Meta-analysis of the Association Between the Level of Cannabis Use and Risk of Psychosis

Exploring causal mechanisms of psychosis risk

Robust epidemiological evidence of risk and protective factors for psychosis is essential to inform preventive interventions. Previous evidence syntheses have classified these risk and protective factors according to their strength of association with psychosis. In this critical review we appraise the distinct and overlapping mechanisms of 25 key environmental risk factors for psychosis, and link these to mechanistic pathways that may contribute to neurochemical alterations hypothesised to underlie psychotic symptoms. We then discuss the implications of our findings for future research, specifically considering interactions between factors, exploring universal and subgroup-specific factors, improving understanding of temporality and risk dynamics, standardising operationalisation and measurement of risk and protective factors, and developing preventive interventions targeting risk and protective factors.

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

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

Accelerated Pace of Aging in Schizophrenia: Five Case-Control Studies

BACKGROUND

Schizophrenia is associated with increased risk of developing multiple aging-related diseases, including metabolic, respiratory, and cardiovascular diseases, and Alzheimer's and related dementias, leading to the hypothesis that schizophrenia is accompanied by accelerated biological aging. This has been difficult to test because there is no widely accepted measure of biological aging. Epigenetic clocks are promising algorithms that are used to calculate biological age on the basis of information from combined cytosine-phosphate-guanine sites (CpGs) across the genome, but they have yielded inconsistent and often negative results about the association between schizophrenia and accelerated aging. Here, we tested the schizophrenia-aging hypothesis using a DNA methylation measure that is uniquely designed to predict an individual's rate of aging.

METHODS

We brought together 5 case-control datasets to calculate DunedinPACE (Pace of Aging Calculated from the Epigenome), a new measure trained on longitudinal data to detect differences between people in their pace of aging over time. Data were available from 1812 psychosis cases (schizophrenia or first-episode psychosis) and 1753 controls. Mean chronological age was 38.9 (SD = 13.6) years.

RESULTS

We observed consistent associations across datasets between schizophrenia and accelerated aging as measured by DunedinPACE. These associations were not attributable to tobacco smoking or clozapine medication.

CONCLUSIONS

Schizophrenia is accompanied by accelerated biological aging by midlife. This may explain the wide-ranging risk among people with schizophrenia for developing multiple different age-related physical diseases, including metabolic, respiratory, and cardiovascular diseases, and dementia. Measures of biological aging could prove valuable for assessing patients' risk for physical and cognitive decline and for evaluating intervention effectiveness.

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.

Downregulation of miR-29a as a possible diagnostic biomarker for schizophrenia

BACKGROUND

MicroRNAs (miRNAs) are epigenetic factors regulating many genes involved in brain development. Dysregulation of miRNA could result in dysregulation of genes which may contribute to diseases affecting the brain and behavior (e.g., schizophrenia). miR-29 family is a miRNA family contributing to brain maturation. miR-29 knockout in animal studies is reported to correlate with psychiatric disorders very similar to those seen in schizophrenia. In this study, we aimed to evaluate the miR-29a level in patients with schizophrenia and its potential value in the diagnosis of schizophrenia.

MATERIALS AND METHODS

The serum sample of 42 patients with schizophrenia and 40 healthy subjects were obtained from the Azeri Recent onset/Acute phase psychosis Survey (ARAS) Cohort study. After preparations, the expression level of miR-29a was investigated by real-time PCR. The SPSS and GraphPad prism software were used to analyze the relation between miR-29a level and clinical parameters and its potential as a biomarker for the diagnosis of schizophrenia.

RESULTS

Our study showed a significantly lower miR-29a level in patients compared to healthy controls (p = 0.0012). Furthermore, miR-29a level was significantly lower in some types of schizophrenia (p = 0.024). miR-29a level was not related to sex, age, or heredity (p > 0.05). miR-29a also showed 80% specificity and 71.43% sensitivity in the diagnosis of schizophrenia.

CONCLUSION

Downregulation of miR-29a in schizophrenia is significantly related to the development of this illness. It might have the potential as a biomarker for schizophrenia.

A cross-sectional study of the relationship between frequency of cannabis use and psychiatric symptoms among people seeking mental health and addiction services in Nova Scotia (2019-21)

BACKGROUND

Cannabis use may be a modifiable risk factor for mental health problems; however, the role of cannabis use frequency in population seeking mental health and addiction services remains unclear. This study aimed to: 1) compare the prevalence and functional impact of psychiatric symptoms among frequent, infrequent, and non-users of cannabis; and 2) evaluate the associations between cannabis use frequency and functional impact of psychiatric symptoms in help-seeking individuals.

METHODS

Data from the Mental Health and Addictions (MHA) Central Intake system in Nova Scotia, Canada was used. Participants aged 19-64 who received MHA Intake assessments from September 2019 to December 2021 with complete information about substance use were included (N = 20,611). Cannabis use frequency over past 30 days was categorized into frequent (>4 times a month), infrequent (≤4 times a month), and non-use. Psychiatric symptomatology consists of five domains: mood, anxiety, psychosis, cognition, and externalizing behaviors. Multivariate ordinal logistic regression was used to examine the associations between cannabis use frequency and functional impact of psychiatric symptoms.

RESULTS

Frequent and infrequent cannabis users had a higher prevalence of psychiatric symptoms in each domain than non-users, while no significant differences were found between frequent and infrequent users. Frequent cannabis use was associated with greater functional impact of psychiatric symptoms in each domain compared to non-users, while infrequent use was only associated with greater functional impact of externalizing behaviors.

CONCLUSION

Frequent cannabis use is associated with increased prevalence and functional impact of psychiatric symptoms among adults seeking mental health services.

Perceptions, Experiences, and Patterns of Cannabis Use in Individuals with Mood and Anxiety Disorders in the Context of Cannabis Legalization and Medical Cannabis Program in Canada - A Qualitative Study

INTRODUCTION

Perceptions of cannabis as a potential medical treatment for mood and anxiety disorders have been increasing in the context of legalizations, availability, and medical cannabis programs, though current evidence predominately indicates risks and negative effects of cannabis use (CU) on mental health outcomes. This study aims to understand motivations, perceptions, effects, and patterns of CU in individuals with mood and anxiety disorders.

METHODS

Thirty-six adult patients diagnosed with mood or anxiety disorders, obsessive-compulsive disorder, or posttraumatic stress disorder who were currently using cannabis completed an in-depth qualitative interview on individual motivations, perceptions, experiences, effects, and patterns of their CU. The thematic analysis focused on phases of CU and sources of cannabis products and information.

RESULTS

Reported motivations for initiation of CU included curiosity, peer pressure, and dissatisfaction with conventional treatments. Factors such as psychotropic effects and coping with mental health symptoms and insomnia contributed to the continuation of CU. More negative effects, including cognitive dysfunction, worsening of mood, and anxiety symptoms, were acknowledged with ongoing CU. Concerning findings included common initiation of CU before age 18, combined medical and recreational CU, rare consultation of medical professionals on CU, and potential effects and harms.

DISCUSSION

Findings indicate individual complexity of motivations, perceptions, and patterns of CU in the study population. The reported potential beneficial effects of specific cannabis products should be further investigated. Findings emphasize patient-provider dialogue on both CU and conventional treatments. Information from this study can contribute to and inform the development of education, prevention, and intervention strategies.

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.

MRBEE: A bias-corrected multivariable Mendelian randomization method

Mendelian randomization (MR) is an instrumental variable approach used to infer causal relationships between exposures and outcomes, which is becoming increasingly popular because of its ability to handle summary statistics from genome-wide association studies. However, existing MR approaches often suffer the bias from weak instrumental variables, horizontal pleiotropy and sample overlap. We introduce MRBEE (MR using bias-corrected estimating equation), a multivariable MR method capable of simultaneously removing weak instrument and sample overlap bias and identifying horizontal pleiotropy. Our extensive simulations and real data analyses reveal that MRBEE provides nearly unbiased estimates of causal effects, well-controlled type I error rates and higher power than comparably robust methods and is computationally efficient. Our real data analyses result in consistent causal effect estimates and offer valuable guidance for conducting multivariable MR studies, elucidating the roles of pleiotropy, and identifying total 42 horizontal pleiotropic loci missed previously that are associated with myopia, schizophrenia, and coronary artery disease.

Use of antipsychotic medication, benzodiazepines, and psychiatric hospitalization in cannabis-related versus cannabis-unrelated schizophrenia - a nationwide, register-based cohort study

BACKGROUND

Evidence suggests that cannabis may be a causal factor for development of schizophrenia. We aimed to investigate whether use of antipsychotic medication, benzodiazepines, and psychiatric service use differs among patients with schizophrenia depending on whether psychosis was precipitated by a diagnosis of cannabis use disorder (CUD).

METHODS

We utilized the nationwide Danish registries to identify all individuals with an incident diagnosis of schizophrenia from 1995 to 2016. We also collected information on whether first CUD diagnosis preceded schizophrenia and thus defined a group of potentially cannabis-related schizophrenia. We compared the cannabis-related schizophrenia group both with all non-cannabis-related patients with schizophrenia and with non-cannabis-related patients with schizophrenia that were propensity-score matched to cases using a range of potentially confounding variables.

RESULTS

We included 35 714 people with incident schizophrenia, including 4116 (11.5%) that were cannabis-related. In the unmatched-comparison analyses, there were no clear differences over time in use of antipsychotics and benzodiazepines related to whether the diagnosis of schizophrenia was cannabis-related. After propensity-score matching, use of antipsychotics and benzodiazepines was significantly lower among cannabis-related cases of schizophrenia. In the unmatched comparison, the cannabis-related group had significantly more days admitted than the non-cannabis-related group. This was markedly attenuated after propensity-score matching.

CONCLUSIONS

Our findings indicate the importance of considering cannabis-related cases of schizophrenia as a potentially distinct disorder in terms of prognosis. It is unclear, however, if these differences are due to different biological types of schizophrenia being compared or if they rather indicate behavioral differences such as reduced adherence and treatment-seeking.

Cannabis and Public Health: A Study Assessing Regular Cannabis Users Through Health Indicators

Background and Objective: An increasing number of countries are deciding to regulate the medicinal and/or recreational use of cannabis (Cannabis sativa L.). However, there is a lack of information on the impact of regular consumption of this substance on public health. In this study, for the first time, regular cannabis consumers in Spain were assessed using health indicators, comparing these data with the general population. Methods: Various items of the Enquesta de Salut de Catalunya (ESCA) and other items related to cannabis use were selected to build a survey and administer it to a representative sample of regular cannabis users in Catalonia. Results: Most of the indicators did not show any deterioration in the health of regular cannabis users compared with the general population. It was observed that users suffered from more sleep problems and about 40% of the sample would like to discontinue cannabis use, suggesting a dependence pattern. About 30% of the sample was able to discontinue the use of prescription medications because of cannabis. Social support and sleep problems, and not cannabis use, were predictors of depression and well-being scores. Conclusions: It seems that regular cannabis use, despite contributing to problems related to sleep quality or dependence, does not have a negative impact on public health in a manner detectable using health indicators.

Increased markers of inflammation after cannabis cessation and their association with psychotic symptoms

INTRODUCTION

A dysbalance of the immune system in psychotic disorders has been well investigated. However, despite a higher prevalence of cannabis (THC) consumption in patients with psychosis, few studies have investigated the impact of this use on inflammatory markers.

METHODS

One hundred and two inpatients were included in this retrospective study. Leukocytic formula, hsCRP, fibrinogen levels and urinary THC were measured, and comparisons were performed at baseline and after 4 weeks of cannabis cessation between cannabis users (THC+) and non-users (THC-).

RESULTS

After cannabis cessation, we found a greater increase in leucocyte level (p < 0.01), monocyte level (p = 0.05) and a statistical trend to a highest increase of lymphocyte level (p = 0.06) between baseline and 4 weeks in the THC+ group as compared to the THC- group. At 4 weeks, highest leucocyte (p = 0.03), lymphocyte (p = 0.04) and monocyte (p < 0.01) counts were found in the THC+ group, whereas at baseline no difference was found. A positive correlation was found between monocyte count at 4 weeks and baseline Positive and Negative Syndrome Scale (PANSS) negative subscore (p = 0.045) and between the variation of monocyte count between baseline and 4 weeks and the PANSS total score at 4 weeks (p = 0.05).

CONCLUSION

THC cessation is associated with an increase in inflammatory markers, including white blood cell, lymphocyte and monocyte levels, which correlates with symptomatology of patients with psychosis.

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.

New-Onset Prolonged Psychosis Following Synthetic Cannabinoid Use in an Older Patient: A Case Report

Synthetic cannabinoids (SCs), a class of new psychoactive substances (NPS) commonly known as "spice," has rapidly gained popularity and become the most ubiquitous NPS on the illegitimate drug market. SCs, unlike natural cannabis (NC), are not controlled by international drug conventions, posing a significant risk to public health. These substances are easily accessible, relatively inexpensive, and challenging to detect in routine drug screenings. The existing literature provides strong evidence of an association between NC use and psychosis, but there is significantly less data on SC psychosis. We present a clinical case report of a 51-year-old African American female with no known psychiatric history who was admitted to the inpatient psychiatric unit after reported paranoia and altered mental status for the preceding six days. During hospitalization, she exhibited disorganization, persecutory delusions, extreme agitation, and bizarre behaviors that included the concealment of a set of stolen keys in her vagina, necessitating an ethics consult. After consideration of differentials, the patient was diagnosed with substance-induced psychotic disorder secondary to SC. The patient was stabilized on 3 mg Risperidone at bedtime. After 16-day hospitalization, she reached her baseline and later revealed that she had recently smoked SC for the first time. The primary goal of this case is to highlight the sequelae of SC-associated psychosis. A SC-associated psychosis could drastically vary from NC and is often undetectable on a typical UDS, which may result in a lifelong primary psychotic disorder misdiagnosis.

Environmental risk factors for schizophrenia and bipolar disorder from childhood to diagnosis: a Swedish nested case-control study

BACKGROUND

Shared genetic risk between schizophrenia (SCZ) and bipolar disorder (BD) is well-established, yet the extent to which they share environmental risk factors remains unclear. We compare the associations between environmental exposures during childhood/prior to disorder onset with the risk of developing SCZ and BD.

METHODS

We conducted a Swedish register-based nested case-control study using 4184 SCZ cases and 18 681 BD cases diagnosed 1988-2013. Cases were matched to five controls by birth year, birth region, and sex. Conditional logistic regression was used to estimate incidence rate ratios (IRR) for SCZ and BD for each exposure (severe childhood infections, adverse childhood experiences (ACEs), substance use disorders (SUDs), urban birth/longest residence).

RESULTS

All SUD types were associated with very high risk (IRR 4.9-25.5), and all forms of ACEs with higher risk (IRR 1.5-4.3) for both disorders. In the mutually adjusted models, ACEs demonstrated slightly higher risk for BD (SCZ IRR 1.30, 1.19-1.42; BD IRR 1.49, 1.44-1.55), while for SUD, risk was higher for SCZ (SCZ IRR 9.43, 8.15-10.92; BD IRR 5.50, 5.15-5.88). Infections were associated with increased risk of BD (IRR 1.21, 1.17-1.26) but not SCZ. Urban birth and urban longest residence were associated with higher risk of SCZ (IRR 1.19, 1.03-1.37), while only the combination of urban birth and rural longest residence showed higher risk for BD (IRR 1.24, 1.13-1.35).

CONCLUSIONS

There were both shared and unique environmental risk factors: SUDs and ACEs were risk factors for both disorders, while infections were more strongly associated with BD and urbanicity with SCZ.

The effect of non-medical cannabis retailer proximity on use of mental health services for psychotic disorders in Ontario, Canada

BACKGROUND

Cannabis is associated with the onset and persistence of psychotic disorders. Evidence suggests that accessibility of substances is associated with an increased risk of use-related harms. We sought to examine the effect of residing in proximity to non-medical cannabis retailers on the prevalence of health service use for psychosis.

METHODS

We conducted a cross-sectional study using linked health administrative data, and used geospatial analyses to determine whether people in Ontario, Canada (aged 14-60 years) resided within walking (1.6 km) or driving (5.0 km) distance of non-medical cannabis retailers (open as of February-2020). We identified outpatient visits, emergency department (ED) visits, and hospitalizations for psychotic disorders between 01-April-2019 and 17-March-2020. We used zero-inflated Poisson regression models and gamma generalized linear models to estimate the association between cannabis retailer proximity and indicators of health service use.

RESULTS

Non-medical cannabis retailers were differentially located in areas with high levels of marginalization and pre-existing health service use for psychosis. People residing within walking or driving distance of a cannabis retailer had a higher rate of psychosis-related outpatient visits, ED visits, and hospitalizations, compared to people living outside these areas. This effect was stronger among those with no prior service use for psychosis.

CONCLUSIONS

Proximity to a non-medical cannabis retailer was associated with higher health service use for psychosis, even after adjustment for prior health service use. These findings suggest that opening of non-medical cannabis retailers could worsen the burden of psychosis on mental health services in areas with high-risk populations.

Assessing the association between global structural brain age and polygenic risk for schizophrenia in early adulthood: A recall-by-genotype study

Neuroimaging studies consistently show advanced brain age in schizophrenia, suggesting that brain structure is often 'older' than expected at a given chronological age. Whether advanced brain age is linked to genetic liability for schizophrenia remains unclear. In this pre-registered secondary data analysis, we utilised a recall-by-genotype approach applied to a population-based subsample from the Avon Longitudinal Study of Parents and Children to assess brain age differences between young adults aged 21-24 years with relatively high (n = 96) and low (n = 93) polygenic risk for schizophrenia (SCZ-PRS). A global index of brain age (or brain-predicted age) was estimated using a publicly available machine learning model previously trained on a combination of region-wise gray-matter measures, including cortical thickness, surface area and subcortical volumes derived from T1-weighted magnetic resonance imaging (MRI) scans. We found no difference in mean brain-PAD (the difference between brain-predicted age and chronological age) between the high- and low-SCZ-PRS groups, controlling for the effects of sex and age at time of scanning (b = -.21; 95% CI -2.00, 1.58; p = .82; Cohen's d = -.034; partial R2 = .00029). These findings do not support an association between SCZ-PRS and brain-PAD based on global age-related structural brain patterns, suggesting that brain age may not be a vulnerability marker of common genetic risk for SCZ. Future studies with larger samples and multimodal brain age measures could further investigate global or localised effects of SCZ-PRS.

Endocannabinoid levels in plasma and neurotransmitters in the brain: a preliminary report on patients with a psychotic disorder and healthy individuals

BACKGROUND

Interactions between the endocannabinoid system (ECS) and neurotransmitter systems might mediate the risk of developing a schizophrenia spectrum disorder (SSD). Consequently, we investigated in patients with SSD and healthy controls (HC) the relations between (1) plasma concentrations of two prototypical endocannabinoids (N-arachidonoylethanolamine [anandamide] and 2-arachidonoylglycerol [2-AG]) and (2) striatal dopamine synthesis capacity (DSC), and glutamate and y-aminobutyric acid (GABA) levels in the anterior cingulate cortex (ACC). As anandamide and 2-AG might reduce the activity of these neurotransmitters, we hypothesized negative correlations between their plasma levels and the abovementioned neurotransmitters in both groups.

METHODS

Blood samples were obtained from 18 patients and 16 HC to measure anandamide and 2-AG plasma concentrations. For all subjects, we acquired proton magnetic resonance spectroscopy scans to assess Glx (i.e. glutamate plus glutamine) and GABA + (i.e. GABA plus macromolecules) concentrations in the ACC. Ten patients and 14 HC also underwent [18F]F-DOPA positron emission tomography for assessment of striatal DSC. Multiple linear regression analyses were used to investigate the relations between the outcome measures.

RESULTS

A negative association between 2-AG plasma concentration and ACC Glx concentration was found in patients (p = 0.008). We found no evidence of other significant relationships between 2-AG or anandamide plasma concentrations and dopaminergic, glutamatergic, or GABAergic measures in either group.

CONCLUSIONS

Our preliminary results suggest an association between peripheral 2-AG and ACC Glx levels in patients.

The protective role of valuing cultural activities on cannabis use in reserve-Dwelling First Nation youth

Cannabis legalization and use across North America disproportionately negatively affects North American Indigenous (NAI) youth. Cultural activities may function as an alternative reinforcer to protect against substance use and promote engagement in substance-free activities. The present study explored the role of valuing cultural activities on positive cannabis expectancies and past-month cannabis use. This was a secondary data analysis of data from one NAI adolescent population reporting any past-month cannabis use. 106 NAI adolescents (50% female) from a Canadian reserve community completed surveys in spring 2017. The Institutional Review Board, tribal chief, and council approved this study and informed consent, assent, and parental permission were obtained from participants. Linear regression results revealed significant main effects of positive cannabis expectancies (b = 2.926, SE = 1.198, p = .017, 95%CI[0.542, 5.309]) and valuing cultural activities (b= -0.471,SE = 0.234, p=.048, 95%CI[-0.937, -0.005]) on cannabis use, but no significant interaction between cannabis expectancies and valuing cultural activities. Previous research found valuing cultural activities significantly moderates the relationship between positive alcohol expectancies and alcohol use. Divergent findings may relate to the different historical significance of alcohol versus cannabis. Alcohol was used as a method to colonize NAIs. Thus, our non-significant interaction may result from cannabis not holding the same historical significance in comparison to alcohol for First Nation people, although this is only a hypothesis and should be confirmed with a follow up study. Despite this, calls from Indigenous communities emphasize the need for strength-based approaches and our results indicate that valuing culture is still significantly related to reduced cannabis use, independent of cannabis expectancies.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Is There a Dose-Response Relationship Between Cannabis Use and Violence? A Longitudinal Study in Individuals with Severe Mental Disorders

Introduction: Recent longitudinal studies point toward the existence of a positive relationship between cannabis use and violence in people with severe mental disorders (SMD). However, the existence of a dose-response relationship between the frequency/severity of cannabis use and violence has seldom been investigated. Therefore, this study aims to determine if such a relationship exists in a psychiatric population. Methods: To do so, a total of 98 outpatients (81 males and 17 females, all over 18 years of age) with SMD were recruited at the Institut universitaire de santé mentale de Montréal (Montréal, Canada) and included in the analyses. Clinical evaluations were conducted every 3 months for a year. Substance use, violent behaviors, and potential covariables were assessed through self-reported assessments, urinary testing, as well as clinical, criminal, and police records. Using generalized estimating equations, the association between cannabis use frequency (nonusers, occasional, regular, and frequent users) and violence was investigated, as well as the association between the severity of cannabis use and violent behaviors. Results: It was found that cannabis use frequency and severity were significant predictors of violent behaviors. After adjustment for time, age, sex, ethnicity, diagnoses, impulsivity, and use of alcohol and stimulants, odds ratios were of 1.91 (p<0.001) between each frequency profile and 1.040 (p<0.001) for each increase of one point of the severity of cannabis use score (ranging from 0 to 79). Conclusions: Despite the high attrition rate, these findings may have important implications for clinicians as cannabis use may have serious consequences in psychiatric populations. Nevertheless, the mechanisms underlying this association remain unclear.

Effects of Cannabidiol and Delta-9-Tetrahydrocannabinol on Plasma Endocannabinoid Levels in Healthy Volunteers: A Randomized Double-Blind Four-Arm Crossover Study

Background: The effects of cannabis are thought to be mediated by interactions between its constituents and the endocannabinoid system. Delta-9-tetrahydrocannabinol (THC) binds to central cannabinoid receptors, while cannabidiol (CBD) may influence endocannabinoid function without directly acting on cannabinoid receptors. We examined the effects of THC coadministered with different doses of CBD on plasma levels of endocannabinoids in healthy volunteers. Methods: In a randomized, double-blind, four-arm crossover study, healthy volunteers (n=46) inhaled cannabis vapor containing 10 mg THC plus either 0, 10, 20, or 30 mg CBD, in four experimental sessions. The median time between sessions was 14 days (IQR=20). Blood samples were taken precannabis inhalation and at 0-, 5-, 15-, and 90-min postinhalation. Plasma concentrations of THC, CBD, anandamide, 2-arachidonoylglycerol (2-AG), and related noncannabinoid lipids were measured using liquid chromatography-mass spectrometry. Results: Administration of cannabis induced acute increases in plasma concentrations of anandamide (+18.0%, 0.042 ng/mL [95%CI: 0.023-0.062]), and the noncannabinoid ethanolamides, docosatetraenylethanolamide (DEA; +35.8%, 0.012 ng/mL [95%CI: 0.008-0.016]), oleoylethanolamide (+16.1%, 0.184 ng/mL [95%CI: 0.076-0.293]), and N-arachidonoyl-L-serine (+25.1%, 0.011 ng/mL [95%CI: 0.004-0.017]) (p<0.05). CBD had no significant effect on the plasma concentration of anandamide, 2-AG or related noncannabinoid lipids at any of three doses used. Over the four sessions, there were progressive decreases in the preinhalation concentrations of anandamide and DEA, from 0.254 ng/mL [95%CI: 0.223-0.286] to 0.194 ng/mL [95%CI: 0.163-0.226], and from 0.039 ng/mL [95%CI: 0.032-0.045] to 0.027 ng/mL [95%CI: 0.020-0.034] (p<0.05), respectively. Discussion: THC induced acute increases in plasma levels of anandamide and noncannabinoid ethanolamides, but there was no evidence that these effects were influenced by the coadministration of CBD. It is possible that such effects may be evident with higher doses of CBD or after chronic administration. The progressive reduction in pretreatment anandamide and DEA levels across sessions may be related to repeated exposure to THC or participants becoming less anxious about the testing procedure and requires further investigation. The study was registered on clinicaltrials.gov (NCT05170217).

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.

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.

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.

Unhealthy behaviors associated with mental health disorders: a systematic comparative review of diet quality, sedentary behavior, and cannabis and tobacco use

Background

There are well-established literatures documenting the associations between mental disorders and unhealthy behaviors such as poor diet quality, sedentary behavior, and cannabis and tobacco use. Few studies have attempted to understand the respective findings in light of each other, however.

Objective

The purpose of this review was to assemble comparable data for each behavior-disorder association and assess the associations in terms of their overall strength. The review aimed to include a representative, but not exhaustive, range of studies that would allow for explorative comparisons.

Methods

Eligible studies were identified via Pubmed searches and citation searching, restricted to publications no older than 2015 written in English. To obtain comparable data, only studies that reported findings as odds ratios were included, and risk of bias related to study samples, behavioral measurement disparities, and control variables was assessed via sensitivity analyses. Findings for each disorder were compared on the basis of different measures of central tendency.

Results

From 3,682 records, 294 studies were included. The review found evidence of associations between each of the four unhealthy behaviors and psychosis, depression, anxiety, bipolar disorder, attention-deficit/hyperactivity disorder (ADHD), and post-traumatic stress disorder (PTSD), while personality disorder was only investigated in relation to cannabis and tobacco use. In overall comparison, the associations were generally of similar strength, and only the association between cannabis use and personality disorder was exceptional in terms of being significantly stronger than its counterparts across disorders and across behaviors. Analyses of bias risk identified some influence from behavioral measurement disparities and lack of adequate statistical control, but findings were generally robust across a range of sensitivity analyses.

Conclusion

This explorative and comparative review found that poor diet quality, sedentary behavior, and cannabis and tobacco use are about equally strongly associated with a range of different mental disorders. Given the general nature of these associations, we should probably understand them to reflect a general and shared etiology. However, the findings in this review should be regarded as tentative until confirmed by more comprehensive investigations.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Stress, Environment and Early Psychosis

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

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

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

Cannabis use influences disorganized symptoms severity but not transition in a cohort of non-help-seeking individuals at-risk for psychosis from São Paulo, Brazil

BACKGROUND

Cannabis use is associated with an increased risk of developing a psychotic disorder. However, in individuals with at-risk mental states for psychosis (ARMS) this association is not clear, as well as the impact of cannabis use on symptom severity. The objective of this study was to evaluate the association of cannabis use patterns and ARMS risk status, transition to psychotic and psychiatric disorders, and psychopathology.

METHOD

A sample of 109 ARMS and 197 control individuals was drawn from the general population. Lifetime, maximum and current amount of cannabis use were assessed with the South Westminster modified questionnaire. Participants were followed-up for a mean of 2.5 years and reassessed for transition to any psychiatric disorder.

RESULTS

There were no differences between ARMS and controls regarding lifetime use, current amount of use, or maximum amount of cannabis use. There were also no differences between those who transitioned to a psychiatric disorder and those who did not regarding cannabis use variables. In ARMS individuals, cannabis use was significantly related to disorganization symptoms.

CONCLUSION

The results of this study suggest that cannabis plays a role in the psychopathology of ARMS individuals, leading to more severe symptomatology.

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.

Assessing evidence supporting cannabis harm reduction practices for adolescents at clinical high-risk for psychosis: a review and clinical implementation tool

Cannabis use is consistently associated with both increased incidence of frank psychotic disorders and acute exacerbations of psychotic symptoms in healthy individuals and people with psychosis spectrum disorders. Although there is uncertainty around causality, cannabis use may be one of a few modifiable risk factors for conversion to psychotic disorders in individuals with Clinical High Risk for Psychosis (CHR-P) syndromes, characterized by functionally impairing and distressing subthreshold psychotic symptoms. To date, few recommendations beyond abstinence to reduce adverse psychiatric events associated with cannabis use have been made. This narrative review synthesizes existing scientific literature on cannabis' acute psychotomimetic effects and epidemiological associations with psychotic disorders in both CHR-P and healthy individuals to bridge the gap between scientific knowledge and practical mental health intervention. There is compelling evidence for cannabis acutely exacerbating psychotic symptoms in CHR-P, but its impact on conversion to psychotic disorder is unclear. Current evidence supports a harm reduction approach in reducing frequency of acute psychotic-like experiences, though whether such interventions decrease CHR-P individuals' risk of conversion to psychotic disorder remains unknown. Specific recommendations include reducing frequency of use, lowering delta-9-tetrahydrocannabinol content in favor of cannabidiol-only products, avoiding products with inconsistent potency like edibles, enhancing patient-provider communication about cannabis use and psychotic-like experiences, and utilizing a collaborative and individualized therapeutic approach. Despite uncertainty surrounding cannabis' causal association with psychotic disorders, cautious attempts to reduce acute psychosis risk may benefit CHR-P individuals uninterested in abstinence. Further research is needed to clarify practices associated with minimization of cannabis-related psychosis risk.

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.

Urbanicity and psychotic disorders: Facts and hypotheses

In the present qualitative literature review, we summarise data on psychotic disorders and urbanicity, focusing particularly on recent findings. Longitudinal studies of the impact of urbanicity on the risk for psychotic disorders have consistently shown a significant association, with a relative risk between 2 and 2.5. However, most of the original studies were conducted in Western Europe, and no incidence studies were conducted in low- and middle-income countries. European studies suggest that neighbourhood-level social fragmentation and social capital may partly explain this association. Exposure to air pollution (positive association) and green space (negative association) may also be part of the explanation, but to date, available data do not make it possible to conclude if they act independently from urbanicity, or as part of the effect of urbanicity on psychotic disorders. Finally, several studies have consistently shown significant associations between the polygenic risk score for schizophrenia and urbanicity, with several possible explanations (pleiotropic effects, results of prodromic symptoms, or selection/intergenerational hypothesis). Thus, more studies are needed to understand the factors that explain the association between urbanicity and the risk of psychotic disorders. Further studies should account for the interdependence and/or interactions of different psychosocial and physical exposures (as well as gene-environment interactions), and explore this association in low- and middle-income countries.

Cannabis and Psychosis

Psychosis and cannabis use may overlap in multiple ways in young people. Research suggests that cannabis use increases risk for having psychotic symptoms, both attenuated (subthreshold) and acute. Cannabis use may also exacerbate psychosis symptoms among young people with underlying psychosis risk and psychotic disorders. Although there are suggestions for treating co-occurring psychosis and cannabis use in young people (e.g., incorporating cannabis use assessment and treatment strategies into specialized early psychosis care), there are many gaps in clinical trial research to support evidence-based treatment of these overlapping concerns.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Cannabis use as a potential mediator between childhood adversity and first-episode psychosis: results from the EU-GEI case-control study

BACKGROUND

Childhood adversity and cannabis use are considered independent risk factors for psychosis, but whether different patterns of cannabis use may be acting as mediator between adversity and psychotic disorders has not yet been explored. The aim of this study is to examine whether cannabis use mediates the relationship between childhood adversity and psychosis.

METHODS

Data were utilised on 881 first-episode psychosis patients and 1231 controls from the European network of national schizophrenia networks studying Gene-Environment Interactions (EU-GEI) study. Detailed history of cannabis use was collected with the Cannabis Experience Questionnaire. The Childhood Experience of Care and Abuse Questionnaire was used to assess exposure to household discord, sexual, physical or emotional abuse and bullying in two periods: early (0-11 years), and late (12-17 years). A path decomposition method was used to analyse whether the association between childhood adversity and psychosis was mediated by (1) lifetime cannabis use, (2) cannabis potency and (3) frequency of use.

RESULTS

The association between household discord and psychosis was partially mediated by lifetime use of cannabis (indirect effect coef. 0.078, s.e. 0.022, 17%), its potency (indirect effect coef. 0.059, s.e. 0.018, 14%) and by frequency (indirect effect coef. 0.117, s.e. 0.038, 29%). Similar findings were obtained when analyses were restricted to early exposure to household discord.

CONCLUSIONS

Harmful patterns of cannabis use mediated the association between specific childhood adversities, like household discord, with later psychosis. Children exposed to particularly challenging environments in their household could benefit from psychosocial interventions aimed at preventing cannabis misuse.

Perturbation of 3D nuclear architecture, epigenomic aging and dysregulation, and cannabinoid synaptopathy reconfigures conceptualization of cannabinoid pathophysiology: part 2-Metabolome, immunome, synaptome

The second part of this paper builds upon and expands the epigenomic-aging perspective presented in Part 1 to describe the metabolomic and immunomic bases of the epigenomic-aging changes and then considers in some detail the application of these insights to neurotoxicity, neuronal epigenotoxicity, and synaptopathy. Cannabinoids are well-known to have bidirectional immunomodulatory activities on numerous parts of the immune system. Immune perturbations are well-known to impact the aging process, the epigenome, and intermediate metabolism. Cannabinoids also impact metabolism via many pathways. Metabolism directly impacts immune, genetic, and epigenetic processes. Synaptic activity, synaptic pruning, and, thus, the sculpting of neural circuits are based upon metabolic, immune, and epigenomic networks at the synapse, around the synapse, and in the cell body. Many neuropsychiatric disorders including depression, anxiety, schizophrenia, bipolar affective disorder, and autistic spectrum disorder have been linked with cannabis. Therefore, it is important to consider these features and their complex interrelationships in reaching a comprehensive understanding of cannabinoid dependence. Together these findings indicate that cannabinoid perturbations of the immunome and metabolome are important to consider alongside the well-recognized genomic and epigenomic perturbations and it is important to understand their interdependence and interconnectedness in reaching a comprehensive appreciation of the true nature of cannabinoid pathophysiology. For these reasons, a comprehensive appreciation of cannabinoid pathophysiology necessitates a coordinated multiomics investigation of cannabinoid genome-epigenome-transcriptome-metabolome-immunome, chromatin conformation, and 3D nuclear architecture which therefore form the proper mechanistic underpinning for major new and concerning epidemiological findings relating to cannabis exposure.

Beyond the Binary: Gender Inclusivity in Schizophrenia Research

Schizophrenia is a severe neuropsychiatric disorder with significant differences in the incidence and symptomology between cisgender men and women. In recent years, considerably more attention has been on the inclusion of sex and gender in schizophrenia research. However, the majority of this research has failed to consider gender outside of the socially constructed binary of men and women. As a result, little is known about schizophrenia in transgender and gender-nonconforming populations. In this review, we present evidence showing that transgender and gender-nonconforming individuals have elevated risk of developing schizophrenia, and we discuss minority stress theory and other potential factors that may contribute to this risk. The need for inclusion of transgender and gender-nonconforming communities in schizophrenia research is emphasized, alongside a discussion on considerations and challenges associated with this type of research. Finally, we offer specific strategies to make research on schizophrenia, and research on other neuropsychiatric disorders, more inclusive of those populations that do not fall within the socially constructed gender binary. If we are to succeed in the development of more personalized therapeutic approaches for all, a better understanding of the variability of the human brain is needed.

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.

The highs and the lows: Recreational marijuana laws and mental health treatment

Recreational marijuana laws (RMLs) continue to grow in popularity, but the effects on mental health treatment are unclear. This paper uses an event-study within a difference-in-differences framework to study the short-run impact of state RMLs on admissions into mental health treatment facilities. The results indicate that shortly after a state adopts an RML, they experience a decrease in the average number of mental health treatment admissions. The findings are driven by white, Black, and Medicaid-funded admissions and are consistent for both male and female admissions. The results are robust to alternative specifications and sensitivity analysis.

Circulating Endocannabinoids and N-Acylethanolamines in Individuals with Cannabis Use Disorder-Preliminary Findings

BACKGROUND

Endocannabinoids and related N-acylethanolamines (NAEs) are bioactive lipids with important physiological functions and putative roles in mental health and addictions. Although chronic cannabis use is associated with endocannabinoid system changes, the status of circulating endocannabinoids and related NAEs in people with cannabis use disorder (CUD) is uncertain.

METHODS

Eleven individuals with CUD and 54 healthy non-cannabis using control participants (HC) provided plasma for measurement by high-performance liquid chromatography-mass spectrometry of endocannabinoids (2-arachidonoylglycerol (2-AG) and N-arachidonoylethanolamine (AEA)) and related NAE fatty acids (N-docosahexaenoylethanolamine (DHEA) and N-oleoylethanolamine (OEA)). Participants were genotyped for the functional gene variant of FAAH (rs324420, C385A) which may affect concentrations of AEA as well as other NAEs (OEA, DHEA).

RESULTS

In overnight abstinent CUD, AEA, OEA and DHEA concentrations were significantly higher (31-40%; p < 0.05) and concentrations of the endocannabinoid 2-AG were marginally elevated (55%, p = 0.13) relative to HC. There were no significant correlations between endocannabinoids/NAE concentrations and cannabis analytes, self-reported cannabis use frequency or withdrawal symptoms. DHEA concentration was inversely related with marijuana craving (r = -0.86; p = 0.001). Genotype had no significant effect on plasma endocannabinoids/NAE concentrations.

CONCLUSIONS

Our preliminary findings, requiring replication, might suggest that activity of the endocannabinoid system is elevated in chronic cannabis users. It is unclear whether this elevation is a compensatory response or a predating state. Studies examining endocannabinoids and NAEs during prolonged abstinence as well as the potential role of DHEA in craving are warranted.

Perspective on clinical high-risk for psychosis in Africa

Clinical High Risk for Psychosis has evolved in recent years as a conceptual and clinical entity, representing a shift in focus from the syndromal psychosis state to a recognition of the pre-psychotic state as a period of potential preventive intervention. Much existing evidence has been generated from well-resourced countries, with a more limited body of literature available from Africa and other Majority World countries. Against a backdrop of prevailing systemic challenges, it is necessary to appraise the state of knowledge on Clinical High Risk for Psychosis in Africa. In this perspective article, we cover epidemiology, risk factors, predictors of psychosis conversion, as well as an overview of sociocultural factors, notably stigma, and the barriers to mental health services in African settings. We discuss existing and promising assessment approaches and reflect on preventive and early intervention strategies. We conclude with recommendations including the need for more clinical, longitudinal, and collaborative research anchored in an integrative transdisciplinary approach. We highlight the need for more culturally valid assessment tools and strategies to improve access to and utilization of services while also reducing stigma.

Emerging adult perceptions of higher-risk cannabis consumption behaviours

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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