The Changing Legal Landscape of Cannabis Use and Its Role in Youth-onset Psychosis

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

BACKGROUND

Epidemiological studies show a dose-response association between cannabis use and the risk of psychosis. This review aimed to determine whether there are identifiable risk-thresholds between the frequency of cannabis use and psychosis development.

METHODS

Systematic search of Embase, MEDLINE, PsycINFO, CINAHL, and Web of Science for relevant studies (1 January 2010-26 April 2021). Case-control or cohort studies that investigated the relationship between cannabis use and the risk of psychosis development that reported effect estimates [odds ratios (OR), hazard ratios (HR), risk ratios (RR)] or the raw data to calculate them, with information on the frequency of cannabis consumption were included. Effect estimates were extracted from individual studies and converted to RR. Two-stage dose-response multivariable meta-analytic models were utilized and sensitivity analyses conducted. The Newcastle Ottawa Scale was used to assess the risk of bias of included studies.

RESULTS

Ten original (three cohorts, seven case-control) studies were included, including 7390 participants with an age range of 12-65 years. Random-effect model meta-analyses showed a significant log-linear dose-response association between cannabis use frequency and psychosis development. A restricted cubic-splines model provided the best fit for the data, with the risk of psychosis significantly increasing for weekly or more frequent cannabis use [RR = 1.01, 95% confidence interval (CI) 0.93-1.11 yearly; RR = 1.10, 95% CI 0.97-1.25 monthly; RR = 1.35, 95% CI 1.19-1.52 weekly; RR = 1.76, 95% CI 1.47-2.12 daily].

CONCLUSION

Individuals using cannabis frequently are at increased risk of psychosis, with no significant risk associated with less frequent use. Public health prevention messages should convey these risk-thresholds, which should be refined through further work.

The Potential Paradoxical Neurocognitive Effects of Cannabis Use in Patients with Psychotic Disorders: A Critical Meta-Review of Meta-Analytical Evidence

Background: The association between cannabis and cognitive functions has been thoroughly studied in psychotic disorders, but conflictual/paradoxical results have emerged. This critical meta-review examined the magnitude of effects of cannabis on neurocognitive functions in patients with psychotic disorders provided by meta-analyses and evaluated the quality of evidence. Methods: A systematic search of meta-analyses was performed in PubMed, PsycINFO, Web of Science, and Google Scholar. Results: The search retrieved six meta-analyses. Quality of evidence varied from very low to moderate quality. No neurocognitive difference was observed between cannabis users and nonusers in first episode of psychosis samples. Limited evidence showed no significant difference in language, psychomotor functioning, and verbal/visual learning/memory, apart from improvements in verbal and visual memory (recognition). Findings showed better neurocognitive performances in cannabis-using patients for planning/reasoning and working memory. There were tendencies toward significance for processing speed and attention. Most effect sizes showed small to moderate degrees of outperformances in cannabis users. Individuals with lifetime use appeared to show better neurocognitive functions. Conclusion: Evidence indicated nonuniform effects of cannabis use across cognitive domains, with some areas suggesting better cognitive performances in cannabis users, entitled the paradoxical effect of the dually diagnosed. Clinical significance of these findings should be interpreted cautiously.

Relationship between cannabis use and psychotic experiences in college students

BACKGROUND

Emerging data suggest cannabis use is a component cause of psychotic disorders; however, the sequence of processes accounting for this association is poorly understood. Some clues have come from studies in laboratory settings showing that acute cannabis intoxication is associated with subclinical hallucinations and delusional thinking, i.e., "psychotic experiences". Although psychotic experiences are relatively common, those that are severe and distressing are linked to an increased risk of developing a psychotic disorder. This study aimed to investigate the association between the frequency of cannabis use and psychotic experiences in young adults.

METHODS

1034 U.S. college students completed questionnaires to assess: cannabis use in the past week, delusional ideation (Peters Delusions Inventory), hallucinations (Launay-Slade Hallucinations Scale-Extended), and depression (Beck Depression Inventory).

RESULTS

Participants reporting higher rates of weekly cannabis use were more likely to report hallucinatory experiences and delusional ideation. The relationship between cannabis use and hallucinatory experiences, but not the relationship between cannabis use and delusional ideation, remained significant after controlling for levels of depression. Moreover, those who reported greater amounts of cannabis use had more distressing delusional ideas, that were held with more conviction.

CONCLUSIONS

Cannabis use is linked to the presence of subclinical hallucinations and delusional ideation in U.S. college students.

Effects of daily Δ9-Tetrahydrocannabinol (THC) alone or combined with cannabidiol (CBD) on cognition-based behavior and activity in adolescent nonhuman primates

BACKGROUND

Daily use of marijuana is rising in adolescents, along with consumption of high potency marijuana products (high % Δ-9-tetrahydrocannabinol or THC). These dual, related trends have opened gaps in understanding the long-term effects of daily consumption of a high dose of THC in adolescents and whether a therapeutic dose of cannabidiol (CBD) modulates THC effects.

METHODS

Adolescent squirrel monkeys (Saimiri boliviensis) were treated daily for four months with vehicle (n = 4), a high THC dose (1 mg/kg i.m.; n = 4), or THC + CBD (1 mg/kg +3 mg/kg i.m.; n = 4), to investigate whether: (1) a daily high THC dose affects performance in tasks of cognition (repeated acquisition, discrimination reversal); (2) a daily high THC dose affects spontaneous behavior and day/night activity (3) tolerance develops to the behavioral effects of THC; (4) whether CBD modulates THC effects.

RESULTS

THC impaired performance of adolescent monkeys in a cognitive test initially, but not performance on a task of cognitive flexibility. THC reduced motor activity and increased sedentary behavior, with tolerance developing after weeks of daily treatment. Co-administered with THC, CBD did not modulate THC effects on cognitive performance, activity or tolerance, but prevented THC-induced emesis on the first day of daily treatment.

CONCLUSIONS

Daily high dosing with THC compromised performance on a task of cognition, and reduced activity in adolescent primates, with tolerance developing within weeks. Whether our observations are relevant to a broader range of cognitive tasks vital for daily function in human adolescents is uncertain.

THC and CBD produce divergent effects on perception and panic behaviours via distinct cortical molecular pathways

Clinical and pre-clinical evidence demonstrates divergent psychotropic effects of THC vs. CBD. While THC can induce perceptual distortions and anxiogenic effects, CBD displays antipsychotic and anxiolytic properties. A key brain region responsible for regulation of cognition and affect, the medial prefrontal cortex (PFC), is strongly modulated by cannabinoids, suggesting that these dissociable THC/CBD-dependent effects may involve functional and molecular interplay within the PFC. The primary aim of this study was to investigate potential interactions and molecular substrates involved in PFC-mediated effects of THC and CBD on differential cognitive and affective behavioural processing. Male Sprague Dawley rats received intra-PFC microinfusions of THC, CBD or their combination, and tested in the latent inhibition paradigm, spontaneous oddity discrimination test, elevated T-maze and open field. To identify local, drug-induced molecular modulation in the PFC, PFC samples were collected and processed with Western Blotting. Intra-PFC THC induced strong panic-like responses that were counteracted with CBD. In contrast, CBD did not affect panic-like behaviours but blocked formation of associative fear memories and impaired latent inhibition and oddity discrimination performance. Interestingly, these CBD effects were dependent upon 5-HT_1A receptor transmission but not influenced by THC co-administration. Moreover, THC induced robust phosphorylation of ERK1/2 that was prevented by CBD, while CBD decreased phosphorylation of p70S6K, independently of THC. These results suggest that intra-PFC infusion of THC promotes panic-like behaviour associated with increased ERK1/2 phosphorylation. In contrast, CBD impairs perceptive functions and latent inhibition via activation of 5-HT_1A receptors and reduced phosphorylation of p70S6K.

Biochemical aspects and therapeutic mechanisms of cannabidiol in epilepsy

Epilepsy is a chronic neurological disease characterized by recurrent epileptic seizures. Studies have shown the complexity of epileptogenesis and ictogenesis, in which immunological processes and epigenetic and structural changes in neuronal tissues have been identified as triggering epilepsy. Cannabidiol (CBD) is a major active component of the Cannabis plant and the source of CBD-enriched products for the treatment of epilepsy and associated diseases. In this review, we provide an up-to-date discussion on cellular and molecular mechanisms triggered during epilepsy crises, and the phytochemical characteristics of CBD that make it an attractive candidate for controlling rare syndromes, with excellent therapeutic properties. We also discuss possible CBD anticonvulsant mechanisms and molecular targets in neurodegenerative disorders and epilepsy. Based on these arguments, we conclude that CBD presents a biotecnological potential in the anticonvulsant process, including decreasing dependence on health care in hospitals, and could make the patient's life more stable, with regard to neurological conditions.

THC and CBD blood and brain concentrations following daily administration to adolescent primates

BACKGROUND

Cannabis availability with high concentrations of Δ-9-tetrahydrocannabinol (THC) and a range of THC to cannabidiol (CBD) ratios has increased in parallel with a rise in daily cannabis consumption by adolescents. Unanswered questions in adolescents include: 1) whether THC blood concentrations and THC metabolites remain stable or change with prolonged daily dosing, 2) whether CBD modulates THC pharmacokinetic properties and alters THC accumulation in brain, 3) whether blood THC levels reflect brain concentrations.

METHODS

In adolescent squirrel monkeys (Saimiri boliviensis), we determined whether a four-month regimen of daily THC (1 mg/kg) or CBD (3 mg/kg) + THC (1 mg/kg) administration (IM) affects THC, THC metabolites, and CBD concentrations in blood or brain.

RESULTS

Blood THC concentrations, THC metabolites and CBD remained stable during chronic treatment. 24 h after the final THC or CBD + THC injection, blood THC and CBD concentrations remained relatively high (THC: 6.0-11 ng/mL; CBD: 9.7-19 ng/mL). THC concentrations in cerebellum and occipital cortex were approximately twice those in blood 24 h after the last dose and did not significantly differ in subjects given THC or CBD + THC.

CONCLUSIONS

In adolescent monkeys, blood levels of THC, its metabolites or CBD remain stable after daily dosing for four months. Our model suggests that any pharmacological interactions between CBD and THC are unlikely to result from CBD modulation of THC pharmacokinetics. Finally, detection of relatively high brain THC concentrations 24 h after the final dose of THC suggests that the prolonged actions of THC may contribute to persistent cognitive and psychomotor disruption after THC- or cannabis-induced euphoria wane.

Cannabis Use in Inpatients With Schizophrenia Spectrum Disorders at a Community Hospital

Background

Cannabis is the second most used recreational drug in the United States and one of the most used substances in patients with schizophrenia spectrum disorder (SSD). Unfortunately, the increased use is likely to continue as more states legalize recreational use of cannabis. Although the association between cannabis and schizophrenia has been studied extensively, the understanding of the relationship is still evolving. In this study, we sought to determine the prevalence and potential factors associated with cannabis use (CU) among inpatients with SSD at a community teaching hospital.

Methods

We performed a retrospective review of the electronic medical charts of patients discharged from the psychiatric unit of our hospital from July 1, 2017 through October 31, 2017. Patients were included in this study if: 1) They were ≥ 18 years old; 2) They had discharge diagnosis of SSD; and 3) They had urine drug testing performed. Pertinent sociodemographic and clinical variables, including substance use status and hospital length of stay (LOS), were abstracted. Univariate frequencies and summary statistics were performed. Odds ratios (ORs) were determined by logistic regression analysis of bivariate and multivariate analyses.

Results

Three hundred sixty-five (52.2%) patients had a discharge diagnosis of SSD, and only 322 had urine toxicology result for cannabinoids and were included in analysis. Of the 322 patients, 41.5% (n = 133) screened positive for cannabinoids. Of the 133 patients, 78% were African American, 15% were Hispanic and 5% were White; 77% were male and the median age was 36 years. Bivariate analyses showed tobacco use (OR: 2.8, 95% confidence interval (CI): 1.7 - 4.6), alcohol use (OR: 3.4, 95% CI: 2.9 - 7.0), younger age (OR: 2.8, 95% CI: 1.8 - 4.5), male gender (OR: 2.9, 95% CI: 2.2 - 3.2), unemployment (OR: 3.91, 95% CI: 3.49 - 7.35), homelessness (OR: 3.18, 95% CI: 2.76 - 3.84) and LOS (OR: 3.46, 95% CI: 2.93 - 4.31) were significantly associated with CU. Result of multivariate analysis was similar to that found in bivariate analysis.

Conclusions

CU appears to be prevalent among patients with SSD. Clinicians and public health professionals are encouraged to understand the health implications of its use in patients with mental illness especially against the backdrop of current marijuana laws.