Cannabis use and psychosis: a review of reviews

Overshadowing and salience attribution in relation to cannabis use

Aberrant attentional salience has been implicated in the cannabis-psychosis association. Here, history and frequency of cannabis use were examined against changes in overshadowing (OS), a cue competition paradigm that involves salience processing. Additionally, we examined the association between OS and alternative measures of aberrant salience, as well as schizotypy, in a non-clinical adult sample. 280 participants completed an online geometry learning-based OS task, while a subset (N = 149) also completed the Salience Attribution Task (SAT) measure of aberrant salience. All completed the Schizotypal Personality Questionnaire (SPQ), Aberrant Salience Inventory (ASI), and the modified Cannabis Experience Questionnaire (CEQmv). Differences across OS and SAT performance stages and between cannabis use groups were assessed using mixed ANOVAs. Multiple regression and correlational analyses assessed the relationships between OS and SAT task metrics and SPQ and ASI subscale scores. Current cannabis users had significantly lower OS scores during the testing phase relative to those who do not use cannabis, at medium effect sizes. Schizotypy or ASI scores did not mediate this relationship. In the SAT, current cannabis users presented significantly higher implicit aberrant salience relative to non-users. Scores in the first training phase of the OS task significantly predicted higher explicit aberrant and adaptive salience scores in the SAT. These data indicate an association between regular cannabis use and abnormalities in cue competition effects in a healthy adult sample. Comparisons of OS and SAT cast new light on putative overlapping mechanisms underlying performance across different measures of salience.

Systematic review and meta-analysis on the effects of chronic peri-adolescent cannabinoid exposure on schizophrenia-like behaviour in rodents

BACKGROUND

The link between cannabis use and schizophrenia is well-established in epidemiological studies, especially among adolescents with early-onset use. However, this association in rodent models is less clear. This meta-analysis examined the effects of adolescent cannabinoid exposure on distinct schizophrenia-like behaviours in rodents and how experimental variations influence outcomes.

METHODS

Following a pre-registered protocol (CRD42022338761), we searched PubMed, Ovid Medline, Embse and APA PsychInfo for English-language original studies until May 2024. We synthesised data from experiments on schizophrenia-like behaviour in rats and mice after repeated peri-pubertal (onset between P23-P45) cannabinoid exposure. Risk of bias was assessed using the SYRCLE's tool.

RESULTS

We included 359 experiments from 108 articles across 9 behavioural tests. We found meta-analytic evidence supporting that CB1R agonists, both natural and synthetic, elicited broad schizophrenia-like behavioural alterations, including impaired working memory [g  = -0.56; (CI: -0.93, -0.18)], novel object recognition [g = -0.66; (CI: -0.97, -0.35)], novel object location recognition [g = -0.70; (CI: -1.07, -0.33]), social novelty preference [g = -0.52; (CI: -0.93, -0.11)], social motivation [g = -0.21; (CI: -0.42, -0.00)], pre-pulse inhibition [g = -0.43; (CI: -0.76, -0.10)], and sucrose preference [g = -0.87; (CI: -1.46, -0.27)]. By contrast, effects on novelty-induced locomotion were negligible. Subgroup analyses revealed similar effects across sexes and species. Substantial variance in the protocols and moderate-to-high heterogeneity in behavioural outcomes were observed. We found CBD may enhance fear memory recall, but data was limited.

DISCUSSION

This is the first meta-analysis to comprehensively assess the link between cannabinoids and schizophrenia-like behaviours in rodents. Our results support epidemiological links between early cannabis use and schizophrenia-like phenotypes, confirming the utility of animal models. Standardising protocols will optimise models to strengthen reproducibility and comparisons, our work provides a framework for refining rodent models to elucidate biological pathways linking cannabis and schizophrenia.

Psychotomimetic compensation versus sensitization

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

Occasional cannabis use is associated with higher premorbid functioning and IQ in youth at clinical high-risk (CHR) for psychosis: Parallel findings to psychosis cohorts

BACKGROUND

Neurocognitive deficits have been widely reported in clinical high-risk for psychosis (CHR) populations. Additionally, rates of cannabis use are high among CHR youth and are associated with greater symptom severity. Cannabis use has been sometimes shown to be associated with better neurocognition in more progressed psychosis cohorts, therefore in this study we aimed to determine whether a similar pattern was present in CHR.

METHODS

CHR participants ages 12-30 from the North American Prodromal Longitudinal Study (NAPLS-3) (N = 698) were grouped according to: "minimal to no cannabis use" (n = 406), "occasional use" (n = 127), or "frequent use" (n = 165). At baseline, cannabis use groups were compared on neurocognitive tests, clinical, and functional measures. Follow-up analyses were used to model relationships between cannabis use frequency, neurocognition, premorbid, and social functioning.

RESULTS

Occasional cannabis users performed significantly better than other use-groups on measures of IQ, with similar trend-level patterns observed across neurocognitive domains. Occasional cannabis users demonstrated better social, global, and premorbid functioning compared to the other use-groups and less severe symptoms compared to the frequent use group. Follow-up structural equation modeling/path analyses found significant positive associations between premorbid functioning, social functioning, and IQ, which in turn was associated with occasional cannabis use frequency.

DISCUSSION

Better premorbid functioning positively predicts both better social functioning and higher IQ which in turn is associated with a moderate cannabis use pattern in CHR, similar to reports in first-episode and chronic psychosis samples. Better premorbid functioning likely represents a protective factor in the CHR population and predicts a better functional outcome.

Behind the heterogeneity in the long-term course of first-episode psychosis: Different psychotic symptom trajectories are associated with different patterns of cannabis and stimulant use

BACKGROUND

Data-driven classification of long-term psychotic symptom trajectories and identification of associated risk factors could assist treatment planning and improve long-term outcomes in psychosis. However, few studies have used this approach, and knowledge about underlying mechanisms is limited. Here, we identify long-term psychotic symptom trajectories and investigate the role of illness-concurrent cannabis and stimulant use.

METHODS

192 participants with first-episode psychosis were followed up after 10 years. Psychotic symptom trajectories were estimated using growth mixture modeling and tested for associations with baseline characteristics and cannabis and stimulant use during the follow-up (FU) period.

RESULTS

Four trajectories emerged: (1) Stable Psychotic Remission (54.2 %), (2) Delayed Psychotic Remission (15.6 %), (3) Psychotic Relapse (7.8 %), (4) Persistent Psychotic Symptoms (22.4 %). At baseline, all unfavorable trajectories (2-4) were characterized by more schizophrenia diagnoses, higher symptom severity, and longer duration of untreated psychosis. Compared to the Stable Psychotic Remission trajectory, unstable trajectories (2,3) showed distinct associations with cannabis/stimulant use during the FU-period, with dose-dependent effects for cannabis but not stimulants (Delayed Psychotic Remission: higher rates of frequent cannabis and stimulant use during the first 5 FU-years; Psychotic Relapse: higher rates of sporadic stimulant use throughout the entire FU-period). The Persistent Psychosis trajectory was less clearly linked to substance use during the FU-period.

CONCLUSIONS

The risk for an adverse long-term course could be mitigated by treatment of substance use, where particular attention should be devoted to preventing the use of stimulants while the use reduction of cannabis may already yield positive effects.

Cannabidiol and neurodegeneration: From molecular mechanisms to clinical benefits

Neurodegenerative disorders (NDs) such as Alzheimer's disease, Parkinson's disease, Huntington's disease, multiple sclerosis, and amyotrophic lateral sclerosis are severe and life-threatening conditions in which significant damage of functional neurons occurs to produce psycho-motor malfunctions. NDs are an important cause of death in the elderly population worldwide. These disorders are commonly associated with the progression of age, oxidative stress, and environmental pollutants, which are the major etiological factors. Abnormal aggregation of specific proteins such as α-synuclein, amyloid-β, huntingtin, and tau, and accumulation of the associated oligomers in neurons are the hallmark pathological features of NDs. Existing therapeutic options for NDs are only symptomatic relief and do not address root-causing factors, such as protein aggregation, oxidative stress, and neuroinflammation. Cannabidiol (CBD) is a non-psychotic natural cannabinoid obtained from Cannabis sativa that possesses multiple pharmacological actions, including antioxidant, anti-inflammatory, and neuroprotective effects in various NDs and other neurological disorders both in vitro and in vivo. CBD has gained attention as a promising drug candidate for the management of neurodegenerative disorders, such as Alzheimer's disease and Parkinson's disease, by inhibiting protein aggregation, free radicals, and neuroinflammation. In parallel, CBD has shown positive results in other neurological disorders, such as epilepsy, depression, schizophrenia, and anxiety, as well as adjuvant treatment with existing standard therapeutic agents. Hence, the present review focuses on exploring the possible molecular mechanisms in controlling various neurological disorders as well as the clinical applications of CBD in NDs including epilepsy, depression and anxiety. In this way, the current review will serve as a standalone reference for the researchers working in this area.

Perspectives of young adults diagnosed with early psychosis using coordinated specialty care in Texas on substance use and substance use interventions

AIM

Despite known prevalence of substance use (SU) among young people experiencing early psychosis and increasing evidence for the relationship between certain substances (e.g., cannabis) and psychosis, there are no specialized interventions developed for effectively addressing substance use among young people participating in coordinated early psychosis services. This study elicited the perspectives of young people with early psychosis participating in Coordinated Specialty Care (CSC) programs about their substance use, including their motivations and concerns around their use, and their ideas on how to best support young people who are interested in reducing or quitting substance use.

METHODS

We recruited young adults (ages 18 to 30) from CSC programs across Texas through flyers sent to program staff inviting young persons willing to talk about substance use to engage in a 60-90 min person-centered, semi-structured, audio-recorded Zoom interview.

RESULTS

A total of 22 young adults were recruited and 18 completed an interview. Participants described mixed positive and negative responses to substance use, and while many understood the importance of discontinuing substance use, many expressed ambivalence related to social, contextual, mental and physical factors that motivated them to keep using. Participants desired practical substance use information, opportunities to explore their substance use ambivalence in supportive relationships, positive peer communities to support healthy choices, help engage, with work, school, and hobbies, and strategies for addressing psychological and physical pain that did not include substance use.

CONCLUSION

Study findings illuminate what motivates young people with early psychosis to initiate, continue, or cut back on substance use, and ideas for CSC practices for exploring substances and helping young people to reduce substance use.

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

BACKGROUND AND HYPOTHESIS

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

STUDY DESIGN

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

STUDY RESULTS

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

CONCLUSIONS

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

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

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

Sociodemographic and treatment-related determinants of recent substance use among adults with comorbid substance misuse and psychotic disorders discharged from substance use treatment

INTRODUCTION

Rates of alcohol and illicit substance use are higher among persons with psychotic disorders relative to the general population. The adverse health and psychological effects of substance use behaviors disproportionately impact persons with psychotic disorders. Prior research has shown that persons with psychotic disorders experience increased difficulty in reducing substance use behaviors, and interventions targeting substance use behavior change among this population have demonstrated limited effectiveness. One reason for this is that little is known about the factors that influence substance use and behavior change among this population. To address these disparities, the present study investigated sociodemographic and treatment-related factors of substance use recurrence among persons with psychotic disorders who received substance use treatment services.

METHODS

Data came from the 2015-2018 Treatment Episode Dataset-Discharges (TEDS-D). TEDS-D collects annual data on adolescent and adult discharges from state-certified substance use treatment centers in the United States. The study conducted all analyses with a subsample of 1956 adult discharges with a psychotic disorder who received services from an outpatient substance use treatment center for at least one month. χ2 tests of independence and multivariable logistic regression analyses were used to examine associations of sociodemographic and treatment-related characteristics with substance use recurrence while in treatment (α < 0.05 analyses). The study presents results from multivariable logistic regression models as adjusted odds ratios (AORs) with 95 % confidence intervals (CI).

RESULTS

Those who were age 50 or older, were referred to treatment by the criminal justice system, and attended substance use self-help groups had lower odds of substance use recurrence while in treatment. Sex, educational attainment, employment status, living situation, type of substance use, and treatment history were not significantly associated with substance use recurrence.

CONCLUSIONS

In designing treatment services, providers should consider whether focusing on sociodemographic, including cultural, factors can affect more positive substance use behavior change and other desired treatment outcomes among those with psychotic disorders and comorbid substance misuse. Further study is needed to identify these factors among specific subpopulations of those with psychotic disorders and substance misuse.

Neighbourhoods & recovery from psychosis in Trinidad: A qualitative study

•Various aspects of neighbourhood environments influence recovery from psychosis.•High levels of violence at the neighbourhood level may negatively affect recovery.•Social cohesion may be a protective factor that promotes recovery.•Normalisation of cannabis use and easy access to cannabis may also hinder recovery.•Community involvement is needed to design interventions targeting these factors.

The Role of Social Deprivation and Cannabis Use in Explaining Variation in the Incidence of Psychotic Disorders: Findings From the EU-GEI Study

BACKGROUND AND HYPOTHESIS

Recent findings suggest the incidence of first-episode psychotic disorders (FEP) varies according to setting-level deprivation and cannabis use, but these factors have not been investigated together. We hypothesized deprivation would be more strongly associated with variation in FEP incidence than the prevalence of daily or high-potency cannabis use between settings.

STUDY DESIGN

We used incidence data in people aged 18-64 years from 14 settings of the EU-GEI study. We estimated the prevalence of daily and high-potency cannabis use in controls as a proxy for usage in the population at-risk; multiple imputations by chained equations and poststratification weighting handled missing data and control representativeness, respectively. We modeled FEP incidence in random intercepts negative binomial regression models to investigate associations with the prevalence of cannabis use in controls, unemployment, and owner-occupancy in each setting, controlling for population density, age, sex, and migrant/ethnic group.

STUDY RESULTS

Lower owner-occupancy was independently associated with increased FEP (adjusted incidence rate ratio [aIRR]: 0.76, 95% CI: 0.61-0.95) and non-affective psychosis incidence (aIRR: 0.68, 95% CI: 0.55-0.83), after multivariable adjustment. Prevalence of daily cannabis use in controls was associated with the incidence of affective psychoses (aIRR: 1.53, 95% CI: 1.02-2.31). We found no association between FEP incidence and unemployment or high-potency cannabis use prevalence. Sensitivity analyses supported these findings.

CONCLUSIONS

Lower setting-level owner-occupancy and increased prevalence of daily cannabis use in controls independently contributed to setting-level variance in the incidence of different psychotic disorders. Public health interventions that reduce exposure to these harmful environmental factors could lower the population-level burden of psychotic disorders.

Factors associated with improved outcomes in the first psychotic episode at a specialized outpatient clinic in northeastern Brazil

OBJECTIVES

The present study aimed to evaluate data from patients admitted to the first-episode psychotic (FEP) outpatient clinic at the Hospital of Clinics of the Federal University of Pernambuco from July 2018 to July 2021, seeking to identify factors related to better clinical outcomes.

METHODS

This study was conducted using a convenience sample, including all patients between 15 and 65 years of age who were admitted to the FEP outpatient clinic from July 2018 to July 2021. Descriptive statistical analysis was performed using mean and standard deviation or median and interquartile range for continuous quantitative variables, and absolute number/percentage for qualitative variables. Paired T-test, a parametric test, was used to compare PANSS scores upon admission and after 6 months. Spearman's correlation test was employed to assess the correlation between duration of untreated psychosis (DUP) and treatment response with other variables.

RESULTS

The sample consisted of 85.3% male individuals, with 50% of patients aged between 19 and 30 years, and 82% residing in the metropolitan area of Recife. Seventy percent of patients responded to the treatment implemented by the outpatient clinic, and only 30% required psychiatric hospitalization within 6 months of follow-up. The majority of patients had a history of psychoactive substance use (82.4%); however, the use of these substances did not impact the prognosis within the analysed sample. The median DUP was 4 weeks, and a shorter DUP was associated with a lower probability of psychiatric hospitalization and a greater treatment response (reduction >50% in PANSS).

CONCLUSION

A shorter DUP was associated with a lower likelihood of psychiatric hospitalization and a greater treatment response. Furthermore, the specialized early psychosis outpatient clinic itself appears to yield positive outcomes, as 70% of the treated patients exhibited a positive treatment response.

Cannabis use and its association with psychopathological symptoms in a Swiss adult population: a cross-sectional analysis

Background

As the most commonly used illicit substance, cannabis is gaining global acceptance through increasing legalization efforts. This shift intensifies the need for research to guide policymakers and healthcare providers in harm reduction and treatment strategies. Nonetheless, the relationship between psychopathological symptoms and cannabis use remains inadequately understood.

Methods

A sample of regular cannabis consumers completed self-reported assessments for depression (Patient Health Questionnaire-9), anxiety (General Anxiety Disorder-7), Attention-Deficit/Hyperactivity Disorder (ADHD; Adult ADHD Self-Report Scale V1.1), and psychosis (Early Recognition Inventory based on IRAOS) as well as previous black-market cannabis use patterns. Cannabis Use Disorder Identification Test Revised (CUDIT-R) was used to identify cannabis use disorder (CUD). To understand psychopathological symptom load related to cannabis consumption as well as cannabis use motives, multiple regression models were performed to identify psychopathological variables predicting cannabis use frequency and quantity. Linear regression and correlation analyses were conducted, adjusting for relevant covariates (age, gender, education, alcohol, other substance use).

Results

Three-hundred-sixty regular cannabis users interested in a study on regulated cannabis access in Basel, Switzerland were examined. In bivariate analysis, cannabis use frequency correlated with depressive (r(358) = 0.16, p = 0.003) and anxiety symptom load (r(358) = 0.11, p = 0.034). Cannabis quantity correlated with depressive (r(358) = 0.15, p = 0.005), ADHD (r(358) = 0.14, p = 0.008), and psychosis symptom load (r(358) = 0.16, p = 0.002). However, in the adjusted regression models only depressive and ADHD symptom loads were significantly associated with cannabis use frequency (p = 0.006 and p = 0.034, respectively) and quantity (p = 0.037 and p = 0.019, respectively). No significant correlations between cannabis consumption and anxiety or psychosis remained after adjustment.

Conclusion

ADHD and depressive symptoms correlate with increased cannabis use in a cohort of regular users, suggesting potential self-medication in nonclinical populations. With the rising availability of cannabis worldwide, these results highlight the necessity for longitudinal studies to disentangle the complex dynamics between cannabis consumption and mental health symptoms.

Contingency Management for Dually Diagnosed Inpatients with Psychosis

Contingency management (CM) is an evidence-based treatment method in substance abuse treatment. However, little is known about its efficacy in dually diagnosed patients with psychosis and in inpatient settings. Therefore, the aim of this study is to investigate the efficacy of CM for dually diagnosed patients with psychosis in an inpatient setting. Furthermore, we investigate the effect of the nature of the reward used (cash vs. prize) on the efficacy of CM. We made use of an 8-week fish-bowl CM intervention by means of a within-subject reversal design with three treatment phases (baseline-intervention-follow-up). Sixty-seven patients were included in this study, of whom thirty-four completed the protocol. The results show no effect of CM on abstinence nor an interaction with clinical or demographic variables. Cash money is as effective as prizes. Future research should further investigate the effect of psychosis and treatment setting on the efficacy of CM, with special attention for Patient Report Experience and Outcome Measures (PREM/PROM).

Self-stigma, religiosity, and perceived social support in people with recent-onset psychosis in the Islamic Republic of Iran: Associations with symptom severity and psychosocial functioning

AIMS

Most evidence on psychosocial factors in recent-onset psychosis comes from high-income countries in Europe, Australia, Canada and the USA, while these factors are likely to differ under varying sociocultural and economic circumstances. In this study, we aimed to investigate associations of self-stigma, religiosity and perceived social support with symptom severity and psychosocial functioning in an Iranian cohort of people with recent-onset psychosis (i.e. illness duration of <2 years).

METHODS

We used baseline data of 361 participants (N = 286 [74%] male, mean age = 34 years [Standard Deviation = 10.0]) from the Iranian Azeri Recent-onset Acute Phase Psychosis Survey (ARAS). We included assessments of self-stigma (Internalized Stigma of Mental Illness, ISMI), religiosity (based on Stark & Glock), perceived social support (Multidimensional Scale of Perceived Social Support, MSPSS), symptom severity (Positive And Negative Syndrome Scale, PANSS) and psychosocial functioning (clinician-rated Global Assessment of Functioning Scale, GAF, and self-reported World Health Organization Disability Assessment Schedule 2.0, WHODAS 2.0). Descriptive analyses were employed to characterize the study sample. Covariate-adjusted ordinal and multivariable linear regression analyses were performed to investigate cross-sectional associations of baseline ISMI, religiosity and MSPSS with concurrent PANSS, GAF and WHODAS 2.0.

RESULTS

Higher self-stigma was associated with poorer self-reported functioning (B = 0.375 [95% Confidence Interval (CI): 0.186, 0.564]) and more severe concurrent symptoms (B = 0.436 [95% CI: 0.275, 0.597]). Being more religious was associated with poorer clinician-rated functioning (OR = 0.967 [95% CI: 0.944, 0.991]), but with less severe symptoms (B = -0.258 [95% CI: -0.427, -0.088]). Stronger social support was associated with poorer clinician-rated (OR = 0.956 [95% CI: 0.935, 0.978]) and self-reported functioning (B = 0.337 [95% CI: 0.168, 0.507]).

CONCLUSION

This study shows that self-stigma, religiosity and perceived social support were associated with symptom severity and clinician-rated as well as self-reported psychosocial functioning in an Iranian cohort of people with recent-onset psychosis. The findings extend previous evidence on these psychosocial factors to one of the largest countries in the Middle East, and suggest that it may be worthwhile to develop strategies aimed at tackling stigma around psychosis and integrate the role of religiosity and social support in mental ill-health prevention and therapy.

Changing cannabis legislation in Canada and a longitudinal look at "regular" cannabis use in patients with eating disorders

Regular cannabis use (CU), defined as "weekly or more often", is associated with a number of negative mental health outcomes. In the last decade, Canada legalized first medical and then recreational CU. Despite higher prevalence in mental health populations, little research has documented changes in frequency of CU with progressive legalization of cannabis. This study examined rates of CU in a sample of 843 treatment-seeking patients with eating disorders (ED) in an outpatient setting between 2004 and 2020. Across ED diagnoses, segmented regression indicated a significant break-point in regular CU in 2014, commensurate with the relaxation of medical cannabis laws. Regular CU increased from 4.9 % to 23.7 % from 2014 to 2020; well above the stable 6 % found in the general population. No significant break-point was observed in either alcohol or illicit substance use over the same time period. Significant increases in regular CU were found in patients with anorexia nervosa and binge eating disorder, while regular use remained stable in patients with bulimia nervosa. Comorbid psychiatric diagnoses did not increase odds of regular CU. Findings suggest certain patient groups with mental illness may be at risk of engaging in high frequency use in the context of legislation implying medical benefits of cannabis.

Effects of Recreational Cannabis Legalization on Mental Health: Scoping Review

OBJECTIVE

Recreational cannabis legalization (RCL) is expanding rapidly. RCL's effects on mental health issues are of particular concern because cannabis use is more frequent among people receiving psychiatric care and is associated with several psychiatric disorders. The authors conducted a scoping review to examine the evidence and discern gaps in the literature concerning the effects of RCL on mental health and to assess the factors responsible for an observed heterogeneity in research results.

METHODS

This scoping literature review followed PRISMA guidelines. Five databases-MEDLINE, CINAHL, Embase, APA PsycInfo, and Web of Science-were searched for English- or French-language reports published between January 1, 2012, and April 30, 2023.

RESULTS

Twenty-eight studies from the United States and Canada were found. The studies were classified by category of the study's data (patients receiving psychiatric care [k=1], death records [k=4], emergency department or hospital records [k=10], and the general population [k=13]) and by the diagnosis (schizophrenia or psychoses, mood disorders, anxiety disorders and symptoms, suicide or suicidal ideation, or other mental health issues) examined. The review findings revealed a paucity of research and indicated mixed and largely inconclusive results of the studies examined. Research gaps were found in the examination of potential changes in cannabis use patterns among people receiving psychiatric care and in the availability of longitudinal studies.

CONCLUSIONS

Clinicians, researchers, and policy makers need to collaborate to address the research gaps and to develop evidence-based policies that reflect a thorough understanding of the effects associated with RCL.

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

BACKGROUND

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

METHOD

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

RESULTS

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

CONCLUSION

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

[Effectiveness of a cannabis prevention program in school: results of a randomized prospective study]

BACKGROUND

In the current debate about legalized access to cannabis for adults in Germany, there is widespread agreement about the need for increased prevention among children and young people. The aim of this work is to examine the effectiveness of a school-based cannabis prevention program on knowledge, attitudes, and behavior.

METHOD

Cluster-randomized waiting list control group study with two study arms: "participation in the 'Der grüne Koffer' prevention program", a collection of methods for cannabis prevention, vs. "no participation" and two measurement time points before and four months after the intervention in four German states.

RESULTS

The mean age of the sample of 3976 adolescents from 280 school classes in grades 8 and 9 was 14.02 years (standard deviation = 0.89). The sex ratio was balanced (49.5% female). Cannabis-related knowledge increased significantly more in the intervention group compared to the control group from the first to the second measurement time point (adjusted beta = 0.25 [95% confidence interval: 0.14-0.37]). Attitudes toward cannabis use did not change significantly in either group. In the 8th grades of the intervention group, significantly fewer adolescents (2.9%) started experimenting with cannabis use for the first time during the observation period than in the control group (5.3%), whereas no group difference was detectable in the 9th grades (interaction grade level x group: odds ratio = 2.17 [1.13-4.15], p = 0.019).

DISCUSSION

The evidence of an effect of participation in the "Der grüne Koffer" prevention program on knowledge and first-time use of cannabis in the 8th grade can be considered promising against the background of previous national and international studies, which could not provide evidence of effects of school-based cannabis prevention in middle and late adolescence.

Psychosis superspectrum I: Nosology, etiology, and lifespan development

This review describes the Hierarchical Taxonomy of Psychopathology (HiTOP) model of psychosis-related psychopathology, the psychosis superspectrum. The HiTOP psychosis superspectrum was developed to address shortcomings of traditional diagnoses for psychotic disorders and related conditions including low reliability, arbitrary boundaries between psychopathology and normality, high symptom co-occurrence, and heterogeneity within diagnostic categories. The psychosis superspectrum is a transdiagnostic dimensional model comprising two spectra-psychoticism and detachment-which are in turn broken down into fourteen narrow components, and two auxiliary domains-cognition and functional impairment. The structure of the spectra and their components are shown to parallel the genetic structure of psychosis and related traits. Psychoticism and detachment have distinct patterns of association with urbanicity, migrant and ethnic minority status, childhood adversity, and cannabis use. The superspectrum also provides a useful model for describing the emergence and course of psychosis, as components of the superspectrum are relatively stable over time. Changes in psychoticism predict the onset of psychosis-related psychopathology, whereas changes in detachment and cognition define later course. Implications of the superspectrum for genetic, socio-environmental, and longitudinal research are discussed. A companion review focuses on neurobiology, treatment response, and clinical utility of the superspectrum, and future research directions.

A national study of clinical discussions about cannabis use among Veteran patients prescribed opioids

BACKGROUND

The Veterans Health Administration tracks urine drug tests (UDTs) among patients on long-term opioid therapy (LTOT) and recommends discussing the health effects of cannabis use.

OBJECTIVE

To determine the occurrence of cannabis-related discussions between providers and patients on LTOT during six months following UDT positive for cannabis, and examine factors associated with documenting cannabis use.

DESIGN

We identified patients prescribed LTOT with a UDT positive for cannabis in 2019. We developed a text-processing tool to extract discussions around cannabis use from their charts.

SUBJECTS

Twelve thousand seventy patients were included. Chart review was conducted on a random sample of 1,946 patients.

MAIN MEASURES

The presence of a cannabis term in the chart suggesting documented cannabis use or cannabis-related discussions. Content of those discussions was extracted in a subset of patients. Logistic regression was used to examine the association between patient factors, including state of residence legal status, with documentation of cannabis use.

KEY RESULTS

Among the 12,070 patients, 65.8% (N = 7,948) had a cannabis term, whereas 34.1% (N = 4,122) of patients lacked a cannabis term, suggesting that no documentation of cannabis use or discussion between provider and patient took place. Among the subset of patients who had a discussion documented, 47% related to cannabis use for medical reasons, 35% related to a discussion of VA policy or legal issues, and 17% related to a discussion specific to medical risks or harm reduction strategies. In adjusted analyses, residents of states with legalized recreational cannabis were less likely to have any cannabis-related discussion compared to patients in non-legal states [OR 0.73, 95% CI 0.64-0.82].

CONCLUSIONS

One-third of LTOT patients did not have documentation of cannabis use in the chart in the 6 months following a positive UDT for cannabis. Discussions related to the medical risks of cannabis use or harm reduction strategies were uncommon.

Cannabis use and cannabis use disorders and their treatment in the Europe

This paper introduces the special issue on cannabis use in Europe. It describes data on the prevalence of cannabis use in Europe and the more limited data on the prevalence of cannabis use disorders, one of the most common forms of drug problem treated in many countries in Europe. It summarises what research has indicated about the adverse effects of acute and chronic cannabis use and discusses potential health system responses that may reduce some of these harms. These include public education about the risks of cannabis use; screening and brief interventions in primary medical settings; and specialist treatment for cannabis use disorders. It briefly indicates the special issues that may need to be addressed in dealing with the high rates of comorbidity between cannabis use disorders, other types of drug use disorders, and common mental disorders.

Association between psychosis and substance use in Kenya. Findings from the NeuroGAP-Psychosis study

Background

Substance use is prevalent among people with mental health issues, and patients with psychosis are more likely to use and misuse substances than the general population. Despite extensive research on substance abuse among the general public in Kenya, there is a scarcity of data comparing substance use among people with and without psychosis. This study investigates the association between psychosis and various substances in Kenya.

Methods

This study utilized data from the Neuro-GAP Psychosis Case-Control Study between April 2018 and December 2022. The KEMRI-Wellcome Trust Research Programme recruited participants from various sites in Kenya, including Kilifi County, Malindi Sub-County, Port Reitz and Coast General Provincial Hospitals, and Moi Teaching and Referral Hospital, as well as affiliated sites in Webuye, Kapenguria, Kitale, Kapsabet, and Iten Kakamega. The collected data included sociodemographic information, substance use, and clinical diagnosis. We used the summary measures of frequency (percentages) and median (interquartile range) to describe the categorical and continuous data, respectively. We examined the association between categorical variables related to psychosis using the chi-square test. Logistic regression models were used to assess the factors associated with the odds of substance use, considering all relevant sociodemographic variables.

Results

We assessed a total of 4,415 cases and 3,940 controls. Except for alcohol consumption (p-value=0.41), all forms of substance use showed statistically significant differences between the case and control groups. Cases had 16% higher odds of using any substance than controls (aOR: 1.16, 95%CI: 1.05-1.28, p=0.005). Moreover, males were 3.95 times more likely to use any substance than females (aOR:3.95; 95%CI: 3.43-4.56). All the categories of living arrangements were protective against substance use.

Conclusion

The findings of this study suggest that psychotic illnesses are associated with an increased likelihood of using various substances. These findings are consistent with those of previous studies; however, it is crucial to investigate further the potential for reverse causality between psychosis and substance abuse using genetically informed methods.

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 use in teenage years: Results of the prevention radar from 2016 to 2023]

Trends des Cannabiskonsums in der Adoleszenz sollen von 2016 bis 2023 abgebildet werden. Basierend auf sieben Wellen des Präventionsradars, einer schulbasierten epidemiologischen Studie in der Sekundarstufe I, wurden die Lebenszeit- und Monatsprävalenzen des Cannabiskonsums von 12-bis 17-Jährigen für den Zeitraum von 2016 bis 2023 ermittelt. Der Auswertung lagen 54.242 Fragebögen mit Angaben zum Konsum von Cannabis zugrunde. Das Geschlechterverhältnis war ausgeglichen (50% weiblich). Das durchschnittliche Alter betrug 13,9 Jahre (SD=1,3). Von 2016 bis zum Ausbruch der COVID-19-Pandemie stieg die Lebenszeitprävalenz des Cannabiskonsums statistisch bedeutsam an, im ersten Jahr der Pandemie sank sie signifikant. Post-pandemisch hatten 12,3% (95 % KI: 11,6-13,1) der Heranwachsenden mindestens einmal in ihrem Leben Cannabis konsumiert. Dieser Wert liegt auf dem Niveau von 2016. Die Monatsprävalenz des Cannabiskonsums lag 2022/2023 bei 3,8% (95% KI: 3,4-4,3). Sowohl die Lebenszeit- als auch die Monatsprävalenz des Cannabiskonsums von Jungen liegen signifikant über den Werten der Mädchen. Angesichts der bekannten Risiken, die mit dem Cannabiskonsum im Jugendalter einhergehen können, ist es besorgniserregend, dass 2022/2023 etwa jeder achte Jugendliche bereits mit Cannabis experimentiert hatte. Konsequente verhältnis- und verhaltenspräventive Maßnahmen sind erforderlich, um den Cannabiskonsums im Teenageralter einzudämmen.

Relapse in schizophrenia: The role of factors other than non-adherence to treatment

AIM

Relapse rates are very high in schizophrenia. However, little is known about the predictors of the time to relapse other than treatment non-adherence. We investigated possible risk factors for the time to relapse in patients with first-episode schizophrenia (n = 107) who received assured treatment by way of long-acting injectable antipsychotic over 24 months and who underwent regular clinical, cognitive, and metabolic assessments.

METHODS

Using Cox regression analyses we assessed selected premorbid and baseline potential predictors of time to relapse. Relapse was defined using operationally defined relapse criteria.

RESULTS

In the primary analysis only neurological soft signs total score retained significance, with higher scores predicting shorter time to relapse (HR = 1.05, 95% CI = 1.01-1.10, p = .029). In a more detailed secondary analysis poorer social relationships predicted shorter time to relapse (HR = 0.85, 95% CI = 0.76-0.95, p = .003).

CONCLUSION

Our predominantly negative findings suggest that many of the previously implicated risk factors for the time to relapse are mediated by non-adherence rather than having a direct effect on relapse-proneness. Neurological soft signs, and perhaps quality of life in social relationships appear to play a role and merit further investigation.

The schizophrenia syndrome, circa 2024: What we know and how that informs its nature

With new data about different aspects of schizophrenia being continually generated, it becomes necessary to periodically revisit exactly what we know. Along with a need to review what we currently know about schizophrenia, there is an equal imperative to evaluate the construct itself. With these objectives, we undertook an iterative, multi-phase process involving fifty international experts in the field, with each step building on learnings from the prior one. This review assembles currently established findings about schizophrenia (construct, etiology, pathophysiology, clinical expression, treatment) and posits what they reveal about its nature. Schizophrenia is a heritable, complex, multi-dimensional syndrome with varying degrees of psychotic, negative, cognitive, mood, and motor manifestations. The illness exhibits a remitting and relapsing course, with varying degrees of recovery among affected individuals with most experiencing significant social and functional impairment. Genetic risk factors likely include thousands of common genetic variants that each have a small impact on an individual's risk and a plethora of rare gene variants that have a larger individual impact on risk. Their biological effects are concentrated in the brain and many of the same variants also increase the risk of other psychiatric disorders such as bipolar disorder, autism, and other neurodevelopmental conditions. Environmental risk factors include but are not limited to urban residence in childhood, migration, older paternal age at birth, cannabis use, childhood trauma, antenatal maternal infection, and perinatal hypoxia. Structural, functional, and neurochemical brain alterations implicate multiple regions and functional circuits. Dopamine D-2 receptor antagonists and partial agonists improve psychotic symptoms and reduce risk of relapse. Certain psychological and psychosocial interventions are beneficial. Early intervention can reduce treatment delay and improve outcomes. Schizophrenia is increasingly considered to be a heterogeneous syndrome and not a singular disease entity. There is no necessary or sufficient etiology, pathology, set of clinical features, or treatment that fully circumscribes this syndrome. A single, common pathophysiological pathway appears unlikely. The boundaries of schizophrenia remain fuzzy, suggesting the absence of a categorical fit and need to reconceptualize it as a broader, multi-dimensional and/or spectrum construct.

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

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

Medical cannabis authorization and risk of emergency department visits and hospitalization due to psychotic disorders: A propensity score-matched cohort study

Despite evidence showing that recreational cannabis use is associated with a higher risk of psychotic disorders, this risk has not been well characterized for patients using medical cannabis. Therefore, this study assessed the risk of emergency department (ED) visits and hospitalization for psychotic disorders (the study outcome) among adult patients authorized to use medical cannabis. We performed a retrospective cohort study on patients authorized to use medical cannabis in a group of Ontario cannabis clinics between 2014 and 2019. Using clinical and health administrative data, each patient was matched by propensity scores to up to 3 population-based controls. Conditional Cox proportional hazards regressions were used to assess the risk. Among 54,006 cannabis patients matched to 161,265 controls, 39 % were aged ≤50 years, and 54 % were female. Incidence rates for psychotic disorders were 3.00/1000 person-years (95%CI: 2.72-3.32) in the cannabis group and 1.88/1000 person-years (1.75-2.03) in the control group. A significant association was observed, with an adjusted hazard ratio of 1.38 (95%CI: 1.19-1.60) in the total sample and 1.63 (1.40-1.91) in patients without previous psychotic disorders. The results suggest that cannabis authorization should include a benefit-risk assessment of psychotic disorders to minimize the risk of events requiring emergency attention.

Aberrant salience in cannabis-induced psychosis: a comparative study

Background

Natural Cannabis (NC) and Synthetic Cannabinoids (SCs) use can increase the risk and exacerbate the course of psychotic disorders. These could be influenced by the Aberrant Salience (AS) construct. It refers to an excess of attribution of meaning to stimuli that are otherwise regarded as neutral, thereby transform them into adverse, dangerous, or mysterious entities. This leads the patient to engage in aberrant and consequently incorrect interpretative efforts concerning the normal perception of reality and its relationship with our analytical abilities. AS appears to play a significant role in the onset and perpetuation of psychotic disorders. The internal conflict arising from aberrant attributions of significance leads to delusional thoughts, ultimately culminating in the establishment of a self-sustaining psychosis.

Aims

To examine the differences between psychoses course not associated with cannabis use and those associated with NC-use and SCs-use, in terms of psychotic and dissociative symptoms, AS, global functioning and suicidal ideation.

Methods

A sample of 62 patients with First Episode Psychosis (FEP) was divided into 3 groups: non cannabis users (non-users, N = 20); NC-users or rather Delta-9-tetrahydrocannabinol (THC) users (THC-users, N = 21); SCs-users, commonly referred to as SPICE-users (SPICE-users, N = 20). Each group underwent assessments at the onset of psychotic symptoms, as well as at the 3 months and 6 months marks, utilizing a range of psychopathological scales. These included the Positive and Negative Syndrome Scale (PANSS) for investigating psychotic symptoms, the Global Assessment of Functioning (GAF) scale for assessing overall functioning, the Dissociative Experiences Scale (DES-II) for measuring dissociative symptoms, the Scale for Suicide Ideation (SSI) for evaluating suicidal ideation and the Aberrant Salience Inventory (ASI) scale for gauging AS.

Results

SPICE-users showed more severe and persistent positive symptoms, while negative symptoms were mostly represented among non-users. Non-users showed better recovery than SPICE-users in global functioning. All groups showed a decrease in both ASI scores and subscale scores. SPICE-users exhibited higher global AS scores and less improvement in this aspect compared to other groups.

Conclusion

This study may help understanding the role of AS in both non-substance-related and substance-induced psychosis. This knowledge may lead clinician to a better diagnosis and identify patient-tailored psychopharmacological treatment.

Modelling the effects of the exposome score within the extended psychosis phenotype

It has been reported that cumulative measures of risk factors for psychosis might help to predict its development. However, it remains unknown as to whether these measures are also associated with the extended psychosis phenotype that refers to a continuum of features bridging subclinical symptoms with clinically relevant outcomes. In this study, we aimed to investigate the association of the exposome score (ES) with psychosis risk in a non-clinical population. A total of 1100 non-clinical adults (aged 18-35 years, 51.4% females) with a negative history of psychiatric treatment were recruited. The Prodromal Questionnaire-16 (PQ-16) was used to screen for psychosis risk. Self-reports were used to record environmental exposures. The ES was significantly higher in participants with the positive PQ-16 screening. Specifically, the prevalence of obstetric complications, non-right handedness, all categories of childhood trauma, and problematic cannabis use was significantly higher in this group of participants. A network analysis demonstrated that the ES was directly connected not only to items representing psychotic experiences ("paranoid thoughts", "a lack of control over own ideas or thoughts", "thought echo", and "being distracted by distant sounds") but also those covering depressive or anxiety symptoms ("uninterested in things used to enjoy" and "feeling anxious when meeting people for the first time"). In conclusion, the ES is associated with the extended psychosis phenotype, suggesting its potential to identify individuals who may benefit from further psychosis risk assessment. The ES appears to contribute to non-specific psychopathology, which may, in some cases, progress to psychosis.

Perspectives toward cannabidiol (CBD) among youth in Early Psychosis Intervention programs: A qualitative study

AIM

Cannabis is used by one third of youth in Early Psychosis Intervention (EPI) programs and high dose consumption of the primary constituent Δ-9 tetrahydrocannabinol (THC) is associated with higher risk for relapse in this group. Cannabidiol (CBD) is a secondary cannabis constituent that may have antipsychotic properties, though its health risks are only beginning to be understood. Little is known about the views of youth in EPI programs toward CBD, including their reasons for use and perceptions of risk.

METHODS

This qualitative study used Interpretive Phenomenological Analysis to investigate the perspectives of a sample (n = 15) of cannabis-consuming youth in EPI programs toward CBD.

RESULTS

Those who used CBD (n = 13) did so for pain relief, THC substitution, relaxation, social reasons, and sleep enhancement. CBD was perceived to be beneficial for health and wellness, though many consumers were disappointed with its effects. Most believed there were no risks associated with its use or were unaware of any risks, and all believed CBD could be used safely.

CONCLUSION

Clinicians should assess THC and CBD consumption patterns, motives for use, and perceptions of risk separately to tailor interventions accordingly. Youth in EPI programs would benefit from education related to the known health risks and benefits associated with this drug. Clinicians in regions where cannabis is regulated should be open to discussing CBD as a safer substitute for THC. The potential for CBD to serve as viable treatment for psychosis requires further study.

Endorsement of psychotic-like experiences and problematic cannabis use associated with worse executive functioning performance in undergraduates

BACKGROUND

Emerging adults who endorse more positive psychotic-like experiences (PLEs; bizarre experiences, delusional ideations) may experience greater cannabis-related impairments in executive function. Negative and depressive PLEs are also associated with cannabis use, however, less is known about their relation to executive functioning. Here, we hypothesize that high positive PLEs and cannabis use are associated with worse performance on computerized versions of the Iowa Gambling Task (IGT) and the Card Sorting Task (CST); exploratory analyses are conducted with negative and depressive PLEs.

METHODS

We recruited university students (N = 543) who completed an online study consisting of self-report measures of problematic cannabis use (Cannabis Use Disorder Identification Test; CUDIT-R) and PLEs (Community Assessment of Psychotic Experiences; CAPE). Of these, n=270 completed the CST and n=251 completed the IGT.

RESULTS

Problematic cannabis use and high endorsement of positive PLEs related to significantly worse performance on the IGT and greater perseverative errors on the CST. In addition, people who endorsed high levels of positive PLEs were also significantly more likely to complete the IGT with less money relative to those who endorsed fewer PLEs, regardless of cannabis use. Further analyses based on negative PLEs revealed a similar pattern for perseverative errors on the CST; depressive PLEs were not related to task performance.

CONCLUSION

Findings highlight that problematic cannabis use and more frequent and distressing positive PLEs are associated with poorer executive functioning. Thus, executive functioning may have implications for intervention among those high on both attributes, who are at high risk of onset of psychosis.

The separate and joint effects of recent interpersonal abuse and cannabis use on psychotic experiences: findings from students in higher education in the United States

BACKGROUND

Various forms of interpersonal abuse (e.g., physical, emotional, sexual) and cannabis use across the lifespan have both been known to increase odds of psychotic experiences; however, there have been few studies examining their separate and joint effects in the United States.

METHODS

We analyzed data from the Healthy Minds Study (2020-2021) and used multivariable logistic regression and interaction contrast ratios to assess separate and joint effects of interpersonal abuse (past 12 months) and cannabis use (past 30 days) on psychotic experiences (past 12 months).

RESULTS

Students who only used cannabis had significantly greater odds of psychotic experiences (aOR: 1.70; 95% CI 1.58-1.82), as well as those who only experienced interpersonal abuse (aOR: 2.40; 95% CI 2.25-2.56). However, those who reported both cannabis use and interpersonal abuse had the greatest odds, exceeding the sum of these individual effects (the combined effect aOR: 3.46; 95% CI 3.19-3.76).

CONCLUSIONS

Recent interpersonal abuse and recent cannabis use both separately and jointly increase odds of having recent psychotic experiences. Future research should continue to examine the potential interactive and additive impact of multiple known exposures to better inform primary and secondary prevention efforts.

Identifying policy options to regulate high potency cannabis: A multiple stakeholder concept mapping study in Washington State, USA

BACKGROUND

Cannabis legalization in some U.S.A. states has catapulted the mass production of concentrates, with tetrahydrocannabinol (THC) concentrations ranging from 50-90%. A major public health concern is that these products will increase cannabis-related harms such as use disorders, psychotic symptoms, and accidental poisonings. This paper describes and contextualizes the results of a study requested by the WA State Legislature to understand perspectives of WA stakeholders on the topic.

METHODS

Concept Mapping (CM), a mixed-methods research approach that supports people-centered policy decisions was utilized. The goal of the study was to explore stakeholders' concern levels and support of policies to address the availability of high THC cannabis products. For analysis purposes, stakeholders were categorized into three groups: community, professionals, and cannabis advocates.

RESULTS

CM generated an inventory of policy ideas for regulating high-potency cannabis from a variety of stakeholders. Notably, stakeholders from community and professional groups supported environmental policy changes such as such as taxation, increasing minimum age for high concentration cannabis products, and advertising prohibition. Meanwhile, cannabis advocates (mostly industry actors) opposed taxation per THC content, proposed lowering taxes, and supported policies with low population impact such as educating parents, teachers, and youth.

CONCLUSION

Support for regulating high concentration THC products varied by stakeholder group. Consistent with how other health compromising industries have historically acted, cannabis industry stakeholders rejected regulation of their products. Future studies should explore non-cannabis industry stakeholders' willingness to work towards minimizing the influence of the cannabis industry in policy development processes to assure public health regulations prevail.

Remission with or without comorbid substance use disorders in early psychosis: long-term outcome in integrated care (ACCESS III study)

Introduction

Schizophrenia-Spectrum-Disorders are associated with poor long-term outcome as well as disability and often severely affect the lives of patients and their families often from symptom onset. Up to 70% of first episode psychosis (FEP) patients suffer from comorbid substance use disorders (SUD). We aimed at studying the course of illness in FEP patients within evidence-based care, with and without comorbid SUD, to examine how decreased, remitted or persistent substance use impacted rates of a combined symptomatic and functional long-term recovery compared with patients without SUD.

Methods

ACCESS III is an integrated care model for FEP or patients in the early phase of non-affective and affective psychotic disorders. Treatment trajectories of patients, who had been in ACCESS care for 1 year, with and without SUD were compared with regard to the course of illness and quality of life using Mixed Model Repeated Measures (MMRM) and recovery rates were compared using binary logistic regression. Change in substance use was coded as either persistent, decreased/remitted or no use.

Results

ACCESS III was a prospective 1-year study (N = 120) in patients aged 12-29 years. Of these, 74 (61.6%) had a comorbid SUD at admission. There were no group differences regarding the course of illness between patients with or without comorbid SUD or between patients with a substance abuse or substance dependence. The only outcome parameter that was affected by SUD was quality of life, with larger improvement found in the group without substance use (p = 0.05) compared to persistent and remitted users. Using LOCF, 44 patients (48.9%) fulfilled recovery criteria at the endpoint; recovery did not differ based on substance use status.

Discussion

SUD and especially substance dependence are common in psychotic disorders even in FEP patients. Evidence-based integrated care led to long-term improvement in patients with comorbid SUD and rate of recovery did not differ for patients with substance use.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

The "Why" in Mental Health, Stigma, and Addictive Behaviors: Causal Inferences in Applied Settings

Mental health problems, broadly understood, are highly prevalent [...].

Association between non-medical cannabis legalization and emergency department visits for cannabis-induced psychosis

A major public health concern of cannabis legalization is that it may result in an increase in psychotic disorders. We examined changes in emergency department (ED) visits for cannabis-induced psychosis following the legalization and subsequent commercialization (removal of restrictions on retail stores and product types) of non-medical cannabis in Ontario, Canada (population of 14.3 million). We used health administrative data containing the cause of all ED visits to examine changes over three periods; 1) pre-legalization (January 2014-September 2018); 2) legalization with restrictions (October 2018 - February 2020); and 3) commercialization (March 2020 - September 2021). We considered subgroups stratified by age and sex and examined cocaine- and methamphetamine-induced psychosis ED visits as controls. During our study, there were 6300 ED visits for cannabis-induced psychosis. The restricted legalization period was not associated with changes in rates of ED visits for cannabis-induced psychosis relative to pre-legalization. The commercialization period was associated with an immediate increase in rates of ED visits for cannabis-induced psychosis (IRR 1.30, 95% CI 1.02-1.66) and no gradual monthly change; immediate increases were seen only for youth above (IRR 1.63, 1.27-2.08, ages 19-24) but not below (IRR 0.73 95%CI 0.42-1.28 ages, 15-18) the legal age of purchase, and similar for men and women. Commercialization was not associated with changes in rates of ED visits for cocaine- or methamphetamine-induced psychosis. This suggests that legalization with store and product restrictions does not increase ED visits for cannabis-induced psychosis. In contrast, cannabis commercialization may increase cannabis-induced psychosis presentations highlighting the importance of preventive measures in regions considering legalization.

Association between cannabis use and symptom dimensions in schizophrenia spectrum disorders: an individual participant data meta-analysis on 3053 individuals

Background

The association between cannabis use and positive symptoms in schizophrenia spectrum disorders is well documented, especially via meta-analyses. Yet, findings are inconsistent regarding negative symptoms, while other dimensions such as disorganization, depression, and excitement, have not been investigated. In addition, meta-analyses use aggregated data discarding important confounding variables which is a source of bias.

Methods

PubMed, ScienceDirect and PsycINFO were used to search for publications from inception to September 27, 2022. We contacted the authors of relevant studies to extract raw datasets and perform an Individual Participant Data meta-analysis (IPDMA). Inclusion criteria were: psychopathology of individuals with schizophrenia spectrum disorders assessed by the Positive and Negative Syndrome Scale (PANSS); cannabis-users had to either have a diagnosis of cannabis use disorder or use cannabis at least twice a week. The main outcomes were the PANSS subscores extracted via the 3-factor (positive, negative and general) and 5-factor (positive, negative, disorganization, depression, excitement) structures. Preregistration is accessible via Prospero: ID CRD42022329172.

Findings

Among the 1149 identified studies, 65 were eligible and 21 datasets were shared, totaling 3677 IPD and 3053 complete cases. The adjusted multivariate analysis revealed that relative to non-use, cannabis use was associated with higher severity of positive dimension (3-factor: Adjusted Mean Difference, aMD = 0.34, 95% Confidence Interval, CI = [0.03; 0.66]; 5-factor: aMD = 0.38, 95% CI = [0.08; 0.63]), lower severity of negative dimension (3-factor: aMD = -0.49, 95% CI [-0.90; -0.09]; 5-factor: aMD = -0.50, 95% CI = [-0.91; -0.08]), higher severity of excitement dimension (aMD = 0.16, 95% CI = [0.03; 0.28]). No association was found between cannabis use and disorganization (aMD = -0.13, 95% CI = [-0.42; 0.17]) or depression (aMD = -0.14, 95% CI = [-0.34; 0.06]).

Interpretation

No causal relationship can be inferred from the current results. The findings could be in favor of both a detrimental and beneficial effect of cannabis on positive and negative symptoms, respectively. Longitudinal designs are needed to understand the role of cannabis is this association. The reported effect sizes are small and CIs are wide, the interpretation of findings should be taken with caution.

Funding

This research did not receive any specific grant or funding. Primary financial support for authors was provided by Le Vinatier Psychiatric Hospital.

How to quit cannabis when you have a mental illness: study from the perspective of patients who have successfully quit

AIMS AND METHOD

Research regarding quitting cannabis use often excludes patients with severe mental illness (SMI). We investigated facilitating and impeding factors in SMI patients and their advice to others, using semi-structured interviews with 12 SMI-patients, who were daily cannabis users for ≥12 months and had fully stopped using for ≥6 months.

RESULTS

Seeking distraction, social contacts in personal environment, avoiding temptation and support from professionals were facilitating factors in stopping. Impeding factors were withdrawal symptoms, user environment, experiencing stress and user's routine. Advice to other patients included to just do it, seek support from others, quit 'cold turkey' and acknowledge that cannabis use is a problem. Advice to mental health professionals is to discuss cannabis use from the start of treatment.

CLINICAL IMPLICATIONS

It is important to inform patients that cannabis use has negative consequences and limits the effects of treatment. Do not judge cannabis use or force the patient to stop.

Socio-demographic profile and clinical co-morbidities of cannabis users attending a tertiary care hospital in India: A retrospective case record study

Context

Cannabis use has been the most commonly used illicit psychoactive substance in India. Increasing use of cannabis has been associated with an increased risk of co-morbid psychotic spectrum disorders with worse outcomes. This risk increases with increased use in a dose-dependent manner. A very complex association exists between cannabis use and mental illness hence it is essential to understand the relationship between the two to facilitate better care and management.

Aim

The present study was conducted to assess the socio-demographic profile and psychiatric co-morbidities of cannabis users attending a tertiary mental health establishment in Goa.

Materials and Methods

A retrospective case record study was carried out among self-reported cannabis users attending services at a tertiary mental health establishment from June 2021 to June 2022. Data regarding cannabis use, clinical profile, and socio-demographic profile of the individuals was obtained and analyzed using appropriate statistical tests.

Results

One hundred and sixty-four cannabis users were evaluated which consisted of 140 males and 24 females, the mean age being 28 years with a standard deviation of 7.68. Ganja was the most commonly used form smoked as joints. The median age of initiation was 18 with females starting at a later age than males. Later initiation was associated with using lower quantities. Concurrent alcohol and nicotine use was present in 90% of the cases. The most commonly associated diagnosis was substance-induced psychosis.

Conclusions

Cannabis use in individuals with mental illness is more common in males and an early age of initiation was linked to earlier age of onset of psychiatric illness.

General hospital admissions in young and middle-aged people who use psychoactive substances: Impact of Covid-19 lockdowns

BACKGROUNDS

The Covid-19 pandemic offered a unique opportunity to investigate trends in hospitalizations related to psychoactive substance intoxication, since the usual health burden of social use at parties and gatherings was likely to be decreased during lockdowns and curfew periods. Since young adults are the main users of psychoactive substances for experimental and recreational purposes, this study identified and compared hospitalization trends in young adults and adults over 30 years old.

METHODS

This national cohort study was conducted using the French hospital discharge database. An interrupted time-series analysis for the period between 2014 and 2020 was performed in two groups: young (age 18-29) and other adults (30+) to ascertain the trends in the monthly incidence of hospitalization related to psychoactive substance intoxication (opiates, cocaine, benzodiazepines, psychostimulants, alcohol and cannabis). Hospitalization characteristics during the first and second lockdown and the period between them were compared to the reference period (from 01/01/2014 to 29/02/2020).

RESULTS

Among 1,358,007 stays associated with psychoactive substance intoxication, 215,430 concerned young adults. Compared with adults 30+, hospitalization trends in young adults showed a greater decrease in the number of stays during lockdown, with a maximum decrease of -39% during the first lockdown (1,566 vs. 2,576; CI95%: 2,285-2,868) versus -20% (10,212 vs. 12,894; CI95%: 12,001-13,787) in the second lockdown. Presentations for alcohol intoxication decreased throughout the pandemic, particularly during the second lockdown, while admissions for benzodiazepine intoxication increased during both lockdowns. Admissions for cannabis intoxication increased throughout the entire period.

CONCLUSIONS

Lockdowns were associated with fewer hospitalizations related to psychoactive substance intoxication in both age groups, especially among young adults, which might reflect a decrease in social use. Recreational use might therefore be an important target for prevention and risk minimization.

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).

Prevalence of smoking, alcohol consumption, and drug abuse in Iranian adults: Results of Azar Cohort Study

Background

Substance abuse has significant health impacts on families and society as a whole. We aimed to provide detailed prevalence estimates of substance abuse among the Azar Cohort Study respondents in Tabriz, Iran.

Methods

Data on 15006 participants of Azar Cohort Study were analyzed. The variables included tobacco smoking, alcohol use, drug abuse, and socio-demographic characteristics. The prevalence of substance abuse (with a 95% confidence interval) was calculated using the direct standardization method.

Results

Overall, 9.3% and 6.2% of the participants were regular and heavy cigarette smokers, respectively. Also, 1.9% and 2.1% of participants reported a history of using illicit drugs and alcohol, respectively. Substance abuse was more prevalent among males than females. Substance abuse varied significantly with age and socioeconomic variables.

Conclusion

We identified specific demographic and socioeconomic groups with a higher prevalence of all studied behaviors. Such high-risk groups should be targeted when designing substance abuse prevention programs.

Cannabis Use and Symptomatic Relapse in First Episode Schizophrenia: Trigger or Consequence? Data From the OPTIMISE Study

BACKGROUND AND HYPOTHESIS

This analysis examined the relationship between cannabis use, compliance with antipsychotics and risk for relapse in patients in remission following a first episode of schizophrenia, schizophreniform, or schizoaffective disorder.

STUDY DESIGN

Analyses were performed on data from a large European study on first episode of schizophrenia, schizophreniform, or schizoaffective disorder (OPTiMiSE). After 10 weeks of antipsychotic treatment, 282/446 patients (63%) met criteria for symptomatic remission; of whom 134/282 (47.5%) then completed a 1-year follow-up. Cross-lagged models and mediation models investigated the temporal relationships between cannabis use, compliance with antipsychotics, social functioning, and symptomatic worsening/relapse.

STUDY RESULTS

Compared to nonusers, cannabis use increased risk for relapse, adjusted hazard ratio (HR) = 3.03 (SE = 0.32), P < .001, even in patients who were compliant with antipsychotic medication, adjusted HR = 2.89, (SE = 0.32), P < .001. Cannabis use preceded symptomatic worsening and was followed by worsening of Positive and Negative Syndrome Scale total score at the 1-year end-point (standardized β = 0.62, SE = 0.19, P = .001) and by worsening of social functioning (coef = -0.66, P ≤ .001).

CONCLUSIONS

In patients in remission from their first episode of schizophrenia, schizophreniform, or schizoaffective disorder, cannabis use increases the rate of relapse in both compliant and noncompliant individuals. Importantly, the temporal relationship between cannabis and relapse was that cannabis use preceded later relapse, noncompliance, and decrease in social functioning, and not that patients began to relapse, then used cannabis. Further research with a precision psychiatry approach might identify those patients in particular danger of relapse when using cannabis.

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.

Directional associations between cannabis use and depression from late adolescence to young adulthood: the role of adverse childhood experiences

BACKGROUND AND AIMS

Although the co-occurrence of cannabis and depression is well established, less is known about the temporal sequence of cannabis use and depression. The present study had three main aims: to test a symptom-driven pathway in which depression may drive increases in cannabis use, to test a substance-induced pathway in which cannabis use may drive increases in depression and to assess a shared vulnerability model assessing associations between individuals who have (and have not) experienced adverse childhood experiences (ACEs).

DESIGN

Data are from an ongoing, longitudinal, cohort study (n = 2234). Data were set up in an accelerated longitudinal design from age 17 to 24 years.

SETTING

Initial sample was recruited from Southern California, USA. The majority of participants still live in Southern California.

PARTICIPANTS

On average, participants were aged 18 years at wave 8, with more than half identifying as female (54.3%; n = 1350). Most participants identified as Hispanic (1127; 45.4%), followed by non-Hispanic white (510; 20.5%), Asian (503; 20.2%), multi-racial/other (284; 11.4%) and non-Hispanic black (60; 2.2%).

MEASUREMENTS

Primary outcomes were past-month days of cannabis use and depression symptoms [patient health questionnaire (PHQ)-8]. The Adverse Childhood Experiences scale was used as our main grouping measure.

FINDINGS

In the full sample, we showed that prior levels of depression symptoms were associated with a decrease in cannabis use [opposite to the proposed symptom driven model; B = -0.33 (-0.58, -0.09)]. Dynamic coupling parameters noted individuals who evidenced greater increases in cannabis use between two prior ages reported greater increases in depressive symptoms between subsequent ages [support for a substance-induced pathway; B = 0.53 (0.18, 0.89)]. Similar to the overall sample, for those who had not experienced ACEs, as cannabis use increased we saw a steady increase in depression [support for a substance induced pathway; B = 0.14 (0.04, 0.29)]. However, for those who experienced ACEs, as cannabis use increased we saw a consistent decrease in depression [opposite to the proposed substance-induced pathway; B = -0.18 (-0.28, -0.08)].

CONCLUSION

There is mixed support for both symptom-driven and substance-induced pathways between cannabis use and depression.