Cannabis use and clinical outcome in people with first-episode schizophrenia spectrum disorders over 24 months of treatment

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

BACKGROUND AND HYPOTHESIS

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

STUDY DESIGN

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

STUDY RESULTS

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

CONCLUSIONS

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

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.

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.

Antipsychotic Use and Psychiatric Hospitalization in First-Episode Non-affective Psychosis and Cannabis Use Disorder: A Swedish Nationwide Cohort Study

BACKGROUND AND HYPOTHESIS

There is a paucity of research on treatment outcomes of patients with psychosis and cannabis use disorder (CUD). We aimed to compare the effectiveness of antipsychotics in reducing the risk of hospitalization in patients with first-episode psychosis (FEP) and co-occurring CUD.

STUDY DESIGN

We utilized a nationwide Swedish cohort of patients with longitudinal register data from the year 2006 to 2021. Participants were patients with FEP and co-occurring CUD (n = 1820, 84.73% men, mean age 26.80 years, SD 8.25 years). The main outcome was hospitalization due to psychotic relapse. Hospitalization due to any psychiatric disorder or substance use disorder (SUD) were examined as secondary outcomes. Within-individual Cox regression models were used to study these associations.

STUDY RESULTS

Use of any antipsychotic was associated with a 33% risk reduction of psychotic relapse (aHR = 0.67; 95% CI 0.60-0.75). Clozapine (0.43; 0.29-0.64), long-acting injectable (LAI) formulations of risperidone (0.40; 0.22-0.71), aripiprazole (0.42; 0.27-0.65), and paliperidone (0.46; 0.30-0.69) were associated with the lowest risk of relapse. The association between the LAI formulation of olanzapine and hospitalization due to psychosis was statistically non-significant (0.61; 0.35-1.05). Clozapine was associated with an 86% risk reduction of hospitalization due to SUD (0.14; 0.05-0.44). Of oral non-clozapine antipsychotics, aripiprazole was associated with the lowest risk of hospitalization due to psychotic relapse (0.61; 0.45-0.83).

CONCLUSIONS

These findings support the use of clozapine, LAI formulations of second-generation antipsychotics other than olanzapine, or oral aripiprazole to prevent hospitalization in FEP and co-occurring CUD.

Management of schizophrenia and comorbid substance use disorders: expert review and guidance

BACKGROUND

Schizophrenia and substance use disorders (SUDs) are often comorbid conditions that present clinical challenges due to their heterogeneity and the difficulties associated with poor physical health, low medication adherence, high relapse and hospitalization rates, and increased risk of mortality. This is often exacerbated by a fragmented health care system that treats addiction and mental illness separately, leading to delays in proper diagnosis and treatment.

MAIN TEXT

The aim of this narrative review, based on an extensive literature search and experts' clinical experience, is to synthesize evidence on the psychopathological and clinical characteristics of patients, the burden and management at the level of healthcare system, and possible gaps in the treatment of schizophrenia with comorbid SUD in order to understand and address the needs of patients. Treatment options, differences between antipsychotic medications, and the benefits of long-acting formulations and partial dopaminergic agonists are described. Partial dopamine agonists (aripiprazole, cariprazine, and brexpiprazole) have demonstrated good control of psychotic symptoms and SUDs with a favorable safety profile.

CONCLUSION

Pharmacological interventions should be accompanied by psychosocial support within an integrated and multidisciplinary approach that promotes shared decision-making and a good therapeutic alliance between the entire medical team and the patient.

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

AIM

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

Background

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

Methods

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

Findings

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

Interpretation

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

Funding

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

Cannabis use among patients presenting to the emergency department for psychosis: Associations with restraint use, medication administration, psychiatric hospitalization, and repeat visits

Cannabis use is associated with increased severity of psychotic symptoms and the risk of acute agitation and aggressive behavior in inpatient (IP) and outpatient settings. Whether or not cannabis use is associated with increased acuity of psychosis-related ED presentations and risk of repeat ED visits for psychosis is unclear. In this retrospective study of 2,134 ED visits for acute psychosis, we investigated the risk of physical restraint, parenteral medication administration, psychiatric hospitalization, and recurrent ED visits. We examined ED visits between March 1, 2019 and February 28, 2021 based on urinary Tetrahydrocannabinol (THC) screen status (positive vs negative vs no screen). The risk of physical restraint, parenteral antipsychotic, and benzodiazepine administration was significantly greater in ED visits with a positive THC screen compared to those with a negative or no THC screen. We did not find an association between a positive urinary THC screen and IP hospitalization or the risk of recurrent ED presentation for psychosis within 90 days. These findings suggest that positive urinary THC may predict acute agitation or acuity of symptoms in ED settings and underscores the importance of screening for THC during ED presentations for psychosis.

Impact of cannabis use and its cessation on the dosage and the efficacy of antipsychotic drugs in in- and outpatients with schizophrenia taking medication: A systematic review and meta-analysis

Compared with the general population, there are more cannabis users among patients suffering from schizophrenia and this consumption seems to impact the course and the treatment of their pathology. The aim of this meta-analysis and systematic review was to assess the impact of cannabis use on the efficacy of treatments, more particularly regarding the antipsychotic dosage, symptoms evolution, therapeutic resistance and the risk of relapse in patients with schizophrenia taking medication. We performed a systematic search of keywords on multiple databases up to August 2020 to identify all studies meeting the following criteria: comparison between cannabis smokers and non-cannabis users in patients with schizophrenia, assessment of antipsychotics doses, information about their efficacy or resistance to treatment and control of the compliance. Standardized mean differences were calculated for antipsychotic dosage and symptoms evolution at discharge, and a systematic review was performed for other outcomes. Twelve studies were included. Cannabis use did not seem to be associated with higher doses of antipsychotics at seven days and at the end of the studies, nor with poorer symptoms evolution, and nor with higher rate of antipsychotic resistance. However, cannabis use seems to be associated with a higher risk of relapse. This meta-analysis provides evidence that previous cannabis use, or occasional use, in patients with schizophrenia taking medication does not impact antipsychotic efficacy as described by antipsychotic dosage or PANSS score.

Prevalence of cannabis use in people with psychosis in KwaZulu-Natal, South Africa

Background

There is a high prevalence of cannabis use in patients with schizophrenia spectrum and other psychotic disorders, with comorbid cannabis use in this population being associated with poorer long-term outcomes.

Aim

To determine the prevalence of cannabis use in patients with a schizophrenia spectrum and other psychotic disorders.

Setting

The study was conducted at a psychiatric hospital in Durban, KwaZulu-Natal Province, South Africa.

Methods

A review of clinical records of patients admitted to the hospital for the period, June 2018 to June 2020, was conducted.

Results

A total of 370 clinical records were reviewed, of which 48.9% reported current and 51.1% lifetime cannabis use. Being male was significantly associated with current and lifetime cannabis use (OR = 4.90, 95% CI 2.49–9.62 and OR = 6.27, 95% CI 3.28–11.95, respectively). Current alcohol use was also associated with current cannabis use (CCU) (OR = 3.06, 95% CI 1.78–5.28), and age 45 years and older was associated with a lower odds of cannabis use (OR = 0.30, 95% CI 0.09–0.96). Forty-eight per cent of participants were admitted three or more times, and readmission was associated with cannabis use (p = 0.01). There was a lack of association between cannabis use, readmission and human immunodeficiency virus (HIV) status, after controlling for variables such as alcohol use and gender.

Conclusion

Almost 50% of people admitted with schizophrenia spectrum and other psychotic disorders have comorbid current and lifetime cannabis use. There is a need for dual diagnosis units to address comorbid substance use in people with psychotic disorders, as it leads to poorer outcomes.

Contribution

The study found that there is a high prevalence of cannabis use in people with psychosis. Therefore, it is imperative that we revise treatment programs in our psychiatric units and there is an urgent need for dual diagnosis programs that address substance use in this group of patients.