The contribution of cannabis use to variation in the incidence of psychotic disorder across Europe (EU-GEI): a multicentre case-control study

Cannabinoid CB1 receptor-sensitive neurodevelopmental processes and trajectories

As high-potency cannabis (with high Δ9-Tetrahydrocannabinol content) becomes easily accessible and widespread, it is of extreme importance for public health that a scientific platform is used to implement practical guidelines, particularly for at-risk populations. Many reviews have been written in the past decade summarizing the impact of cannabis in the developing brain. One critical concept frequently mentioned but not discussed in detail is whether there are sensitive neurodevelopmental events driving the age-specific sensitivity to cannabis, particularly those mediated by cannabinoid type 1 receptor signaling. By integrating available data from humans and animal models, the goal of the present expert review article is to provide a mechanistic overview on how cannabis exposure during sensitive periods of neural circuit plasticity and development can result in lasting consequences. Here we used the frontal cortex as a proxy to align the trajectory of the brain cannabinoid system between humans and rodents. Both the strengths and limitations of available mechanistic studies on the effects of cannabis and cannabinoids were discussed using a developmental framework from which neural circuit adaptations during sensitive periods are considered. Such an approach is needed to align key neurodevelopmental variables through the lifespan, which in turn will provide valuable insights applicable to the human brain by defining the underpinning mechanisms of sensitive periods and how the impact of cannabis changes from childhood to adolescence, and thereafter through young adulthood.

Effects of persistent cannabis use on depression, psychosis, and suicidality following cannabis-induced psychosis: A longitudinal study

BACKGROUND AND OBJECTIVES

Cannabis use is associated with psychotic disorder onset and exacerbation. This study examines how continued cannabis use affects depressive symptoms, psychotic symptoms, and suicidal behaviors following cannabis-induced first-episode psychosis (FEP).

METHODS

Sixty-five participants (aged 16-50 years) with FEP were recruited from psychiatric inpatient facilities in northern Italy. Participants were categorized into two groups: non-cannabis users (NCU) and cannabis users (CU), based on substance use during the 9-month follow-up. Twenty-one participants (32.3%) were lost to follow-up, with a final sample of 44 subjects (NCU = 22, CU = 22). Assessments were conducted at baseline, 3 months, and 9 months using PANSS, CDSS, SSI, and GAF scales).

RESULTS

CU exhibited persistently higher depression (CDSS) and suicidality (SSI) scores than NCU throughout follow-up, with significant differences at both 3 months (CDSS: p = .000006; SSI: p < .001) and 9 months (CDSS: p = .0000001; SSI: p < .001). Positive psychotic symptoms improved in both groups, though CU showed slower recovery and higher relapse rates (59.9% vs. 18.8%). PANSS positive subscale scores remained significantly higher in CU at 3 months (p = .001) and 9 months (p < .0002). GAF scores improved significantly only in NCU (p = .024 at 9 months).

DISCUSSION AND CONCLUSIONS

Continued cannabis use adversely affects depressive and psychotic symptoms and suicidality in FEP patients, while cannabis cessation is associated with improved clinical outcomes.

SCIENTIFIC SIGNIFICANCE

This study tracks depressive symptoms, suicidality, and psychotic manifestations in cannabis-induced FEP, demonstrating that continued use is associated with treatment-resistant depressive symptoms even when psychotic symptoms improve, highlighting the need for integrated clinical approaches.

Perturbations of CB1 receptor signalling during adolescence impair cortical myelination in female rats

The constant increase in cannabis use among adolescents raises concerns about its potential neurobehavioral effects. Adolescence is a critical period for brain development, involving significant changes in grey and white matter. Grey matter decreases as the brain undergoes synaptic pruning, while white matter increases due to myelination. Cannabis use during this developmental window, particularly its active ingredient delta-9-tetrahydrocannabinol (THC), may disrupt these processes, increasing the risk of developing psychiatric disorders later in life. While the impact of THC on grey matter has been explored, the specific role of CB1 receptors as well as the effect of THC exposure in adolescent myelination remain unclear. This study investigates how CB1 receptor blockade and THC exposure during adolescence affect myelination in the prefrontal cortex of female rats. Blocking CB1 receptors during adolescence hindered myelination in the prefrontal cortex. Behaviourally, this disruption in myelin formation was associated with increased risk-taking behaviour. Notably, our data suggest that alterations in the AKT/Hippo/YAP signalling pathway may play a crucial role in mediating these effects. Supporting the involvement of the endocannabinoid system in cortical myelination during adolescence, we found that administering exogenous THC impaired myelin formation only when given during early to mid-adolescence. Moreover, when a more intensive THC exposure protocol was applied during this developmental period, the effects on myelination were long-lasting and persisted into adulthood. Overall, these data support a role for CB1 receptors in shaping cortical myelination in adolescent female rats and show that adolescent exposure to THC might adversely impact this developmental process.

Patterns of past month cannabis consumption and cannabis use disorder - Insights from a nationally representative survey

BACKGROUND

As cannabis usage continues to surge in the United States, understanding the nuances between medical and recreational use, as well as the frequency of past-month consumption, is critical for public health. The need to differentiate these patterns and assess their implications for Cannabis Use Disorder (CUD) is important for both clinical care and health policy in the United States.

METHODS

This study utilized data from the AmeriSpeak® web-based panel, a nationally representative sample of U.S. households. Participants (n = 1719) were adults aged 18 and older who completed a self-report survey in December 2023 or January 2024 and reported past-month cannabis use. The Cannabis Use Disorder Identification Test (CUDIT) was employed to measure usage frequency and identify CUD risk, with scores of 8 or more indicating hazardous use and scores of 12 or more indicating possible CUD. Multinomial logistic regressions were conducted to explore associations between sociodemographic characteristics and cannabis dependence, further segmented by past-month frequency of medical and recreational use.

RESULTS

Approximately 10 % of adults reported past-month medical cannabis use and 17 % reported recreational use. Any past-month medical cannabis use was associated with a 26 % CUD rate (95 % CI: 19.8-30.4) and hazardous use rate of 25 % (95 % CI: 18.5-31.2). When broken down by frequency, CUD rates ranged from 16 % to 34 % for people who use cannabis for medical purposes : occasional use (19 %, 95 % CI: 13.7-24.3), moderate use (24 %, 95 % CI: 17.5-30.5), and daily or near-daily use (31 %, 95 % CI: 24.1-38.3). People who use cannabis for non-medical (recreational) reasons showed a 21 % overall CUD rate (95 % CI: 17.7-25.2), with segmented rates by frequency indicating 10 % for occasional use (95 % CI: 6.2-13.8), 24 % for moderate use (95 % CI: 18.1-29.9), and 32 % for daily or near-daily use (95 % CI: 25.3-38.7). Younger adults (18-29) and males were identified as the most at-risk groups, exhibiting the highest CUD scores across both medical and recreational categories.

DISCUSSION

Over a quarter of people who use cannabis meet the criteria for CUD, underscoring the importance of more precise assessments of cannabis use patterns. While no significant differences between medical and recreational cannabis use were observed, the nuances in usage patterns become obscured when grouping all individuals who use cannabis in the past-month together, potentially masking important differences in risk levels. Integrating frequency and quantity metrics into clinical assessments, similar to practices in alcohol consumption research, is imperative. This approach allows healthcare providers to gain a comprehensive understanding of cannabis use behaviors and associated CUD risks, providing crucial insights for developing targeted interventions, support services, and strategies to address cannabis-related health risks effectively.

Cannabis or Cannabinoids for the Management of Chronic Noncancer Pain: Best Practice Advice From the American College of Physicians

DESCRIPTION

The American College of Physicians' Population Health and Medical Science Committee (PHMSC) developed this best practice advice to inform clinicians about what is currently known about the benefits and harms of cannabis or cannabinoids in the management of chronic noncancer pain and to provide advice for clinicians counseling patients seeking this therapy.

METHODS

The PHMSC considers areas where evidence is uncertain or emerging or practice does not follow the evidence to provide clinical advice based on a review and assessment of scientific work, including systematic reviews and individual studies. Sources of evidence included a living systematic review on cannabis and cannabinoid treatments for chronic noncancer pain and a series of living systematic reviews and primary studies.

BEST PRACTICE ADVICE 1A

Clinicians should counsel patients about the benefits and harms of cannabis or cannabinoids when patients are considering whether to start or continue to use cannabis or cannabinoids to manage their chronic noncancer pain.

BEST PRACTICE ADVICE 1B

Clinicians should counsel the following subgroups of patients that the harms of cannabis or cannabinoid use for chronic noncancer pain are likely to outweigh the benefits: young adult and adolescent patients, patients with current or past substance use disorder, patients with serious mental illness, and frail patients and those at risk for falling.

BEST PRACTICE ADVICE 2

Clinicians should advise against starting or continuing to use cannabis or cannabinoids to manage chronic noncancer pain in patients who are pregnant or breastfeeding or actively trying to conceive.

BEST PRACTICE ADVICE 3

Clinicians should advise patients against the use of inhaled cannabis to manage chronic noncancer pain.

Early onset marijuana use and suicidal ideation among African American college students

Between 2013 and 2019 the suicide rate for African American young persons 15-24 years of age rose by 47% for males and 59% for females. Presently, little is known about factors that contribute to the suicidal behavior of African Americans in late adolescence and emerging adulthood. However, considering the coinciding increase in high potency marijuana use among African American young persons and literature suggesting a potential link between marijuana use and suicidal behavior, we examined early onset marijuana use as a risk factor for suicidal ideation. The sample included 221African American students (70% female and Mage = 20.3, SD = 1.97) attending an HBCU between 2019 and 2020. We employed multivariable logistic regression analysis that included suicidal ideation as the outcome variable and early onset marijuana use as the explanatory variable, while controlling for demographic factors and mental health treatment status. Approximately 19% of the sample reported suicidal ideation. Early onset marijuana use was reported by 28% of students. Compared to students who never used marijuana, early onset users were three times as likely to report suicidal ideation (AOR = 3.33, 95% CI = 1.06-10.44). In conclusion, early onset marijuana use may place African American young persons at increased risk for suicidal ideation. Marijuana use may be an important malleable risk factor that can be targeted in suicide prevention interventions designed for African American college students. More research is warranted.

Methylomic signature of current cannabis use in two first-episode psychosis cohorts

The rising prevalence and legalisation of cannabis worldwide have underscored the need for a comprehensive understanding of its biological impact, particularly on mental health. Epigenetic mechanisms, specifically DNA methylation, have gained increasing recognition as vital factors in the interplay between risk factors and mental health. This study aimed to explore the effects of current cannabis use and high-potency cannabis on DNA methylation in two independent cohorts of individuals experiencing first-episode psychosis (FEP) compared to control subjects. The combined sample consisted of 682 participants (188 current cannabis users and 494 never users). DNA methylation profiles were generated on blood-derived DNA samples using the Illumina DNA methylation array platform. A meta-analysis across cohorts identified one CpG site (cg11669285) in the CAVIN1 gene that showed differential methylation with current cannabis use, surpassing the array-wide significance threshold, and independent of the tobacco-related epigenetic signature. Furthermore, a CpG site localised in the MCU gene (cg11669285) achieved array-wide significance in an analysis of the effect of high-potency (THC = > 10%) current cannabis use. Pathway and regional analyses identified cannabis-related epigenetic variation proximal to genes linked to immune and mitochondrial function, both of which are known to be influenced by cannabinoids. Interestingly, a model including an interaction term between cannabis use and FEP status identified two sites that were significantly associated with current cannabis use with a nominally significant interaction suggesting that FEP status might moderate how cannabis use affects DNA methylation. Overall, these findings contribute to our understanding of the epigenetic impact of current cannabis use and highlight potential molecular pathways affected by cannabis exposure.

Falling Through the Cracks: Perspectives From Local Leaders on Substance Use and Psychosis Treatment for Youth

Objective: Explore local leaders' perceptions of substance use and psychosis treatment to inform the implementation of an assertive community treatment model for historically marginalized youth. Methods: Interviews were conducted with local leaders in a Northeast city with relevant expertise. Interviews were recorded, transcribed, and analyzed using the Consolidated Framework of Implementation Research domains. Results: Fifteen leaders completed interviews and four key themes emerged: (1) A patchwork of systems attempts to catch youth early on, but often fails; (2) The inability to simultaneously address mental health and substance use concerns complicates care; (3) An ideal program would be flexible in the ways the current system is inflexible; (4) factors important in tailoring a program to serve historically marginalized youth. Conclusion: When designing a program to support the engagement of youth with symptoms of psychosis and SUD, it is important to take a patient-centered and flexible approach that accounts for the community-based setting.

[Impact of the legalization of recreational cannabis on the risk of psychosis: A systematic review of the literature]

INTRODUCTION

Cannabis is the most consumed illicit substance in Europe. Although its sale and use remain generally prohibited, European public policies have evolved in recent years by legalizing cannabis for medical use and considering its legalization for recreational use. However, in the literature there are arguments in favor of a particular relationship between cannabis consumption and the development of psychotic symptoms. Thus, since cannabis consumption tends to increase with legalization, the aim of this review was to investigate the impact of the legalization of cannabis for recreational use on the risk of psychosis in regions of the world already concerned.

METHOD

A systematic review of the literature was carried out in April 2024 in the PubMed-Medline database according to PRISMA criteria. The sequence of keywords used was as follows: ("Cannabis" [Mesh] or cannabis) AND (("Psychotic Disorders" [Mesh] or Psychotic Disorders) or ("Schizophrenia Spectrum and Other Psychotic Disorders" [Mesh]) or ("Schizophrenia" [Mesh] or Schizophrenia)) AND legal use. The inclusion criteria applied for the selection of articles in this systematic review were: (1) any article investigating the potential impact of the legalization of cannabis for recreational use on the risk of psychosis (any type of psychosis diagnosed according to ICD-9, ICD-10, DSM-4 or DSM-5) by the intermediary of epidemiological (incidence or prevalence) and/or clinical (ambulatory consultations, emergency visits or hospitalizations) criteria, (2) any type of study (cross-sectional, longitudinal, prospective, retrospective, interventional and experimental) with a methodology including a temporal and/or geographic comparison of the risk of psychosis associated with the legalization of cannabis for recreational use with the exception of literature reviews and clinical cases descriptions, (3) absence of limitation for the age of the populations studied and for the date of publication, and (4) articles written in English or French. After evaluation by the two authors of the 160 articles identified, seven studies investigating the impact of the legalization of cannabis for recreational use on the risk of psychosis were included in this systematic literature review.

RESULTS

Four of the studies showed no increase in the use of health services for psychosis following the legalization of cannabis for recreational use whereas three other studies highlighted a negative impact of the legalization of cannabis for recreational use on the risk of psychosis. All of these studies were carried out in North America and were characterized by a low level of scientific evidence.

CONCLUSION

Given the complexity of assessing the impact of the legalization of cannabis for recreational use on the risk of psychosis, additional investigations through studies of better scientific quality are essential. However, based on the data already available, there is some evidence that there is a potential negative impact on mental health due to the legalization of cannabis for recreational use. In this context, in the event of legalization of cannabis for recreational use it seems essential to recommend lower risk use of cannabis (limit the frequency of use, delay the age of first consumption, control the THC content of products and promote prevention/education). Finally, in order to enable dynamic evolution of public health strategies the establishment of continued monitoring is essential as cannabis legalization evolves.

High-Potency Cannabis Use and Health: A Systematic Review of Observational and Experimental Studies

OBJECTIVE

Amid continuously rising concentrations of delta-9-tetrahydrocannabinol (THC) in cannabis (i.e., potency), high-potency cannabis is a major topic in contemporary cannabis policy discussions, yet its impact on health is not well understood. The authors conducted a systematic review of observational and experimental studies examining the relationship between high-potency cannabis use and a range of health outcomes.

METHODS

Records were obtained from a systematic search of five biomedical research databases. The authors developed ecologically relevant potency (percent THC) exposure-comparison categories (1%-9%, 10%-19%, 20%-30%, kief/resin [∼30%-50%], concentrates [≥60%]) and used a landmark scientific report on cannabis and cannabinoids to determine outcome eligibility. Two reviewers independently conducted article screening and selection, extraction, and quality assessment. Findings were synthesized using both quantitative (association direction, binomial test) and narrative approaches. Certainty in the evidence was determined via the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) framework.

RESULTS

Of 4,545 screened records, 42 were eligible. Most studies addressed outcomes in the mental health, "problem" cannabis use, and other substance use domains. Findings in the "problem" cannabis use domain were suggestive of an association with higher-potency cannabis use. Findings were less consistent in other domains but tended to favor poorer outcomes with higher-potency use. Therapeutic outcomes were limited and mixed. Overall, certainty in the evidence was "very low."

CONCLUSIONS

Findings within the "problem" cannabis use domain were suggestive of an association with high-potency use. Research is largely limited to cross-sectional studies spanning few adverse health domains, underscoring the need for prospective studies probing therapeutic, cardiorespiratory, cancer, and pre- and perinatal outcomes. Policies to curb high-potency cannabis use may be warranted while the evidence base improves.

Rastafarianism: When Religious Beliefs Conflict With Medical Necessity-A Case Report and Review of the Literature Around an Ethically Complicated Case

Background: Rastafarianism maintains that cannabis is a sacred element of the religious practice, and followers of the religion traditionally engage cautiously with western medicine. This case involves Mr. I, a 72-year-old Rastafari male with acute myelogenous leukemia (AML) and hepatic decompensation, who developed delirium with psychotic features which were initially managed with quetiapine. His family expressed concerns with psychotropic medications and requested using dronabinol, a synthetic cannabinoid, to manage his symptoms considering the spiritual significance of cannabinoids in the Rastafari culture. The psychiatry team's dissenting recommendations regarding dronabinol was met with resistance, and the family voiced that they felt their religious beliefs were not being respected and considered bringing in their own marijuana products. Following an ethics consultation, a compromise was reached to trial low-dose dronabinol. However, Mr. I's symptoms worsened, prompting discontinuation of dronabinol and management with olanzapine. Discussion: This case exemplifies the complexities of clinical care when religious beliefs conflict with medical necessity. We discuss the limited indications for dronabinol and potential adverse effects on delirium's behavioral symptoms. Concerns about fungal sensitization from cannabinoid products in the context of immunosuppressive chemotherapy and the effects of cannabinoids on hepatic dysfunction are also explored. Moreover, we emphasize the importance of cultural sensitivity for Rastafari individuals who view marijuana as sacred and therapeutic. Balancing cultural and religious sensitivity with ethical, evidence-based medicine through a thorough discussion of risks and benefits is essential for optimal decision-making in such ethical dilemmas.

Cannabis use and suicide in people with a diagnosis of schizophrenia: a systematic review and meta-analysis of longitudinal, case control, and cross-sectional studies

Cannabis use is highly prevalent in people with schizophrenia and is related to adverse clinical outcomes, including relapse and hospitalization. However, the relationship between cannabis and suicide remains inconclusive. This study aimed to systematically review and meta-analyze the relationship between cannabis use and suicide-related outcomes in people with schizophrenia. A comprehensive search of Medline, Embase, and PsycINFO for cross-sectional, case-control, and longitudinal studies was conducted using search terms from database inception to November 2024 inclusive. Computation of odds ratios (ORs) and hazard ratios (HRs) was performed using random effects models with DerSimonian-Laird estimation. All studies were appraised for quality. We also evaluated heterogeneity, publication bias and performed sub-group analyses and meta-regression. Twenty-nine studies comprising 36 samples met eligibility criteria. Cannabis use was not associated with odds of suicide death or suicidal ideation but was associated with risks of suicide death (HR = 1.21, 95% CI = 1.04 - 1.40) and odds of attempted suicide (OR = 1.40, 95% CI = 1.16 - 1.68). While between-sample heterogeneity was moderate in analyses of attempted suicide (I2 = 39.6%, p = 0.03), there was no publication bias. Summary effects remained significant in most sub-groups, but just failed to reach significance in longitudinal studies of attempted suicide (OR = 1.40, 95% CI = 0.97 - 1.68) and studies investigating first episode samples (OR = 1.24, 95% CI = 0.99 - 1.55). Cannabis use is significantly associated with some, but not all, suicide-related outcomes in people with schizophrenia. More work is needed to examine potential mechanisms of significant relationships.

Does Cannabis Use Contribute to Schizophrenia? A Causation Analysis Based on Epidemiological Evidence

Cannabis abuse has been linked to acute psychotic symptoms as well as to the development of schizophrenia. Although the association has been well described, causation has not yet been investigated. Therefore, we investigated whether cannabis or cannabinoid use is causal for the development of schizophrenia, conducting a systematic literature review according to the PRISM guidelines. Epidemiological studies and randomized clinical trials investigating the links between cannabis and psychosis-like events (PLE) and schizophrenia were identified (according to PRISM guidelines), and relevant studies were included in a Forest plot analysis. Confounder analysis was performed using a funnel plot, and the Hill causality criteria were used to estimate causation. A total of 18 studies fulfilled the search criteria; 10 studies were included in a forest plot. All studies reported an increased risk for PLE or schizophrenia, and nine of the ten studies, a significant increase; the overall OR was calculated to be 2.88 (CI 2.24 to 3.70), with a twofold-higher risk calculated for cannabis use during adolescence. Confounder effects were indicated by a funnel plot. The Hill criteria indicated a high likelihood for the contribution of cannabis to schizophrenia development. Cannabinoids likely contribute to chronic psychotic events and schizophrenia, especially if taken during adolescence. This effect likely increases with a high cannabis THC concentration and increased frequency of cannabis use, and is stronger in males than in females. This points to the possibility of a selective cannabis toxicity on synaptic plasticity in adolescence, as compared to adult cannabis use. Cannabis use should be regulated and discouraged, and prevention efforts should be strengthened, especially with reference to adolescence.

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.

Cannabis use patterns and association with hyperemesis: A comprehensive review

BACKGROUND

Cannabis use in the general population is prevalent and is rising because of increased acceptance of its use, legalization in most US states, and perceived health benefits. Cannabis product potency has dramatically increased with higher delta-9-tetrahydrocannabinol content. Cannabis has documented antiemetic properties and cannabinoid pharmaceuticals are used in disorders like chemotherapy-induced nausea and vomiting.

PURPOSE

Forty to eighty percent of cyclic vomiting syndrome (CVS) patients use cannabis products, which reportedly reduce stress as well as nausea and vomiting. Cannabinoid hyperemesis syndrome (CHS) has a presentation similar to CVS, but is associated with longstanding, high dose cannabis use, and is thought to be relieved by sustained cannabis abstinence. Most CHS patients have used cannabis on a daily or near-daily basis for more than 2 years. Compulsive hot-water bathing behaviors are reported by most CHS patients, but are not specific for this disorder as they are also noted by about half of CVS patients. Episodic vomiting associated with cannabis use contributes to extensive health resource use, including emergency department visits and inpatient hospitalizations, and impacts patients and their families negatively. Treatment for CHS overlaps with CVS although cannabis abstinence remains the cornerstone of its management. Challenges associated with cannabis use cessation in CHS include patient skepticism of the role of cannabis as a cause of symptoms, perceived benefits of cannabis, and a lack of other effective therapies. In this review, we highlight cannabis use patterns in the US and discuss diagnosis and management of CHS and gaps in knowledge about this disorder.

Cannabis, cannabinoids and health: a review of evidence on risks and medical benefits

The legalization of cannabis for medical and recreational purposes has progressed internationally. Cannabis and cannabinoids are advocated for a plethora of medical indications. An increasing number of medical and nonmedical users regularly consume large doses of delta-9-Tetrahydrocannabinol (THC), the main active component of cannabis. Aim: to summarize the evidence on (1) risks of recreational cannabis use and (2) effectiveness and safety of medicinal cannabis. Findings on recreational use: Cannabis is mostly used to experience its acute rewarding effects. Regular use of high THC products can produce addiction (cannabis use disorder or CUD). Acute consumption of high THC doses (including unintentionally) can cause time-limited mental, gastrointestinal, and cardiovascular problems and motor vehicle accidents. Chronic patterns of cannabis use have been associated with multiple adverse outcomes that are of particular concern among adolescents and young adults, such as, disrupted learning, impaired cognitive performance, reduced educational attainment and an increased risk of CUD, psychosis/schizophrenia, mood and anxiety disorders and suicidal behaviors. There is debate about the extent to which cannabis use is a cause of these adverse outcomes. Physical health risks (e.g., respiratory and cardiovascular, prematurity and restricted fetal growth, hyperemesis syndrome among others) have also been linked with repeated consumption of cannabis with a high THC content. Findings on medical cannabis use: Herbal cannabis, medicines from extracted or synthetized cannabinoids-often used as adjuvants to standard medicines-may produce small to modest benefits. This is primarily the case in treating chronic pain, muscle spasticity, chemotherapy-induced nausea and vomiting, and refractory epilepsy (in the case of cannabidiol, CBD). The evidence is inconclusive on their value in treating mental disorders and other medical conditions. Safety: Cannabis-based medicine is generally well tolerated. There is a risk of mild to moderate adverse effects and CUD.

Cannabis Use Cessation and the Risk of Psychotic Disorders: A Case-Control Analysis from the First Episode Case-Control EU-GEI WP2 Study: L'arrêt de l'utilisation du cannabis et le risque de troubles psychotiques: Une analyse cas-témoins tirée de l'étude cas-témoins EU-GEI WP2 centrée sur les premiers épisodes psychotiques

OBJECTIVES

To establish whether the risk of psychotic disorders in cannabis users changes with time following cannabis cessation using data from the European Network of National Networks studying Gene-Environment Interactions in Schizophrenia (EU-GEI) case-control study.

METHODS

The EU-GEI case-control study collected data from first episode psychosis patients and population controls across sites in Europe and Brazil between May 2010 and April 2015. Adjusted logistic regressions were applied to examine whether the odd of psychosis case status changed: (1) with time following cannabis cessation and (2) across different cannabis use groups.

RESULTS

Psychosis risk declined following cessation of cannabis use (β = -0.002; 95% CI -0.004 to 0.000; P = 0.067). When accounting for duration of use, this effect remained (β = -0.003; 95% CI -0.005 to -0.001; P = 0.013). However, in models adjusting for frequency and potency of use the result was not significant. Analysis of different cannabis use groups indicated that ex-users who stopped 1 to 4 weeks previously had the highest risk for psychotic disorder compared to never users (OR = 6.89; 95% CI 3.91-12.14; P < 0.001); risk declined for those who stopped 5 to 12 weeks previously (OR = 2.70; 95% CI 1.73-4.21; P < 0.001) and 13 to 36 weeks previously (OR = 1.53; 95% CI 1.00-2.33; P = 0.050). Ex-users who stopped 37 to 96 weeks (OR = 1.01; 95% CI 0.66-1.57; P = 0.949), 97 to 180 weeks (OR = 0.73; 95% CI 0.45-1.19; P = 0.204), and 181 weeks previously or more (OR = 1.18; 95% CI 0.76-1.83; P = 0.456) had similar psychosis risk to those who had never-used cannabis.

CONCLUSION

Risk of psychotic disorder appears to decline with time following cannabis cessation, receding to that of those who have never used cannabis after 37 weeks or more of abstinence. Although, preliminary results suggest that frequent users of high potency types of cannabis might maintain an elevated risk compared to never users even when abstaining for longer than 181 weeks.

Applying machine learning to international drug monitoring: classifying cannabis resin collected in Europe using cannabinoid concentrations

In Europe, concentrations of ∆9-tetrahydrocannabinol (THC) in cannabis resin (also known as hash) have risen markedly in the past decade, potentially increasing risks of mental health disorders. Current approaches to international drug monitoring cannot distinguish between different types of cannabis resin which may have contrasting health effects due to THC and cannabidiol (CBD) content. Here, we compared concentrations of THC and CBD in different types of cannabis resin collected in Europe (either Moroccan-type, or Dutch-type). We then tested the ability of machine learning algorithms to classify the type of cannabis resin (either Moroccan-type, or Dutch-type) using routinely collected monitoring data on THC and CBD. Finally, we applied the optimal algorithm to new samples collected in countries where the type of cannabis resin was unknown, the UK and Denmark. Results showed that overall, Dutch-type samples had higher THC (Hedges' g = 2.39) and lower CBD (Hedges' g = 0.81) than Moroccan-type samples. A Support Vector Machine algorithm achieved classification accuracy exceeding 95%, with little variation in this estimate, good interpretability, and plausibility. It made contrasting predictions about the type of cannabis resin collected in the UK (94% Moroccan-type; 6% Dutch-type) and Denmark (36% Moroccan-type; 64% Dutch-type). In conclusion, we provide proof-of-concept evidence for the potential of machine learning to inform international drug monitoring. Our findings should not be interpreted as objective confirmatory evidence but suggest that Dutch-type cannabis resin has higher THC concentrations than Moroccan-type cannabis resin, which may contribute to variation in drug markets and health outcomes for people who use cannabis in Europe.

Cannabis and psychopathology: 2024 Snapshot of a meandering journey

Background

Cannabis has been associated with psychopathology since ancient times, but controversies continue despite important advances in the field. This article is the fourth one in our decadal series of review articles that have been providing an update snapshot of the meandering journey of the research findings in this area.

Aims

This narrative review of a comprehensive literature search over the past 10 years aims to provide an update and current understanding, while raising unanswered questions for the future, focusing on the following areas: (a) nosological changes in cannabis-related psychiatric syndromes; (b) psychopathology associated with the newer category of synthetic cannabinoids; (c) cannabis withdrawal syndrome); (d) cannabis and psychosis; (e) cannabis and mood disorders; (f) cannabis and suicidality; (g) prenatal cannabis use and psychopathology in the offspring; (h) effect of recent liberal policy overhaul on cannabis control in certain countries/areas on psychopathology and adverse outcomes; (i) cannabis and cognition; and (j) cannabis, psychopathology, and genetics.

Methods

The data search strategies involved a combination of electronic databases and manual hand-searching of relevant publications and cross-references using selected search terms. The primary electronic search focused on Medline and PubMed Central databases but extended to databases such as Google Scholar, PsychINFO, Scopus, and Ovid for specific sections. Key references identified through electronic and manual searches provided additional material. Inclusion criteria for the review spanned studies published between January 2014 and June 2024, with more emphasis placed on recent studies (post-2020) while ensuring historical coverage.

Results

The narrative review aimed to be comprehensive, including a broad range of research without strict methodological exclusions. Strengths and limitations of cited research are discussed when applicable, maintaining consistency with three prior reviews. We focused on psychopathology and psychiatric syndromes, human (rather than animal) studies, and applied (rather than basic) research. We have only focused on policy with reference to psychopathology and not on that entire area because that would be beyond the scope of this article. There are important updates in all the areas covered. There are newer syndromal entities in ICD-11, which also includes synthetic cannabinoids for the first time. Cannabis withdrawal syndrome has been better characterized. The association between cannabis and psychosis has been robustly established especially for very high-potency cannabis and for vulnerable populations, particularly young people. Work is in progress elucidating the causal mechanisms. The links between cannabis and mood disorders as well as suicidality and cognitive impairment are better characterized, though questions remain. Recent liberalizing policies on cannabis have produced newer findings on prenatal and accidental cannabis use (with deleterious effects on the offspring) and on later psychopathology (mixed findings, but a documented increase in emergency visits related to recent cannabis use). This is an area which will require active monitoring for new data.

Conclusion

The field of cannabis use and psychopathology continues to collect new data and settle some old controversies while raising new questions, which are important to address in view of the wide use of cannabis worldwide and its implications for public health.

Mapping the exposome of mental health: exposome-wide association study of mental health outcomes among UK Biobank participants

BACKGROUND

Dissecting the exposome linked to mental health outcomes can help identify potentially modifiable targets to improve mental well-being. However, the multiplicity of exposures and the complexity of mental health phenotypes pose a challenge that requires data-driven approaches.

METHODS

Guided by our previous systematic approach, we conducted hypothesis-free exposome-wide analyses to identify factors associated with 7 psychiatric diagnostic domains and 19 symptom dimensions in 157,298 participants from the UK Biobank Mental Health Survey. After quality control, 294 environmental, lifestyle, behavioral, and economic variables were included. An Exposome-Wide Association Study was conducted per outcome in two equally split datasets. Variables associated with each outcome were then tested in a multivariable model.

RESULTS

Across all diagnostic domains and symptom dimensions, the top three exposures were childhood adversities and traumatic events. Cannabis use was associated with common psychiatric disorders (depressive, anxiety, psychotic, and bipolar manic disorders), with ORs ranging from 1.10 to 1.79 in the multivariable models. Additionally, differential associations were identified between specific outcomes-such as neurodevelopmental disorders, eating disorders, and self-harm behaviors-and exposures, including early life experiences (being adopted), lifestyle (time spent using computers), and dietary habits (vegetarian diet).

CONCLUSIONS

This comprehensive mapping of the exposome revealed that several factors, particularly in the domains of those previously well-studied were shared across mental health phenotypes, providing further support for transdiagnostic pathoetiology. Our findings also showed that distinct relations might exist. Continued exposome research through multimodal mechanistic studies guided by the transdiagnostic mental health framework is required to better inform public health policies.

Cognitive presentation at psychosis onset through premorbid deterioration and exposure to environmental risk factors

BACKGROUND

Previous studies identified clusters of first-episode psychosis (FEP) patients based on cognition and premorbid adjustment. This study examined a range of socio-environmental risk factors associated with clusters of FEP, aiming a) to compare clusters of FEP and community controls using the Maudsley Environmental Risk Score for psychosis (ERS), a weighted sum of the following risks: paternal age, childhood adversities, cannabis use, and ethnic minority membership; b) to explore the putative differences in specific environmental risk factors in distinguishing within patient clusters and from controls.

METHODS

A univariable general linear model (GLS) compared the ERS between 1,263 community controls and clusters derived from 802 FEP patients, namely, low (n = 223) and high-cognitive-functioning (n = 205), intermediate (n = 224) and deteriorating (n = 150), from the EU-GEI study. A multivariable GLS compared clusters and controls by different exposures included in the ERS.

RESULTS

The ERS was higher in all clusters compared to controls, mostly in the deteriorating (β=2.8, 95% CI 2.3 3.4, η2 = 0.049) and the low-cognitive-functioning cluster (β=2.4, 95% CI 1.9 2.8, η2 = 0.049) and distinguished them from the cluster with high-cognitive-functioning. The deteriorating cluster had higher cannabis exposure (meandifference = 0.48, 95% CI 0.49 0.91) than the intermediate having identical IQ, and more people from an ethnic minority (meandifference = 0.77, 95% CI 0.24 1.29) compared to the high-cognitive-functioning cluster.

CONCLUSIONS

High exposure to environmental risk factors might result in cognitive impairment and lower-than-expected functioning in individuals at the onset of psychosis. Some patients' trajectories involved risk factors that could be modified by tailored interventions.

An analysis of the cultivation, consumption and composition of home-grown cannabis following decriminalisation in the Australian Capital Territory

The Australian Capital Territory (ACT), a region that includes Australia's capital, Canberra, decriminalised small-scale cannabis cultivation and possession in January 2020. Here, we examined cannabis use and cultivation behaviours, experiences and attitudes of current and past small-scale ACT cannabis cultivators. ACT residents (n = 311) who currently cultivate or have previously cultivated cannabis completed a cross-sectional online survey ('CAN-ACT') and provided home-grown cannabis for phytocannabinoid analysis (optional). Reasons for cultivation included a preference for home-grown cannabis to self-supply, enjoyment of the process and avoiding criminal networks. Cannabis intake was a median of 1 gram on a typical day used and the number of plants grown per year was a median of 4. Various cultivation challenges were identified, most commonly mould, nutrient deficiency and spider mites. Cannabis samples (n = 71) generally exhibited moderate THC content (mean 8.99 ± SEM 0.51% [w/w]) and low CBD content (< 0.1%). Few samples exceeded contaminant guidelines for heavy metals or pesticides. Respondents identified various grey areas in current legislation that might lead to inadvertent criminal activity, and many (52%) remained anxious about arrest. In general, recent legislative changes appear to support community needs. Options for further legislative refinement are discussed.

Synaptic Density in Early Stages of Psychosis and Clinical High Risk

Importance

Synaptic dysfunction is involved in schizophrenia pathophysiology. However, whether in vivo synaptic density is reduced in early stages of psychosis, including its high-risk states, remains unclear.

Objective

To investigate whether synaptic density (synaptic vesicle glycoprotein 2A [SV2A] binding potential) is reduced in first-episode psychosis (FEP) and in clinical high risk (CHR) and investigate the effect of cannabis use on synaptic density and examine its relationship with psychotic symptoms and gray matter microstructure across groups.

Design, Setting, and Participants

This cross-sectional study was performed in a tertiary care psychiatric hospital from July 2021 to October 2023. Participants were patients with antipsychotic-free or minimally exposed FEP or CHR and healthy controls with a clean urine drug screen (except cannabis).

Main Outcomes and Measures

Synaptic density was quantified with dynamic 90-minute [18F]SynVesT-1 positron emission tomography (PET) scans across prioritized brain regions of interest (ROIs) delineated in individual magnetic resonance images (MRIs). Cannabis use was confirmed with urine drug screens. Gray matter microstructure was assessed using diffusion-weighted MRI to estimate neurite density.

Results

A total of 49 participants were included, including 16 patients with FEP (mean [SD] age, 26.1 [4.6] years; 9 males and 7 females), 17 patients at CHR (mean [SD] age, 21.2 [3.5] years; 8 males and 9 females), and 16 healthy controls (mean [SD] age, 23.4 [3.6] years; 7 males and 9 females). Synaptic density was significantly different between groups (F2,273 = 4.02, P = .02, Cohen F = 0.17; ROI: F5,273 = 360.18, P < .01, Cohen F = 2.55) with a group × ROI interaction (F10,273 = 2.67, P < .01, Cohen F = 0.32). Synaptic density was lower in cannabis users (F1,272 = 5.31, P = .02, Cohen F = 0.14). Lower synaptic density across groups was associated with more negative symptoms (Positive and Negative Syndrome Scale negative scores: F1,81 = 4.31, P = .04, Cohen F = 0.23; Scale of Psychosis-Risk Symptoms negative scores: F1,90 = 4.12, P = .04, Cohen F = 0.21). SV2A binding potential was significantly associated with neurite density index (F1,138 = 6.76, P = .01, Cohen F = 0.22).

Conclusions and Relevance

This study found that synaptic density reductions were present during the early stages of psychosis and its risk states and associated with negative symptoms. The implications of SV2A for negative symptoms in psychosis and CHR warrant further investigation. Future studies should investigate the impact of cannabis use on synaptic density in CHR longitudinally.

The Complex Relationship Between Cannabis Use and Mental Health: Considering the Influence of Cannabis Use Patterns and Individual Factors

The relationship between cannabis use and mental health is complex, as studies often report seemingly contradictory findings regarding whether cannabis use results in more positive or negative treatment outcomes. With an increasing number of individuals using cannabis for both recreational (i.e., non-medical) and medical purposes, it is critical to gain a deeper understanding of the ways in which cannabis may be helpful or harmful for those diagnosed with psychiatric disorders. Although cannabis is composed of hundreds of compounds, studies assessing the effects of "cannabis" most often report the impact of delta-9-tetrahydrocannabinol (d9-THC), the primary intoxicating constituent of the plant. While d9-THC has documented therapeutic properties, negative clinical outcomes commonly associated with cannabis are generally related to d9-THC exposure. In contrast, non-intoxicating cannabinoids such as cannabidiol (CBD) show promise as potential treatment options for psychiatric symptoms. In this article, findings from studies and reviews examining the relationship between mental health conditions (mood, anxiety, psychosis, and post-traumatic stress disorder [PTSD]) and cannabis use are summarized to highlight critical variables that are often overlooked, including those associated with cannabis use patterns (e.g., frequency of use, amount used, cannabinoid exposure, product choice, and route of administration). Further, this article explores individual factors (e.g., age, sex, genetics/family history) that likely impact cannabis-related outcomes. Research to date suggests that youth and those with a family history or genetic liability for psychiatric disorders are at higher risk for negative outcomes, while more research is needed to fully understand unique effects related to sex and older age.

Comprehensive spatial distribution of patients with first-episode psychosis (FEP) and its relation to socio-economic factors

BACKGROUND

The functional-cognitive impact of first-episode psychosis (FEP) is extremely relevant and implies dysfunction from early life stages like adolescence and youth. Like other illnesses, FEP incidence is also influenced by environmental factors. It is necessary to attend to this age group with early interventions and to act on the environmental factors that the literature correlates with increased FEP incidence: socio-economic aspects, social adversity, bullying at school or cannabis use. In this context, identifying the areas of cities where FEP patients concentrate is important to perform early interventions. The spatial analysis of patient distribution in a whole city is one way to identify the most vulnerable areas and to propose psycho-social interventions for the possible prevention and/or early detection of FEP by improving urban mental health.

METHODS

An epidemiological study of point patterns to determine the areas of a city with a higher incidence of patients with FEP. To do so, the addresses of FEP cases were georeferenced from 1 January 2016 to 31 October 2022, and 109 FEP patients were analysed. Data from a random sample of 383 controls, comprising their addresses, age, and sex, were randomly obtained from the official city council database. By GIS, the areas with higher FEP incidence were analysed to see if they coincided with the zones where inhabitants with lower incomes lived.

RESULTS

The risk ratio of the FEP patients was compatible with the constant risk ratio in Albacete (p = 0.22). When performing the process separately with cases and controls only in men and women, the results were not significant for both distributions (p value: 0.12 and 0.57, respectively). Nonetheless, areas within the city had a significantly higher risk. These groups of cases coincided with those who had lower income and more inequality for women, but this pattern was not clear for men.

CONCLUSIONS

Classifying city areas per income can help to determine the zones at higher risk of FEP, which would allow early healthcare and preventive measures for these zones.

Season of birth and schizotypy in a sample of undergraduate students

PURPOSE

In line with the psychotic continuum theory, the study of psychometric schizotypy in non-clinical samples has been proposed as a convenient yet powerful method for studying the etiology of psychosis. Based on this paradigm, several studies explored the association between season of birth (SoB) and schizotypy but led to inconsistent results. Building on the analysis of the previous studies, in the present study, we aimed to advance our understanding by improving the methodology (using a homogeneous group, eliminating unreliable respondents, taking into account potential confounders) and the reporting.

METHODS

Subjects were recruited among undergraduate students from 3 Romanian Universities. To limit the potential influence of invalid response, we applied methods for detecting unreliable and/or biased questionnaires and excluded subjects with unreliable/ biased answers from the analyses. Schizotypal dimensions were measured using the Romanian translation of the 22-items Schizotypal Personality Questionnaire-Brief (SPQ-B). The association between schizotypy scores and season of birth was explored using linear regression.

RESULTS

In a sample of 484 undergraduate students from Romania, we found that being born in late winter/early spring (February and March) was associated to higher total schizotypy score and disorganization. Furthermore, we found that restricting the sample to subjects born in an urban environment increased the strength of the association.

CONCLUSION

This study is consistent with an association between SoB and the risk of psychotic disorders.

The effects of recent stressful life events on outcomes in individuals at clinical high risk for psychosis: results from the longitudinal EU-GEI high-risk study

BACKGROUND

Recent stressful life events (SLE) are a risk factor for psychosis, but limited research has explored how SLEs affect individuals at clinical high risk (CHR) for psychosis. The current study investigated the longitudinal effects of SLEs on functioning and symptom severity in CHR individuals, where we hypothesized CHR would report more SLEs than healthy controls (HC), and SLEs would be associated with poorer outcomes.

METHODS

The study used longitudinal data from the EU-GEI High Risk study. Data from 331 CHR participants were analyzed to examine the effects of SLEs on changes in functioning, positive and negative symptoms over a 2-year follow-up. We compared the prevalence of SLEs between CHR and HCs, and between CHR who did (CHR-T) and did not (CHR-NT) transition to psychosis.

RESULTS

CHR reported 1.44 more SLEs than HC (p < 0.001), but there was no difference in SLEs between CHR-T and CHR-NT at baseline. Recent SLEs were associated with poorer functioning and more severe positive and negative symptoms in CHR individuals (all p < 0.01) but did not reveal a significant interaction with time.

CONCLUSIONS

CHR individuals who had experienced recent SLEs exhibited poorer functioning and more severe symptoms. However, as the interaction between SLEs and time was not significant, this suggests SLEs did not contribute to a worsening of symptoms and functioning over the study period. SLEs could be a key risk factor to becoming CHR for psychosis, however further work is required to inform when early intervention strategies mitigating against the effects of stress are most effective.

Determining the diagnostic cut-off on the Chinese version of severity of dependence scale for cannabis

Introduction

Cannabis use and misuse are surging among the Chinese community in East and Southeast Asia. A quick screening instrument that can effectively identify users with dependence for early intervention is in utmost need. This study examined the psychometric properties of the Chinese version of the Severity of Dependence Scale for cannabis (C-SDS-C) in screening for the DSM-5 defined Cannabis Use Disorder (CUD).

Methods

A retrospective chart review was conducted on Chinese-speaking individuals reporting cannabis use from three different substance use studies. Their demographic data, frequency of cannabis use within the past 30 days, scorings for the C-SDS-C and the severity of CUD at baseline were analyzed.

Results

The C-SDS-C exhibited high reliability (Cronbach's alpha = 0.778). It had a strong correlation with the severity of CUD (r = 0.456, p <.001) and a moderate correlation with the frequency of cannabis use within the past 30 days (r = 0.335, p = .001). All items loaded into a single factor which accounted for 56.64% of the variance. Receiver operating characteristic analysis demonstrated that a C-SDS-C cut-off score of ≥ 3 provided optimal discrimination for moderate to severe CUD among Chinese-speaking individuals using cannabis.

Conclusion

The C-SDS-C is a valid and reliable screening instrument to identify cannabis users with moderate-to-severe CUD in the Chinese-speaking population.

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

BACKGROUND

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

METHODS

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

RESULTS

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

DISCUSSION

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

Cannabis Consumption Among Adults Aged 55-65 in Canada, 2018-2021

Cannabis consumption among aging adults in Canada is increasing. The aims of the study were to examine cannabis consumption patterns before and after non-medical cannabis legalization and assess whether these patterns differ between men and women. Data were analyzed from Canadian respondents in a repeat cross-sectional survey conducted in 2018-2021. Analyses were conducted among adults aged 55-65 (n = 18,177) who had consumed cannabis in the past 12-month (n = 4119). Past 12-month cannabis consumption significantly increased among 55-65-year-olds from 2018 (19.3%) to the first-year post-legalization in 2019 (24.5%; p < .001), but remained stable thereafter (24.3%, and 25.6% in 2020 and 2021). More men reported past 12-month consumption than women (28.4% vs. 21.4%; p < .001). A substantial number of cannabis consumers consumed to manage a physical or mental health condition. Targeted messaging might be beneficial for this age group, including possible interactions with other medications. This research may be helpful for informing age-adapted cannabis education.

Cannabinoid hyperemesis syndrome in pregnancy: a case series and review

Background

Cannabinoid hyperemesis syndrome (CHS) is a syndrome of cyclic nausea and vomiting in the setting of chronic cannabis use. To date, only 11 cases of CHS in pregnancy have been reported.

Case presentation

We describe two cases of uncontrolled vomiting in pregnancy due to CHS. Case 1 represents a 30-year-old Caucasian woman presenting in the 5th week of gestation with nausea, vomiting and abdominal pain intermittently of 1 week duration. Physical work-up was normal, and symptoms resolved with supportive treatment within 3 days, only to occur again at the 14th week of gestation, and again at the 30th week of gestation. Link between symptom relief and hot bathing led to suspicion for CHS, confirmed with positive cannabis urine toxicology screening. Nausea, vomiting and pain subsided with cannabis cessation, and baby was born healthy at 38 + 5 weeks gestation. Case 2 describes a 28-year-old Caucasian woman presenting in the 16th week of gestation with nausea, vomiting and abdominal pain. Physical examination was normal, and symptoms self-resolved. Two weeks later, in the 18th week of gestation, the patient re-presented to the emergency room with sudden re-occurrence of nausea, vomiting and abdominal pain. Once again, a link between symptom relief and hot bathing was noted on admission. The patient was educated on possible links of chronic cannabis use with CHS symptoms and subsequently relayed extensive (>14 years) cannabis use history. Symptoms resolved with cannabis cessation. Baby was born at 37 weeks gestation, with low birth weight of 2180 g requiring 5 days neonatal intensive care unit (NICU) treatment. Regular follow-up up to 5 months post-partum confirmed no CHS relapse with cannabis cessation.

Conclusion

CHS in pregnancy is likely under-reported, reflective possibly of limited physician and patient awareness of this condition, as well as patient concealment of cannabis use in pregnancy. In cases of severe, cyclic nausea and vomiting in pregnancy unresponsive to typical anti-emetic treatment, comprehensive social history including cannabis use should be sought, and associated hot bathing for symptomatic relief out-ruled.

Cannabinoids for treating psychiatric disorders in youth: a systematic review of randomized controlled trials

BACKGROUND

Cannabinoids have been of increasing interest mainly due to their putative efficacy in a wide array of psychiatric, psychosomatic, and neurological conditions.

AIMS

This systematic review aims to synthesize results from randomized placebo-controlled trials regarding the efficacy and the dosage of cannabinoids as therapeutics in psychiatric disorders in children, adolescents, and young adults.

METHODS

All publications up to June 30th, 2024, were included from PubMed and Embase. Eligibility criteria in accordance with the PRISMA-guidelines was applied. RCTs providing pre- and post-treatment parameters on cannabinoid therapies for mental disorders in comparison to controls in an age range from 0 to 25 years were included. Effect sizes were calculated as Hedges' g for primary outcomes, and a multilevel random-effects meta-analysis was conducted to account for dependent outcomes from same study populations.

RESULTS

We identified 7603 records, of which 8 independent clinical trials (reported in 9 publications) met the pre-established eligibility criteria, comprising 474 unique participants (245 treatment, 229 control). Analysis of 13 primary outcomes (of 7 clinical trials) revealed a modest positive overall effect for symptom improvement or normalization of brain physiology (Hedges' g = 0.308, 95% CI: 0.167, 0.448). Autism spectrum disorder studies showed the most consistent evidence (g = 0.264, 95% CI: 0.107, 0.421), while other conditions showed wider confidence intervals. Age-stratified analysis showed that adult populations (mean age 23.3 years, n = 5 outcomes) demonstrated higher effect sizes (g = 0.463, SD = 0.402) compared to pediatric populations (mean age 11.8 years, n = 8 outcomes; g = 0.318, SD = 0.212). Whole plant preparations (g = 0.328, 95% CI: 0.083, 0.573) and pharmaceutical cannabinoids (g = 0.292, 95% CI: 0.069, 0.515) showed comparable effects. CBD dosages ranged from 17.5 mg to 600 mg per day, with no significant correlation between dosage and effect size (ρ = -0.014, p = 0.963). Mild to moderate side effects were reported, but no serious adverse events. Risk of bias assessment ranged from low (n = 3) to high (n = 5).

CONCLUSION

While meta-analysis of effect sizes for primary outcomes revealed modest positive effects, particularly for autism spectrum disorders, the current evidence remains insufficient to broadly recommend cannabinoids for treating mental disorders in youth populations. Larger, controlled studies with standardized outcomes are needed to establish definitive clinical recommendations.

Changes in Cannabis Use Patterns in Psychiatric Populations Pre- and Post-Legalization of Recreational Cannabis Use in Canada: A Repeated Cross-Sectional Survey

Objective

Since the federal Canadian government legalized cannabis in 2018, cannabis use in the general population has slightly increased. However, little is known about the impact of cannabis legalization on pattens of cannabis use in psychiatric populations.

Method

We studied changes in daily/almost daily and average 30-day cannabis use amongst individuals currently using cannabis who reported past 12-month experiences of specific mental health disorders and among those without past 12-month experiences of any mental health disorder before and after Canadian legalization of recreational cannabis use (N = 13,527). Data came from Canadian respondents in Wave 1 (August-October 2018), Wave 2 (September-October 2019), and Wave 3 (September-November 2020) of the International Cannabis Policy Study (ICPS).

Results

After adjustment for covariates, among individuals currently using cannabis, the odds of using cannabis daily/almost daily increased only in individuals with schizophrenia between Wave 1 and Waves 3 (aOR = 9.19, 95% CI: 2.46 - 34.37). Similarly, significant increases in average 30-day cannabis use between Wave 1 (M = 12.80, SE = 1.65) and Wave 3 (M = 18.07, SE = 1.03) were observed only among individuals with schizophrenia, F (1,2) = 4.58, p < .05. No significant changes in daily/almost daily or average past 30-day cannabis use were observed in those without mental health problems or those reporting anxiety, depression, PTSD, bipolar disorder, or substance use disorders.

Conclusions

Since legalization, cannabis use has significantly increased only among people with schizophrenia, highlighting the need for targeted public health prevention programs.

A proof-of-concept analysis of data from the first NHS clinic for young adults with comorbid cannabis use and psychotic disorders

BACKGROUND

Cannabis use severely affects the outcome of people with psychotic disorders, yet there is a lack of treatments. To address this, in 2019 the National Health Service (NHS) Cannabis Clinic for Psychosis (CCP) was developed to support adults suffering from psychosis to reduce and/or stop their cannabis use.

AIMS

Examine outcome data from the first 46 individuals to complete the CCP's intervention.

METHOD

The sample (N = 46) consisted of adults (aged ≥ 18) with psychosis under the care of the South London and Maudsley NHS Foundation Trust, referred to the CCP between January 2020 and February 2023, who completed their intervention by September 2023. Clinical and functional measures were collected before (T0) and after (T1) the CCP intervention (one-to-one sessions and peer group attendance). Primary outcomes were changes in the Cannabis Use Disorders Identification Test-Revised (CUDIT-R) score and pattern of cannabis use. Secondary outcomes included T0-T1 changes in measures of delusions, paranoia, depression, anxiety and functioning.

RESULTS

A reduction in the mean CUDIT-R score was observed between T0 (mean difference = 17.10, 95% CI = 15.54-18.67) and T1, with 73.91% of participants achieving abstinence and 26.09% reducing the frequency and potency of their use. Significant improvements in all clinical and functional outcomes were observed, with 90.70% being in work or education at T1 compared with 8.70% at T0. The variance in CUDIT-R scores explained between 34 and 64% of the variance in our secondary measures.

CONCLUSIONS

The CCP intervention is a feasible strategy to support cannabis use cessation/reduction and improve clinical and functional outcomes of people with psychotic disorders.

Polygenic and Polyenvironment Interplay in Schizophrenia-Spectrum Disorder and Affective Psychosis; the EUGEI First Episode Study

BACKGROUND

Multiple genetic and environmental risk factors play a role in the development of both schizophrenia-spectrum disorders and affective psychoses. How they act in combination is yet to be clarified.

METHODS

We analyzed 573 first episode psychosis cases and 1005 controls, of European ancestry. Firstly, we tested whether the association of polygenic risk scores for schizophrenia, bipolar disorder, and depression (PRS-SZ, PRS-BD, and PRS-D) with schizophrenia-spectrum disorder and affective psychosis differed when participants were stratified by exposure to specific environmental factors. Secondly, regression models including each PRS and polyenvironmental measures, including migration, paternal age, childhood adversity and frequent cannabis use, were run to test potential polygenic by polyenvironment interactions.

RESULTS

In schizophrenia-spectrum disorder vs controls comparison, PRS-SZ was the strongest genetic predictor, having a nominally larger effect in nonexposed to strong environmental factors such as frequent cannabis use (unexposed vs exposed OR 2.43 and 1.35, respectively) and childhood adversity (3.04 vs 1.74). In affective psychosis vs controls, the relative contribution of PRS-D appeared to be stronger in those exposed to environmental risk. No evidence of interaction was found between any PRS with polyenvironmental score.

CONCLUSIONS

Our study supports an independent role of genetic liability and polyenvironmental risk for psychosis, consistent with the liability threshold model. Whereas schizophrenia-spectrum disorders seem to be mostly associated with polygenic risk for schizophrenia, having an additive effect with well-replicated environmental factors, affective psychosis seems to be a product of cumulative environmental insults alongside a higher genetic liability for affective disorders.

Cannabis use in youth is associated with chronic inflammation

BACKGROUND

Markers of inflammation and cannabis exposure are associated with an increased risk of mental disorders. In the current study, we investigated associations between cannabis use and biomarkers of inflammation.

METHODS

Utilizing a sample of 914 participants from the Avon Longitudinal Study of Parents and Children, we investigated whether interleukin-6 (IL-6), tumor necrosis factor α (TNFα), C-reactive protein (CRP), and soluble urokinase plasminogen activator receptor (suPAR) measured at age 24 were associated with past year daily cannabis use, less frequent cannabis use, and no past year cannabis use. We adjusted for a number of covariates including sociodemographic measures, body mass index, childhood trauma, and tobacco smoking. We found evidence of a strong association between daily or near daily cannabis use and suPAR.

RESULTS

We did not find any associations between less frequent cannabis use and suPAR. We did not find evidence of an association between IL-6, TNFα or CRP, and cannabis use.

CONCLUSIONS

Our finding that frequent cannabis use is strongly associated with suPAR, a biomarker of systemic chronic inflammation implicated in neurodevelopmental and neurodegenerative processes is novel. These findings may provide valuable insights into biological mechanisms by which cannabis affects the brain and impacts the risk of serious mental disorders.

The impact of schizophrenia genetic load and heavy cannabis use on the risk of psychotic disorder in the EU-GEI case-control and UK Biobank studies

BACKGROUND

The association between cannabis and psychosis is established, but the role of underlying genetics is unclear. We used data from the EU-GEI case-control study and UK Biobank to examine the independent and combined effect of heavy cannabis use and schizophrenia polygenic risk score (PRS) on risk for psychosis.

METHODS

Genome-wide association study summary statistics from the Psychiatric Genomics Consortium and the Genomic Psychiatry Cohort were used to calculate schizophrenia and cannabis use disorder (CUD) PRS for 1098 participants from the EU-GEI study and 143600 from the UK Biobank. Both datasets had information on cannabis use.

RESULTS

In both samples, schizophrenia PRS and cannabis use independently increased risk of psychosis. Schizophrenia PRS was not associated with patterns of cannabis use in the EU-GEI cases or controls or UK Biobank cases. It was associated with lifetime and daily cannabis use among UK Biobank participants without psychosis, but the effect was substantially reduced when CUD PRS was included in the model. In the EU-GEI sample, regular users of high-potency cannabis had the highest odds of being a case independently of schizophrenia PRS (OR daily use high-potency cannabis adjusted for PRS = 5.09, 95% CI 3.08-8.43, p = 3.21 × 10-10). We found no evidence of interaction between schizophrenia PRS and patterns of cannabis use.

CONCLUSIONS

Regular use of high-potency cannabis remains a strong predictor of psychotic disorder independently of schizophrenia PRS, which does not seem to be associated with heavy cannabis use. These are important findings at a time of increasing use and potency of cannabis worldwide.

Clinical and public safety risks associated with cannabis legalization and frequency of cannabis use among forensic mental health patients

BACKGROUND

There are ongoing concerns regarding the impact of Canada's cannabis legalization and commercialization on vulnerable persons such as those with serious forms of mental illness, including persons with schizophrenia-spectrum disorders and users of forensic mental health services. The primary objective of this study was to investigate the potential harms and mental health-related impacts associated with cannabis legalization on a sample of forensic patients in Ontario (N = 187).

METHODS

Using a pseudo-prospective design, we investigated the frequency of cannabis use over a four-year period encompassing two years preceding and two years following the legislative change. We recorded clinical and public safety outcomes (i.e., mental health deterioration, length of stay in the forensic system, rates of hospital readmission, victimization and violence) over the same period to test relationships between these variables and rates of cannabis use.

RESULTS

We found that one-third of patients either self-reported or were discovered, via urine testing, to have used cannabis over the study period. Frequency of use was lower in the pre-legalization period, and then gradually and significantly increased after legalization. Compared to patients with no cannabis use, those with one or more instances of use were more likely to be readmitted to hospital and had higher rated static risk factors for violence. However, there were no observed differences in the actual rate of violence between patients using and not using cannabis, nor differences in the rate of violence over time. Over half of the patients who used cannabis experienced a worsening of their mental health status in the week following use.

CONCLUSIONS

Cannabis use among those with SMI is associated with adverse clinical outcomes. Results from this study suggest that the mental health burdens associated with cannabis use have risen in terms of delayed clinical recovery and progress through the forensic system since legalization.

Dopaminergic system and neurons: Role in multiple neurological diseases

The dopaminergic system is a complex and powerful neurotransmitter system in the brain. It plays an important regulatory role in motivation, reward, cognition, and motor control. In recent decades, research in the field of the dopaminergic system and neurons has increased exponentially and is gradually becoming a point of intervention in the study and understanding of a wide range of neurological diseases related to human health. Studies have shown that the dopaminergic system and neurons are involved in the development of many neurological diseases (including, but not limited to Parkinson's disease, schizophrenia, depression, attention deficit hyperactivity disorder, etc.) and that dopaminergic neurons either have too much stress or too weak function in the dopaminergic system can lead to disease. Therefore, targeting dopaminergic neurons is considered key to treating these diseases. This article provides a comprehensive review of the dopaminergic system and neurons in terms of brain region distribution, physiological function and subtypes of dopaminergic neurons, as well as the role of the dopaminergic system and neurons in a variety of diseases.

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.

Prenatal cannabis exposure and the risk for neuropsychiatric anomalies in the offspring: a systematic review and meta-analysis

OBJECTIVE

To evaluate the association between cannabis use during pregnancy and the risk for long-term neuropsychiatric pathology in the offspring.

DATA SOURCES

MEDLINE, EMBASE, and Cochrane library databases were systematically searched until January 22, 2024, with no language or date restrictions.

STUDY ELIGIBILITY CRITERIA

Studies were eligible for inclusion if they reported quantitative data on any long-term neuropsychiatric outcome in offspring whose mothers used cannabis during pregnancy for medical or recreational use, by any route and at any trimester, in comparison to offspring of women who abstained from cannabis use during pregnancy. All observational study designs were included in the analysis.

STUDY APPRAISAL AND SYNTHESIS METHODS

A systematic review and meta-analysis were performed according to the PRISMA and MOOSE guidelines. The data was extracted independently by 2 reviewers. The following offspring outcomes were of interest: attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorder (ASD), depression, anxiety, psychotic disorders, as well as cannabis and other substance use. Odds ratios (OR) and 95% confidence intervals (CI) were pooled for each neuropsychiatric outcome in the offspring of women exposed to cannabis during pregnancy compared with nonexposed. Data were pooled using random-effects models.

RESULTS

Eighteen eligible observational studies were included in the systematic review, and 17 were included in the final quantitative analysis, representing 534,445 participants. After adjusting for confounders, the pooled OR for ADHD was 1.13 (95% CI 1.01-1.26); for ASD, the pooled OR was 1.04 (95% CI 0.74-1.46); for psychotic symptoms, the pooled OR was 1.29 (95% CI 0.97-1.72); for anxiety, the pooled OR was 1.34 (95% CI 0.79-2.29); for depression, the pooled OR was 0.72 (95% CI 0.11-4.57); and for offspring's cannabis use, the pooled OR was 1.20 (95% CI 1.01-1.42).

CONCLUSION

Prenatal cannabis exposure is not associated with an increased risk of ASD, psychotic symptoms, anxiety, or depression in offspring. However, it may slightly elevate the risk of ADHD and predispose offspring to cannabis consumption. Despite these findings, caution is warranted regarding cannabis use during pregnancy. Further research is imperative, especially given the increasing potency of cannabis in recent years.

Differences in total and differential white blood cell counts and in inflammatory parameters between psychiatric inpatients with and without recent consumption of cannabinoids, opioids, or cocaine: A retrospective single-center study

Several drugs of abuse may exert their action by modulating the immune system. Despite this, individuals using substances of abuse are often excluded from immunopsychiatry studies. We conducted a retrospective, single-center study to examine differences in circulating immune/inflammatory parameters (i.e., total and differential white blood cell (WBC) counts, neutrophil-to-lymphocyte ratio, monocyte-to-lymphocyte (MLR) ratio, platelet-to-lymphocyte ratio, and C-reactive protein) between psychiatric inpatients with a positive urine test to cannabinoids, opioids, or cocaine, and those with negative toxicology. A total of 927 inpatients were included. Patients with positive toxicology (n = 208) had significantly higher WBC counts (P < 0.001, η 2p = 0.02), as well as increased neutrophils (P = 0.002, η 2p = 0.01), monocytes (P < 0.001, η 2p = 0.02), lymphocytes (P < 0.001, η 2p = 0.02), and eosinophils (P = 0.01, η 2p = 0.01) compared to those with negative toxicology (n = 719). The increase in neutrophil counts was particularly evident in patients who tested positive for cannabinoids (n = 168; P < 0.001, η 2p = 0.02). In contrast, eosinophil counts were particularly increased in the cocaine-positive subgroup (n = 27; P = 0.004, η 2p = 0.01). Patients with a positive urine test to opioids (n = 13) were characterized by a significantly lower MLR (P = 0.03, η 2p = 0.005). The type of psychiatric diagnosis moderated the differences in neutrophil counts between patients with a positive and negative toxicology to cannabinoids. Notably, significantly higher neutrophil counts were found only in patients diagnosed with a psychotic disorder (P < 0.001, η 2p = 0.03). Taken together, our findings suggest that drugs of abuse may differently impact the immune/inflammatory response system in individuals diagnosed with psychiatric conditions. Specifically, recent cannabinoids use may be associated with an acute activation of the inflammatory response system, particularly in individuals with a psychotic disorder, while cocaine and opioid use may be associated with eosinophilia and a decrease in the MLR, respectively, regardless of the primary psychiatric diagnosis.

Adverse Ocular Impact and Emerging Therapeutic Potential of Cannabis and Cannabinoids: A Narrative Review

Cannabis is the most used drug worldwide with an estimated 219 million users. This narrative review aims to explore the adverse effects and therapeutic applications of cannabis and cannabinoids on the eye, given its growing clinical and non-clinical uses. The current literature reports several adverse ocular effects of cannabis and cannabinoids, including eyelid tremor, ptosis, reduced corneal endothelial cell density, dry eyes, red eyes, and neuro-retinal dysfunction. Cannabinoids may transiently impair night vision, depth perception, binocular and monocular contrast sensitivity, and dynamic visual acuity. Cannabinoids are not currently considered a first-line treatment option for any ocular conditions. Δ-9-tetrahydrocannabinol been shown to result in short-term intraocular pressure reduction, but insufficient evidence to support its use in treating glaucoma exists. Potential therapeutic applications of cannabinoids include their use as a second-line agent for treatment-refractory blepharospasm, for dry eye disease given corneal anti-inflammatory properties, and for suppression of pendular nystagmus in individuals with multiple sclerosis, which all necessitate further research for informed clinical practices.

The effect of polygenic risk score and childhood adversity on transdiagnostic symptom dimensions at first-episode psychosis: evidence for an affective pathway to psychosis

Childhood adversity is associated with various clinical dimensions in psychosis; however, how genetic vulnerability shapes the adversity-associated psychopathological signature is yet to be studied. We studied data of 583 First Episode Psychosis (FEP) cases from the EU-GEI FEP case-control study, including Polygenic risk scores for major depressive disorder (MDD-PRS), bipolar disorder (BD-PRS) and schizophrenia (SZ-PRS); childhood adversity measured with the total score of the Childhood Trauma Questionnaire (CTQ); and positive, negative, depressive and manic psychopathological domains from a factor model of transdiagnostic dimensions. Genes and environment interactions were explored as a departure from a multiplicative effect of PRSs and total CTQ on each dimension. Analyses were adjusted for age, sex, 10 PCA, site of recruitment and for medication. A childhood adversity and PRS multiplicative interaction was observed between A) the CTQ and MDD-PRS on the predominance of positive (β = 0.42, 95% CI = [0.155, 0.682], p = 0.004); and depressive (β = 0.33, 95% CI = [0.071, 0.591], p = 0.013) dimensions; B) between the CTQ and BD-PRS on the positive dimension (β = 0.45, 95% CI = [0.106, 0.798], p = 0.010), and C) with the CTQ and SZ-PRS on the positive dimension (β = -0.34, 95% CI = [-0.660, -0.015], p = 0.040). Bonferroni corrected p-value of significance was set at 0.0125. In conclusion, despite being underpowered, this study suggests that genetic liability for MDD and BD may have a moderating effect on the sensibility of childhood adversity on depressive and positive psychotic dimensions. This supports the hypothesis of an affective pathway to psychosis in those exposed to childhood adversity.

Impact of cannabinoids on synapse markers in an SH-SY5Y cell culture model

Patients suffering from schizophrenic psychosis show reduced synaptic connectivity compared to healthy individuals, and often, the use of cannabis precedes the onset of schizophrenic psychosis. Therefore, we investigated if different types of cannabinoids impact methylation patterns and expression of schizophrenia candidate genes concerned with the development and preservation of synapses and synaptic function in a SH-SY5Y cell culture model. For this purpose, SH-SY5Y cells were differentiated into a neuron-like cell type as previously described. Effects of the cannabinoids delta-9-THC, HU-210, and Anandamide were investigated by analysis of cell morphology and measurement of neurite/dendrite lengths as well as determination of methylation pattern, expression (real time-qPCR, western blot) and localization (immunocytochemistry) of different target molecules concerned with the formation of synapses. Regarding the global impression of morphology, cells, and neurites appeared to be a bit more blunted/roundish and to have more structures that could be described a bit boldly as resembling transport vesicles under the application of the three cannabinoids in comparison to a sole application of retinoic acid (RA). However, there were no obvious differences between the three cannabinoids. Concerning dendrites or branch lengths, there was a significant difference with longer dendrites and branches in RA-treated cells than in undifferentiated control cells (as shown previously), but there were no differences between cannabinoid treatment and exclusive RA application. Methylation rates in the promoter regions of synapse candidate genes in cannabinoid-treated cells were in between those of differentiated cells and untreated controls, even though findings were significant only in some of the investigated genes. In other targets, the methylation rates of cannabinoid-treated cells did not only approach those of undifferentiated cells but were also valued even beyond. mRNA levels also showed the same tendency of values approaching those of undifferentiated controls under the application of the three cannabinoids for most investigated targets except for the structural molecules (NEFH, MAPT). Likewise, the quantification of expression via western blot analysis revealed a higher expression of targets in RA-treated cells compared to undifferentiated controls and, again, lower expression under the additional application of THC in trend. In line with our earlier findings, the application of RA led to higher fluorescence intensity and/or a differential signal distribution in the cell in most of the investigated targets in ICC. Under treatment with THC, fluorescence intensity decreased, or the signal distribution became similar to the dispersion in the undifferentiated control condition. Our findings point to a decline of neuronal differentiation markers in our in vitro cell-culture system under the application of cannabinoids.

Epigenetic effects of cannabis: A systematic scoping review of behavioral and emotional symptoms associated with cannabis use and exocannabinoid exposure

BACKGROUND

Recent research suggests that epigenetic modifications may mediate the behavioral effects of cannabis, influencing exocannabinnoids' long term effects in cognitive function and its role in the emergence of psychotic symptoms.

BASIC PROCEDURES

In this systematic scoping review, we assessed the current evidence of epigenetic effects associated with the use of cannabis or exocannabinoid administration and their relationship with behavioral and emotional symptoms. We searched PubMed, Cochrane CENTRAL, and Web of Science, up to January 2022, using the terms "cannabis" and "epigenetics." The search yielded 178 articles, of which 43 underwent full article revision; 37 articles were included in the review.

MAIN FINDINGS

The gathered evidence included observational cross-sectional studies conducted on human subjects and experimental designs using animal models that conveyed disparity in administration dosage, methods of cannabis use assessment and targeted epigenetic mechanisms. Nine studies performed epigenome-wide analysis with identification of differentially methylated sites; most of these studies found a global hypomethylation, and enrichment in genes related to cellular survival and neurodevelopment. Other studies assessed methylation at specific genes and found that cannabis exposure was associated with reduced methylation at Cg05575921, DNMT1, DRD2, COMT, DLGAP2, Arg1, STAT3, MGMT, and PENK, while hypermethylation was found at DNMT3a/b, NCAM1, and AKT1.

CONCLUSIONS

The review found evidence of an exocannabinoid-induced epigenetic changes that modulate depressive-anxious, psychotic, and addictive behavioural phenotypes. Further studies will require dosage exposure/administration uniformization and a customized pool of genes to assess their suitability as biomarkers for psychiatric diseases.

Academic orientation and cannabis use-findings from a population-based study of Swedish adolescents in upper secondary school

AIM

To examine the association between academic orientation and frequent cannabis use among Swedish adolescents in upper secondary school and include pupils from introductory programs (IPs), a large group of adolescents previously overlooked in research on adolescent cannabis use.

METHODS

We used cross-sectional data from two anonymous school surveys carried out in upper secondary school in 2021. The samples consisted of pupils from all academic orientations, and the analysis included 3151 pupils in higher education preparatory programs (HEPs), 1010 pupils in vocational programs (VPs), and 819 pupils in IPs. The association between the exposure academic orientation and the outcome frequent (21+ times) cannabis was analyzed using multi-level mixed-effects Poisson regression.

RESULTS

Estimates from the first model showed a significant (P < 0.05) 2.45 times higher risk of frequent cannabis use among pupils in IPs compared with in HEPs [incidence rate ratio (IRR) 2.45, 95% confidence interval (CI) 1.28-4.66] and 82% higher in VPs (IRR 1.82, 95% CI 1.09-3.04) compared with in HEPs. However, the associations between academic orientation and frequent (21+ times) cannabis use were attenuated and no longer significant when socioeconomic status, truancy, school dissatisfaction, and early onset of substance use were adjusted for.

CONCLUSIONS

There was a higher risk of frequent (21+ times) cannabis use among pupils in IPs, and this differential was explained by higher exposure to risk factors in this group. This result is important from a policy perspective as it provides knowledge of a previously neglected risk group for frequent cannabis use.