The Effect of Age of Initiation of Cannabis Use on Psychosis, Depression, and Anxiety among Youth under 25 Years

Association between cannabis potency and mental health in adolescence

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Understanding youth and young adult cannabis use in Canada post-legalization: a scoping review on a public health issue

BACKGROUND

Canada legalized recreational cannabis in 2018, and one of the primary objectives of the Cannabis Act was to protect youth by reducing their access to cannabis and providing public education. Canada has the highest prevalence of cannabis use worldwide, particularly among youth and young adults under the age of 25. Cannabis use is linked with many adverse effects for youth and young adults including psychosis, anxiety, depression, respiratory distress, cannabinoid hyperemesis syndrome, and impaired cognitive performance. Despite the high prevalence of cannabis use and the evolution of policies in Canada and globally, significant knowledge and research gaps remain regarding youth and young adult cannabis use. The aim of this scoping review is to map the extent, nature, and range of evidence available on youth and young adult cannabis use in Canada since its legalization, in order to strengthen policies, services, treatments, training, and public education strategies.

METHODS

Using a scoping review framework developed by Arksey and O'Malley, along with the PRISMA-ScR guidelines, we conducted a rigorous search in five academic databases: MEDLINE, Embase, APA PsycINFO, CINAHL and Web of Science Core Collection. We included empirical studies that collected data in Canada after the legalization of recreational cannabis (October 2018) and focused on youth or young adults < 30. Two reviewers independently screened articles in two stages and extracted relevant information from articles meeting the inclusion criteria.

RESULTS

Of the 47 articles meeting our inclusion criteria, 92% used quantitative methods, 6% were qualitative, and 2% used a mixed-methods approach. Over two-thirds (68%) used secondary data. These studies were categorized into six focus areas: (1) prevalence, patterns, and trends, (2) cannabis-related injuries and emergency department (ED) visits, (3) rates and patterns during the pandemic, (4) perceptions of cannabis use, (5) prevention tools, and (6) cannabis-related offenses. Key findings from the studies reviewed include an increase in cannabis use among 18-24-year-olds post-legalization, with mixed results for youth under 18. ED visits for intentional and unintentional cannabis-related injuries have increased in young children and teens. Perception studies show a mix of concern and normalization of cannabis use. Though limited, prevention studies are promising in raising awareness. A decline in cannabis-related offenses was noted by one study. The review highlights several research gaps, including the need for more qualitative data, disaggregation of demographic data, intervention research, and comprehensive studies on the physical and mental health impacts of cannabis use among youth and young adults.

CONCLUSION

Maintaining a public health approach is critical, with a focus on reducing the high prevalence of cannabis use among youth and young adults. This involves implementing prevention strategies to minimize harms, enhancing public education, minimizing commercialization, reducing youth access to cannabis, promoting guidelines for lower-risk cannabis use and harm reduction strategies, and increasing training for healthcare providers.

A survey of educator perspectives toward teaching harm reduction cannabis education

INTRODUCTION

Substance use is common among youth which can adversely affect youth health. Despite the legalization of cannabis in Canada and much of the United States, there is a lack of harm reduction cannabis education in schools. In addition, educators may not feel prepared to teach students about cannabis.

METHODS

A cross-sectional survey explored educator perceptions toward teaching harm reduction substance use education to students in grades 4-12. Data analysis included descriptive statistics to evaluate demographic variables, ANOVAs to identify subgroup differences, and inductive thematic analysis to establish themes from open-ended responses. From the sample of 170 educators, the majority were female (77%) and worked as classroom teachers (59%).

RESULTS

Ninety-two percent of educators felt harm reduction was an effective approach to substance use education, and 84% stated that they would feel comfortable teaching cannabis harm reduction education to students. While 68% of educators believed they would be able to recognize if a student was under the influence of cannabis, only 39% felt certain about how to respond to student cannabis use, and just 8% felt that their current teacher training allowed them to intervene and prevent cannabis-related harms. Most educators (89%) expressed interest in harm reduction training, particularly interactive training (70%) and instructor-led lessons (51%). Online curriculum resources were preferred by 57%. Responses differed by gender and age group, with females of any age and educators under 40 reporting greater support of harm reduction approaches and more interest in training.

CONCLUSION

Educators expressed considerable support for harm reduction substance use education, but many felt unprepared to address this topic with students. The findings identified a need for educator training on harm reduction substance use education, so that educators can help students make informed choices around substance use, thereby promoting youth health and safety.

Prevalence and factors associated with depression and anxiety among young school-going adolescents in the Western Cape Province of South Africa

INTRODUCTION

Between 10 and 20% of children and adolescents globally experience common mental health conditions such as depression or anxiety. Given the dearth of mental health services in low- and middle-income countries, most mental health conditions among adolescents remain undiagnosed and untreated. In South Africa, few studies have explored the prevalence of depression and anxiety among young adolescents aged 10-14 years. This study examined the prevalence of, and factors associated with depression and anxiety among young school-going adolescents in the Western Cape Province of South Africa.

METHODS

A cross-sectional study was conducted in 10 schools in the Western Cape Province from February to July 2022. Data were collected using a tablet-based survey and included sociodemographic items, the Generalized Anxiety Disorder 7-item scale (GAD-7), the Patient Health Questionnaire for Adolescents (PHQ-A) and other psychosocial measures. The prevalence of depression and anxiety was estimated based on cut-off scores for the GAD-7 and PHQ-A. Multivariable logistic regression models were used to investigate the associations between sociodemographic and psychosocial factors, and depression and anxiety.

RESULTS

Of the 621 adolescents, 33.5% (n = 208) reported experiencing symptoms of depression and 20.9% (n = 130) symptoms of anxiety potentially indicative of a diagnosis. The results of the multivariable logistic regression model indicate that being in a higher grade in school (AOR = 1.65, CI:1.43-1.92), any lifetime alcohol use (AOR = 1.62, CI:1.04-2.64), other drug use (AOR = 2.07, CI:1.06-4.04), and witnessing violence among adults at home (AOR = 2.12, CI:1.07-1.41) were significantly associated with experiencing depressive symptoms. Being in a higher grade in school (AOR = 1.69, CI: 1.42-2.01), poor emotional regulation skills (AOR = 1.03, CI: 1.00-1.07), and the use of cannabis (AOR = 1.03, CI: 1.00-1.07) were significantly associated with experiencing anxiety symptoms.

CONCLUSION

These findings add to our understanding of school-going adolescents' pressing mental health needs and suggest that mental health adolescent and caregiver interventions may be required to address mental health symptoms and associated risk factors.

A case study in developmental discontinuity: PROSPER Interventions and adolescent substance use trajectories shape young adult substance use and mental health problems

The loss of John Schulenberg reverberates across the developmental and prevention sciences. In honor of his many contributions, this paper applies his ideas of developmental continuity and discontinuity to understand the process by which PROSPER delivered universal prevention programs (delivered in Grades 6 and 7) affect young adult outcomes. Guided by these developmental models, we deconstructed adolescent substance use initiation trajectories into two discrete phases-early and late adolescence, demarcated by substance use initiation levels at the end of 9th grade. We evaluated the effects of PROSPER interventions on these phases, and in turn, the effects of adolescent substance use initiation on young adult antisocial behavior, alcohol and drug use consequences, and depression symptoms. This sample included 1,984 young adults who participated in the PROSPER intervention trial in Grade 6 (two cohorts, 2002 and 2003), followed over 8 adolescent measurement occasions (Fall and Spring of Grade 6; Spring of Grades 7-12). Young adult outcomes were averaged across three waves (collected at ages 20, 23, and 25). PROSPER interventions were associated with reduced substance use initiation in early adolescence, but not escalation during late adolescence. In turn, substance use in both early and late adolescence was uniquely associated with young adult antisocial behavior, depression symptoms, and substance use consequences. PROSPER interventions were associated with young adult antisocial behavior and problematic substance use via reduced risk for early initiation status. Findings are discussed in terms of developmental continuity and discontinuity.

The Interaction of Cannabis Consumption with Heavy Episodic Drinking and Alcohol-induced Blackouts in Relation to Cannabis Use Consequences Among Recent Undergraduate College Cannabis Users

Introduction

Risky alcohol use patterns, characterized by heavy episodic drinking (HED) and alcohol-induced blackout, are prevalent in college students. However, it is not clear if experiencing HED and blackout among college-attending cannabis users heightens risk for adverse cannabis use consequences. The purpose of this study was to examine whether heavy episodic drinking and blackout episodes moderate the relationship between cannabis consumption and cannabis use consequences among college students.

Methods

Undergraduate college students (n = 4331) were recruited from a Midwest University in 2021. This analysis used a subset of data from past 6-month cannabis users (n= 772; 17.8% of the full sample). Among cannabis users, 64.5% identified as female and 87.8% were White with an average age of 19.99 (SD=2.88). A linear regression was conducted with two two-way interactions of cannabis consumption and HED frequency as well as cannabis consumption and alcohol-induced blackout episodes.

Results

Results showed a statistically significant positive association between cannabis consumption and cannabis use consequences (B=0.73, p<.001), adjusting for the other variables in the model. Blackout, but not HED, was a significant moderator (B=0.19, p=.003).

Discussion

The findings of this study indicate that blackout experiences amplify the relationship between cannabis use and cannabis-related consequences among college students. This underscores that blackouts not only signal a risk of problematic drinking but also exacerbate the association between cannabis use and its negative consequences.

Conclusion

Findings may inform college campus interventions targeting cannabis and alcohol concurrent-users who experience alcohol-induced blackouts to reduce their additional risk for cannabis-related consequences.

Youth cannabis use and subsequent health service use for mood and anxiety disorders: A population-based cohort study

Epidemiologic research suggests a modest association between youth cannabis use and mood and anxiety disorders (MADs). However, current evidence is based mostly on cohort studies using data from the 20th century when cannabis was significantly less potent than today. We linked population-based survey data from 2009 to 2012 with administrative records of health services covered under universal healthcare up to 2017. The cohort included youth aged 12 to 24 years at baseline living in Ontario, Canada with no prior MAD health service use (n = 8,252). We conducted a multivariable Cox model to estimate the association between cannabis use frequency (never, Collapse

Key Words

• Anxiety disorders
• Cannabis
• Mood disorders
• Psychiatry
• Youth

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MESH Headings

• Humans
• Adolescent
• Anxiety Disorders/epidemiology
• Anxiety Disorders/therapy
• Cannabis
• Cohort Studies
• Ontario/epidemiology
• Hospitalization
• Patient Acceptance of Health Care

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Affiliation(s)

André J McDonald Epidemiology Division, Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada; Institute for Mental Health Policy Research, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Peter Boris Centre for Addictions Research, St. Joseph's Healthcare Hamilton, Hamilton, Ontario, Canada; Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, Ontario, Canada; Michael G. DeGroote Centre for Medicinal Cannabis Research, McMaster University, Hamilton, Ontario, Canada.
Paul Kurdyak Institute for Mental Health Policy Research, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Ontario, Canada; ICES, Toronto, Ontario, Canada; Department of Psychiatry, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
Jürgen Rehm Epidemiology Division, Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada; Institute for Mental Health Policy Research, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Department of Psychiatry, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada; Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Institute of Clinical Psychology and Psychotherapy, Technische Universität Dresden, Dresden, Germany; Department of Psychiatry and Psychotherapy, Centre for Interdisciplinary Addiction Research (ZIS), University Medical Centre Hamburg-Eppendorf, Hamburg, Germany; Institute of Medical Science, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada; I.M. Sechenov First Moscow State Medical University (Sechenov University), Moscow, Russian Federation
Michael Roerecke Epidemiology Division, Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada; Institute for Mental Health Policy Research, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
Susan J Bondy Epidemiology Division, Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada

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Impact of non-medical cannabis legalization with market restrictions on health service use and incident cases of psychotic disorder in Ontario, Canada

BACKGROUND

Cannabis is a risk factor in the onset and persistence of psychotic disorders. There is concern that non-medical cannabis legalization in Canada may have population-level impacts on psychotic disorders. We sought to examine changes in health service use and incident cases of psychotic disorder following cannabis legalization, during a period of tight restrictions on retail stores and product types.

METHODS

We conducted a cross-sectional interrupted time-series analysis using linked population-based health administrative data from Ontario (Canada) from January 2014 to March 2020. We identified psychosis-related outpatient visits, emergency department visits, hospitalizations, and inpatient length of stay, as well as incident cases of psychotic disorders, among people aged 14 to 60 years.

RESULTS

We did not find evidence of increases in health service use or incident cases of psychotic disorders over the short-term (17 month) period following cannabis legalization. However, we found clear increasing trends in health service use and incident cases of substance-induced psychotic disorders over the entire observation window (2014-2020).

CONCLUSION

Our findings suggest that the initial period of tight market restriction following legalization of non-medical cannabis was not associated with an increase in health service use or frequency of psychotic disorders. A longer post-legalization observation period, which includes expansion of the commercial cannabis market, is needed to fully understand the population-level impacts of non-medical cannabis legalization; thus, it would be premature to conclude that the legalization of non-medical cannabis did not lead to increases in health service use and incident cases of psychotic disorder.

A systematic evidence map of the association between cannabis use and psychosis-related outcomes across the psychosis continuum: An umbrella review of systematic reviews and meta-analyses

While the legal status and public perception of cannabis are currently changing in many countries, one of the important considerations from a public health viewpoint is its potential association with adverse health outcomes such as the development of psychosis. We conducted an umbrella review of systematic reviews and meta-analyses using the AMSTAR-2 to assess the quality of included reviews. We further created an evidence map to visualize and facilitate the overview of the published evidence synthesis on the association between cannabis use and all psychosis-related outcomes and risk moderators in healthy, high-risk, and clinical populations. Overall, we found 32 systematic reviews and meta-analyses. Based on a synthesis of current evidence, cannabis use is associated with subclinical psychosis states (psychotic-like experiences) and traits (schizotypal personality) in the healthy population, as well as earlier onset and development of psychosis. An association with the clinical-high-risk state for psychosis, attenuated psychosis symptoms and transition to psychosis in this population could not be confirmed. An association between cannabis use and psychosis outcomes in patients with psychotic disorder could solely be confirmed regarding relapse. Whether causal effects underlie those associations has not sufficiently been addressed in the evidence synthesis to date.

Do Anxiety Symptoms Mediate the Association Between Cannabis Use Frequency and Psychotic-Like Experiences in Emerging Adult Undergraduates?

OBJECTIVE

Cannabis is commonly used by Canadian emerging adults (ages 18-25 years), many of whom attend post-secondary institutions. Frequent cannabis use is linked with psychotic-like experiences (PLEs); however, the exact nature of this association remains unclear. Anxiety symptoms may mediate this association, as they are prevalent in emerging adults and have been independently linked with both cannabis use and PLEs. Past work found that anxiety mediated the association between cannabis use frequency and attenuated positive psychotic symptoms (further along the psychosis continuum than PLEs), however this research had yet to be validated in the Canadian population, and trait rather than state anxiety (frequency of anxiety symptoms) was studied. Thus, our primary objective was to examine if anxiety symptoms mediated the association between cannabis use frequency and PLEs in Canadian emerging adult undergraduates. Despite known sex differences in cannabis use, expression of anxiety, and PLEs, past work did not evaluate the potential impact of biological sex on the anxiety-mediated model, and thus is the secondary objective of the present study.

METHODS

1,266 first-/second-year emerging adult undergraduates from five Canadian universities provided cross-sectional, self-report survey data in fall 2021 semester. Validated measures of cannabis use frequency, anxiety, and PLEs were administered.

RESULTS

Path analyses supported mediation from cannabis use to PLEs through anxiety (b  =  0.07, P < 0.001, 95% bootstrap CI [0.03, 0.10]). No direct effect was found (P  =  0.457), suggesting that the cannabis-to-PLEs association was mediated by anxiety. Mediation did not depend on biological sex (i.e., bootstrapped 95% CIs crossed zero).

CONCLUSIONS

Anxiety symptoms mediated the association between cannabis use and PLEs in emerging adults regardless of their biological sex. Assuming replication in prospective research, results highlight anxiety as an important intervention target in frequent cannabis-using emerging adults, to potentially prevent development/worsening of PLEs, and in turn psychotic illness.

Emerging adult perceptions of higher-risk cannabis consumption behaviours

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

Youth cannabis use in Canada post-legalization: service providers' perceptions, practices, and recommendations

BACKGROUND

In 2018, Canada legalized recreational cannabis use with the purpose of protecting youth and restricting access. However, concerns have been raised that this objective has not been met as rates of cannabis use among youth aged 16-24 have not declined. Youth cannabis use is associated with various adverse effects including psychosis, anxiety, depression, suicidality, respiratory distress, cannabinoid hyperemesis syndrome, and intoxications. Service providers play a crucial role in addressing youth cannabis use. This study aimed to understand Ontario service providers' perceptions, practices, and recommendations on youth cannabis use.

METHODS

This mixed method study included a survey and two focus groups. The survey was distributed to mental health service providers serving youth aged 16-24 across Ontario who were given the option to participate in a focus group. The survey included closed and open-ended questions regarding perceptions, practices, and recommendations, while the focus groups explored these categories in greater depth. Descriptive statistics were used to analyze close-ended questions and interpretative content analysis was applied for open-ended questions. Focus group data were analyzed using thematic analysis.

RESULTS

The survey was completed by 160 service providers and 12 participated in two focus groups. Regarding perceptions, 60% of survey participants agreed with legalization, 26% had a strong understanding of medical versus recreational cannabis, 84% believed that cannabis has physical and mental health risks, and 49% perceived stigmatization. Less than half of the survey participants reported screening or assessing cannabis use, 16% stated they are highly familiar with treating cannabis use, and 67% reported that they rarely work with families. Subthemes identified in the focus groups under perceptions included normalization and stigmatization, harms for youth, and stigma, racism, and discrimination. Subthemes under practice included cannabis not being the primary focus, challenges with screening, assessment, and intervention, and referral to specialized services. Both the survey and focus group participants recommended increasing public education, enhancing service provider training, improving regulation and policies, reducing stigma and minimization, improving service access, and providing more culturally responsive services.

CONCLUSION

Youth cannabis use in Canada remains a significant public health concern, necessitating a more comprehensive plan to protect Ontario youth and reduce associated harms.

Adverse childhood experiences and adolescent cannabis use trajectories: findings from a longitudinal UK birth cohort

BACKGROUND

Adverse childhood experiences (ACEs) are classically defined as physical abuse, sexual abuse, emotional abuse, emotional neglect, bullying, parental substance use or abuse, violence between parents, parental mental health problems or suicide, parental separation, or a parent convicted of criminal offence. Exposure to ACEs can be associated with cannabis use, but no comparisons across all adversities have been made while also considering timing and frequency of cannabis use. We aimed to explore the association between ACEs and cannabis use timing and frequency in adolescence, considering the cumulative number of ACEs and individual ACEs.

METHODS

We used data from the Avon Longitudinal Study of Parents and Children, a longitudinal UK birth cohort study. Longitudinal latent classes of cannabis use frequency were derived from self-reported data at multiple timepoints in participants aged 13-24 years. ACEs between ages 0 years and 12 years were derived from prospective and retrospective reports at multiple timepoints by parents and the participant. Multinomial regression was used to analyse the effect of both cumulative exposure to all ACEs and the ten individual ACEs on cannabis use outcomes.

FINDINGS

5212 participants (3132 [60·0%] were female and 2080 [40·0%] were male; 5044 [96·0%] were White and 168 [4·0%] were Black, Asian, or minority ethnic) were included in this study. After adjustment for polygenic risk and environmental risk factors, participants who had 4 or more ACEs at age 0-12 years were at increased risk of early persisting regular cannabis use (relative risk ratio [RRR] 3·15 [95% CI 1·81-5·50]), later onset regular use (1·99 [1·14-3·74]), and early persisting occasional use (2·55 [1·74-3·73]) compared with low or no cannabis use. After adjustment, early persisting regular use was associated with parental substance use or abuse (RRR 3·90 [95% CI 2·10-7·24]), parental mental health problems (2·02 [1·26-3·24]), physical abuse (2·27 [1·31-3·98]), emotional abuse (2·44 [1·49-3·99]), and parental separation (1·88 [1·08-3·27]) compared with low or no cannabis use.

INTERPRETATION

Risks for problematic adolescent cannabis use are highest for individuals reporting 4 or more ACEs, and were particularly raised for those with parental substance use or abuse. Public health measures to address ACEs might reduce adolescent cannabis use.

FUNDING

The Wellcome Trust, UK Medical Research Council, Alcohol Research UK.

Mental health and cannabis use among Canadian youth: Integrated findings from cross-sectional and longitudinal analyses

BACKGROUND AND PURPOSE

Using data from two methodologically independent youth research studies in Canada, the Health Behaviour in School-aged Children (HBSC) study and the Cannabis, Obesity, Mental health, Physical activity, Alcohol, Smoking, and Sedentary behaviour (COMPASS) study, the objective of this study was to compare associations between youth's mental health and cannabis use across samples. Using similar indicators in both studies, our goal was to affirm the potential for nationally representative cross-sectional analyses (HBSC) to replicate findings found in a longitudinal non-representative data source (COMPASS), enhancing opportunity for causal inferences.

METHODS

Data were collected from grade 9 and 10 Canadian students participating in the 2017/18 HBSC (n=8462) and 2017/18 to 2018/19 waves of COMPASS (n=32,023). Using multivariable Poisson regression models, the strength and statistical significance of the effects of mental health indicators on cannabis use outcomes were estimated within both studies and compared for consistency. Using a 2-year linked sample of students participating in COMPASS, models examining the impact of mental health indicators on cannabis use initiation and maintenance over time were similarly fit using Poisson regression to estimate relative risk.

RESULTS

Similar associations between mental health problems and cannabis use were observed in both data sources. The direction, magnitude, and precision of the estimates for restless sleep, loneliness, poor wellbeing, and cannabis use were highly comparable across both studies. Worse mental health was consistently associated with current and lifetime cannabis use among youth.

DISCUSSION

Cross-sectional and longitudinal findings from two large methodologically diverse studies in Canada demonstrate a replicable association between indicators of mental health and youth cannabis use. Similarities were identified and two generalizations may be concluded: 1) potentially causal etiological relationships inferred from HBSC data were supported in longitudinal findings based on COMPASS, and 2) longitudinal COMPASS data aligns with nationally representative data from HBSC.

Chronic Δ9-tetrahydrocannabinol impact on plasticity, and differential activation requirement for CB1-dependent long-term depression in ventral tegmental area GABA neurons in adult versus young mice

The ventral tegmental area (VTA) mediates incentive salience and reward prediction error through dopamine (DA) neurons that are regulated by local VTA GABA neurons. In young mice, VTA GABA cells exhibit a form of synaptic plasticity known as long-term depression (LTD) that is dependent on cannabinoid 1 (CB1) receptors preceded by metabotropic glutamate receptor 5 (mGluR5) signaling to induce endocannabinoid production. This LTD was eliminated following chronic (7-10 consecutive days) exposure to the marijuana derived cannabinoid Δ9 -tetrahydrocannabinol (THC). We now examine the mechanism behind THC-induced elimination of LTD in adolescents as well as plasticity induction ability in adult versus young male and female mice using whole-cell electrophysiology experiments of VTA GABA cells. Chronic THC injections in adolescents resulted in a loss of CB1 agonist-mediated depression, illustrating chronic THC likely desensitizes or removes synaptic CB1. We noted that seven days withdrawal from chronic THC restored LTD and CB1 agonist-induced depression, suggesting reversibility of THC-induced changes. Adult mice continue to express functional mGluR5 and CB1, but require a doubling of the synaptic stimulation compared to young mice to induce LTD, suggesting a quantitative difference in CB1-dependent plasticity between young and adult mice. One potential rationale for this difference is changes in AMPA and NMDA glutamate receptors. Indeed, AMPA/NMDA ratios were increased in in adults compared to young mice. Lastly, we performed quantitative reverse-transcription PCR and identified that CB1, DAGLα, and GluA1 levels increased following chronic THC exposure. Collectively, our data demonstrate the first age-dependent GABA neuron plasticity in the VTA, which could have implications for decreased THC dependence capacity in adults, as well as the mechanism behind chronic THC-induced synaptic alterations in young mice.

An anxiety management intervention for people with substance use disorders (ITASUD): An intervention mapping approach based on Peplau's theory

Background

The comorbidity of anxiety and drug use disorders complicates treatment prognosis, and one of the greatest challenges is to address the environmental and behavioral factors involved. The aim of this study was to describe the uses of intervention mapping in the design of a theory and evidence-based complex intervention to develop skills around the management of anxiety for cocaine users in outpatient addiction treatment.

Methods

The six steps of the intervention mapping approach, which are needs assessment, creation of matrices of performance objectives, selection of methods and practical strategies, program development, adoption and implementation, and evaluation were applied to develop the Interpersonal Theory of nursing to Anxiety management in people with Substance Use Disorders (ITASUD) intervention. The theory used for the conceptual model was interpersonal relations theory. All theory-based methods and practical applications were developed at the individual level, acting in behavioral, interpersonal, organizational and community environments.

Results

The intervention mapping provided a broad overview of the problem and outcome expectations. The ITASUD intervention consists of five consecutive sessions of 110-min targeting individual determinants of anxiety (knowledge, triggers, relief behaviors, self-efficacy and relations), delivered by a trained nurse using Peplau's concepts of interpersonal relations. Intervention Mapping is a multi-step process that incorporates theory, evidence, and stakeholder perspectives to ensure that implementation strategies effectively address key determinants of change.

Conclusions

The intervention mapping approach increases the effectiveness of the intervention since the matrices provide a broad view of all factors that affect the problem and facilitate replication through transparency of the determinants, methods, and applications used. ITASUD addresses all factors that play an important role in substance use disorders based on a theoretical basis, which provides the translation of evidence from research into effective practice, policy, and public health improvements.

The CannTeen Study: Cannabis use disorder, depression, anxiety, and psychotic-like symptoms in adolescent and adult cannabis users and age-matched controls

BACKGROUND

Adolescence is characterised by psychological and neural development. Cannabis harms may be accentuated during adolescence. We hypothesised that adolescents would be more vulnerable to the associations between cannabis use and mental health and addiction problems than adults.

METHOD

As part of the 'CannTeen' study, we conducted a cross-sectional analysis. There were 274 participants: split into groups of adolescent users (n = 76; 16-17 years old) and controls (n = 63), and adult users (n = 71; 26-29 years old) and controls (n = 64). Among users, cannabis use frequency ranged from 1 to 7 days/week, while controls had 0-10 lifetime exposures to cannabis. Adolescent and adult cannabis users were matched on cannabis use frequency (mean=4 days/week). We measured Diagnostic and Statistical Manual (DSM-5) Cannabis Use Disorder (CUD), Beck Depression Inventory, Beck Anxiety Inventory and Psychotomimetic States Inventory-adapted.

RESULTS

After adjustment for covariates, adolescent users were more likely to have severe CUD than adult users (odd ratio = 3.474, 95% confidence interval (CI) = 1.501-8.036). Users reported greater psychotic-like symptoms than controls (b = 6.004, 95% CI = 1.211-10.796) and adolescents reported greater psychotic-like symptoms than adults (b = 5.509, 95% CI = 1.070-9.947). User-group was not associated with depression or anxiety. No significant interactions between age-group and user-group were identified. Exploratory analyses suggested that cannabis users with severe CUD had greater depression and anxiety levels than cannabis users without severe CUD.

CONCLUSION

Adolescent cannabis users are more likely than adult cannabis users to have severe CUD. Adolescent cannabis users have greater psychotic-like symptoms than adult cannabis users and adolescent controls, through an additive effect. There was no evidence of an amplified vulnerability to cannabis-related increases in subclinical depression, anxiety or psychotic-like symptoms in adolescence. However, poorer mental health was associated with the presence of severe CUD.

Cannabis Use in Autism: Reasons for Concern about Risk for Psychosis

Being particularly vulnerable to the pro-psychotic effects of cannabinoid exposure, autism spectrum individuals present with an increased risk of psychosis, which may be passed on to their own children. More specifically, cannabis exposure among autism spectrum individuals seems to exert disruptive epigenetic effects that can be intergenerationally inherited in brain areas which play a critical role in schizophrenia pathophysiology. Additionally, because of such cannabinoid-induced epigenetic effects, autism candidate genes present with bivalent chromatin markings which make them more vulnerable to subsequent disruption, possibly leading to psychosis onset later in life. Thus, findings support a developmental trajectory between autism and psychosis, as per endocannabinoid system modulation. However, such evidence has not received the attention it deserves.

Cannabis use among youth in Canada: a scoping review protocol

INTRODUCTION

Canadian youth (aged 15-24) have the highest rates of cannabis use globally. There are increasing concerns about the adverse effects of cannabis use on youth physical and mental health. However, there are gaps in our understanding of risks and harms to youth. This scoping review will synthesise the literature related to youth cannabis use in Canada. We will examine the relationship between youth cannabis use and physical and mental health, and the relationship with use of other substances. We will also examine prevention strategies for youth cannabis use in Canada and how the literature addresses social determinants of health.

METHODS AND ANALYSIS

Using a scoping review framework developed by Arksey and O'Malley, we will conduct our search in five academic databases: MEDLINE, Embase, APA PsycInfo, CINAHL and Web of Science's Core Collection. We will include articles published between 2000 and 2021, and articles meeting the inclusion criteria will be charted to extract relevant themes and analysed using a qualitative thematic analysis approach.

ETHICS AND DISSEMINATION

This review will provide relevant information about youth cannabis use and generate recommendations and gaps in the literature. Updated research will inform policies, public education strategies and evidence-based programming. Results will be disseminated through an infographic, peer-reviewed publication and presentation at a mental health and addiction conference. Ethics approval is not required for this scoping review.

Generalized Anxiety Disorder 7-Item (GAD-7) Scores in Medically Authorized Cannabis Patients-Ontario and Alberta, Canada

OBJECTIVES

Despite increasing rates of legalization of medical cannabis worldwide, the current evidence available on its effect on mental health outcomes including anxiety is of mixed results. This study assesses the effect of medical cannabis on generalized anxiety disorder 7-item (GAD-7) scores in adult patients between 2014 and 2019 in Ontario and Alberta, Canada.

METHODS

An observational cohort study of adults authorized to use medical cannabis. The GAD-7 was administered at the time of the first visit to the clinic and subsequently over the follow-up time period of up to 3.2 years. Overall changes in GAD-7 scores were computed (mean change) and categorized as: no change (<1 point); improvement; or worsening-over time.

RESULTS

A total of 37,303 patients had initial GAD-7 scores recorded and 5,075 (13.6%) patients had subsequent GAD-7 follow-up scores. The average age was 54.2 years (SD 15.7 years), 46.0% were male, and 45.6% noted anxiety symptoms at the baseline. Average GAD-7 scores were 9.11 (SD 6.6) at the baseline and after an average of 282 days of follow-up (SD 264) the average final GAD-7 score recorded was 9.04 (SD 6.6): mean change -0.23 (95% CI, -0.28 to -0.17, t[5,074]: -8.19, p-value <0.001). A total of 4,607 patients (90.8%) had no change in GAD-7 score from their initial to final follow-up, 188 (3.7%) had a clinically significant decrease, and 64 (1.3%) noted a clinically significant increase in their GAD-7 scores.

CONCLUSIONS

Overall, there was a statistically significant decrease in GAD-7 scores over time (in particular, in the 6-12-month period). However, this change did not meet the threshold to be considered clinically significant. Thus, we did not detect clinical improvements or detriment in GAD-7 scores in medically authorized cannabis patients. However, future well-controlled clinical trials are needed to fully examine risks or benefits associated with using medical cannabis to treat anxiety conditions.

The Effect of Perceived Vaccination on Students’ Online Learning Intentions: A Moderated Mediation Model

The current study proposed and tested a moderated mediation model to reveal the effect of perceived vaccination (PV) on students’ online learning intentions (SOLI) during the COVID-19 pandemic. A questionnaire was distributed to 663 full- and part-time students at Vietnamese universities, and 632 responses were analyzed. SPSS 20 software and Hayes SPSS Process Macro (model 5) were used to test five hypotheses, all of which were supported. The study found that students’ online learning intentions decreased after being fully vaccinated against COVID-19 and that perceived invulnerability played a mediating role in the relationship between perceived vaccination and students’ online learning intentions. The study also revealed that student age moderated a negative association between perceived vaccination and online learning intention, as this negative relationship was stronger for younger students than for older students. Theoretical and practical implications from our research contribute recommendations for governments, policymakers, and educators to consider adjusting educational management strategy, as well as adopting appropriate forms of learning in different epidemic contexts and vaccine coverage rates.

Associations between cannabis use, cannabis use disorder, and mood disorders: longitudinal, genetic, and neurocognitive evidence

RATIONALE

Cannabis use among people with mood disorders increased in recent years. While comorbidity between cannabis use, cannabis use disorder (CUD), and mood disorders is high, the underlying mechanisms remain unclear.

OBJECTIVES

We aimed to evaluate (1) the epidemiological evidence for an association between cannabis use, CUD, and mood disorders; (2) prospective longitudinal, genetic, and neurocognitive evidence of underlying mechanisms; and (3) prognosis and treatment options for individuals with CUD and mood disorders.

METHODS

Narrative review of existing literature is identified through PubMed searches, reviews, and meta-analyses. Evidence was reviewed separately for depression, bipolar disorder, and suicide.

RESULTS

Current evidence is limited and mixed but suggestive of a bidirectional relationship between cannabis use, CUD, and the onset of depression. The evidence more consistently points to cannabis use preceding onset of bipolar disorder. Shared neurocognitive mechanisms and underlying genetic and environmental risk factors appear to explain part of the association. However, cannabis use itself may also influence the development of mood disorders, while others may initiate cannabis use to self-medicate symptoms. Comorbid cannabis use and CUD are associated with worse prognosis for depression and bipolar disorder including increased suicidal behaviors. Evidence for targeted treatments is limited.

CONCLUSIONS

The current evidence base is limited by the lack of well-controlled prospective longitudinal studies and clinical studies including comorbid individuals. Future studies in humans examining the causal pathways and potential mechanisms of the association between cannabis use, CUD, and mood disorder comorbidity are crucial for optimizing harm reduction and treatment strategies.

The prevalence and pattern of cannabis use among patients attending a methadone treatment clinic in Nairobi, Kenya

BACKGROUND

Cannabis use during methadone treatment may negatively impact treatment outcomes. The aim of this study was to determine the prevalence and pattern of cannabis use among patients attending a methadone treatment clinic in Nairobi, Kenya.

METHODS

This was a retrospective study of 874 patients on methadone therapy at a methadone maintenance treatment clinic in Nairobi, Kenya from December 2014 to November 2018. Data on sociodemographic characteristics and drug use patterns based on urine drug screens was collected from patient files. Data was analyzed using Statistical Package for the Social Sciences (SPSS) for windows version 23.0.

RESULTS

Point prevalence of cannabis use was 85.8% (95% CI, 83.3 - 88.0) at baseline and 62.7% (95% CI, 59.5 - 65.8) during follow-up. A pattern of polysubstance use was observed where opioids, cannabis and benzodiazepines were the most commonly used drugs. The mean age of the patients was 35.3 (SD 9.0) years with the majority being male, unemployed (76%), (51.4%) had reached primary level of education, and (48.5%) were divorced or separated. University education was associated with reduced risk for cannabis use OR = 0.1 (95% CI, 0.02-0.8, p = 0.031).

CONCLUSION

Cannabis use is prevalent among patients attending a methadone treatment clinic in Kenya, suggesting need for targeted interventions to address the problem of cannabis use during methadone treatment.

Cannabis and Mental Health: Adverse Outcomes and Self-Reported Impact of Cannabis Use by Mental Health Status

Background: Cannabis can induce negative outcomes among consumers with mental health conditions. This study examined medical help-seeking behavior, patterns of adverse effects, and perceived impacts of cannabis among consumers with and without mental health conditions. Methods: Data came from the International Cannabis Policy Study, via online surveys conducted in 2018. Respondents included 6,413 past 12-month cannabis consumers aged 16-65, recruited from commercial panels in Canada and the US. Regression models examined differences in adverse health effects and perceived impact of cannabis among those with and without self-reported past 12-month experience of anxiety, depression, PTSD, bipolar disorder, psychosis. Results: Overall, 7% of past 12-month consumers reported seeking medical help for adverse effects of cannabis, including panic, dizziness, nausea. Help-seeking was greater for those with psychosis (13.8%: AOR = 1.78; 1.11-2.87), depression (8.9%: AOR = 1.57; 1.28-1.93), and bipolar disorder (10.1%: AOR = 1.53; 1.44-2.74). Additionally, 54.1% reported using cannabis to manage symptoms of mental health, with higher rates among those with bipolar (90.8%) and PTSD (90.7%). Consumers reporting >1 condition were more likely to perceive positive impacts on friendships, physical/mental health, family life, work, studies, quality of life (all p < .001). Consumers with psychosis were most likely to perceive negative effects across categories. Conclusion: For conditions with substantial evidence suggesting cannabis is harmful, greater help-seeking behaviors and self-perceived negative effects were observed. Consumers with mental health conditions generally perceive cannabis to have a positive impact on their lives. The relationship between cannabis and mental health is disorder specific and may include a combination of perceived benefits and harms.

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.

Variations of cannabis-related adverse mental health and addiction outcomes across adolescence and adulthood: A scoping review

INTRODUCTION

Evidence supporting associations between cannabis use and many health outcomes is growing, however it remains unclear how such associations vary across the lifespan. We therefore aim to answer the following questions: (1) Are the risks of cannabis's adverse effects on mental health and addiction-related outcomes different in adolescents than in adults? (2) What are the relationships between these cannabis's adverse effects and (a) an individual's age at first cannabis use, (b) age at assessment, and (c) duration of cannabis use?

METHODS

We searched Medline, Embase, CINAHL, and PsychINFO from inception to 18 October 2021. Two reviewers independently screened studies and descriptively synthesized results.

RESULTS

We included 140 studies. Cannabis effects on mental health and addiction-related outcomes were worse in adolescents, early cannabis initiators and cannabis users who consumed for longest periods. Evidence of worse long-term adverse effects in adolescents was substantial for psychosis, cannabis, and nicotine use disorders; mixed for depression, suicidality, other substance use and disorders; and limited for anxiety. Additionally, acute cannabis exposure had the opposite trend with adults more often reporting adverse effects than adolescents.

CONCLUSION

The available evidence suggests that cannabis use should be delayed as late as possible in adulthood and shortened in duration across the lifespan to decrease the risk of negative outcomes, while emphasizing the need for adapted harm reduction approaches. This scoping review provides evidence on the role of age and duration of exposure as determinants of cannabis-related adverse effects, which may inform prevention and harm reduction strategies.

SYSTEMATIC REVIEW REGISTRATION

https://doi.org/10.17605/OSF.IO/BYG72.

Impact of Acute and Chronic Cannabis Use on Stress Response Regulation: Challenging the Belief That Cannabis Is an Effective Method for Coping

Although research has only recently started to examine the impact of cannabis use on stress response, there is some evidence that indicates acute and chronic impacts of cannabis on these processes. In this paper, we review processes involved in regulating the stress response and we review the influence of acute and chronic exposure to cannabis on patterns and regulation of the stress response. We also highlight the role of stress as a risk factor for initiation and maintenance of cannabis use. In this context, we examine moderating variables, including sex and life adversity. In light of recent observations indicating increasing prevalence of cannabis use during pregnancy, we provide additional focus on cannabis use in this vulnerable population, including how acute and chronic stress may predispose some individuals to use cannabis during pregnancy. While this line of research is in its infancy, we review available articles that focus on the perinatal period and that examined the association between cannabis use and various life stressors, including partner violence, job loss, and lack of housing. We also review psychiatric co-morbidities (e.g., post-traumatic stress disorder, anxiety). A better understanding of the way stress and cannabis use relate within the general population, as well as within certain subgroups that may be at a greater risk of using and/or at greater risk for adverse outcomes of use, may lead to the development of novel prevention and intervention approaches.

Adverse events of recreational cannabis use reported to the French addictovigilance network (2012-2017)

AIMS

To describe the adverse events (AEs) of recreational cannabis use in France between 2012 and 2017.

METHODS

AEs related to recreational cannabis use, alone or in combination with alcohol and/or tobacco reported to the French Addictovigilance Network were analysed (excluding cannabidiol and synthetic cannabinoids).

RESULTS

Reporting of AEs tripled between 2012 (n = 179, 6.3%, 95% confidence interval [CI] = 5.4-7.2) and 2017 (n = 562, 10.1%, 95% CI = 9.3-10.9), reaching 2217 cases. They concerned mainly men (76.4%) and users aged between 18 and 34 years (18-25: 30.9%; 26-34: 26.3%, range: 12-84 years). Cannabis was mainly inhaled (71.6%) and exposure was most often chronic (64.2%). Many types of AEs were reported: psychiatric (51.2%), neurological (15.6%), cardiac (7.8%) and gastrointestinal (7.7%), including unexpected AEs (n = 34, 1.1%). The most common effect was dependence, ranging from 10.1% (95% CI = 7.9-12.3) to 20.3% (95% CI = 17.3-23.2) over the study period. Cannabinoid hyperemesis syndrome (n = 87, 2.8%) emerged from 2015. Deaths accounted for 0.2% of all AEs (4 men and 3 women aged on average 35 years). A chronic pattern of cannabis use was reported in 4 of them (intracranial hypertension in the context of lung cancer, suicide, cerebral haematoma, neonatal death with concomitant chronic alcohol use), while in the other cases the toxicological analysis identified cannabis use (ruptured aneurysm and unknown aetiology).

CONCLUSION

This study showed a multitude of AEs related to recreational cannabis use, including unexpected AEs and deaths. It highlights the problem of dependence and the emergence of cannabinoid hyperemesis syndrome.

Cannabis Use and Prospective Long-Term Association with Anxiety: A Systematic Review and Meta-Analysis of Longitudinal Studies: Usage du cannabis et association prospective à long terme avec l'anxiété: une revue systématique et une méta-analyse d'études longitudinales

OBJECTIVES

Cannabis use is proposed as a risk factor for psychosis and is associated with depressive disorders. However, the relationship between recreational cannabis use and its longitudinal implications on anxiety conditions is less studied. The aim of this investigation is to systematically evaluate published literature and perform a meta-analysis of the data.

METHODS

A systematic search was performed of MEDLINE, Embase, and PsychINFO from inception to May 31, 2020, in addition to a hand search. Longitudinal studies that evaluated the relationship of cannabis use and development of anxiety were included. Where applicable, adjusted odds ratios (ORs) were extracted, pooled, and evaluated using random-effects meta-analysis.

RESULTS

After screening of unique abstracts (n = 6835), the final evaluation included 24 studies, of which 10 reported ORs that were analyzed quantitatively. Cannabis use was significantly associated with increased odds of developing any anxiety conditions (OR = 1.25; 95% CI, 1.01 to 1.54). Cannabis use was not significantly associated with developing generalized anxiety disorder, panic disorder, or social anxiety disorder. Review of studies not reporting OR revealed mixed results but are suggestive of a link between cannabis use and increased rates/severity of anxiety.

CONCLUSIONS

Published evidence suggests that cannabis use is likely associated with increased risk of anxiety in the long term but variability of study designs precludes declaration of a causal relationship. Awareness of this association is of relevance for both clinical practice and mental health policy implementation.

Neurodevelopmental Effects of Cannabis Use in Adolescents and Emerging Adults with ADHD: A Systematic Review

OBJECTIVE

Systematically review the scientific literature to characterize the effects of cannabis use on brain structure, function, and neurodevelopmental outcomes in adolescents and young adults with ADHD.

METHOD

Systematic review following PRISMA guidelines utilizing PubMed, Embase, PsycINFO, and Cochrane CENTRAL trials register from inception until 1 January 2020. Articles that examined the impact of cannabis use on youth with ADHD were included.

RESULTS

Eleven studies were identified that compared outcomes for individuals with ADHD who used cannabis or synthetic cannabinoids against those with ADHD who did not. Seven of these studies used neuroimaging techniques, including fMRI, structural MRI, and SPECT. Differential regions of activation were identified, including the right hippocampus and cerebellar vermis, and bilateral temporal lobes. Morphological differences were identified in the right precentral and postcentral gyri, left nucleus accumbens, right superior frontal and postcentral gyri. No study identified any additive or ADHD × cannabis use interaction on neuropsychological tasks of executive function. Two studies found adverse differential impacts of early-onset cannabis use in this population.

CONCLUSION

A dearth of evidence is available on the impact of cannabis use on the developing brain and functioning for individuals with ADHD, despite the elevated risk for substance use in this population. The limited, potentially underpowered evidence does not support the hypothesis that cannabis use has a deleterious impact on neuropsychological tasks in transitional age youth with ADHD. Larger and longer-term studies are needed, however, to better inform clinicians and patients as to the impacts of cannabis use in youth with ADHD.

Changes in patient health questionnaire (PHQ-9) scores in adults with medical authorization for cannabis

Background

Legal access to medical cannabis is increasing world-wide. Despite this, there is a lack of evidence surrounding its efficacy on mental health outcomes, particularly, on depression. This study assesses the effect of medical cannabis on Patient Health Questionnaire (PHQ-9) scores in adult patients between 2014 and 2019 in Ontario and Alberta, Canada.

Methods

An observational cohort study of medically authorized cannabis patients in Ontario and Alberta. Overall change in PHQ-9 scores from baseline to follow-up were evaluated (mean change) over a time period of up to 3.2 years.

Results

37,338 patients from the cohort had an initial PHQ-9 score recorded with 5103 (13.7%) patients having follow-up PHQ-9 scores. The average age was 54 yrs. (SD 15.7), 46% male, 50% noted depression at baseline. The average PHQ-9 score at baseline was 10.5 (SD 6.9), following a median follow-up time of 196 days (IQR: 77–451) the average final PHQ-9 score was 10.3 (SD 6.8) with a mean change of − 0.20 (95% CI: − 0.26, − 0.14, p-value < 0.0001). Overall, 4855 (95.1%) had no clinically significant change in their PHQ-9 score following medical cannabis use while 172 (3.4%) reported improvement and 76 (1.5%) reported worsening of their depression symptoms.

Conclusions

Although the majority showed no clinically important changes in PHQ-9 scores, a number of patients showed improvement or deteriorations in PHQ-9 scores. Future studies should focus on the parallel use of screening questionnaires to control for PHQ-9 sensitivity and to explore potential factors that may have attributed to the improvement in scores pre- and post- 3-6 month time period.

Assessing the current state of medical education on cannabis in Canada: Preliminary findings from Quebec

The legalization of recreational cannabis across Canada has revealed the importance of medical education on cannabis-related topics. A recent study has indicated that Canadian physicians report a significant gap in current versus desired knowledge regarding the therapeutic use of cannabis. However, the state of education on cannabis has never been studied in Canadian medical schools. This article presents the preliminary findings of a survey conducted to understand the perceptions of Quebec's medical students regarding cannabis-related teachings in their current curriculum. Overall, students reported very low to low levels of exposure to, knowledge of, and comfort levels with cannabis-related subjects. The majority of students reported that they felt that their medical curricula did not prepare them to face cannabis-related issues in their future practices. Strategies need to be developed for improving medical school curriculum regarding cannabis-related issues. These findings provide potential key strategies to improve curricula.

Psychotic disorder and cannabis use: Canadian hospitalization trends, 2006-2015

INTRODUCTION

Given the recent and impending changes to the legal status of nonmedical cannabis use in Canada, understanding the effects of cannabis use on the health care system is important for evaluating the impact of policy change. The aim of this study was to examine pre-legalization trends in hospitalizations for mental and behavioural disorders due to the use of cannabis, according to demographics factors and clinical conditions.

METHODS

We assessed the total number of inpatient hospitalizations for psychiatric conditions with a primary diagnosis of a mental or behavioural disorder due to cannabis use (ICD-10-CA code F12) from the Hospital Mental Health Database for ten years spanning 2006 to 2015, inclusive. We included hospitalizations from all provinces and territories except Quebec. Rates (per 100 000 persons) and relative proportions of hospitalizations by clinical condition, age group, sex and year are reported.

RESULTS

Between 2006 and 2015, the rate of cannabis-related hospitalizations in Canada doubled. Of special note, however, is that hospitalizations during this time period for those with the clinical condition code "mental and behavioural disorders due to use of cannabinoids, psychotic disorder" (F12.5) tripled, accounting for almost half (48%) of all cannabis-related hospitalizations in 2015.

CONCLUSION

Further research is required to investigate the reasons for the increase in hospitalizations for cannabis-related psychotic disorder. The introduction of high-potency cannabinoid products and synthetic cannabinoids into the illicit market are considered as possible factors.

Heavy cannabis use, dependence and the brain: a clinical perspective

AIMS

To summarize and evaluate our knowledge of the relationship between heavy cannabis use, cannabis use disorder (CUD) and the brain.

METHODS

Narrative review of relevant literature identified through existing systematic reviews, meta-analyses and a PubMed search. Epidemiology, clinical representations, potential causal mechanisms, assessments, treatment and prognosis are discussed.

RESULTS

Although causality is unclear, heavy and dependent cannabis use is consistently associated with a high prevalence of comorbid psychiatric disorders and learning and memory impairments that seem to recover after a period of abstinence. Evidence regarding other cognitive domains and neurological consequences, including cerebrovascular events, is limited and inconsistent. Abstinence after treatment is only achieved in a minority of cases; treatment targeted at reduction in use appears have some success. Potential moderators of the impact of CUD on the brain include age of onset, heaviness of use, CUD severity, the ratio of ∆9-tetrahydrocannabinol to cannabidiol and severity of comorbid disorders.

CONCLUSIONS

Current evidence of long-term effects of daily cannabis use and cannabis use disorder on brain-related outcomes is suggestive rather than conclusive, but use is associated with psychiatric morbidity and with cognitive impairments that recover after a period of abstinence.

Cannabis Use and the Risk for Psychosis and Affective Disorders

Objective: This review discusses the relationship between cannabis use and psychotic, bipolar, depressive, and anxiety disorders, as well as suicide. It summarizes epidemiological evidence from cross-sectional and long-term prospective studies and considers possible etiological mechanisms. Methods: Systematic reviews and methodologically robust studies in the field (from inception to February 2019) were identified using a comprehensive search of Medline, PsychINFO, and Embase and summarized using a narrative synthesis. Results: Consistent evidence, both from observational and experimental studies, has confirmed the important role of cannabis use in the initiation and persistence of psychotic disorders. The size of the effect is related to the extent of cannabis use, with greater risk for early cannabis use and use of high-potency varieties and synthetic cannabinoids. Accumulating evidence suggests that frequent cannabis use also increases the risk for mania as well as for suicide. However, the effect on depression is less clear and findings on anxiety are contradictory with only a few methodologically robust studies. Furthermore, the relationship with common mental disorders may involve reverse causality, as depression and anxiety are reported to lead to greater cannabis consumption in some studies. Pathogenetic mechanisms focus on the effect of tetrahydrocannabinol (THC, the main psychoactive ingredient of cannabis) interacting with genetic predisposition and perhaps other environmental risk factors. Cannabidiol (CBD), the other important ingredient of traditional cannabis, ameliorates the psychotogenic effects of THC but is absent from the high-potency varieties that are increasingly available. Conclusions: The evidence that heavy use of high-THC/low-CBD types of cannabis increases the risk of psychosis is sufficiently strong to merit public health education. Evidence of similar but smaller effects in mania and suicide is growing, but is not convincing for depression and anxiety. There is much current interest in the possibility that CBD may be therapeutically useful.