Risk-thresholds for the association between frequency of cannabis use and the development of psychosis: a systematic review and meta-analysis

Treatment demand for cannabis use problems: analyses of routine data from 30 European countries

Cannabis use and treatment demand has risen in the past decade. Previous analyses of treatment demand are limited by methodological constraints or are outdated. Cross-country differences and trends in cannabis treatment demand are described using data from the European Monitoring Centre for Drugs and Drug Addiction. Two novel indicators are employed: firstly, the cannabis-attributable treatment fraction (CATF) is obtained by dividing the number of treatment entrants for cannabis use problems by the number of treatment entrants for any substance use problem, accounting for possible changes in the reporting system. Secondly, comparing the number of treatment entrants for cannabis use problems to the number of people who use cannabis (near) daily yields the treated-user-ratio (TUR), which considers a proxy for treatment need (frequent use). Across 30 countries with available data, the importance of cannabis in European treatment facilities varies greatly (CATF: min = 3%; max = 65%), with lower estimates in Eastern European countries. Across 20 countries with complete data, the CATF has risen from 29.4% in 2013 to 37.1% in 2020. The TUR calculated on 26 countries suggests that about 3 in 100 frequent users have sought treatment for their cannabis use problems. Over time, treatment demand has increased at a slower pace than treatment need in most countries. One in three treatment entrants for substance use problems in Europe are due to cannabis, with large variations between countries. There are indications for a widening treatment gap for cannabis use problems. In countries liberalising cannabis laws, monitoring changes in treatment access and demand is warranted.

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.

Do anxiety symptoms and coping motives serially mediate the association between psychotic-like experiences and cannabis-related problems in undergraduate recent cannabis users?

Many Canadian emerging adults (ages 18-25 years) use cannabis, with 60 % of past-three-month users experiencing one or more cannabis-related problems (i.e., adverse consequences of use). While psychotic-like experiences (PLEs) and cannabis problems overlap, little is known about the mechanisms explaining this link. One hypothesis is that PLEs are distressing and give rise to anxiety, with which emerging adults attempt to cope through increased cannabis use, in turn increasing their risk for cannabis-related problems. We tested a chained-mediational model to determine if anxiety and coping-with-anxiety motives for cannabis use sequentially mediated the link between PLEs and cannabis problems in emerging adult undergraduates; a conditional process model tested for moderation by sex. Emerging adult cannabis users (N = 413; mean [SD] age = 19.1 [1.5] years; 71.9 % female) from five Canadian universities provided cross-sectional, self-report survey data in fall 2021. Validated measures of PLEs, anxiety, cannabis coping-with-anxiety motives, and cannabis-related problems were administered. Path analyses supported the hypothesized chained mediational indirect effect (b = 0.027, 95 % bootstrap CI [0.012, 0.050]). No direct effect was found (p =.698), suggesting that the PLEs-to-cannabis problems association is fully explained by anxiety and cannabis coping-with-anxiety motives. Inconsistent with hypotheses, mediation did not depend on sex (95 % CIs crossed zero); therefore, anxiety and cannabis coping-with-anxiety motives explain the link between PLEs and cannabis problems in emerging adults regardless of their sex. Results highlight anxiety and cannabis coping-with-anxiety motives as potentially important intervention targets in cannabis-using emerging adults with PLEs, possibly preventing the development/worsening of cannabis-related problems.

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.

Comparing Cannabis Use for Pain to Use for Other Reasons in Primary Care Patients

BACKGROUND

Medical cannabis is commonly used for chronic pain, but little is known about differences in characteristics, cannabis use patterns, and perceived helpfulness among primary care patients who use cannabis for pain versus nonpain reasons.

METHODS

Among 1688 patients who completed a 2019 cannabis survey administered in a health system in Washington state, where recreational use is legal, participants who used cannabis for pain (n = 375) were compared with those who used cannabis for other reasons (n = 558) using survey and electronic health record data. We described group differences in participant characteristics, use patterns, and perceptions and applied adjusted multinomial logistic and modified Poisson regression.

RESULTS

Participants who used cannabis for pain were significantly more likely to report using applied (50.7% vs 10.6%) and beverage cannabis products (19.2% vs 11.6%), more frequent use (47.1% vs 33.1% for use ≥2 times per day; 81.6% vs 69.7% for use 4 to 7 days per week), and smoking tobacco cigarettes (19.2% vs 12.2%) than those who used cannabis for other reasons. They were also significantly more likely to perceive cannabis as very/extremely helpful (80.5% vs 72.7%), and significantly less likely to use cannabis for nonmedical reasons (4.8% vs 58.8%) or report cannabis use disorder symptoms (51.7% vs 61.1%).

DISCUSSION

Primary care patients who use cannabis for pain use it more frequently, often in applied and ingested forms, and have more co-use of tobacco, which may differentially impact safety and effectiveness. These findings suggest the need for different approaches to counseling in clinical care.

The Translational Future of Stress Neurobiology and Psychosis Vulnerability: A Review of the Evidence

Psychosocial stress is a well-established risk factor for psychosis, yet the neurobiological mechanisms underlying this relationship have yet to be fully elucidated. Much of the research in this field has investigated hypothalamic-pituitary-adrenal (HPA) axis function and immuno-inflammatory processes among individuals with established psychotic disorders. However, as such studies are limited in their ability to provide knowledge that can be used to develop preventative interventions, it is important to shift the focus to individuals with increased vulnerability for psychosis (i.e., high-risk groups). In the present article, we provide an overview of the current methods for identifying individuals at high-risk for psychosis and review the psychosocial stressors that have been most consistently associated with psychosis risk. We then describe a network of interacting physiological systems that are hypothesised to mediate the relationship between psychosocial stress and the manifestation of psychotic illness and critically review evidence that abnormalities within these systems characterise highrisk populations. We found that studies of high-risk groups have yielded highly variable findings, likely due to (i) the heterogeneity both within and across high-risk samples, (ii) the diversity of psychosocial stressors implicated in psychosis, and (iii) that most studies examine single markers of isolated neurobiological systems. We propose that to move the field forward, we require well-designed, largescale translational studies that integrate multi-domain, putative stress-related biomarkers to determine their prognostic value in high-risk samples. We advocate that such investigations are highly warranted, given that psychosocial stress is undoubtedly a relevant risk factor for psychotic disorders.

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.

A Lifestyle Risk Reduction Model for Preventing High-Risk Substance Use Across the Lifespan

While effective models of alcohol and drug prevention exist, they often focus solely on youth or young adults. This article describes the Lifestyle Risk Reduction Model (LRRM), an approach applicable across the lifespan. The intent behind the LRRM is to guide the development of prevention and treatment programs provided to individuals and small groups. The LRRM authors' goals are to help individuals reduce risk for impairment, addiction, and substance use's negative consequences. The LRRM identifies six key principles that conceptualize the development of substance-related problems by drawing parallels with health conditions, such as heart disease and diabetes, which often result from combined effects of biological risk and behavioral choices. The model also proposes five conditions that describe important steps for individuals as they progress toward greater perception of risk and lower risk behavior. One LRRM-based indicated prevention program (Prime For Life) shows positive results in cognitive outcomes and in impaired driving recidivism for people across the lifespan. The model emphasizes common elements across the lifespan, responds to contexts and challenges that change across the life course, complements other models, and is usable for universal, selective, and indicated prevention programs.

Ethnoracial Variation in Risk for Psychotic Experiences

BACKGROUND & HYPOTHESIS

Psychotic disorders are inequitably distributed by race in the United States, although it is not known whether this is due to assessment biases or inequitable distributions of risk factors. Psychotic experiences are subclinical hallucinations and delusions used to study the etiology of psychosis, which are based on self-report and therefore not subject to potential clinician biases. In this study, we test whether the prevalence of psychotic experiences (PE) varies by race and if this variance is explained by socioenvironmental risk factors.

STUDY DESIGN

Data on demographics, PE, and socioenvironmental risk factors were collected through the National Survey of Poly-victimization and Mental Health, a national probability sample of US young adults. Logistic regression analyses were used to determine whether PE prevalence varied by race/ethnicity and, if so, whether this was attenuated with inclusion of indicators of income, education, urban/rural living, discrimination, and trauma exposure.

STUDY RESULTS

Black and Hispanic respondents reported PE at significantly greater rates than White or "other" ethnoracial groups, with hallucinations more commonly reported by Hispanic respondents. PE were significantly associated with police violence exposure, discrimination, adverse childhood experiences, and educational attainment. These factors statistically explained ethnoracial differences in the likelihood of overall PE occurrence and of nearly all PE subtypes.

CONCLUSIONS

Previously observed racial differences in psychosis extend beyond clinical schizophrenia, and therefore, are unlikely to be explained entirely by clinician biases. Instead, racial disparities in PE appear to be driven by features of structural racism, trauma, and discrimination.

Risk factors for cannabis use disorders and cannabis psychosis in Japan: Second report of a survey on cannabis-related health problems among community cannabis users using social networking services

AIM

To determine the risk factors for cannabis use disorders and cannabis psychosis in Japan based on a 2021 online survey among Japanese users of social network services.

METHODS

The 3142 respondents who had used cannabis within the preceding year were categorized into two groups based on the development of cannabis use disorder and/or cannabis psychosis. Analyses were performed to determine these conditions' risk factors.

RESULTS

Multivariate analysis revealed that factors significantly associated with cannabis use disorders were "cannabis-use initiation at a young age" (p = 0.004, OR: 0.951, 95% CI [0.920-0.984]), "family history of mental health problems" (p < 0.001, OR: 1.988, 95% CI [1.545-2.556]), "psychiatric disorders preceding cannabis use" (p = 0.039, OR: 1.672, 95% CI [1.026-2.722]), and "use of cannabis products other than dry flower" (p < 0.001, OR: 2.725, 95% CI [1.844-4.026]). Factors significantly associated with cannabis psychosis were "cannabis-use initiation at a young age" (p = 0.011, OR: 0.888, 95% CI [0.811-0.973]) and "family history of mental health problems" (p = 0.002, OR: 2.531, 95% CI [1.400-4. 576]).

CONCLUSION

Risk factors for problematic cannabis use were cannabis initiation at a young age, pre-cannabis psychiatric disorders, family history of mental health problems, and the use of cannabis products other than dry flower. However, the causal relationship among these factors remains ambivalent.

Psychosocial factors associated with the risk of developing psychosis in a Mexican general population sample

Epidemiological evidence has linked an array of sociodemographic and psychosocial factors with an increased risk of developing psychosis. However, research in samples from low- and middle-income countries is still scarce. This study used a Mexican sample to explore (i) sociodemographic and psychosocial differences between individuals with and without a positive screen for Clinical High-Risk for psychosis (CHR), and (ii) sociodemographic and psychosocial factors associated with screening positive for CHR. The sample consisted of 822 individuals from the general population who completed an online survey. Of the participants, 17.3% (n = 142) met the CHR screening criteria. Comparisons between those who screened positive (CHR-positive group) and those who did not (Non-CHR group) showed that participants in the CHR-positive group were younger, had a lower educational level, and reported more mental health problems than the Non-CHR group. Furthermore, relative to the Non-CHR group, the CHR-positive group had a greater prevalence of medium/high risk associated with cannabis use, a higher prevalence of adverse experiences (bullying, intimate partner violence, and experiencing a violent or unexpected death of a relative or friend), as well as higher levels of childhood maltreatment, poorer family functioning, and more distress associated with the COVID-19 pandemic. Groups did not differ in sex, marital/relationship status, occupation, and socio-economic status. Finally, when examined in multivariate analyses, the variables associated with screening positive for CHR were: having an unhealthy family functioning (OR = 2.75, 95%CI 1.69-4.46), a higher risk associated with cannabis use (OR = 2.75, 95%CI 1.63-4.64), a lower level of education (OR = 1.55, 95%CI 1.003-2.54), having experienced a major natural disaster (OR = 1.94, 95%CI 1.18-3.16), having experienced a violent or unexpected death of a relative or friend (OR = 1.85, 95%CI 1.22-2.81), higher levels of childhood emotional abuse (OR = 1.88, 95%CI 1.09-3.25), physical neglect (OR = 1.68, 95%CI 1.08-2.61), and physical abuse (OR = 1.66, 95%CI 1.05-2.61), and higher COVID-related distress (OR = 1.10, 95%CI 1.01-1.20). An older age was a protective factor for screening positive for CHR (OR = 0.96, 95%CI 0.92-0.99). Overall, the findings highlight the importance of examining potential psychosocial contributors to psychosis vulnerability across different sociocultural contexts to delineate risk and protective processes relevant to specific populations and better target preventive intervention efforts.

Psychotic features, particularly mood incongruence, as a hallmark of severity of bipolar I disorder

BACKGROUND

The occurrence of psychotic features within mood episodes in patients with bipolar I disorder (BD I) has been associated in some studies with a more severe clinical and socio-professional profile. In contrast, other studies establishing the associations of psychotic features in BD I, and in particular of mood-congruent (MC) and mood-incongruent (MI) features, with clinical characteristics have yielded contradictory results. However, many pre-existing studies have been affected by serious methodological limitations. Using a sample of thoroughly assessed patients with BD I our aims were to: (1) establish the proportion of those with MI and MC features, and (2) compare BD I patients with and without psychotic features as well as those with MI to those with MC features on a wide array of socio-demographic and clinical characteristics including course, psychiatric comorbidity and treatment.

METHODS

A sample of 162 treated patients with BD I (60.5% female, mean age = 41.4 (s.d: 10.2) years) was recruited within a large family study of mood disorders. Clinical, course and treatment characteristics relied on information elicited through direct diagnostic interviews, family history reports and medical records.

RESULTS

(1) A total of 96 patients (59.3%) had experienced psychotic features over their lifetime. Among them, 44.8% revealed MI features at least once in their lives. (2) Patients with psychotic features were much less likely to be professionally active, revealed alcohol abuse more frequently and used health care, particularly inpatient treatment, more frequently than those without psychotic features. Within patients with psychotic symptoms, those with MI features showed more clinical severity in terms of a higher likelihood of reporting hallucinations, suicidal attempts and comorbid cannabis dependence.

CONCLUSION

Our data provide additional support for both the distinction between BD-I with and without psychotic features as well as the distinction between MI and MC psychotic features. The more severe course of patients with psychotic features, and particularly those with MI psychotic features, highlights the need for thorough psychopathological evaluations to assess the presence of these symptoms to install appropriate treatment.

Cannabis and Intentional Self-injury: a Narrative Review

Purpose of Review

Observational studies assessing the association of cannabis use with subsequent intentional self-injury have reported mixed findings. Longitudinal studies examining the association of cannabis use with subsequent suicide death are notably rare. Our objective was to review longitudinal studies examining cannabis use and subsequent self-harm, suicide attempt, or suicide death.

Recent Findings

Few population-based studies have focused on self-harm with considerable variability across studies in how this outcome has been operationalized. Studies assessing the association between cannabis use and suicide attempt are equivocal in their conclusions and heterogenous in terms of samples utilized and assessment of confounding bias. The results of one meta-analysis were suggestive of dose dependency. For suicide death, the findings are inconsistent, and there is reason for concern of selection bias.

Summary

The existing evidence base on these associations is not yet rigorous enough to allow drawing conclusions on causality. However, cannabis might be seen as an adverse prognostic marker for intentional self-injury.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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