The blind men and the elephant: Systematic review of systematic reviews of cannabis use related health harms

Recreational cannabis policy reform-What mental health nurses need to know about minimising harm and contributing to the reform debate

The recently rapidly evolving legal status of recreational cannabis in various countries has triggered international debate, particularly around measures required to minimise resulting harms. The present article argues that mental health nurses should have a key role in promoting safe and appropriate use of recreational cannabis, and minimising harm based on the extant evidence. The article summarises the factors driving legalisation, outlines the evident medicinal benefits of cannabis, and appraises the evidence on the negative mental health impacts associated with use. We go on to discuss research findings on the potentially deleterious mental health effects resulting from legalising recreational cannabis and strategies to minimise these harms, including directions for future research and evaluation. Further, we consider the importance of the implementation of harm minimisation measures that are context-specific, using Thailand as an example. Finally, we present the key health promotion messages that mental health nurses should aim to convey to people who use or consider using recreational cannabis. Ultimately, we aim to provide a summary of the existing evidence that mental health nurses can draw upon to promote mental health and engage with the policy reform debate.

Cannabis use, health problems, and criminal offences in Germany: national and state-level trends between 2009 and 2021

The German federal government plans to decriminalise cannabis. The impact of this policy on use prevalence, cannabis-related health and legal problems cannot be fully anticipated and should be viewed in context with current trends. We used routine data on (a) cannabis use (population-based surveys), (b) cannabis-related diagnoses (ICD-10 code F12) in outpatient medical settings and (c) minor law offences (registered violations against the narcotics law for possessing small amounts) to analyse age and sex-specific trends by federal state between 2009 and 2021. To enable comparisons across time and federal state besides crude prevalence rates, age-standardised rates were calculated. Between 2009 and 2021, the age-standardised prevalence of cannabis use (5.7-10.6%), rate of diagnoses (1.1-3.7 per 1,000), and legal offences (1.8-3.1 per 1,000) increased, with the largest increase noted for cannabis-related diagnoses. Relatively, increases were most pronounced for older users (40-to-59-year-olds: use and offences; 35-to-44-year-olds: cannabis-related diagnoses) and rather stagnant for minors. Cannabis use and health problems appear to be more pronounced in Northern and city states, while no clear geographic trend was observed for law offences. Cannabis-related outpatient treatment demand has risen more steeply than use prevalence suggesting an increasing challenge for the health care system. Despite rising rates for documented offences, the long-term implications of law violations on social and occupational life are poorly understood but may be considered for evaluations of the proposed law changes.

Associations Between Cannabis Use and Mental Distress in Young People: A Longitudinal Study

PURPOSE

Despite a large number of studies on the relation between cannabis use and mental distress in adolescence, results are inconclusive regarding the nature of this association. The aim of the present study is to expand this body of research by analyzing the within-person association between changes in cannabis use and changes in mental distress among young people.

METHODS

We used longitudinal data from a national sample of young people in Norway. The cohort was assessed in 1992 (T1), 1994 (T2), 1999 (T3), and 2005 (T4). The cumulative response rate was 60%. Respondents who participated in all four waves, aged 11-18 years at T1 (N = 1,988) were analyzed. Within-person association between changes in cannabis use and changes in mental distress in terms of symptoms of depression, anxiety, suicidal ideation, and deliberate self-harm were estimated by applying fixed-effects modeling.

RESULTS

For males, an increase in cannabis use from no use to more than 10 times/year was significantly associated with increased risk for anxiety (relative risk [RR]: 1.72, p = .009), depressed mood (RR: 1.49, p < .001), and suicidal ideation (RR: 3.43, p = .012). For females, the corresponding increase in cannabis use yielded an increased risk for anxiety (RR: 1.38, p = .023) and suicidal ideation (RR: 2.47, p = .002).

DISCUSSION

Increased cannabis use during adolescence and young adulthood seem to increase the risk for symptoms of mental distress. Although the associations appear to be more pronounced among males, it was only for depression that there was a statistically significant gender difference in the association.

Associations between simultaneous use of alcohol and cannabis and cannabis-related problems in 2014-2016: evidence from the Washington panel survey

BACKGROUND

To address the research question of how simultaneous users of alcohol and cannabis differ from concurrent users in risk of cannabis use problems after the recreational marijuana legalization in Washington State.

METHODS

We used generalized estimating equations with a Poisson distribution to analyze the association between simultaneous use of alcohol and marijuana (SAM) and cannabis-related problems compared to concurrent use. The data is a longitudinal sample of drinkers and cannabis users (n = 257, 47% female) aged 18 years and older from Washington State in 2014-2016. We adjusted for survey weights to account for differential probability of selection and response rates. The primary outcome is the past-six-month CUDIT problem subscale (ranging from 0 to 28), which is the total score for seven CUDIT problem items, after excluding the three items that covered marijuana use frequency. Covariates include marijuana use frequency (daily/near daily use, regular use, or infrequent use), marijuana daily quantity, alcohol daily volume, panel survey cycle, medical marijuana recommendation, driving time to nearest marijuana outlet, age of marijuana use onset, and other demographics.

RESULTS

After adjusting for covariates, we found that compared to concurrent use, SAM was significantly positively associated with CUDIT problem subscale (IRR = 1.68, 95% CI: 1.25-2.27, p < 0.001); daily/near daily use of marijuana was strongly significantly associated with CUDIT problem subscale compared with infrequent use (IRR = 5.1, 2.71-9.57, p < 0.001) or regular use (IRR = 3.05, 1.91-4.85, p < 0.001). Secondary analyses using CUDIT total score as the outcome also showed a significant positive association with SAM compared to concurrent use (IRR = 1.17, 1.02-1.34, p < 0.05).

CONCLUSIONS

This study highlighted the importance of SAM, in addition to cannabis use frequency for predicting cannabis-related problems.

Cannabis-Induced Gastrointestinal Tract Symptoms in the Adult Population: A Systematic Review

OBJECTIVE

Cannabinoid usage is widespread in the self-management of various medical ailments. However, adverse effects have been reported with use, especially pertaining to the gastrointestinal system in adults and aged patients. These range from nausea, vomiting, bloating, or abdominal pain. This systematic review of previously reported cannabis-induced gastrointestinal symptoms in the adult population from the literature provides an analysis of relevant data to enhance knowledge and awareness of this topic.

METHODS

PubMed, Ovid MEDLINE, Cochrane Central, EMBASE, and Google Scholar databases were searched for relevant studies published from inception to March 2023.

RESULTS

The search yielded 598 results, of which 13 were deemed relevant and underwent further review. These included two systematic reviews, one retrospective cohort study, one retrospective chart review, two cross-sectional studies, one survey, and six case reports. The Cochrane Risk Tool for bias analysis was applied where relevant. The total number of people in the studies selected for analysis was 79, 779. Twelve out of the thirteen included studies reported some type of gastrointestinal tract symptoms experienced in medical and/or recreational cannabis users ranging from nausea, vomiting, diarrhoea, abdominal pain to adult intussusception.

CONCLUSION

Potential limitations include small sample sizes, variation in research methodologies, varied studied designs, and limited availability of data on specific populations such as geriatric users. Further research is warranted to add to current evidence pertaining to this emerging topic of significance, fill the broad knowledge gaps and contribute to evidence-based guidelines for healthcare professionals, ensuring safe prescribing practices and provision of quality care.

Neurocognitive Impact of Exposure to Cannabis Concentrates and Cannabinoids Including Vaping in Children and Adolescents: A Systematic Review

During adolescence, significant changes unfold in the brain's maturation process. The density of white matter increases, accompanied by the pruning back of gray matter. This critical and vulnerable period becomes especially noteworthy in the context of drug use, as adolescents are extensively exposed to substances such as tobacco, alcohol, and cannabis. The concern is heightened now that cannabis has been legalized for recreational use in many places, leading to increased exposure levels. Additionally, knowledge about the impact of cannabis on neurocognitive development during this stage is limited. This knowledge gap compounds the issue, making it even more concerning. Therefore, a systematic review was carried out based on the 2020 Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, using medical databases such as PubMed, PubMed Central (PMC), Medline, Cochrane Library, Internet Archive Scholar, and Embase-Elsevier for relevant medical literature. The identified articles were reviewed, eligibility criteria were applied, and 19 research articles were identified. The final papers explored the correlation between children's and adolescents' exposure to cannabis-containing compounds and subsequent changes in the central nervous system (CNS). Findings revealed a considerable impact, ranging from transient alterations in mood to permanent cognitive function and sensory processing changes, affecting the deterioration of the quality of life of these individuals in adulthood. Presently, most studies were conducted on animals, and the few studies on humans have considerable limitations, such as the type of study, age of the population, and small samples, among others. For this reason, it is essential for the scientific community and public health organizations, in general, to conduct more studies that demonstrate the true neurobiological impact of this drug and its accessibility to young people and, based on the results, consider its legalization or propose regulations for its use and commercialization.

Adolescent alcohol and cannabis use as risk factors for head trauma in the Northern Finland Birth Cohort study 1986

BACKGROUND

The aim of this study was to assess the associations between cannabis use and frequency of alcohol intoxication in adolescence with the risk of traumatic brain injury and craniofacial fractures in early adulthood. Hypothesis was that using alcohol and cannabis in adolescence could increase the risk for head traumas.

METHODS

Data from the Northern Finland Birth Cohort 1986 (n = 9432 individuals) were used to investigate the prospective association between the self-reported frequency of alcohol intoxication (n = 6472) and cannabis use (n = 6586) in mid-adolescence and register-based, head trauma diagnoses by ages 32-33 years. To test the robustness of these associations, the statistical models were adjusted for a range of other confounders such as illicit drug use, previous head trauma and self-reported mental health problems.

RESULTS

In multivariate analyses, cannabis use was statistically significantly associated with a greater risk of traumatic brain injury among females [hazard ratio (HR) 1.9, 95% confidence interval (CI) 1.1-3.2, P = 0.024). Frequent alcohol intoxication was a statistically significant independent risk factor for both traumatic brain injury (HR 2.6, 95% CI 1.7-3.9, P < 0.001) and craniofacial fractures (HR 2.7, 95% CI 1.6-4.8, P < 0.001) among males.

CONCLUSIONS

Cannabis use in adolescence appears to associate independently with elevated risk for traumatic brain injury among females, and frequent alcohol intoxication in adolescence seems to associate with elevated risk of both traumatic brain injury and craniofacial fractures among males.

Trends in past-month cannabis use among US adults across a range of disabilities and health conditions, 2015-2019

INTRODUCTION

While there is increasing interest in the use of cannabis to manage a range of health-related symptoms, little is known about trends in recent cannabis use with respect to various health conditions.

METHODS

We examined data from a US representative sample of noninstitutionalized adults age ≥ 18 from the 2015-2019 National Survey on Drug Use and Health (N = 214,505). We estimated the pooled prevalences followed by linear time trends, overall, and by disability (i.e., difficulty hearing, seeing, thinking, walking, dressing, doing errands) and lifetime (i.e., bronchitis, cancer, diabetes, hepatitis, kidney disease) and current (i.e., asthma, depression, heart disease, hypertension) health condition status using logistic regression. Models with year-by-condition status interaction terms were used to assess differential time trends, adjusting for demographic characteristics.

RESULTS

From 2015 to 2019, cannabis use increased significantly among adults with and without each disability and health condition examined. However, the increase was more rapid among those with (versus without) difficulty hearing (89.8% increase [4.9% to 9.3%] vs. 37.9% increase [8.7% to 12.0%], p = 0.015), difficulty walking (84.1% increase [6.3% to 11.6%] vs. 36.8% increase [8.7% to 11.9%], p < 0.001), 2-3 impairments (75.3% increase [9.3% to 16.3%] vs. 36.6% increase [8.2% to 11.2%], p = 0.041), and kidney disease (135.3% increase [3.4% to 8.0%] vs. 38.4% increase [8.6% to 11.9%], p = 0.045).

CONCLUSION

Given the potential adverse effects of cannabis, prevention and harm reduction efforts should focus on groups at increasingly higher risk for use, including those with disabilities and kidney disease.

Health, safety, and socioeconomic impacts of cannabis liberalization laws: An evidence and gap map

Background

Globally, cannabis laws and regulations are rapidly changing. Countries are increasingly permitting access to cannabis under various decriminalization, medicalization, and legalization laws. With strong economic, public health, and social justice incentives driving these domestic cannabis policy reforms, liberalization trends are bound to continue. However, despite a large and growing body of interdisciplinary research addressing the policy-relevant health, safety, and socioeconomic consequences of cannabis liberalization, there is a lack of robust primary and systematic research that comprehensively investigates the consequences of these reforms.

Objectives

This evidence and gap map (EGM) summarizes the empirical evidence on cannabis liberalization policies. Primary objectives were to develop a conceptual framework linking cannabis liberalization policies to relevant outcomes, descriptively summarize the empirical evidence, and identify areas of evidence concentration and gaps.

Search Methods

We comprehensively searched for eligible English-language empirical studies published across 23 academic databases and 11 gray literature sources through August 2020. Additions to the pool of potentially eligible studies from supplemental sources were made through November 2020.

Selection Criteria

The conceptual framework for this EGM draws upon a legal epidemiological perspective highlighting the causal effects of law and policy on population-level outcomes. Eligible interventions include policies that create or expand access to a legal or decriminalized supply of cannabis: comprehensive medical cannabis laws (MCLs), limited medical cannabidiol laws (CBDLs), recreational cannabis laws (RCLs), industrial hemp laws (IHLs), and decriminalization of cultivations laws (DCLs). Eligible outcomes include intermediate responses (i.e., attitudes/behaviors and markets/environments) and longer-term consequences (health, safety, and socioeconomic outcomes) of these laws.

Data Collection and Analysis

Both dual screening and dual data extraction were performed with third person deconfliction. Primary studies were appraised using the Maryland Scientific Methods Scale and systematic reviews were assessed using AMSTAR 2.

Main Results

The EGM includes 447 studies, comprising 438 primary studies and nine systematic reviews. Most research derives from the United States, with little research from other countries. By far, most cannabis liberalization research focuses on the effects of MCLs and RCLs. Studies targeting other laws-including CBDLs, IHLs, and DCLs-are relatively rare. Of the 113 distinct outcomes we documented, cannabis use was the single most frequently investigated. More than half these outcomes were addressed by three or fewer studies, highlighting substantial evidence gaps in the literature. The systematic evidence base is relatively small, comprising just seven completed reviews on cannabis use (3), opioid-related harms (3), and alcohol-related outcomes (1). Moreover, we have limited confidence in the reviews, as five were appraised as minimal quality and two as low quality.

Authors’ Conclusions

More primary and systematic research is needed to better understand the effects of cannabis liberalization laws on longer-term-and arguably more salient-health, safety, and socioeconomic outcomes. Since most research concerns MCLs and RCLs, there is a critical need for research on the societal impacts of industrial hemp production, medical CBD products, and decriminalized cannabis cultivation. Future research should also prioritize understanding the heterogeneous effects of these laws given differences in specific provisions and implementation across jurisdictions.

Deciphering the mechanisms of reciprocal regulation or interdependence at the cannabinoid CB1 receptors and cyclooxygenase-2 level: Effects on mood, cognitive implications, and synaptic signaling

The lipid endocannabinoid system refers to endogenous cannabinoids (eCBs), the enzymes involved in their synthesis and metabolism, and the G protein-coupled cannabinoid receptors (GPCRs), CB1, and CB2. CB1 receptors (CB1Rs) are distributed in the brain at presynaptic terminals. Their activation induces inhibition of neurotransmitter release, which are gamma-aminobutyric acid (GABA), glutamate (Glu), dopamine, norepinephrine, serotonin, and acetylcholine. Postsynaptically localized CB1Rs regulate the activity of selected ion channels and N-methyl-D-aspartate receptors (NMDARs). CB2Rs are mainly peripheral and will not be considered here. Anandamide metabolism, mediated by cyclooxygenase-2 (COX-2), generates anandamide-derived prostanoids. In addition, COX-2 regulates the formation of CB1 ligands, which reduce excitatory transmission in the hippocampus (HC). The role of CB1Rs and COX-2 has been described in anxiety, depression, and cognition, among other central nervous system (CNS) disorders, affecting neurotransmission and behavior of the synapses. This review will analyze common pathways, mechanisms, and behavioral effects of manipulation at the CB1Rs/COX-2 level.

The Role of Savoring in Young Adult Cannabis Use and Associated Consequences: A Replication Study

Young adults exhibit high rates of cannabis use and are at heightened risk of experiencing negative cannabis-associated consequences. The purpose of the present study was to replicate and extend to prior work on savoring, the ability to experience positive experiences/emotions, and cannabis use frequency on cannabis-associated consequences. Young adults (18-25 years old, N = 122, 36.1% women) who reported weekly cannabis use completed self-report surveys. Savoring was significantly associated with cannabis use frequency (r = .28, p < .01) and cannabis-associated consequences (r = -.20, p < .05). Cannabis use frequency was significantly and negatively associated with cannabis-associated consequences (r = -.24, p < .01). However, the interaction between cannabis use frequency and savoring on cannabis-associated consequences was not significant (b = 0.0004, p = .91, 95% CI [-0.007, 0.008]). When the interaction was removed, neither cannabis use frequency (b = -0.14, p = .08, CI [-0.29, -0.02]) nor savoring (b = -0.05, p = .16, CI [-0.13, 0.02]) were associated with cannabis-associated consequences. Results did not replicate previous findings regarding the moderating role of savoring in the relationship between cannabis use frequency and cannabis-associated consequences. Future research may explore why findings did not replicate by using more fine-grained assessment methods and comprehensive measures of cannabis use.

The association between cannabis use and subjective memory complaints in older adults in the United States

OBJECTIVE

The U.S. population is aging and increasing numbers of older adults are using cannabis. Cognitive decline is common in older age and subjective memory complaints (SMC) have been associated with increased risk for dementia. While residual cognitive effects of cannabis use at younger ages are well understood, the links between cannabis use and cognition in older adults is less clear. The present study represents the first population-level analysis of cannabis use and SMC in older adults in the U.S.

METHOD

We used the National Survey of Drug Use and Health (NSDUH) dataset to evaluate SMC in respondents over age 50 (N = 26,399) according to past-year cannabis use.

RESULTS

Results revealed that 13.2% (95%CI: 11.5%-15.0%) of those who reported cannabis use also reported SMC, compared to 6.4% (95%CI: 6.1%-6.8%) among individuals with no cannabis use. Logistic regression revealed a two-fold increase (OR = 2.21, 95%CI: 1.88-2.60) of reporting SMC in respondents who had used cannabis in the past year, which was attenuated (OR = 1.38, 95%CI: 1.10-1.72) when controlling for additional factors. Other covariates, including physical health conditions, misuse of other substances, and mental illness also significantly contributed to SMC outcomes.

CONCLUSIONS

Cannabis use represents a modifiable lifestyle factor that has potential for both risk and protective properties that may impact the trajectory of cognitive decline in older age. These hypothesis generating results are important for characterizing and contextualizing population-level trends related to cannabis use and SMC in older adults.

Measuring cannabis quantities in online surveys: A rapid review and proposals for ways forward

OBJECTIVES

Cannabis use quantities are relevant for determining cannabis-related harms. This research aims to provide an overview of the available methods to assess quantities through self-report.

METHODS

A rapid review of various strategies to collect information on cannabis use quantities through self-report. Two independent literature searches resulted in n = 38 studies included for review.

RESULTS

A total of n = 14 studies employed methods for collecting cannabis use quantities that are not suitable for online surveys (e.g., rolling a fake joint). Of the remaining n = 24 studies with items that are suitable for online surveys, the quantity assessment was performed in three different ways. The data collection was either carried out by asking (a) for the total number of joints (i.e., crude joint method), (b) for the total weight (i.e., crude weight method), or (c) for specific products separately, for example, for the amount of flower and resin (i.e., product-specific method). In only n = 8 studies, cannabis use quantities were ascertained by providing visual aids (e.g., illustration of various amounts of flower).

CONCLUSIONS

The crude joint method and the product-specific method are the two most promising methods to collect information on cannabis use quantities. Using visual aids may potentially improve the accuracy of those methods.

Pharmacosophrosyne Revisited: Drug Use and Virtue Ethics

In a 1959 article, John C. Ford, SJ (1902-1989), proposed the existence of a new virtue to regulate recreational drug use which he names "pharmacosophrosyne." This article analyzes the soundness of Ford's proposal and extends it by providing a mereological analysis of how pharmacosophrosyne relates to the virtues of temperance and sobriety. It then shows how understanding both pharmacosophrosyne and sobriety can inform a moral evaluation of recreational drug use.

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).

Dimensionality and differential functioning of DSM-5 cannabis use disorder criteria in an online sample of adults with frequent cannabis use

The DSM-5 criteria for cannabis use disorder (CUD) combine DSM-IV dependence and abuse criteria (without legal problems) and new withdrawal and craving criteria. Information on dimensionality, internal reliability, and differential functioning of the DSM-5 CUD criteria is lacking. Additionally, dimensionality of the DSM-5 withdrawal items is unknown. This study examined the psychometric properties of the DSM-5 CUD criteria among adults who used cannabis in the past 7 days (N = 5,119). Adults with frequent cannabis use were recruited from the US general population through social media and filled in a web-based survey about demographics and cannabis use behaviors. Factor analysis was used to assess dimensionality, and item response theory analysis models were used to explore relationships between the criteria and the underlying latent trait (CUD), and whether each criterion and the criteria set functioned differently by demographic and clinical characteristics: sex, age, state-level cannabis laws, reasons for cannabis use, and frequency of use. The DSM-5 CUD criteria showed unidimensionality and provided information about the CUD latent trait across the severity spectrum. The cannabis withdrawal items indicated one underlying latent factor. While some CUD criteria functioned differently in specific subgroups, the criteria set as a whole functioned similarly across subgroups. In this online sample of adults with frequent cannabis use, evidence supports the reliability, validity, and utility of the DSM-5 CUD diagnostic criteria set, which can be used for determining a major risk of cannabis use, i.e., CUD, to inform cannabis policies and public health messaging, and for developing intervention strategies.

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.

Exclusive Therapeutic Use of Cannabis in a Large Sample of Daily Cannabis Users in France: A Cross-Sectional Survey

Many cannabis users report therapeutic benefits from cannabis consumption, even when not recommended by a physician. To date, few data on therapeutic users of cannabis in France are available. Using a cross-sectional survey held in 2020, we collected sociodemographic, health and substance use data from 4150 daily cannabis users in France. We used multivariable logistic regression to assess factors associated with exclusive therapeutic use of cannabis. Approximately 10% (n = 453) of the participants reported using cannabis exclusively for therapeutic purposes. Exclusive therapeutic users of cannabis differed from non-exclusive (i.e. recreational and mixed) users, especially regarding age (aOR [95%CI] = 1.01 [1.00-1.02]), employment (aOR = 0.61 [0.47-0.79]), urban area of residence (aOR = 0.75 [0.60-0.94]), physical (aOR = 2.95 [2.34-3.70]) and mental health condition (aOR = 2.63 [1.99-3.49]), mode of cannabis administration (non-smoked, aOR = 1.89 [1.22-2.95); smoked with little tobacco, aOR = 1.39 [1.09-1.76]), frequency of cannabis use (aOR = 1.04 [1.01-1.06]), home cultivation (aOR = 1.56 [1.13-2.15]), at-ridsk alcohol use (aOR = 0.68 [0.54-0.84]), and previous-month opiate use (aOR = 1.67 [1.22-2.30]). A greater understanding of the distinct profiles of regular cannabis users could inform harm reduction strategies and care access for this population. Further studies are needed to better understand the boundaries between therapeutic and recreational use.

Modulation of pulmonary immune function by inhaled cannabis products and consequences for lung disease

The lungs, in addition to participating in gas exchange, represent the first line of defense against inhaled pathogens and respiratory toxicants. Cells lining the airways and alveoli include epithelial cells and alveolar macrophages, the latter being resident innate immune cells important in surfactant recycling, protection against bacterial invasion and modulation of lung immune homeostasis. Environmental exposure to toxicants found in cigarette smoke, air pollution and cannabis can alter the number and function of immune cells in the lungs. Cannabis (marijuana) is a plant-derived product that is typically inhaled in the form of smoke from a joint. However, alternative delivery methods such as vaping, which heats the plant without combustion, are becoming more common. Cannabis use has increased in recent years, coinciding with more countries legalizing cannabis for both recreational and medicinal purposes. Cannabis may have numerous health benefits owing to the presence of cannabinoids that dampen immune function and therefore tame inflammation that is associated with chronic diseases such as arthritis. The health effects that could come with cannabis use remain poorly understood, particularly inhaled cannabis products that may directly impact the pulmonary immune system. Herein, we first describe the bioactive phytochemicals present in cannabis, with an emphasis on cannabinoids and their ability to interact with the endocannabinoid system. We also review the current state-of-knowledge as to how inhaled cannabis/cannabinoids can shape immune response in the lungs and discuss the potential consequences of altered pulmonary immunity. Overall, more research is needed to understand how cannabis inhalation shapes the pulmonary immune response to balance physiological and beneficial responses with potential deleterious consequences on the lungs.

Screening, brief intervention, and referral to treatment (SBIRT) for cannabis: A scoping review

INTRODUCTION

Screening, brief intervention, and referral to treatment (SBIRT) has been used to change substance use behavior. Despite cannabis being the most prevalent federally illicit substance, we have limited understanding of use of SBIRT for managing cannabis use. This review aimed to summarize the literature on SBIRT for cannabis use across age groups and contexts over the last two decades.

METHODS

This scoping review followed the a priori guide outlined by the PRISMA (Preferred Reporting Items for Scoping Reviews and Meta-Analyses) statement. We gathered articles from PsycINFO, PubMed, Sage Journals Online, ScienceDirect, and SpringerLink.

RESULTS

The final analysis includes forty-four articles. Results indicate inconsistent implementation of universal screens and suggest screens assessing cannabis-specific consequences and utilizing normative data may increase patient engagement. Broadly, SBIRT for cannabis demonstrates high acceptability. However, the impact of SBIRT on behavior change across various modifications to intervention content and modality has been inconsistent. In adults, patients with primary cannabis use are not engaging in recommended treatment at similar rates to other substances. Results also suggest a lack of research addressing referral to treatment in adolescents and emerging adults.

DISCUSSION

Based on this review, we offer several to improve each component of SBRIT that may increase implementation of screens, effectiveness of brief interventions, and engagement in follow-up treatment.

Cannabis legalization and cannabis use, daily cannabis use and cannabis-related problems among adults in Ontario, Canada (2001-2019)

BACKGROUND

In the context of cannabis legalization in Canada, we examined the effects on cannabis patterns of consumption, including cannabis use, daily cannabis use and cannabis-related problems. In addition, we examined differential effects of cannabis legalization by age and sex.

METHODS

A pre-post design was operationalized by combining 19 iterations of the Centre for Addiction and Mental Health (CAMH) Monitor Surveys (N = 52,260; 2001-2019): repeated, population-based, cross-sectional surveys of adults in Ontario. Participants provided self-reports of cannabis use (past 12 months), daily cannabis use (past 12 months) and cannabis-related problems though telephone interviews. The effects of cannabis legalization on cannabis patterns of consumption were examined using logistic regression analyses, with testing of two-way interactions to determine differential effects by age and sex.

RESULTS

Cannabis use prevalence increased from 11 % to 26 % (p < 0.0001), daily cannabis use prevalence increased from 1 % to 6 % (p < 0.0001) and cannabis-related problems prevalence increased from 6 % to 14 % (p < 0.0001) between 2001 and 2019. Cannabis legalization was associated with an increased likelihood of cannabis use (OR, 95 % CI: 1.62, 1.40-1.86), daily cannabis use (1.59, 1.21-2.07) and cannabis-related problems (1.53, 1.20-1.95). For cannabis-related problems, a significant two-way interaction was observed between cannabis legalization and age (p = 0.0001), suggesting differential effects among adults ≥55 years.

CONCLUSIONS

Cannabis legalization was associated with an increased likelihood of cannabis use, daily cannabis use and cannabis-related problems. Given increases in these cannabis patterns of consumption, broader dissemination and uptake of targeted prevention tools is indicated.

Endocannabinoid System and Exogenous Cannabinoids in Depression and Anxiety: A Review

Background: There is a growing liberalization of cannabis-based preparations for medical and recreational use. In multiple instances, anxiety and depression are cited as either a primary or a secondary reason for the use of cannabinoids. Aim: The purpose of this review is to explore the association between depression or anxiety and the dysregulation of the endogenous endocannabinoid system (ECS), as well as the use of phytocannabinoids and synthetic cannabinoids in the remediation of depression/anxiety symptoms. After a brief description of the constituents of cannabis, cannabinoid receptors and the endocannabinoid system, the most important evidence is presented for the involvement of cannabinoids in depression and anxiety both in human and from animal models of depression and anxiety. Finally, evidence is presented for the clinical use of cannabinoids to treat depression and anxiety. Conclusions: Although the common belief that cannabinoids, including cannabis, its main studied components-tetrahydrocannabinol (THC) and cannabidiol (CBD)-or other synthetic derivatives have been suggested to have a therapeutic role for certain mental health conditions, all recent systematic reviews that we report have concluded that the evidence that cannabinoids improve depressive and anxiety disorders is weak, of very-low-quality, and offers no guidance on the use of cannabinoids for mental health conditions within a regulatory framework. There is an urgent need for high-quality studies examining the effects of cannabinoids on mental disorders in general and depression/anxiety in particular, as well as the consequences of long-term use of these preparations due to possible risks such as addiction and even reversal of improvement.

Risk of readmission among individuals with cannabis use disorder during a 15-year cohort study: the impact of socio-economic factors and psychiatric comorbidity

BACKGROUND AND AIM

Cannabis use disorder (CUD) is one of the main reasons for seeking substance treatment in the Nordic countries, but there are few studies on readmission to care. We aimed to characterize CUD readmission and estimate the magnitude of how socio-economic factors and psychiatric comorbidity influence the risk of CUD readmission.

DESIGN, SETTING AND PARTICIPANTS

This was a nation-wide cohort study carried out between 2001 and 2016 in Sweden. The participants were individuals with CUD, aged 17 years and above (n = 12 143).

MEASUREMENTS

Information on predictors was obtained from registers and included education, income and psychiatric comorbidity assessed by six disease groups. The outcome measure was readmission, defined as a CUD visit to health-care at least 6 months after initial CUD diagnosis. Hazard ratios (HR) were estimated using Cox survival analyses and flexible parametric survival analyses to assess risk of readmission and how the risk varied with age.

FINDINGS

The vast majority of CUD visits took place in outpatient care (~80%). Approximately 23% of the included individuals were readmitted to care during follow-up. The fully adjusted model showed an increased risk of readmission among those with schizophrenia and other psychotic disorders [HR = 1.54, 95% confidence interval (CI) = 1.29-1.84], low education (HR = 1.40, 95% CI = 1.24-1.57), personality disorders (HR = 1.27, 95% CI = 1.05-1.54) or mood disorders (HR = 1.27, 95% CI = 1.12-1.45). Flexible parametric modeling revealed increased risk of readmission mainly in individuals aged 18-35 years.

CONCLUSIONS

The risk of readmission was highest among those with low education, schizophrenia and other psychotic disorders, mood-related disorders or personality disorders. Individuals aged 18-35 years showed the highest risk of readmission. Our findings highlight individuals with complex health-care needs.

Canada’s Cannabis Legalization with Strict Public Health Control

Abstract: Aims: To describe the impact of the legalization of cannabis for recreational use under strict public health control in 2018 on the following outcomes: cannabis use and use patterns, attributable harm, economic considerations. Methodology: Narrative review based on government documents, surveys, and published literature. Results: The 12-month prevalence increased after legalization and has decreased during the COVID-19 pandemic. Little change in prevalence for adolescents. Persons with daily use remained stable. No rigorous studies on changes in attributable health harm, but some indication that harm, as measured in prevalence of cannabis use disorders, treatment rate, and attributable traffic injury remained stable. No data yet available for cancer. Cannabis attributable emergency visits increased, including among children (poisoning). Cannabis-related offences decreased as biggest public health gain. Economic predictions were not realized, and there is some pressure from cannabis industry to loosen public health regulations in order to increase use. Conclusions: Overall, while not achieving its main objectives of more youth protection and decreases in cannabis-attributable health harm, legalization with strict public health control resulted in less cannabis-related offences and up to now did not seem to increase cannabis-attributable disease burden.

Cannabis use disorder in relation to socioeconomic factors and psychiatric comorbidity: A cluster analysis of three million individuals born in 1970-2000

BACKGROUND

Cannabis use disorder (CUD) is one of the main reasons for seeking substance use treatment. It is thus important to monitor and increase knowledge of individuals with CUD utilizing healthcare. We aimed to examine the number of CUD diagnoses over time, compare individuals with CUD with those without and identify subgroups based on CUD diagnosis, sex, birth year, socioeconomic factors and psychiatric comorbidity.

METHODS

A Swedish, population-based study with 3,307,759 individuals, born in 1970-2000, with register data extending to 2016. K-mode cluster analysis was used to identify potential subgroups.

RESULTS

The number of individuals with a CUD diagnosis was 14,046 (0.42%). CUD diagnoses increased over time (born 1990-1994: 61 per 100,000, born 1995-2000: 107 per 100,000, by 2016). A majority of those with a CUD had another psychiatric diagnosis (80%, compared with 19% for those without CUD). Four clusters were identified. Cluster 1 comprised mainly men with low income and substance use disorders, clusters 2, 3 and 4 comprised mainly women with higher proportions of mood-related, neurotic and stress-related and behavioural disorders.

CONCLUSIONS

There was an increase in CUD diagnoses in Sweden over time, especially among younger birth cohorts. Individuals with CUD were more often male, from younger birth cohorts, with lower education and income than those without CUD. Men and women with CUD exhibited differences in education, income and psychiatric comorbidity. Our results demonstrate the importance of monitoring the impact of socioeconomic factors and psychiatric comorbidity in relation to CUD.

Towards a dispositionalist (and unifying) account of addiction

Addiction theorists have often utilized the metaphor of the blind men and the elephant to illustrate the complex nature of addiction and the varied methodological approaches to studying it. A common purported upshot is skeptical in nature: due to these complexities, it is not possible to offer a unifying account of addiction. I think that this is a mistake. The elephant is real-there is a there there. Here, I defend a dispositionalist account of addiction as the systematic disposition to fail to control one's desires to engage in certain types of behaviors. I explain this position, defend the inclusion of desires and impaired control, and flesh out the notion of systematicity central to my account. I then illustrate how my dispositionalist framework can unify the disparate and seemingly incompatible accounts of addiction (and their respective methodological approaches). I close with a brief plan to extend and implement my account.

Daily cannabis use during the novel coronavirus disease (COVID-19) pandemic in Canada: a repeated cross-sectional study from May 2020 to December 2020

Background

Daily cannabis use is most strongly implicated in the cannabis-attributable burden of disease. In the context of the novel coronavirus disease (COVID-19) pandemic in Canada, we characterized trends in daily cannabis use in the overall sample and various population subgroups, and examined risk characteristics associated with daily cannabis use.

Methods

A cross-sectional design was operationalized using data from six waves of a national, online survey of adults residing in Canada who spoke English (N = 6,021; May-08 2020 to December-01 2020). Trends were characterized using the Cochran-Armitage test and risk characteristics were identified using chi-square test and logistic regression analysis.

Results

Daily cannabis use in the overall sample remained stable (5.34% – 6.10%; p = 0.30). This pattern of findings extended to various population subgroups as well. The odds of daily cannabis use were higher for those who: were males (Odds Ratio; 95% Confidence Interval: 1.46; 1.15 – 1.85), were between 18 – 29 years (2.36; 1.56 – 3.57), 30 – 39 years (2.65; 1.93 – 3.64) or 40–49 years (1.74; 1.19 – 2.54), self-identified as white (1.97; 1.47 – 2.64), had less than college or university completion (1.78; 1.39 – 2.28), engaged in heavy episodic drinking (2.05; 1.62 – 2.61), had a job that increased the risk of contracting COVID-19 (1.38; 1.01 – 1.88), experienced loneliness 5–7 days in the past week (1.86; 1.26 – 2.73) and felt very worried (2.08; 1.21 – 3.58) or somewhat worried (1.83; 1.11 – 3.01) about the pandemic’s impact on their financial situation.

Conclusions

Daily cannabis use did not change in the overall sample or various population subgroups during the pandemic. Pandemic-related risks and impacts were associated with daily cannabis use.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13011-022-00441-x.

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

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

Mortality risk for individuals with cannabis use disorders in relation to alcohol use disorders: Results of a follow-up study

BACKGROUND

There are few studies on mortality on individuals entering treatment for cannabis use disorders.

OBJECTIVES

To estimate mortality risk for individuals treated for cannabis use disorders comparing patients with concomitant alcohol use disorders to those with only cannabis use disorders.

METHODS

Follow-up study on 1136 residents in Northern Italy who turned to health services following problems caused by cannabis use disorders between 2009 and 2019. Individuals with concomitant use of opioids, amphetamines, cocaine, or injecting drugs were excluded. Crude mortality rates per 1000 Person Years (CMR), and standardized mortality ratios adjusted for age, sex and calendar year (SMR) were calculated.

RESULTS

Elevated CMRs (CMR 4.4, 3-6.4), higher among patients with concomitant alcohol use disorders (CMR 10.2, 6.6-15.6) compared to those with only cannabis use disorders (CMR 1.8, 0.9-3.6) were found. Regarding excess mortality with respect to the general population, SMRs were higher and statistically significant (SMR 5.4, 3.7-7.8), both among patients with concomitant alcohol use disorders (SMR 10.2, 6.6-15.6) and among those with only cannabis use disorders (SMR 2.3, 1.1-4.5).

CONCLUSIONS

The results of this study show that individuals with only cannabis use disorders have a lower mortality risk compared to those with both cannabis and alcohol use disorders.

Identifying risk-thresholds for the association between frequency of cannabis use and development of cannabis use disorder: A systematic review and meta-analysis

BACKGROUND

Cannabis use disorder (CUD) affects one-in-five cannabis users, presenting a major contributor to cannabis-associated disease burden. Epidemiological data identify the frequency of cannabis use as a risk factor for CUD. This review aimed to determine quantifiable risk-thresholds of the frequency of cannabis use for developing CUD.

METHODS

Systematic search of Medline, EMBASE, PsycInfo, CINAHL, and Web of Science for cohort/case-control studies that assessed the association between frequency of cannabis use and CUD from 2000 to 2022. Effect estimates were converted to risk ratios (RR). A random-effects multi-level multivariate meta-analytic approach was utilized, and sensitivity analyses conducted. Quality of included studies was assessed with the Newcastle Ottawa Scale.

RESULTS

Six prospective cohort studies were included in this review, drawn from two main source studies. Random-effect modeling showed a significant log-linear dose-response association between the frequency of cannabis use and CUD risk (p < 0.0001). The risk of CUD increased from RR:2.03 (95% CI:1.85-2.22) for 'yearly' use, to RR:4.12 (95% CI:3.44-4.95) for 'monthly" use, RR:8.37 (95% CI:6.37-11.00) for 'weekly' use, and RR:16.99 (95% CI:11.80-24.46) for 'daily' use. Multi-level modeling showed an absolute risk increase (ARI) from 3.5% (95% CI:2.6-4.7) for 'yearly' use, to 8.0% (95% CI:5.3-12.1) for 'monthly' use, to 16.8% (95% CI:8.8-32.0) for 'weekly' use, and 36% (95% CI:27.047.9) for 'daily' use.

CONCLUSION

A limited risk of CUD as a potential outcome of cannabis use exists even at infrequent levels of use, but significantly increases as frequency of use increases. Corresponding information should be conveyed to cannabis users as part of targeted prevention messaging to promote safer cannabis use.

Practical Considerations for the Use of Cannabis in Cancer Pain Management—What a Medical Oncologist Should Know

Pain is a highly debilitating emotional and sensory experience that significantly affects quality of life (QoL). Numerous chronic conditions, including cancer, are associated with chronic pain. In the setting of malignancy, pain can be a consequence of the tumor itself or of life-saving interventions, including surgery, chemotherapy, and radiotherapy. Despite significant pharmacological advances and awareness campaigns, pain remains undertreated in one-third of patients. To date, opioids have been the mainstay of cancer pain management. The problematic side effects and unsatisfactory pain relief of opioids have revived patients’ and physicians’ interest in finding new solutions, including cannabis and cannabinoids. The medical use of cannabis has been prohibited for decades, and it remains in Schedule 1 of the Misuse of Drugs Regulations. Currently, the legal context for its usage has become more permissive. Various preclinical and observational studies have aimed to prove that cannabinoids could be effective in cancer pain management. However, their clinical utility must be further supported by high-quality clinical trials.

Long-term and serious harms of medical cannabis and cannabinoids for chronic pain: a systematic review of non-randomised studies

OBJECTIVE

To establish the prevalence of long-term and serious harms of medical cannabis for chronic pain.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

MEDLINE, EMBASE, PsycINFO and CENTRAL from inception to 1 April 2020.

STUDY SELECTION

Non-randomised studies reporting on harms of medical cannabis or cannabinoids in adults or children living with chronic pain with ≥4 weeks of follow-up.

DATA EXTRACTION AND SYNTHESIS

A parallel guideline panel provided input on the design and interpretation of the systematic review, including selection of adverse events for consideration. Two reviewers, working independently and in duplicate, screened the search results, extracted data and assessed risk of bias. We used random-effects models for all meta-analyses and the Grades of Recommendations, Assessment, Development and Evaluation approach to evaluate the certainty of evidence.

RESULTS

We identified 39 eligible studies that enrolled 12 143 adult patients with chronic pain. Very low certainty evidence suggests that adverse events are common (prevalence: 26.0%; 95% CI 13.2% to 41.2%) among users of medical cannabis for chronic pain, particularly any psychiatric adverse events (prevalence: 13.5%; 95% CI 2.6% to 30.6%). Very low certainty evidence, however, indicates serious adverse events, adverse events leading to discontinuation, cognitive adverse events, accidents and injuries, and dependence and withdrawal syndrome are less common and each typically occur in fewer than 1 in 20 patients. We compared studies with <24 weeks and ≥24 weeks of cannabis use and found more adverse events reported among studies with longer follow-up (test for interaction p<0.01). Palmitoylethanolamide was usually associated with few to no adverse events. We found insufficient evidence addressing the harms of medical cannabis compared with other pain management options, such as opioids.

CONCLUSIONS

There is very low certainty evidence that adverse events are common among people living with chronic pain who use medical cannabis or cannabinoids, but that few patients experience serious adverse events.

Low income and schizophrenia risk: a narrative review

Despite decades of research, the precise etiology of schizophrenia is not fully understood. Ample evidence indicates that the disorder derives from a complex interplay of genetic and environmental factors during vulnerable stages of brain maturation. Among the plethora of risk factors investigated, stress, pre- and perinatal insults, and cannabis use have been repeatedly highlighted as crucial environmental risk factors for schizophrenia. Compelling findings from population-based longitudinal studies suggest low income as an additional risk factor for future schizophrenia diagnosis, but underlying mechanisms remain unclear. In this narrative review, we 1) summarize the literature in support of a relationship between low (parental) income and schizophrenia risk, and 2) explore the mediating role of chronic stress, pre- and perinatal factors, and cannabis use as established risk factors for schizophrenia. Our review describes how low income facilitates the occurrence and severity of these established risk factors and thus contributes to schizophrenia liability. The broadest influence of low income was identified for stress, as low income was found to be associated with exposure to a multitude of severe psychological and physiological stressors. This narrative review adds to the growing literature reporting a close relationship between income and mental health.

Trajectories of adolescent psychotic-like experiences and early cannabis exposure: Results from a Finnish Birth Cohort Study

BACKGROUND

Longitudinal studies examining the effect of cannabis exposure (CE) on the prognosis of adolescents with psychotic-like experiences (PLEs) are scarce. We examined trajectories of mental health in adolescents with PLEs and cannabis exposure.

METHODS

The Northern Finland Birth Cohort 1986 (n = 6552) with linkage to nationwide register data was used. Information on lifetime cannabis exposure was collected when participants were aged 15/16. Register-based outcome data on diagnoses made in clinical practice were obtained until age 33. Logistic regression was used to study the association of PLE/CE patterns and subsequent psychiatric disorders. The group with neither PLEs nor CE was utilized as the reference group. Parental psychiatric disorders, family structure, sex, frequent alcohol intoxications, daily smoking and illicit substance use other than cannabis were adjusted for.

RESULTS

In all, 6552 subjects (49.2 % males) were included in analysis. PLEs with cannabis exposure were associated with any psychiatric disorder (OR = 2.59; 95 % CI 1.82-3.68), psychotic disorders (OR = 3.86; 95 % CI 1.83-8.11), mood disorders (OR 4.07; 95 % CI 2.74-6.04), depressive disorders (OR = 4.35; 95 % CI 2.93-6.48), anxiety disorders (OR = 2.06; 95 % CI 1.34-3.17) and substance use disorders (OR = 2.26; 95 % CI 1.13-4.50) compared to reference group. Effect sizes were greater for group with both PLEs and cannabis use than for group with PLEs only.

CONCLUSIONS

Early-onset cannabis use is an adverse prognostic marker for adolescents with PLEs after extensive confounder control including other substance use.

Examining Risk Factors in the Cannabis–Suicide Link: Considering Trauma and Impulsivity among University Students

Cannabis is a commonly used substance among university students that may have several negative health repercussions, including suicidal ideation (SI) and suicide attempts (SA). The factors that contribute to or help explain this relation remain uncertain. Earlier negative experiences, especially trauma encountered during early life, have been associated with the development of psychopathology upon later stressor encounters. In the current study, we examined the associations between SI and SA with problematic cannabis use among young adults and the role of earlier trauma experiences and trait impulsiveness in understanding this link. Among university students (N = 539), problematic cannabis use was moderately related to lifetime and past-12-months suicidal ideation and attempts. Impulsiveness mediated the relationship between problematic cannabis use and lifetime SI and SA. Moreover, previous life trauma moderated the relationship between problematic cannabis use and SA, such that the association between problematic cannabis use and SA was stronger among those who experienced high levels of trauma. These findings highlight behavioral and environmental factors that could predict suicide ideation and attempts among young cannabis users. Accordingly, trait impulsiveness and early trauma experiences should be considered, alongside problematic cannabis use, in suicide-risk detection and prevention strategies among young adults.

Association between cannabis use and suicidal behavior: A systematic review of cohort studies

The use of cannabis is highly prevalent worldwide, with known short and long-term adverse effects. However, the relationship between cannabis use and suicidal behavior remains relatively unexplored and this paper aims to unify existing literature on the topic. A systematic review was conducted using MEDLINE, Embase, PsycINFO and LILACS databases with a supplementary search to identify cohort articles published up to January 2020, with no age delimitation for the samples. This review aimed to address the relationship between cannabis use and suicidal behavior, defined as suicidal ideation, attempted suicide or completed suicide. Twenty-two articles were identified, with no clear consensus, irrespective of the outcome being investigated. This was the case even when taking into consideration only those studies with a sound methodology (according to the Newcastle-Ottawa scale). Studies that identified an association explored the importance of the endocannabinoid system as well as the psychosocial context of the individual while developing suicidal behavior, with certain studies demonstrating that greater intensity or precocity of cannabis use increases the strength of this association. The relationship between cannabis use and suicidal behavior is complex, with no consensus in the literature. Further studies with standardized definitions for cannabis use, including frequency of use, along with improved controls for confounding variables are needed.

Impact of the policy environment on substance use among sexual minority women

Background:

Sexual minority women (SMW) are at greater risk for heavy episodic drinking, frequent marijuana use, and tobacco use than heterosexual women. Because past research has suggested the political and social environment may influence disparities in substance use by sexual orientation, this study examined associations of the U.S. state-level policy environment on substance use by SMW.

Methods:

A total of 732 SMW participants were recruited from two national online panels: a general population panel (n = 333) and a sexual minority-specific panel (n = 399). Past year substance use was defined by number of days of heavy episodic drinking (HED; 4+ drinks in a day), weekly tobacco use (once a week or more vs. less or none), and weekly marijuana use (once a week or more vs. less or none). Comprehensive state policy protection was defined by enactment of five policies protecting rights of sexual minorities. Regression models compared substance use outcomes for SMW living in states with comprehensive policy protections to SMW living in states with fewer or no protections. Models also assessed the impact of state policies related to alcohol (state monopoly on alcohol wholesale or retail sales), tobacco (state enactment of comprehensive smoke-free workplace laws) and marijuana (legalization of purchase, possession, or consumption of marijuana for recreational use).

Results:

Comprehensive policy protections were associated with fewer HED days. Recreational marijuana legalization was associated with higher odds of weekly use.

Conclusions:

Findings underscore the importance of policy protections for sexual minorities in reducing substance use, particularly HED, among SMW.

How do cannabis users mentally travel in time? Evidence from an fMRI study of episodic future thinking

RATIONALE

Episodic future thinking (EFT) is a cognitive function that allows individuals to imagine novel experiences that may happen in the future. Prior studies show that EFT is impaired in different groups of substance users. However, there is no evidence regarding the neurobiological mechanisms of EFT in cannabis users.

OBJECTIVES

We aimed to compare brain activations of regular cannabis users and non-using controls during an EFT fMRI task. Exploratory analyses were also conducted to investigate the association between EFT and cannabis use variables (e.g., duration of use, age onset, frequency of use).

METHODS

Twenty current cannabis users and 22 drug-naïve controls underwent an fMRI scanning session while completing a task involving envisioning future-related events and retrieval of past memories as a control condition. The EFT fMRI task was adapted from the autobiographical interview and composed of 20 auditory cue sentences (10 cues for past and 10 cues for future events). Participants were asked to recall a past or generate a future event, in response to the cues, and then rate their vividness after each response.

RESULTS

We found that cannabis users compared to non-user controls had lower activation within the cerebellum, medial and superior temporal gyrus, lateral occipital cortex, and occipital fusiform gyrus while envisioning future events. Cannabis users rated the vividness of past events significantly lower than non-users (P < 0.005). There were marginal group differences for rating the vividness of future events (P = 0.052). Significant correlations were also found between the medial and superior temporal gyrus activities and behavioral measures of EFT and episodic memory.

CONCLUSIONS

Cannabis users, compared to drug-naïve controls, have lower brain activation in EFT relevant regions. Thus, any attempts to improve aberrant EFT performance in cannabis users may benefit from EFT training.

Standardized Cannabis Smoke Extract Induces Inflammation in Human Lung Fibroblasts

Cannabis (marijuana) is the most commonly used illicit product in the world and is the second most smoked plant after tobacco. There has been a rapid increase in the number of countries legalizing cannabis for both recreational and medicinal purposes. Smoking cannabis in the form of a joint is the most common mode of cannabis consumption. Combustion of cannabis smoke generates many of the same chemicals as tobacco smoke. Although the impact of tobacco smoke on respiratory health is well-known, the consequence of cannabis smoke on the respiratory system and, in particular, the inflammatory response is unclear. Besides the combustion products present in cannabis smoke, cannabis also contains cannabinoids including Δ⁹-tetrahydrocannabinol (Δ⁹-THC) and cannabidiol (CBD). These compounds are hydrophobic and not present in aqueous solutions. In order to understand the impact of cannabis smoke on pathological mechanisms associated with adverse respiratory outcomes, the development of in vitro surrogates of cannabis smoke exposure is needed. Therefore, we developed a standardized protocol for the generation of cannabis smoke extract (CaSE) to investigate its effect on cellular mechanisms in vitro. First, we determined the concentration of Δ⁹-THC, one of the major cannabinoids, by ELISA and found that addition of methanol to the cell culture media during generation of the aqueous smoke extract significantly increased the amount of Δ⁹-THC. We also observed by LC-MS/MS that CaSE preparation with methanol contains CBD. Using a functional assay in cells for CB1 receptors, the major target of cannabinoids, we found that this CaSE contains Δ⁹-THC which activates CB1 receptors. Finally, this standardized preparation of CaSE induces an inflammatory response in human lung fibroblasts. This study provides an optimized protocol for aqueous CaSE preparation containing biologically active cannabinoids that can be used for in vitro experimentation of cannabis smoke and its potential impact on various indices of pulmonary health.

Relationships of Cannabis Policy Liberalization With Alcohol Use and Co-Use With Cannabis: A Narrative Review

PURPOSE

The liberalization of cannabis policies has the potential to affect the use of other substances and the harms from using them, particularly alcohol. Although a previous review of this literature found conflicting results regarding the relationship between cannabis policy and alcohol-related outcomes, cannabis policies have continued to evolve rapidly in the years since that review.

SEARCH METHODS

The authors conducted a narrative review of studies published between January 1, 2015, and December 31, 2020, that assessed the effects of cannabis policies on the use of alcohol in the United States or Canada.

SEARCH RESULTS

The initial search identified 3,446 unique monographs. Of these, 23 met all inclusion criteria and were included in the review, and five captured simultaneous or concurrent use of alcohol and cannabis.

DISCUSSION AND CONCLUSIONS

Associations between cannabis policy liberalization and alcohol use, alcohol-related outcomes, and the co-use of alcohol and cannabis were inconclusive, with studies finding positive associations, no associations, and negative associations. Although several studies found that cannabis policy liberalization was associated with decreases in alcohol use measures, these same studies showed no impact of the cannabis policy on cannabis use itself. The lack of a consistent association was robust to subject age, outcome measure (e.g., use, medical utilization, driving), and type of cannabis policy; however, this may be due to the small number of studies for each type of outcome. This paper discusses several notable limitations of the evidence base and offers suggestions for improving consistency and comparability of research going forward, including a stronger classification of cannabis policy, inclusion of measures of the alcohol policy environment, verification of the impact of cannabis policy on cannabis use, and consideration of mediation effects.

Changes in cannabis use and associated correlates during France's first COVID-19 lockdown in daily cannabis users: results from a large community-based online survey

BACKGROUND

Lockdown measures during the first wave of the COVID-19 pandemic in France led to serious public health concerns over people who use illicit drugs, especially in terms of mental health. We assessed changes in cannabis use during the first lockdown in France among daily cannabis users and associated correlates.

METHODS

CANNAVID is a French, national, cross-sectional web-based survey, conducted from 17 April to 11 May 2020. Daily cannabis users aged ≥ 18 years and living in France were invited to participate through advertisements. Respondents completed an ad hoc questionnaire on a dedicated online platform. We analyzed changes in cannabis use during the first lockdown (i.e., stopped, decreased, unchanged, or increased) and performed a multinomial logistic regression analysis to evaluate correlates of these changes.

RESULTS

Of the 4019 participants, 74.0% were men. Median age was 27 years (interquartile range: 22-37). With regard to cannabis use, 293 (7.3%) persons stopped, 1153 (28.7%) decreased, 1146 (28.5%) did not change, and 1427 (35.5%) increased their use during the lockdown. A multinomial logistic regression model revealed several sociodemographic, behavioral and health-related factors associated with changes in cannabis use. Compared with participants with an unchanged level of cannabis use during the lockdown, those who increased and those who stopped cannabis use were more likely to have increased tobacco and alcohol use and to have experienced depression and sleep disorders intensification. Those who stopped cannabis use were also more likely to have increased benzodiazepine use and to have experienced pain increase during lockdown.

CONCLUSIONS

France's first COVID-19-related lockdown had a differential impact on daily cannabis users' consumption patterns. Most study respondents reported changes to their cannabis consumption pattern. Those who reported a stable cannabis use were more likely to report fewer negative changes. Specific interventions are needed for this population, as well as research to assess the long-term impacts of these changes.

Gender Differences in Dual Diagnoses Associated with Cannabis Use: A Review

Gender differences in psychiatric disorders and drug use are well known. Cannabis is the most widely used illegal drug among young people. In recent years, its use has been related to the development of psychiatric pathologies; however, few studies have incorporated the gender perspective as of yet. The present work analyses the literature to determine the existence of gender differences in the development of psychotic, depressive and anxious symptoms associated with cannabis use. First, we describe cannabis misuse and its consequences, paying special attention to adolescent subjects. Second, the main gender differences in psychiatric disorders, such as psychosis, depression, anxiety and cannabis use disorders, are enumerated. Subsequently, we discuss the studies that have evaluated gender differences in the association between cannabis use and the appearance of psychotic, depressive and anxious symptoms; moreover, we consider the possible explanations for the identified gender differences. In conclusion, the studies referred to in this review reveal the existence of gender differences in psychiatric symptoms associated with cannabis use, although the direction of such differences is not always clear. Future research is necessary to discern the causal relationship between cannabis use and the development of psychiatric symptoms, as well as the gender differences found.

Associations of Healthcare Service Utilization With Cannabis Use Status, Use Reasons, and Use Characteristics Among Those Age 50 and Older

Cannabis use has increased steadily among older adults, and they are a significant proportion of medical cannabis users. Using 2015-2019 National Survey on Drug Use and Health data (n = 44,007 age 50+), we examined whether the numbers of emergency department (ED) visits and nights hospitalized are associated with cannabis use status, use reason (nonmedical-only, medical-only, and medical and nonmedical), and use characteristics. Past-year users had higher rates of any ED visit (30.0%) and hospitalization (14.7%) than prior-to-past-year users and never users. However, negative binomial regression models showed that past-year users did not differ from never users on numbers of ED visits and nights hospitalized, although they had more ED visits than prior-to-past-year users (IRR = 1.21, 95% CI = 1.10-1.34). Medical-only users had more ED visits (IRR = 1.38, 95% CI = 1.02-1.88) than nonmedical-only users. Cannabis use and use characteristics were not associated with nights hospitalized. The study findings provide insights into older cannabis users' healthcare utilization.

Trends of Substance Use among Individuals with Cardiovascular Disease in the United States, 2015-2019

Despite the adverse effects of substance use on health among individuals with preexisting cardiovascular disease (CVD), little is known about trends and correlates for substance use among individuals with CVD. We examined trends of use in tobacco, alcohol, and cannabis among US adults with heart disease. Using nationally representative data from the 2015–2019 National Survey on Drug Use and Health (N = 7339), we conducted survey-adjusted logistic regression analyses to test the significance of trends in substance use while controlling for sociodemographic factors and related correlates. Results showed that the prevalence of cannabis use among adults with a heart condition significantly increased. Notably, the prevalence of cannabis use increased by 91% among non-Hispanic Whites, while the increasing trends were not present among other racial/ethnic groups. Our results also showed that increase in cannabis use was associated with easier access, lower disapproval, and risk perceptions of cannabis. Special attention is needed to raise awareness of the risk associated with cannabis use among individuals with CVD and the implementation of an early screening and treatment strategy among those with CVD.

Geospatiotemporal and causal inference study of cannabis and other drugs as risk factors for female breast cancer USA 2003-2017

Breast cancer (BC) is the commonest human cancer and its incidence (BC incidence, BCI) is rising worldwide. Whilst both tobacco and alcohol have been linked to BCI genotoxic cannabinoids have not been investigated. Age-adjusted state-based BCI 2003-2017 was taken from the Surveillance Epidemiology and End Results database of the Centers for Disease Control. Drug use from the National Survey of Drug Use and Health, response rate 74.1%. Median age, median household income and ethnicity were from US census. Inverse probability weighted (ipw) multivariable regression conducted in R. In bivariate analysis BCI was shown to be significantly linked with rising cannabis exposure {β-est. = 3.93 [95% confidence interval 2.99, 4.87], P = 1.10 × 10^-15}. At 8 years lag cigarettes:cannabis [β-est. = 2660 (2150.4, 3169.3), P = 4.60 × 10^-22] and cannabis:alcoholism [β-est. = 7010 (5461.6, 8558.4), P = 1.80 × 10^-17] were significant in ipw-panel regression. Terms including cannabidiol [CBD; β-est. = 16.16 (0.39, 31.93), P = 0.446] and cannabigerol [CBG; β-est. = 6.23 (2.06, 10.39), P = 0.0034] were significant in spatiotemporal models lagged 1:2 years, respectively. Cannabis-liberal paradigms had higher BCI [67.50 ± 0.26 v. 65.19 ± 0.21/100 000 (mean ± SEM), P = 1.87 × 10^-11; β-est. = 2.31 (1.65, 2.96), P = 9.09 × 10^-12]. 55/58 expected values >1.25 and 13/58 >100. Abortion was independently and causally significant in space-time models. Data show that exposure to cannabis and the cannabinoids Δ9-tetrahydrocannabinol, CBD, CBG and alcoholism fulfil quantitative causal criteria for BCI across space and time. Findings are robust to adjustment for age and several known sociodemographic, socio-economic and hormonal risk factors and establish cannabinoids as an additional risk factor class for breast carcinogenesis. BCI is higher under cannabis-liberal legal paradigms.

Lower-Risk Cannabis Use Guidelines (LRCUG) for reducing health harms from non-medical cannabis use: A comprehensive evidence and recommendations update

BACKGROUND

Cannabis use is common, especially among young people, and is associated with risks for various health harms. Some jurisdictions have recently moved to legalization/regulation pursuing public health goals. Evidence-based 'Lower Risk Cannabis Use Guidelines' (LRCUG) and recommendations were previously developed to reduce modifiable risk factors of cannabis-related adverse health outcomes; related evidence has evolved substantially since. We aimed to review new scientific evidence and to develop comprehensively up-to-date LRCUG, including their recommendations, on this evidence basis.

METHODS

Targeted searches for literature (since 2016) on main risk factors for cannabis-related adverse health outcomes modifiable by the user-individual were conducted. Topical areas were informed by previous LRCUG content and expanded upon current evidence. Searches preferentially focused on systematic reviews, supplemented by key individual studies. The review results were evidence-graded, topically organized and narratively summarized; recommendations were developed through an iterative scientific expert consensus development process.

RESULTS

A substantial body of modifiable risk factors for cannabis use-related health harms were identified with varying evidence quality. Twelve substantive recommendation clusters and three precautionary statements were developed. In general, current evidence suggests that individuals can substantially reduce their risk for adverse health outcomes if they delay the onset of cannabis use until after adolescence, avoid the use of high-potency (THC) cannabis products and high-frequency/-intensity of use, and refrain from smoking-routes for administration. While young people are particularly vulnerable to cannabis-related harms, other sub-groups (e.g., pregnant women, drivers, older adults, those with co-morbidities) are advised to exercise particular caution with use-related risks. Legal/regulated cannabis products should be used where possible.

CONCLUSIONS

Cannabis use can result in adverse health outcomes, mostly among sub-groups with higher-risk use. Reducing the risk factors identified can help to reduce health harms from use. The LRCUG offer one targeted intervention component within a comprehensive public health approach for cannabis use. They require effective audience-tailoring and dissemination, regular updating as new evidence become available, and should be evaluated for their impact.