging evidence of connectivity during acute cannabinoid administration. A pre-registered (PROSPERO ID: CRD42020184264) systematic review of 13 studies comprising 318 participants (mean age of 25 years) was conducted and reported using the PRISMA checklist. During THC and THCv exposure vs placebo reduced connectivity with the NAcc was widely reported. Limited evidence shows that such effects are offset by co-administration of CBD. NAcc-frontal region connectivity was associated with intoxication levels. Cannabis intoxication vs placebo was associated with lower striatal-ACC connectivity. CBD and CBDv vs placebo were associated with both higher and lower connectivity between striatal-prefrontal/other regions. Overall, cannabis and cannabinoids change functional connectivity in the human brain during resting state as a function of the type of cannabinoid examined.

Severity of emergency department presentations due to acute drug toxicity in Europe: a longitudinal analysis over a 6-year period (2014-2019) stratified by sex

OBJECTIVE

To investigate whether the severity of acute recreation drug toxicity presentations to emergency departments (EDs) in Europe has changed in recent years and to uncover potential sex differences.

DESIGN

We analysed presentations to 36 EDs in 24 European countries relating to acute recreational drug toxicity, with separate analysis for presentations involving lone use of cannabis, cocaine, and heroin. As severity markers, we calculated rates of hospitalization, admission to ICU, intubation, and death by annual quarters between 2014 and 2019. Trends on severity over time were estimated by logistic regression. Differences between men and women were assessed by interaction. Sensitivity analysis was performed including only EDs that provided data for all 24 quarters. Analyses of intoxications taken altogether were adjusted by age and sex, while of lone intoxications being also adjusted by ethanol co-ingestion.

RESULTS

There were 43 633 presentations (median age = 31 years, interquartile range = 25-40 years, men = 76.5%) resulting in 10 344 hospitalizations (23.9%), 2568 ICU admissions (5.9%), 1391 intubations (3.2%), and 171 deaths (0.39%). Hospitalization, ICU admission and death did not differ by sex, but intubation was more frequent in men (3.4% vs. 2.3%, P < 0.001). No significant changes in the severity of drug intoxications over time were found when considered altogether, neither for lone cannabis (n = 4264) nor cocaine (n = 3562). Conversely, significant increases in hospitalization [odds ratios (OR) = 1.023, 95% confidence interval (CI) = 1.004-1.041], ICU admission (OR = 1.080, 95% CI = 1.042-1.118) and in intubation (OR = 1.049, 95% CI = 1.001-1.099) were detected for lone heroin presentations (n = 1997). Sensitivity analysis (32 245 presentations, 14 EDs, 9 countries) confirmed the overall absence of changes in severity markers (except for death rate, which significantly decreased by quarter: OR = 0.968, 95% CI = 0.943-0.994). Additionally, it suggested an increased risk over time of intubation for cocaine (OR = 1.068, 95% CI = 1.009-1.130) and confirmed the increased risk of ICU admission for heroin (OR = 1.058, 95% CI = 1.013-1.105). Changes in severity over time did not differ according to sex in the main analysis of the whole cohort, while a significantly higher decrease in risk of death in men was found in the sensitivity analysis (OR = 0.894, 95% CI = 0.825-969 vs. OR = 0.949, 95% CI = 0.860-1.048; P interaction = 0.042).

CONCLUSIONS

The severity of presentations to European EDs remained mainly unchanged during 2014-2019, but the risk of death may have decreased. Conversely, intubation in lone cocaine and ICU admission in lone heroin intoxications have increased. Although men and women exhibited a similar pattern over the period for the majority of comparisons, our data suggest that women exhibited a smaller decrease of the overall risk of death.

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

OBJECTIVES

The liberalisation of cannabis laws, the increasing availability and potency of cannabis has renewed concern about the risk of psychosis with cannabis.

METHODS

The objective of the WFSBP task force was to review the literature about this relationship.

RESULTS

Converging lines of evidence suggest that exposure to cannabis increases the risk for psychoses ranging from transient psychotic states to chronic recurrent psychosis. The greater the dose, and the earlier the age of exposure, the greater the risk. For some psychosis outcomes, the evidence supports some of the criteria of causality. However, alternate explanations including reverse causality and confounders cannot be conclusively excluded. Furthermore, cannabis is neither necessary nor sufficient to cause psychosis. More likely it is one of the multiple causal components. In those with established psychosis, cannabis has a negative impact on the course and expression of the illness. Emerging evidence also suggests alterations in the endocannabinoid system in psychotic disorders.

CONCLUSIONS

Given that exposure to cannabis and cannabinoids is modifiable, delaying or eliminating exposure to cannabis or cannabinoids, could potentially impact the rates of psychosis related to cannabis, especially in those who are at high risk for developing the disorder.

Associations Between Canada's Cannabis Legalization and Emergency Department Presentations for Transient Cannabis-Induced Psychosis and Schizophrenia Conditions: Ontario and Alberta, 2015-2019

OBJECTIVE

Cannabis legalization in many jurisdictions worldwide has raised concerns that such legislation might increase the burden of transient and persistent psychotic illnesses in society. Our study aimed to address this issue.

METHODS

Drawing upon emergency department (ED) presentations aggregated across Alberta and Ontario, Canada records (April 1, 2015-December 31, 2019), we employed Seasonal Autoregressive Integrated Moving Average (SARIMA) models to assess associations between Canada's cannabis legalization (via the Cannabis Act implemented on October 17, 2018) and weekly ED presentation counts of the following ICD-10-CA-defined target series of cannabis-induced psychosis (F12.5; n = 5832) and schizophrenia and related conditions ("schizophrenia"; F20-F29; n = 211,661), as well as two comparison series of amphetamine-induced psychosis (F15.5; n = 10,829) and alcohol-induced psychosis (F10.5; n = 1,884).

RESULTS

ED presentations for cannabis-induced psychosis doubled between April 2015 and December 2019. However, across all four SARIMA models, there was no evidence of significant step-function effects associated with cannabis legalization on post-legalization weekly ED counts of: (1) cannabis-induced psychosis [0.34 (95% CI -4.1; 4.8; P = 0.88)]; (2) schizophrenia [24.34 (95% CI -18.3; 67.0; P = 0.26)]; (3) alcohol-induced psychosis [0.61 (95% CI -0.6; 1.8; P = 0.31); or (4) amphetamine-induced psychosis [1.93 (95% CI -2.8; 6.7; P = 0.43)].

CONCLUSION

Implementation of Canada's cannabis legalization framework was not associated with evidence of significant changes in cannabis-induced psychosis or schizophrenia ED presentations. Given the potentially idiosyncratic rollout of Canada's cannabis legalization, further research will be required to establish whether study results generalize to other settings.

Cannabis use as a predictor and outcome of positive and negative affect in college students: An ecological momentary assessment study

BACKGROUND

Reinforcement models identify negative affect (NA) and positive affect (PA) to be important momentary determinants and outcomes of cannabis use. Sensitization and allostatic models further suggest that these mood-cannabis associations are stronger among individuals with more cannabis-related problems. Despite this theoretical background and the fact that cannabis is commonly used for its mood-enhancing effects among college students, surprisingly, little is known about the momentary associations between mood and cannabis use in this population.

AIMS

To examine the associations between (a) momentary within-person variations in NA (worried, stressed, nervous) and PA (happy, enthusiastic, proud, excited) and intention to use cannabis within the next hour, (b) the within-person variations in time elapsed since last cannabis use, amount used and momentary NA and PA, and (c) to test whether cannabis-related problems moderate the stated associations.

METHOD

Eighty, more-than-weekly, cannabis using students at the University of Amsterdam reported on cannabis use, NA and PA three times daily for 14 consecutive days. Mixed-effects models were performed to analyze the dataset.

RESULTS

Within-persons, relatively high PA and low NA were associated with a higher likelihood of intending to use cannabis. Within-persons, more recent and greater amounts of cannabis use were associated with relatively high PA. More recent cannabis use was associated with relatively low NA. Cannabis-related problems did not moderate the associations.

CONCLUSIONS

While recent cannabis use related to higher PA and lower NA, high PA but low NA preceded use, supporting positive reinforcement rather than negative reinforcement in this college sample of regular cannabis users.

Trends in Psychiatric Hospitalizations of Patients With Dual Diagnosis in Spain

OBJECTIVE

Substance use disorders are highly prevalent in people living with a mental health disorder. Co-occurring substance use disorders have been associated with a worse prognosis and poorer adherence to treatment. The aim of this study was to analyze the temporal trends in the prevalence of substance use disorders in patients admitted to a psychiatric inpatient unit between 1998 and 2020.

METHODS

This is a retrospective study based on the registry of 18,367 hospitalizations and 7,124 patients with a mental health disorder admitted during the period 1998 to 2020 in Malaga, Spain. Time trend analysis by gender and substance used was calculated using a segmented regression model. The permutation test was used to determine inflection points. A sensitivity analysis was performed based on the assumptions of autocorrelation and homoscedasticity.

RESULTS

A total of 22.2% of admissions had a diagnosis of mental health disorder and co-occurring substance use disorders. Prevalence was higher among males (30.0%) than females (9.4%; p < .001). Patients with both disorders had a shorter length of stay by 2 days (p < .001) and a younger age at first admission (by 6.5 years; p < .001) compared to patients without substance use disorders. There was no difference in the total number of hospitalizations between the two groups. Psychotic disorders and multiple drug use disorders were the most prevalent diagnoses in men compared to women, whereas personality disorders and alcohol use were the most common diagnoses in women. We observed an increase in the prevalence of dual diagnosis between 2005 and 2020. There was a 3.0% increase in cannabis-related admissions per year during the whole study period (p < .001). Cannabis and cocaine use disorders have become the most prevalent in the last 10 years, while opioid and alcohol use disorders have decreased.

CONCLUSIONS

Co-occurring substance use disorders are highly prevalent among hospitalized patients. In recent years, the pattern of substance use has shifted, with cannabis being the most prevalent, while opiates and alcohol substance use have decreased. We need to devise a specialized approach and integrative treatment for patients with co-occurring disorders.

Cannabis flower prices and transitions to legal sources after legalization in Canada, 2019-2020

BACKGROUND

The post-tax price of legal cannabis has the potential to influence whether consumers transition from the illegal to legal cannabis market. The aims of the study were to: 1) estimate the percentage who report purchasing dried flower at different sources; 2) estimate the unit price of dried flower; and 3) examine the association between price and legality of purchase source.

METHODS

Repeat cross-sectional survey data come from Canadian respondents from the International Cannabis Policy Study conducted in 2019 and 2020. Respondents were recruited through online commercial panels, of legal age to purchase cannabis (up to 65 years), and purchased dried flower in the past 12-months (n = 4923). Weighted binary logistic regression models examined the association between price and legality of source.

RESULTS

The proportion of consumers last purchasing dried flower from legal sources increased from 2019 to 2020 (45.7% vs 58.1%) and in the past 12-months, the average percent of dried flower consumers reported purchasing from legal sources increased from 2019 to 2020 (55.7% vs 67.5%). The mean price of legal dried flower decreased in 2020 ($12.63 vs $11.16; p < 0.001), but remained more expensive than illegal dried flower in both years ($12.63 vs $9.04 in 2019; p < 0.001, $11.16 vs $9.41 in 2020; p < 0.001).

CONCLUSIONS

Two years after legalization in Canada, the price of dried flower from legal sources decreased, along with a greater percentage of consumers purchasing from legal sources than after one year. Price and retail policies must continue to encourage the transition to the legal market in Canada.

Considerations for Cannabinoids in Perioperative Care by Anesthesiologists

Increased usage of recreational and medically indicated cannabinoid compounds has been an undeniable reality for anesthesiologists in recent years. These compounds’ complicated pharmacology, composition, and biological effects result in challenging issues for anesthesiologists during different phases of perioperative care. Here, we review the existing formulation of cannabinoids and their biological activity to put them into the context of the anesthesia plan execution. Perioperative considerations should include a way to gauge the patient’s intake of cannabinoids, the ability to gain consent properly, and vigilance to the increased risk of pulmonary and airway problems. Intraoperative management in individuals with cannabinoid use is complicated by the effects cannabinoids have on general anesthetics and depth of anesthesia monitoring while simultaneously increasing the potential occurrence of intraoperative hemodynamic instability. Postoperative planning should involve higher vigilance to the risk of postoperative strokes and acute coronary syndromes. However, most of the data are not up to date, rending definite conclusions on the importance of perioperative cannabinoid intake on anesthesia management difficult.

Cannabis-related emergency department visits by youths and their outcomes in Ontario: a trend analysis

BACKGROUND

Cannabis-related emergency department visits can be an entry point for youths to mental health and substance use care systems. We aimed to examine trends in cannabis-related emergency department visits as a function of youths' age and sex.

METHODS

Using administrative data, we examined all visits to emergency departments in Ontario, Canada, from 2003 to 2017, by youth aged 10-24 years (grouped as 10-13, 14-18 and 19-24 yr) to determine trends in cannabis-related emergency department visits. Cannabis-related visits were identified using International Statistical Classification of Diseases and Related Health Problems, 10th Revision codes for cannabis poisoning and mental disorders due to cannabinoids. We categorized presentations as "less severe" versus "more severe" using scores assigned by nurses at triage.

RESULTS

We examined 14 697 778 emergency department visits. Cannabis-related visits increased from 3.8 per 10 000 youths (95% confidence interval [CI] 3.5-4.0) in 2003 to 17.9 (95% CI 17.4-18.4) in 2017, a 4.8-fold increase (95% CI 4.4-5.1). Rates increased for both sexes and each age group. Males were more likely to have a visit than females (rate ratios ≥ 1.5 in 2003 and 2017). The number of cannabis-related visits in 2017 was 25.0 per 10 000 (95% CI 24.0-25.9) among youth aged 19-24 years, 21.9 per 10 000 (95% CI 20.9-22.9) among those aged 14-18 years, and 0.8 per 10 000 (95% CI 0.5-1.0) among those aged 10-13 years. In 2017, 88.2% (95% CI 87.3%-89.0%) of cannabis-related visits and 58.1% (95% CI 58.0%-58.2%) of non-cannabis-related visits were triaged as "more severe," (rate ratio 1.52, 95% CI 1.50-1.53). Similarly, in 2017, 19.0% (95% CI 18.0%-20.1%) of cannabis-related visits and 5.8% (95% CI 5.7%-5.8%) of non-cannabis-related visits resulted in hospital admission (rate ratio 3.3, 95% CI 3.1-3.5).

INTERPRETATION

Rates of cannabis-related emergency department visit by youths aged 10-24 years increased almost fivefold from 2003 to 2017, with increases in visit severity and hospital admissions. These trends describe an emerging public health problem, and research is needed to identify the causes of this increase and the health and social consequences of cannabis-related visits for these youths.

The relation between cannabis use, dependence severity and white matter microstructure: A diffusion tensor imaging study

Despite the significant societal and personal burden of cannabis use, the impact of long‐term use and Cannabis Use Disorder (CUD) on white matter microstructure is still unclear. Previous studies show inconsistent findings, in part due to heterogeneity in methodology, variable severity of cannabis use, and potential confounding effects of other mental health issues and substance use. The goal of this diffusion tensor imaging (DTI) study was to compare whole‐brain white matter microstructure between 39 near daily cannabis users and 28 controls closely matched on age, sex, alcohol use, cigarette use and mental health. Within the group of cannabis users, associations between white matter microstructure and recent cannabis use, dependence severity, and age of onset and duration of weekly use were investigated. White matter microstructure did not differ between cannabis users and controls and did not covary with recent cannabis use, dependence severity, or duration of use. Earlier onset of weekly cannabis use was related to lower fractional anisotropy (FA) in various sections of the right inferior longitudinal fasciculus and uncinate fasciculus. These findings suggest that long‐term near‐daily cannabis use does not necessarily affect white matter microstructure, but vulnerability may be higher during adolescence. These findings underscore the importance of sample composition and warrant further studies that investigate the moderating role of age of onset in the impact of cannabis on the brain.

Substance-induced psychosis as a risk factor for unipolar depression or anxiety disorders-A nationwide register-based prospective cohort study

BACKGROUND

Substance-induced psychosis has previously been linked to increased incidence of schizophrenia and bipolar disorder. We aimed to investigate if substance-induced psychosis is associated with increased risk of depression or anxiety.

METHODS

We conducted a nationwide prospective register-based cohort study from 1994 to 2017, including all individuals with substance-induced psychosis, and age-and-sex matched controls without substance-induced psychosis. We investigated time to either depression or anxiety, as well as time to depression and time to anxiety, in stratified Cox regression models.

RESULTS

We included 5,557 individuals with substance-induced psychosis and 55,562 controls. Substance-induced psychosis was associated with increased risk of either depression or anxiety (HR=7.05, 95% CI 6.71-7.41), depression (HR=5.40, 95% CI 4.77-6.11), or anxiety (HR=7.05, 95% CI 5.99-8.31). Analyses of individual types of substance-induced psychosis revealed similar hazard ratios across substances. Associations between substance-induced psychosis and depression or anxiety were stronger in people without preceding alcohol or substance use disorders. While strongest shortly after incident substance-induced psychosis, the increased incidence of depression and anxiety remained more than double over the full period of follow-up.

LIMITATIONS

Only psychiatric disorders treated either in psychiatric inpatient or outpatient units, supplemented with information on psychiatric medication, was available. Exact times of onset were similarly unknown, and only dates of first treatment were available.

CONCLUSIONS

Substance-induced psychosis is a strong predictor of later onset of depression or anxiety. Regardless of whether this association is causal, this highlights the need for increased monitoring and possibly improved treatment of patients with substance-induced psychosis.

Public health monitoring of cannabis use in Europe: prevalence of use, cannabis potency, and treatment rates

Background

Cannabis is one of the most widely used substances worldwide. Heavy use is associated with an increased risk of cannabis use disorders, psychotic disorders, acute cognitive impairment, traffic injuries, respiratory problems, worse pregnancy outcomes, and there are indications for genotoxic and epigenotoxic adverse effects. International regulation of medical and non-medical cannabis use is changing rapidly and substantially, highlighting the importance of robust public health monitoring. This study aimed to describe the trends of key public health indicators in European Union (27 member states + UK, Norway and Turkey) for the period 2010 to 2019, their public health implications, and to identify the steps required to improve current practice in monitoring of cannabis use and harm in Europe.

Methods

Data on four key cannabis indicators (prevalence of use, prevalence of cannabis use disorder [CUD], treatment rates, and potency of cannabis products) in Europe were extracted from the United Nations Office on Drugs and Crime, European Monitoring Centre for Drugs and Drug Addiction and the Global Burden of Disease study. For prevalence of use and CUD, the first and last available estimate in each country were compared. For treatment rates and cannabis potency, linear regression models were conducted.

Findings

Between 2010 and 2019, past-month prevalence of cannabis use increased by 27% in European adults (from 3·1 to 3·9%), with most pronounced relative increases observed among 35-64 year-olds. In 13 out of 26 countries, over 20% of all past-month users reported high-risk use patterns. The rate of treatment entry for cannabis problems per 100,000 adults increased from 27·0 (95% CI: 17·2 to 36·8) to 35·1 (95% CI: 23·6 to 46·7) and has mostly plateaued since 2015. Modest increases in potency were found in herbal cannabis (from 6·9% to 10·6% THC) while median THC values tripled in cannabis resin (from 7·6% to 24·1% THC).

Interpretation

In the past decade, cannabis use, treatment rates and potency levels have increased in Europe highlighting major concerns about the public health impact of cannabis use. Continued monitoring and efforts to improve data quality and reporting, including indicators of high-risk use and cannabis-attributable harm, will be necessary to evaluate the health impact of international changes in cannabis regulation.

Funding

This study received no specific funding.

Cannabinoids for the treatment of cannabis use disorder: New avenues for reaching and helping youth?

Cannabis use peaks during adolescence and emerging adulthood, and cannabis use disorder (CUD) is associated with a wide range of adverse outcomes. This is particularly pertinent in youth, because the developing brain may be more vulnerable to adverse effects of frequent cannabis use. Combining evidence-based psychosocial interventions with safe and effective pharmacotherapy is a potential avenue to improve youth outcomes, but we lack approved CUD pharmacotherapies. Here, we review new potential avenues for helping youth with CUD, with a particular focus on cannabinoid-based treatments. Evidence from placebo-controlled RCTs suggests synthetic delta-9-tetrahydrocannabinol (THC) decreases withdrawal symptoms, but not cannabis use, in adults with daily cannabis use/CUD, while findings regarding formulations containing THC combined with cannabidiol (CBD) are mixed. Preliminary evidence from two placebo-controlled RCTs in adults with CUD suggests that both Fatty Acid Amide Hydrolase inhibitors and CBD can reduce cannabis use. However, larger trials are needed to strengthen the evidence. Findings from adults point to cannabinoid-based treatments as a potential strategy that should be examined in youth with CUD.

Cannabis adulterated with the synthetic cannabinoid receptor agonist MDMB-4en-PINACA and the role of European drug checking services

BACKGROUND

European drug checking services exchange information on drug trends within the Trans European Drug Information (TEDI) network, allowing monitoring and coordination of responses. Starting in Spring 2020, several services detected the synthetic cannabinoid receptor agonist MDMB-4en-PINACA in adulterated low-THC cannabis products.

METHODS

Cannabis products suspected of adulteration were analyzed for the presence of MDMB-4en-PINACA by 9 services in 8 countries within the TEDI network. If available, phytocannabinoid analysis was also performed.

RESULTS

1142 samples sold as cannabis in herbal, resin and e-liquid form were analyzed, of which 270 were found to contain MDMB-4en-PINACA. All cannabis samples contained low THC (<1%), except the e-liquids which contained no phytocannabinoids. Three serious health incidents requiring hospitalization after use of an adulterated cannabis sample were reported.

CONCLUSION

Adulteration of cannabis with synthetic cannabinoid receptor agonists is a new phenomenon that carries risk for people who use it. Given that cannabis consumers are not a usual target group for drug checking services, services and associated harm reduction interventions could be reconfigured to include them.

Long-Term Consequences of Adolescent Exposure to THC-Rich/CBD-Poor and CBD-Rich/THC-Poor Combinations: A Comparison with Pure THC Treatment in Female Rats

Cannabis is the most-used recreational drug worldwide, with a high prevalence of use among adolescents. In animal models, long-term adverse effects were reported following chronic adolescent exposure to the main psychotomimetic component of the plant, delta-9-tetrahydrocannabinol (THC). However, these studies investigated the effects of pure THC, without taking into account other cannabinoids present in the cannabis plant. Interestingly, cannabidiol (CBD) content seems to mitigate some of the side effects of THC, at least in adult animals. Thus, in female rats, we evaluated the long-term consequences of a co-administration of THC and CBD at a 3:1 ratio, chosen based on the analysis of recently confiscated illegal cannabis samples in Europe. CBD content is able to mitigate some of the long-term behavioral alterations induced by adolescent THC exposure as well as long-term changes in CB1 receptor and microglia activation in the prefrontal cortex (PFC). We also investigated, for the first time, possible long-term effects of chronic administration of a THC/CBD combination reminiscent of "light cannabis" (CBD:THC in a 33:1 ratio; total THC 0.3%). Repeated administration of this CBD:THC combination has long-term adverse effects on cognition and leads to anhedonia. Concomitantly, it boosts Glutamic Acid Decarboxylase-67 (GAD67) levels in the PFC, suggesting a possible lasting effect on GABAergic neurotransmission.

Cannabis exposure during adolescence: A uniquely sensitive period for neurobiological effects

Adolescence is a crucial developmental period where neural circuits are refined and the brain is especially vulnerable to external insults. The endocannabinoid (eCB) system undergoes changes during adolescence which affect the way in which it modulates the development of other systems, in particular dopamine circuits, which show protracted development into adolescence. Given the rise of cannabis use by adolescents and young people, as well as variants containing increasingly higher concentrations of THC, it is now crucial to understand the unique effects of adolescent exposure to cannabis on the developing brain and it might shape future adult vulnerabilities to conditions such as psychosis, schizophrenia, addiction and more. Here we discuss the development of the eCB system across the lifespan, how CB1 receptors modulate dopamine release and potential neurobiological and behavioral effects of adolescent THC exposure on the developing brain such as alterations in excitatory/inhibitory balance during this developmental period.

Exploring the use of cannabis as a substitute for prescription drugs in a convenience sample

BACKGROUND

The use of cannabis as medicine (CaM) both prescribed and non-prescribed has increased markedly in the last decade, mirrored in a global shift in cannabis policy towards a more permissive stance. There is some evidence that cannabis functions as a substitute for prescription drugs, particularly opioids; however, more knowledge is needed on the motives of substitution users, their patterns of use, and perceived effects of substitution use.

AIMS

To explore who substitutes prescription drugs with cannabis, the type of prescription drugs substituted and the type of cannabis used, and the impact that substitution with cannabis has on prescription drug use as well as the motives for substitution in terms of experienced effects and side effects.

METHODS

A self-selected convenience sample was recruited through social media, public media, and patient organizations to take part in an anonymous online survey. Inclusion criteria were 18 years or older and use of cannabis (prescribed or non-prescribed) with a medical purpose.

RESULTS

The final sample included 2.841 respondents of which the majority (91%) used non-prescribed cannabis, and more than half (54.6%) had used CaM with the purpose of replacing a prescribed drug. Compared to non-substitution users, substitution users were more likely to be women and to use CaM in the treatment of chronic pain and other somatic conditions. Pain medication (67.2%), antidepressants (24.5%), and arthritis medication (20.7%) were the most common types of drugs replaced with CaM. Among substitution users, 38.1% reported termination of prescription drug use, and 45.9% a substantial decrease in prescription drug use. The most frequent type of cannabis used as a substitute was CBD-oil (65.2%), followed by 'hash, pot or skunk' (36.6%). More than half (65.8%) found CaM much more effective compared to prescription drugs, and 85.5% that the side effects associated with prescription drug use were much worse compared to use of CaM.

CONCLUSION

CaM is frequently used as a substitute for prescription drugs, particularly opioids. More research is needed on the long-term consequences of use of CaM, including the impact from low and high THC cannabis products on specific somatic and mental health conditions.

Preliminary in vivo evidence of lower hippocampal synaptic density in cannabis use disorder

Cannabis is one of the most commonly and widely used psychoactive drugs. The rates of cannabis misuse have been increasing. Therefore, understanding the effects of cannabis use on the brain is important. Adolescent and adult rodents exposed to repeated administration of cannabinoids show persistent microstructural changes in the hippocampus both pre- and post-synaptically. Whether similar alterations exist in human cannabis users, has not yet been demonstrated in vivo. Positron emission tomography (PET) and [¹¹C]UCB-J, a radioligand for the synaptic vesicle glycoprotein 2A (SV2A), were used to study hippocampal synaptic integrity in vivo in an equal number (n = 12) of subjects with DSM-5 cannabis use disorder (CUD) and matched healthy controls (HC). Arterial sampling was used to measure plasma input function. [11C]UCB-J binding potential (BP_ND) was estimated using a one-tissue (1T) compartment model with centrum semiovale as the reference region. Hippocampal function was assessed using a verbal memory task. Relative to HCs, CUDs showed significantly lower [¹¹C]UCB-J BP_ND in the hippocampus (~10%, p = 0.008, effect size 1.2) and also performed worse on the verbal memory task. These group differences in hippocampal BP_ND persisted after correction for volume differences (p = 0.013), and correction for both age and volume (p = 0.03). We demonstrate, for the first time, in vivo evidence of lower hippocampal synaptic density in cannabis use disorder. These results are consistent with the microstructural findings from experimental studies with cannabinoids in animals, and studies of hippocampal macrostructure in human with CUD. Whether the lower hippocampal synaptic density resolves with abstinence warrants further study.

The Effects of Acute Δ9-Tetrahydrocannabinol on Striatal Glutamatergic Function: A Proton Magnetic Resonance Spectroscopy Study

BACKGROUND

Cannabis and its main psychoactive component, Δ⁹-tetrahydrocannabinol (THC), can elicit transient psychotic symptoms. A key candidate biological mechanism of how THC induces psychotic symptoms is the modulation of glutamate in the brain. We sought to investigate the effects of acute THC administration on striatal glutamate levels and its relationship to the induction of psychotic symptoms.

METHODS

We used proton magnetic resonance spectroscopy to measure glutamate levels in the striatum in 20 healthy participants after THC (15 mg, oral) and matched placebo administration in a randomized, double-blind, placebo-controlled design. Psychotic symptoms were measured using the Psychotomimetic States Inventory.

RESULTS

We found that THC administration did not significantly change glutamate (glutamate plus glutamine relative to creatine) concentration in the striatum (p = .58; scaled Jeffreys-Zellner-Siow Bayes factor = 4.29). THC increased psychotic symptoms, but the severity of these symptoms was not correlated with striatal glutamate levels.

CONCLUSIONS

These findings suggest that oral administration of 15 mg of THC does not result in altered striatal glutamate levels. Further work is needed to clarify the effects of THC on striatal glutamate.

A latent class analysis of cannabis use products in a general population sample of adolescents and their association with paranoia, hallucinations, cognitive disorganisation and grandiosity

Adolescents have access to a wide range of cannabis products with patterns of use becoming increasingly diverse. This study aimed to identify subgroups of adolescents in the general population who use similar types of cannabis and their association with psychotic experiences. Data on cannabis use were obtained from 467 adolescents aged between 16 and 17 years. Latent class analysis (LCA) identified groups of adolescents based on the type of cannabis used in the past 12 months. Univariate analysis explored differences in socio-demographics, substance use and mental health symptoms between groups. Multivariate analysis examined associations between class membership and psychotic experiences controlling for frequency and amount of cannabis. Finally, we explored the association between motives for cannabis and class membership using multi-nominal logistic regression. LCA identified 3 classes of adolescents: (i) herbal only (47.9%); (ii) skunk only (20.8%) and (3) mixed use (31.3%). Relative to non-users, skunk only use was associated with a 2-fold increase in paranoia (OR = 2.45, 95% CI = 1.29-4.63), along with, sleep disturbance and anxiety. Monthly cannabis use and consuming 2 or more joints on one occasion was associated with a 2-fold increase in hallucinations (OR = 2.2; 95% CI = 1.0-4.8 and OR = 1.9; 95% CI = 1.2-3.2), but did not reach the Bonferroni corrected p-value. Expansion and conformity motives differentiated the mixed cannabis class from the herbal only class. The findings suggest that different subgroups of cannabis users exist in adolescence as defined by the type of cannabis consumed and are differentially related to psychotic experiences and motives for use.

Daily use of high-potency cannabis is associated with more positive symptoms in first-episode psychosis patients: the EU-GEI case-control study

BACKGROUND

Daily use of high-potency cannabis has been reported to carry a high risk for developing a psychotic disorder. However, the evidence is mixed on whether any pattern of cannabis use is associated with a particular symptomatology in first-episode psychosis (FEP) patients.

METHOD

We analysed data from 901 FEP patients and 1235 controls recruited across six countries, as part of the European Network of National Schizophrenia Networks Studying Gene-Environment Interactions (EU-GEI) study. We used item response modelling to estimate two bifactor models, which included general and specific dimensions of psychotic symptoms in patients and psychotic experiences in controls. The associations between these dimensions and cannabis use were evaluated using linear mixed-effects models analyses.

RESULTS

In patients, there was a linear relationship between the positive symptom dimension and the extent of lifetime exposure to cannabis, with daily users of high-potency cannabis having the highest score (B = 0.35; 95% CI 0.14-0.56). Moreover, negative symptoms were more common among patients who never used cannabis compared with those with any pattern of use (B = -0.22; 95% CI -0.37 to -0.07). In controls, psychotic experiences were associated with current use of cannabis but not with the extent of lifetime use. Neither patients nor controls presented differences in depressive dimension related to cannabis use.

CONCLUSIONS

Our findings provide the first large-scale evidence that FEP patients with a history of daily use of high-potency cannabis present with more positive and less negative symptoms, compared with those who never used cannabis or used low-potency types.

The why behind the high: determinants of neurocognition during acute cannabis exposure

Acute cannabis intoxication may induce neurocognitive impairment and is a possible cause of human error, injury and psychological distress. One of the major concerns raised about increasing cannabis legalization and the therapeutic use of cannabis is that it will increase cannabis-related harm. However, the impairing effect of cannabis during intoxication varies among individuals and may not occur in all users. There is evidence that the neurocognitive response to acute cannabis exposure is driven by changes in the activity of the mesocorticolimbic and salience networks, can be exacerbated or mitigated by biological and pharmacological factors, varies with product formulations and frequency of use and can differ between recreational and therapeutic use. It is argued that these determinants of the cannabis-induced neurocognitive state should be taken into account when defining and evaluating levels of cannabis impairment in the legal arena, when prescribing cannabis in therapeutic settings and when informing society about the safe and responsible use of cannabis.

Role of Cannabidiol in the Therapeutic Intervention for Substance Use Disorders

Drug treatments available for the management of substance use disorders (SUD) present multiple limitations in efficacy, lack of approved treatments or alarming relapse rates. These facts hamper the clinical outcome and the quality of life of the patients supporting the importance to develop new pharmacological agents. Lately, several reports suggest that cannabidiol (CBD) presents beneficial effects relevant for the management of neurological disorders such as epilepsy, multiple sclerosis, Parkinson's, or Alzheimer's diseases. Furthermore, there is a large body of evidence pointing out that CBD improves cognition, neurogenesis and presents anxiolytic, antidepressant, antipsychotic, and neuroprotective effects suggesting potential usefulness for the treatment of neuropsychiatric diseases and SUD. Here we review preclinical and clinical reports regarding the effects of CBD on the regulation of the reinforcing, motivational and withdrawal-related effects of different drugs of abuse such as alcohol, opioids (morphine, heroin), cannabinoids, nicotine, and psychostimulants (cocaine, amphetamine). Furthermore, a special section of the review is focused on the neurobiological mechanisms that might be underlying the 'anti-addictive' action of CBD through the regulation of dopaminergic, opioidergic, serotonergic, and endocannabinoid systems as well as hippocampal neurogenesis. The multimodal pharmacological profile described for CBD and the specific regulation of addictive behavior-related targets explains, at least in part, its therapeutic effects on the regulation of the reinforcing and motivational properties of different drugs of abuse. Moreover, the remarkable safety profile of CBD, its lack of reinforcing properties and the existence of approved medications containing this compound (Sativex®, Epidiolex®) increased the number of studies suggesting the potential of CBD as a therapeutic intervention for SUD. The rising number of publications with substantial results on the valuable therapeutic innovation of CBD for treating SUD, the undeniable need of new therapeutic agents to improve the clinical outcome of patients with SUD, and the upcoming clinical trials involving CBD endorse the relevance of this review.

Public health impacts to date of the legalisation of medical and recreational cannabis use in the USA

The legality of cannabis use has been changing in a number of jurisdictions around the world. In the U.S., it has been legalised for medicinal and/or recreational uses in 34 jurisdictions and counting. This study leverages the decades-long experience of legalisation in the U.S. to provide an overview of the associated changes in public attitudes, cannabis markets and adverse health effects. We found a broad-based warming of public attitudes toward legalisation, potentially influenced by the increasingly positive portrayal of cannabis in media and declines in cannabis risk perceptions. Potency of cannabis products increased significantly while prices fell sharply. Although adults were less responsive to price changes than adolescents, adults who use cannabis regularly were sensitive to prices, with an estimated 10% price reduction leading to about 2.5% increase in the rate of use. Overall, past-year cannabis use has increased in adults since 2002, and adults over 26 years old who resided in states with medicinal cannabis laws were more likely to have used cannabis in the past 30 days, to have used daily, and to have higher rates of cannabis use disorders than adults who resided in states without legalised medicinal cannabis. Traffic fatalities involving cannabis temporarily increased in some states post-legalisation, and there were more presentations to medical services related to chronic regular cannabis use. There is suggestive evidence that adverse health consequences have increased among people who use cannabis regularly since legalisation. More robust research is needed to determine whether these effects of legalisation are temporary or long-term.

Changes in delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) concentrations in cannabis over time: systematic review and meta-analysis

BACKGROUND AND AIMS

Cannabis products with high delta-9-tetrahydrocannabinol (THC) concentrations carry an increased risk of addiction and mental health disorders, while it has been suggested that cannabidiol (CBD) may moderate the effects of THC. This study aimed to systematically review and meta-analyse changes in THC and CBD concentrations in cannabis over time (PROSPERO registration: CRD42019130055).

DESIGN

Embase, MEDLINE® and Epub Ahead of Print, In-Process and Other Non-Indexed Citations and Daily, Global Health, PsycINFO and Scopus were searched from inception to 27/03/2019 for observational studies reporting changes in mean THC and/or CBD concentration in cannabis over at least three annual time points. Searches and extraction were conducted by two independent reviewers. Random effects meta-regression models estimated annual changes in THC and CBD for each product within each study; these estimates were pooled across studies in random effects models.

RESULTS

We identified 12 eligible studies from the USA, UK, Netherlands, France, Denmark, Italy and New Zealand. For all herbal cannabis, THC concentrations increased by 0.29% each year (95% CI: 0.11, 0.47), P < 0.001 based on 66 747 cannabis samples from eight studies, 1970-2017. For cannabis resin, THC concentrations increased by 0.57% each year (95% CI: 0.10, 1.03), P = 0.017 based on 17 371 samples from eight studies, 1975-2017. There was no evidence for changes in CBD in herbal cannabis [-0.01% (95% CI: -0.02, 0.01), P = 0.280; 49 434 samples from five studies, 1995-2017] or cannabis resin [0.03% (95% CI: -0.11, 0.18), P = 0.651; 11 382 samples from six studies, 1992-2017]. Risk of bias was low apart from non-random sampling in most studies. There was evidence of moderate to substantial heterogeneity.

CONCLUSIONS

Concentrations of delta-9-tetrahydrocannabinol (THC) in international cannabis markets increased from 1970 to 2017 while cannabidiol (CBD) remained stable. Increases in THC were greater in cannabis resin than herbal cannabis. Rising THC in herbal cannabis was attributable to an increased market share of high-THC sinsemilla relative to low-THC traditional herbal cannabis.

Use of alcohol, tobacco, cannabis, and other substances during the first wave of the SARS-CoV-2 pandemic in Europe: a survey on 36,000 European substance users

BACKGROUND

SARS-CoV-2 reached Europe in early 2020 and disrupted the private and public life of its citizens, with potential implications for substance use. The objective of this study was to describe possible changes in substance use in the first months of the SARS-CoV-2 pandemic in Europe.

METHODS

Data were obtained from a cross-sectional online survey of 36,538 adult substance users from 21 European countries conducted between April 24 and July 22 of 2020. Self-perceived changes in substance use were measured by asking respondents whether their use had decreased (slightly or substantially), increased (slightly or substantially), or not changed during the past month. The survey covered alcohol (frequency, quantity, and heavy episodic drinking occasions), tobacco, cannabis, and other illicit drug use. Sample weighted data were descriptively analysed and compared across substances.

RESULTS

Across all countries, use of all substances remained unchanged for around half of the respondents, while the remainder reported either a decrease or increase in their substance use. For alcohol use, overall, a larger proportion of respondents indicated a decrease than those reporting an increase. In contrast, more respondents reported increases in their tobacco and cannabis use during the previous month compared to those reporting decreased use. No distinct direction of change was reported for other substance use.

CONCLUSIONS

Our findings suggest changes in use of alcohol, tobacco and cannabis during the initial months of the pandemic in several European countries. This study offers initial insights into changes in substance use. Other data sources, such as sales statistics, should be used to corroborate these preliminary findings.

Extensive phytocannabinoid profiles of seized cannabis and cannabis-based medicines - Identification of potential distinguishing markers

As the frequency of cannabis-based therapy increases, the ability to distinguish intake of cannabis-based medicines from recreational cannabis use becomes desirable. Minor cannabinoids have been suggested to indicate recreational cannabis use in biological matrices but are unreliable when presumably also present in directly plantderived medicines. Thus, for therapeutics such as medical cannabis, Sativex® and Dronabinol, a more thorough investigation of cannabinoid profiles is required to identify possible distinguishing markers. In this study, 16 phytocannabinoids were quantified in samples of seized and medical cannabis, Sativex® and Dronabinol from two different manufacturers, using a validated LC-MS/MS method. Analytes included delta-9- tetrahydrocannabinol, tetrahydocannabinolic acid A, cannabidiol, cannabidiolic acid, cannabigerol, cannabigerolic acid, cannabinol, cannabinolic acid, cannabichromene, cannabichromenic acid, cannabicyclol, cannabicyclolic acid, tetrahydrocannabivarin, tetrahydrocannabivarinic acid, cannabidivarin and cannabidivarinic acid. Resultant cannabinoid profiles were compared, and markers were suggested. Characteristics of Sativex® included a specific cannabidiol/tetrahydrocannabinol ratio and presence of cannabichromene, while acidic cannabinoids, cannabigerol and cannabinol occurred in only low amounts. As expected, the predominant ingredient in Dronabinol was tetrahydrocannabinol, but minor cannabinoids were quantified as well. Medical marihuana and seized cannabis were compared separately in a principal component analysis. Several medical marihuana varieties were found to significantly differ from seized cannabis, mostly regarding contents of tetrahydocannabinolic acid A and tetrahydrocannabivarinic acid and cannabidiolic and cannabidivarinic acid respectively.

Annual incidence of cannabis-induced psychosis, other substance-induced psychoses and dually diagnosed schizophrenia and cannabis use disorder in Denmark from 1994 to 2016

BACKGROUND

Worldwide, cannabis is the most used illegal substance, and the use of cannabis has increased over the years. An increase in the level of tetrahydrocannabinol (THC) in cannabis has also been seen. It is currently unclear whether this has led to an increase in the incidence of cannabis-induced psychosis. We aimed to investigate (1) the development of incidence of cannabis-induced psychosis over time compared with other substance-induced psychoses and (2) the development of incident cases of cannabis-induced psychosis over time compared with dual diagnosis defined as schizophrenia and a cannabis use disorder.

METHOD

Data on psychiatric diagnoses were extracted from the Danish Psychiatric Central Research Register and summarized per year as both absolute incidence (number of cases) and incidence rates per 100 000 person years.

RESULTS

The incidence rate of cannabis-induced psychosis increased steadily from 2.8 per 100 000 person years in 2006 to 6.1 per 100 000 person years in 2016. There was a corresponding increase in dual diagnosis with schizophrenia and cannabis use disorder, but a decrease in alcohol-induced psychosis. The data showed no trend in the other substance-induced psychosis investigated in this thesis.

CONCLUSION

The increase in cannabis-induced psychosis follows both the increase in the level of THC in cannabis, and the increase in cannabis use. The change in diagnostic practice does not appear to explain the increase in incidence of cannabis-induced psychosis.

Concentration of tetrahidrocannabinol in joints

Purpose

This study aims to assess the potency and dose of Δ-9-Tetrahidrocannabinol (THC) and Cannabidiol (CBD) in cannabis joints. This will enable better estimates of the degree of exposure in a user and contribute towards a better understanding of potential harmful effects.

Design/methodology/approach

Analysis of intact joints confiscated by law enforcement on the street in the autonomous region of Castilla y León (Spain) during the years 2017–2019.

Findings

This study analysed THC, CBN and CBD in marijuana joints (N = 744). Joints contain cannabis and tobacco (N = 729), had a median net weight 0.69 g (IQR = 0.28); concentration THC median was 6.30%(IQR = 4.51) and THC median dose 42 mg (IQR = 32.75). A total of 35.5% mixed joints contained CBN – median percentage 0.61% (IQR = 0.51). CBD was detected 10.3% of mixed joints – median percentage 0.13% (IQR = 0.12) and median dose 1 mg (IQR = 0.92). CBD/THC ratio presented median value of 0.02 (IQR = 0.02). The samples analysed comprised pure cannabis joints (N = 15), with THC median 11.86% (IWR = 6.30) or median dose of 118 mg.

Originality/value

The study found high values for concentration and dose of THC and CBD in cannabis joints, warning of high exposures for the user and associated potential consequences. The results obtained contribute new perspectives on the definition of a standard cannabis unit.

Cannabinoid use and self-injurious behaviours: A systematic review and meta-analysis

BACKGROUND

The increasing availability of high-potency cannabis-derived compounds and the use of synthetic cannabinoids may be responsible for severe side effects like cognitive impairment, psychosis or self-injurious behaviours (SIB). In particular, SIB like non-suicidal self-injury (NSSI) and deliberate self-harm (DSH) raise growing concern as a possible consequence of cannabis use. However, the research to date has not addressed the relationship between cannabinoid use and SIB systematically.

METHODS

We conducted a systematic review on PubMed up to March 2020, using search terms related to cannabinoids and SIB.

RESULTS

The search yielded a total of 440 abstracts. Of those, 37 studies published between 1995 and 2020 were eligible for inclusion. Cannabinoid use was significantly associated with SIB at the cross-sectional (OR=1.569, 95%CI [1.167-2.108]) and longitudinal (OR=2.569, 95%CI [2.207-3.256]) level. Chronic use, presence of mental disorders, depressive symptoms, emotional dysregulation and impulsive traits might further increase the likelihood of self-harm in cannabis users. Synthetic cannabinoids may trigger highly destructive SIB mainly through the psychotomimetic properties of these compounds.

CONCLUSION

Cannabinoid use was associated with an increased prevalence of self-injury and may act as a causative factor with a duration-dependent manner. Emotional regulation and behavioural impulsivity functions might crucially moderate this association. Future studies should further investigate the mechanisms underlying this association, while exploring potential therapeutic applications of substances modulating the endocannabinoid system.

Supporting Future Cannabis Policy - Developing a Standard Joint Unit: A Brief Back-Casting Exercise

The standardization of cannabis doses is a priority for research, policy-making, clinical and harm-reduction interventions and consumer security. Scientists have called for standard units of dosing for cannabis, similar to those used for alcohol. A Standard Joint Unit (SJU) would facilitate preventive and intervention models in ways similar to the Standard Drink (SD). Learning from the SD experiences allows researchers to tackle emerging barriers to the SJU by applying modern forecasting methods. During a workshop at the Lisbon Addictions Conference 2019, a back-casting foresight method was used to address challenges and achieve consensus in developing an SJU. Thirty-two professionals from 13 countries and 10 disciplines participated. Descriptive analysis of the workshop was carried out by the organizers and shared with the participants in order to suggest amendments. Several characteristics of the SJU were defined: (1) core values: easy-to use, universal, focused on THC, accurate, and accessible; (2) key challenges: sudden changes in patterns of use, heterogeneity of cannabis compounds as well as in administration routes, variations over time in THC concentrations, and of laws that regulate the legal status of recreational and medical cannabis use); and (3) facilitators: previous experience with standardized measurements, funding opportunities, multi-stakeholder support, high prevalence of cannabis users, and widespread changes in legislation. Participants also identified three initial steps for the implementation of a SJU by 2030: (1) Building a task-force to develop a consensus-based SJU; (2) Expanded available national-level data; (3) Linking SJU consumption to the concept of "risky use," based on evidence of harms.

Investigating the Residual Effects of Chronic Cannabis Use and Abstinence on Verbal and Visuospatial Learning

Rationale: Regular cannabis users have been shown to differ from non-using controls in learning performance. It is unclear if these differences are specific to distinct domains of learning (verbal, visuospatial), exacerbate with extent of cannabis exposure and dissipate with sustained abstinence. Objective: This study examines different domains of learning (verbal, visuospatial) in current and abstaining cannabis users, and the role of chronicity of use. Methods: In a cross-sectional design, we examined 127 psychiatrically healthy participants (65 female) with mean aged of 34 years. Of these, 69 individuals were current regular cannabis users (mean 15 years use), 12 were former cannabis users abstinent for ~2.5 yrs (after a mean of 16 years use), and 46 were non-cannabis using controls. Groups were compared on verbal learning performance assessed via the California Verbal Learning Test (CVLT-II) and for visuospatial learning measured with the Brown Location Test (BLT). We explored the association between CVLT/BLT performance and cannabis use levels in current and former users. Results: Current cannabis use compared to non-use was associated with worse performance on select aspects of verbal learning (Long Delay Cued Recall) and of visuospatial learning (Retroactive Interference and LD Rotated Recall). Prolonged abstinence was associated with altered verbal learning but intact visuospatial learning. There were non-significant correlations between distinct cannabis use measures, age and learning in both current and former users. Conclusions: Our findings suggest cannabis use status (current use, former use) affects different domains of learning (verbal and visuospatial) in a distinct fashion. These findings might be accounted for in the design of cognitive interventions aimed to support abstinence in cannabis users.

Cannabis Use, Cannabis Use Disorder, and Comorbid Psychiatric Illness: A Narrative Review

BACKGROUND

The landscape of attitudes, legal status and patterns of use of cannabis is rapidly changing in the United States and elsewhere. Therefore, the primary aim of this narrative review is to provide a concise overview of the literature on the comorbidity of cannabis use and cannabis use disorder (CUD) with other substance use and psychiatric disorders, and to use this information to accurately guide future directions for the field.

METHODS

A literature review of PubMed was conducted for studies relating to cannabis use, CUD, and a co-occurring psychiatric disorder. To provide an overview of representative data, the literature review focused on national-level, population-based work from the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) and National Survey on Drug Use and Health (NSDUH) surveys. Considering rapidly changing cannabis laws, recent (past five-year) studies were addressed.

RESULTS

A strong body of literature shows associations between cannabis use and CUD with other drug use, psychosis, mood disorders, anxiety disorders, and personality disorders. The strongest evidence of a potential causal relationship exists between cannabis use and psychotic disorders. While some evidence shows potential directionality between cannabis use and mood and anxiety disorders, results are inconsistent. Studies have established higher rates of CUD among those with personality disorders, but little about the specifics of this relationship is understood.

CONCLUSIONS

Although the general population in the United States increasingly perceives cannabis to be a harmless substance, empirical evidence shows that cannabis use is associated both with CUD and comorbid psychiatric illness. However, there is mixed evidence regarding the role of cannabis in the etiology, course, and prognosis of a co-occurring disorder across all categories of psychiatric disorders. Future research should expand on the existing body of literature with representative, longitudinal data, in order to better understand the acute and long-term effects of cannabis on comorbid psychiatric illness.

Adverse effects of Δ9-tetrahydrocannabinol on neuronal bioenergetics during postnatal development

Ongoing societal changes in views on the medical and recreational roles of cannabis increased the use of concentrated plant extracts with a Δ⁹-tetrahydrocannabinol (THC) content of more than 90%. Even though prenatal THC exposure is widely considered adverse for neuronal development, equivalent experimental data for young age cohorts are largely lacking. Here, we administered plant-derived THC (1 or 5 mg/kg) to mice daily during P5–P16 and P5–P35 and monitored its effects on hippocampal neuronal survival and specification by high-resolution imaging and iTRAQ proteomics, respectively. We found that THC indiscriminately affects pyramidal cells and both cannabinoid receptor 1⁺ (CB₁R)⁺ and CB₁R^– interneurons by P16. THC particularly disrupted the expression of mitochondrial proteins (complexes I–IV), a change that had persisted even 4 months after the end of drug exposure. This was reflected by a THC-induced loss of membrane integrity occluding mitochondrial respiration and could be partially or completely rescued by pH stabilization, antioxidants, bypassed glycolysis, and targeting either mitochondrial soluble adenylyl cyclase or the mitochondrial voltage-dependent anion channel. Overall, THC exposure during infancy induces significant and long-lasting reorganization of neuronal circuits through mechanisms that, in large part, render cellular bioenergetics insufficient to sustain key developmental processes in otherwise healthy neurons.

Repeated THC exposure in juvenile mice compromises the limbic circuitry, with life-long impairment to the respiration of neurons.