Effects of Extended Cannabis Abstinence on Cognitive Outcomes in Cannabis Dependent Patients with Schizophrenia vs Non-Psychiatric Controls

Cannabis cravings predict cigarette use in schizophrenia: a secondary analysis from two cannabis abstinence studies

CLINICAL TRIAL NAME

Effects of Repetitive Transcranial Magnetic Stimulation (rTMS) on Cannabis Use and Cognitive Outcomes in SchizophreniaURL: www.clinicaltrials.gov; Registration Number: NCT03189810.

Endorsement of psychotic-like experiences and problematic cannabis use associated with worse executive functioning performance in undergraduates

BACKGROUND

Emerging adults who endorse more positive psychotic-like experiences (PLEs; bizarre experiences, delusional ideations) may experience greater cannabis-related impairments in executive function. Negative and depressive PLEs are also associated with cannabis use, however, less is known about their relation to executive functioning. Here, we hypothesize that high positive PLEs and cannabis use are associated with worse performance on computerized versions of the Iowa Gambling Task (IGT) and the Card Sorting Task (CST); exploratory analyses are conducted with negative and depressive PLEs.

METHODS

We recruited university students (N = 543) who completed an online study consisting of self-report measures of problematic cannabis use (Cannabis Use Disorder Identification Test; CUDIT-R) and PLEs (Community Assessment of Psychotic Experiences; CAPE). Of these, n=270 completed the CST and n=251 completed the IGT.

RESULTS

Problematic cannabis use and high endorsement of positive PLEs related to significantly worse performance on the IGT and greater perseverative errors on the CST. In addition, people who endorsed high levels of positive PLEs were also significantly more likely to complete the IGT with less money relative to those who endorsed fewer PLEs, regardless of cannabis use. Further analyses based on negative PLEs revealed a similar pattern for perseverative errors on the CST; depressive PLEs were not related to task performance.

CONCLUSION

Findings highlight that problematic cannabis use and more frequent and distressing positive PLEs are associated with poorer executive functioning. Thus, executive functioning may have implications for intervention among those high on both attributes, who are at high risk of onset of psychosis.

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.

Does tobacco dependence worsen cannabis withdrawal in people with and without schizophrenia-spectrum disorders?

BACKGROUND AND OBJECTIVES

Rates of cannabis use disorder (CUD) are higher in people with schizophrenia than in the general population. Irrespective of psychiatric diagnosis, tobacco co-use is prevalent in those with CUD and leads to poor cannabis cessation outcomes. The cannabis withdrawal syndrome is well-established and increases cannabis relapse risk. We investigated whether cannabis withdrawal severity differed as a function of high versus no/low tobacco dependence and psychiatric diagnosis in individuals with CUD.

METHOD

Men with CUD (N = 55) were parsed into four groups according to schizophrenia diagnosis and tobacco dependence severity using the Fagerstrom Test for Nicotine Dependence (FTND): men with schizophrenia with high tobacco dependence (SCT+, n = 13; FTND ≥ 5) and no/low tobacco dependence (SCT-, n = 22; FTND ≤ 4), and nonpsychiatric controls with high (CCT+, n = 7; FTND ≥ 5) and no/low (CCT-, n = 13; FTND ≤ 4) tobacco dependence. Participants completed the Marijuana Withdrawal Checklist following 12-h of cannabis abstinence.

RESULTS

There was a significant main effect of tobacco dependence on cannabis withdrawal severity (p < .001). Individuals with high tobacco dependence had significantly greater cannabis withdrawal severity (M = 13.85 [6.8]) compared to individuals with no/low tobacco dependence (M = 6.49, [4.9]). Psychiatric diagnosis and the interaction effects were not significant. Lastly, cannabis withdrawal severity positively correlated with FTND (r = .41, p = .002).

CONCLUSION AND SCIENTIFIC SIGNIFICANCE

Among individuals with CUD and high tobacco dependence, cannabis withdrawal severity was elevated twofold, irrespective of diagnosis, relative to individuals with CUD and no/low tobacco dependence. Findings from this study emphasize the importance of addressing tobacco co-use when treating CUD.

Genetic influences on the interplay between obsessive-compulsive behavior symptoms and cannabis use during adolescence

INTRODUCTION

There are overlapping biological origins and behaviors associated with obsessive-compulsive symptoms (OCS) and cannabis use. There is also evidence that OCS and cannabis use are associated over time. Thus, we investigated polygenic predisposition for OCS as predictive of OCS and cannabis use from age 17 to 19. We hypothesized that greater genetic risk for OCS would predict both OCS and cannabis use.

METHODS

The current study used participants from the Project Alliance 1 study, a US-based sample, for whom genomic, OCS, and cannabis use data were available (n = 547). Polygenic risk scores (PRS) were formed via a meta-genome-wide association study on OCS and examined as a predictor of OCS and cannabis use at age 17 and 19. The sample was diverse (52.4% male; 45% European American, 30% African American, 14% multiracial, 5% Hispanic/Latino, 4% Asian American, and 2% other groups). Sensitivity analysis was performed by gender for European American and African American subsamples.

RESULTS

Across the whole sample, the greater polygenic risk for OCS was negatively associated with cannabis use at age 17 and positively associated with OCS at 19. Cannabis use at age 17 was positively associated with OCS at age 19. The association between polygenic risk for OCS and cannabis use at age 17 was replicated in European American males, whereas the association between cannabis use at age 17 and OCS at age 19 was replicated in African American males.

CONCLUSIONS

Cannabis use may exacerbate OCS through adolescence, and genetic predisposition for OCS may be associated with lower cannabis use in efforts to avoid exacerbation of OCS.

Contingency Management for Treatment of Cannabis Use Disorder in Co-Occurring Mental Health Disorders: A Systematic Review

Amongst individuals with a mental health disorder, a comorbid diagnosis of cannabis use disorder (CUD) is associated with numerous adverse consequences, including more severe symptom profiles, poorer treatment response, and reduced psychosocial functioning. Contingency management (CM), a method to specifically reinforce target behavior attainment (e.g., substance use abstinence), may provide an effective intervention in treating cannabis use in patients with a dual diagnosis of CUD and a mental health disorder. A systematic search examining the effects of CM on cannabis use, clinical, cognitive, and psychosocial outcomes in patients with a mental health disorder on PubMed, PsycINFO, and EMBASE databases up to November 2022 was performed. Six studies met inclusion criteria for our review. We found CM to be efficacious in producing cannabis use reductions and abstinence amongst individuals with a psychotic-spectrum or major depressive disorder. Additional longitudinal studies with larger sample sizes, other psychiatric populations, and longer follow-up periods are needed to evaluate the sustained effects of CM.

Consensus paper of the WFSBP task force on cannabis, cannabinoids and psychosis

OBJECTIVES

The liberalisation of cannabis laws, the increasing availability and potency of cannabis has renewed concern about the risk of psychosis with cannabis.

METHODS

The objective of the WFSBP task force was to review the literature about this relationship.

RESULTS

Converging lines of evidence suggest that exposure to cannabis increases the risk for psychoses ranging from transient psychotic states to chronic recurrent psychosis. The greater the dose, and the earlier the age of exposure, the greater the risk. For some psychosis outcomes, the evidence supports some of the criteria of causality. However, alternate explanations including reverse causality and confounders cannot be conclusively excluded. Furthermore, cannabis is neither necessary nor sufficient to cause psychosis. More likely it is one of the multiple causal components. In those with established psychosis, cannabis has a negative impact on the course and expression of the illness. Emerging evidence also suggests alterations in the endocannabinoid system in psychotic disorders.

CONCLUSIONS

Given that exposure to cannabis and cannabinoids is modifiable, delaying or eliminating exposure to cannabis or cannabinoids, could potentially impact the rates of psychosis related to cannabis, especially in those who are at high risk for developing the disorder.

Investigating repetitive transcranial magnetic stimulation on cannabis use and cognition in people with schizophrenia

Cannabis use disorder (CUD) occurs at high rates in schizophrenia, which negatively impacts its clinical prognosis. These patients have greater difficulty quitting cannabis which may reflect putative deficits in the dorsolateral prefrontal cortex (DLPFC), a potential target for treatment development. We examined the effects of active versus sham high-frequency (20-Hz) repetitive transcranial magnetic stimulation (rTMS) on cannabis use in outpatients with schizophrenia and CUD. Secondary outcomes included cannabis craving/withdrawal, psychiatric symptoms, cognition and tobacco use. Twenty-four outpatients with schizophrenia and CUD were enrolled in a preliminary double-blind, sham-controlled randomized trial. Nineteen participants were randomized to receive active (n = 9) or sham (n = 10) rTMS (20-Hz) applied bilaterally to the DLPFC 5x/week for 4 weeks. Cannabis use was monitored twice weekly. A cognitive battery was administered pre- and post-treatment. rTMS was safe and well-tolerated with high treatment retention (~90%). Contrast estimates suggested greater reduction in self-reported cannabis use (measured in grams/day) in the active versus sham group (Estimate = 0.33, p = 0.21; Cohen’s d = 0.72), suggesting a clinically relevant effect of rTMS. A trend toward greater reduction in craving (Estimate = 3.92, p = 0.06), and significant reductions in PANSS positive (Estimate = 2.42, p = 0.02) and total (Estimate = 5.03, p = 0.02) symptom scores were found in the active versus sham group. Active rTMS also improved attention (Estimate = 6.58, p < 0.05), and suppressed increased tobacco use that was associated with cannabis reductions (Treatment x Time: p = 0.01). Our preliminary findings suggest that rTMS to the DLPFC is safe and potentially efficacious for treating CUD in schizophrenia.

Neurocognitive moderation of repetitive transcranial magnetic stimulation (rTMS) effects on cannabis use in schizophrenia: a preliminary analysis

Repetitive transcranial magnetic stimulation (rTMS) is a promising treatment for cannabis use disorder in schizophrenia; however, gaps in the literature remain as to the potential role of neurocognitive functioning in treatment response. We evaluated the moderating role of select cognitive functions including baseline executive functioning, verbal memory, and sustained attention, and we explore the mediating role of changes in task performance on changes in cannabis use in both active and sham rTMS groups. Participants underwent high-frequency (20 Hz) rTMS applied to the bilateral dorsolateral prefrontal cortex 5x/week for 4 weeks. Weekly self-report of cannabis use and semi-quantitative urinary carboxy-tetrahydrocannabinol levels were recorded. A neurocognitive battery assessing verbal memory, visuospatial working memory, verbal working memory, sustained attention, delayed discounting, and complex planning was administered pre- and post-treatment. Better baseline performance on tasks assessing sustained attention, delayed discounting, and complex planning moderated the extent to which participants in the active group reduced cannabis use. There were no significant indirect pathways between treatment, changes in neuropsychological performance, and changes in cannabis use; however, active rTMS improved complex planning and sustained attention. These preliminary findings suggest that there is a moderating role of sustained attention, delayed discounting, and complex planning on the effects of rTMS on cannabis use. Further, mediation models suggest rTMS may exert direct effects on cannabis use independent of its effects on cognitive functioning in people with SCZ. Trial Registration: clinicaltrials.gov: NCT03189810.

Does cannabis use predict aggressive or violent behavior in psychiatric populations? A systematic review

Background: Despite an increase in information evaluating the therapeutic and adverse effects of cannabinoids, many potentially important clinical correlates, including violence or aggression, have not been adequately investigated.Objectives: In this systematic review, we examine the published evidence for the relationship between cannabis and aggression or violence in individuals with psychiatric disorders.Methods: Following PRISMA guidelines, articles in English were searched on PubMed, Google Scholar, MEDLINE, and PsycINFO from database inception to January 2022. Data for aggression and violence in people with psychiatric diagnoses were identified during the searches.Results: Of 391 papers identified within the initial search, 15 studies met inclusion criteria. Cross-sectional associations between cannabis use and aggression or violence in samples with post-traumatic stress disorder (PTSD) were found. Moreover, a longitudinal association between cannabis use and violence and aggression was observed in psychotic-spectrum disorders. However, the presence of uncontrolled confounding factors in the majority of included studies precludes any causal conclusions.Conclusion: Although cannabis use is associated with aggression or violence in individuals with PTSD or psychotic-spectrum disorders, causal conclusions cannot be drawn due to methodological limitations observed in the current literature. Well-controlled, longitudinal studies are needed to ascertain whether cannabis plays a causal role on subsequent violence or aggression in mental health disorders.

Effects of 28 days of cannabis abstinence on cognition in major depressive disorder: A pilot study

BACKGROUND AND OBJECTIVES

Cannabis is a widely used substance that may impair select cognitive domains, including attention and memory. Problematic cannabis use is a common clinical problem among patients with major depressive disorder (MDD). Few studies have investigated the effects of cannabis abstinence on cognition in MDD. Thus, our study aimed to determine whether a 28-day period of cannabis abstinence is associated with improvements in cognition in patients with MDD and comorbid cannabis use disorder (CUD).

METHODS

We evaluated the effects of 28 days of cannabis abstinence on cognition in MDD patients with comorbid CUD facilitated by contingency management, motivational interviewing, psychoeducation, and coping-skills training (N = 11). Primary outcomes included Baseline to Day 28 changes in verbal memory and learning, while secondary outcomes included Baseline to Day 28 changes in working memory, visuospatial working memory (VSWM), visual search speed, mental flexibility, response inhibition, attention, manual dexterity, and fine motor movement.

RESULTS

Eight participants (72.7%) met the pre-specified criteria for cannabis abstinence and three participants significantly reduced their cannabis use (≥90%). Visual search speed, selective attention, and VSWM improved over the study period. These improvements were not associated with changes in cannabis metabolite levels from baseline to endpoint.

DISCUSSION AND CONCLUSIONS

Our findings suggest that 28 days of cannabis abstinence may improve select cognitive domains in patients with MDD and comorbid CUD.

SCIENTIFIC SIGNIFICANCE

This is the first study to longitudinally examine the effects of cannabis on cognition in MDD.

CLINICAL TRIAL

Effects of Cannabis Abstinence on Symptoms and Cognition in Depression (NCT03624933; https://www.

CLINICALTRIALS

gov).

Cannabis use and effect of cannabis abstinence on cognitive functioning in young people — an observational case-control follow-up study from rehabilitation centre in Andhra Pradesh

Background

Cannabis is the most commonly used illicit substance globally, in India particularly. In recent times, younger people started abusing cannabis, resulting in academic decline and psychological disorders. Research from developed countries had shown that abstinence from cannabis reverses cognitive decline in the young population to a certain extent. Studies on this topic have been very few in India. We intended to assess the effects of cannabis use and abstinence from cannabis on the cognitive functioning of young adults.

The study was an observational study including 50 consecutive young male patients, who got admitted to our rehabilitation centre with cannabis use disorder (group A). The Montreal Cognitive Assessment (MoCA) test was used to assess the baseline cognitive functioning of these patients initially after 1 week of abstinence and compared with 50 graduate students with no history of cannabis use (group B). The MoCA test was re-administered to group A subjects after 3 months of strict abstinence from cannabis use.

Results

There was a statistically significant difference between the baseline MoCA score of cannabis users and the controls (P < 0.001). Both the duration (r = −0.296, P = 0.036) and the quantity (r= −0.491, P < 0.001) of cannabis use had a negative correlation with the MoCA score. When the MoCA test was re-administered after 3 months of abstinence, we found a statistically significant improvement in cognitive functioning in cannabis users (P < 0.001), but the mean score was still less than the mean score of the control group (24.08 ± 2.66 vs 28.62 ± 0.85, P < 0.001) showing only partial improvement.

Conclusion

This study showed that cognitive deficits were seen in cannabis users as compared to nonusers. It also had shown that abstinence from cannabis had partially reversed the impairment, but still some deficits were remaining. There is an urgent need for primary prevention strategies at community level to decrease the prevalence of cannabis use.

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.

Sensory gating in tobacco-naïve cannabis users is unaffected by acute nicotine administration

OBJECTIVES

Long-term cannabis use has been associated with the appearance of psychotic symptoms and schizophrenia-like cognitive impairments; however these studies may be confounded by concomitant use of tobacco by cannabis users. We aimed to determine if previously observed cannabis-associated deficits in sensory gating would be seen in cannabis users with no history of tobacco use, as evidenced by changes in the P50, N100, and P200 event-related potentials. A secondary objective of this study was to examine the effects of acute nicotine administration on cannabis users with no tobacco use history.

METHODS

Three components (P50, N100, P200) of the mid-latency auditory-evoked response (MLAER) were elicited by a paired-stimulus paradigm in 43 healthy, non-tobacco smoking male volunteers between the ages of 18-30. Cannabis users (CU, n = 20) were administered nicotine (6 mg) and placebo gum within a randomized, double-blind design. Non-cannabis users (NU, n = 23) did not receive nicotine.

RESULTS

Between-group sensory gating effects were only observed for the N100, with CUs exhibiting a smaller N100 to S1 of the paired stimulus paradigm, in addition to reduced dN100 (indicating poorer gating). Results revealed no significant sensory gating differences with acute administration of nicotine compared to placebo cannabis conditions.

CONCLUSIONS

These findings suggest a relationship between gating impairment and cannabis use; however, acute nicotine administration nicotine does not appear to impact sensory gating function.

Cannabis and Cognitive Functioning: From Acute to Residual Effects, From Randomized Controlled Trials to Prospective Designs

In recent years, several jurisdictions have revised their regulation policy toward both medical and recreational use of cannabis. These changes have elicited concerns regarding how legalization impacts academic achievement and work performance. This review evaluates the acute and long-term (residual) association between cannabis use and cognitive functioning that underlies poor academic and work performance. Relative to other reviews, this article focuses on cross-over randomized controlled trials and prospective designs given that they allow to test the impairing effects of cannabis exposure at the within-subject level. Acute cannabis cognitive effects are discussed separately for known confounding factors such as levels of delta-9-tetrahydrocannabinol (Δ⁹-THC), Δ⁹-THC:cannabidiol ratio, previous cannabis use and, comorbidity with psychosis-spectrum disorders. The cognitive residual effects of cannabis are detailed in relation to duration of abstinence, frequency of use, comorbidity with psychosis-spectrum disorders, types of cognitive domains assessed, and age of cannabis use initiation. Moreover, considering the fact that adequate longitudinal studies can make inferences about causality between cannabis use and impaired cognitive functioning when disentangling between-subject from within-subject variation, proofs for the three main non-mutually exclusive hypotheses about this relationship will be presented: i) the cognitive vulnerability hypothesis as part of the more general common antecedent hypothesis, ii) the concurrent cannabis impairing hypothesis, and iii) the neurotoxic hypothesis of cannabis. Current research provides evidence for mild to moderate acute cannabis effects on episodic and working memory, processing speed, and executive functions. Mild residual impairing effects were also observed in these exact same cognitive domains, suggesting that adverse effects following cannabis intoxication persist at least days or weeks following cannabis abstinence. Relative to adult-onset, adolescent-onset cannabis use seems to explain the dose-response relationship and is associated with longer lasting residual effects even in mild users (<weekly). The association between cannabis and cognition is likely explained by common antecedents, such that genetic and shared environment factors predispose individuals to both cannabis use and cognitive deficits, and to a lesser degree, neurotoxic effects.

Assessing Changes in Symptoms of Depression and Anxiety During Four Weeks of Cannabis Abstinence Among Adolescents

Background: Cannabis use is prevalent among adolescents, and many report using in attempts to alleviate negative mood and anxiety. Abstinence from substances such as alcohol and tobacco has been reported to improve symptoms of anxiety and depression. Few studies have examined the effect of cannabis abstinence on symptoms of anxiety and depression. Objective: To test the effect of 4 weeks of continuous cannabis abstinence on depressive and anxious symptoms. Methods: Healthy, non-treatment seeking adolescents who used cannabis at least weekly (n = 179) were randomized to either 4 weeks of cannabis abstinence achieved through a contingency management paradigm (CB-Abst) or cannabis use monitoring without an abstinence requirement (CB-Mon). Abstinence was assessed by self-report verified with quantitative assay of urine for cannabinoids. Anxiety and depressive symptoms were assessed weekly with the Mood and Anxiety Symptom Questionnaire (MASQ). Results: Symptoms of depression and anxiety decreased throughout the study for all participants (MASQ-AA: stnd beta = -0.08, p = 0.01, MASQ-GDA: stnd beta = -0.11, p = 0.003, MASQ-GDD: stnd beta = -0.08, p = 0.02) and did not differ significantly between randomization groups (p's > 0.46). Exploratory analyses revealed a trend that abstinence may be associated with greater improvement in symptoms of anxiety and depression among those using cannabis to cope with negative affect and those with potentially hazardous levels of cannabis use. Conclusions: Among adolescents who use cannabis at least weekly, 4 weeks of cannabis abstinence was not associated with a significant change in anxiety or depressive symptoms compared to continued use. For recreational cannabis users who may be concerned about reducing their use for fear of increased symptoms of anxiety and depression, findings suggest that significant symptom worsening may not occur within the first 4 weeks of abstinence. Further studies are needed in clinical populations where anxiety and depression symptoms are measured more frequently and for a longer period of abstinence. Future studies are also needed to determine whether there are subgroups of adolescents who are uniquely impacted by sustained cannabis abstinence.

The Behavioral Sequelae of Cannabis Use in Healthy People: A Systematic Review

Background: Cannabis is known to have a broad range of effects on behavior, including experiencing a "high" and tranquility/relaxation. However, there are several adverse behavioral sequalae that can arise from cannabis use, depending on frequency of use, potency (e.g., THC content), age of onset, and cumulative exposure. This systematic review examined evidence for cannabis-related adverse behavioral sequalae in otherwise healthy human subjects. Methods: Following PRISMA guidelines, we conducted a systematic review of cross-sectional and longitudinal studies from 1990 to 2020 that identified cannabis-related adverse behavioral outcomes in subjects without psychiatric and medical co-morbidities from PubMed and PsychInfo searches. Key search terms included "cannabis" OR "tetrahydrocannabinol" OR "cannabidiol" OR "marijuana" AND "anxiety" OR "depression" OR "psychosis" OR "schizophrenia" "OR "IQ" OR "memory" OR "attention" OR "impulsivity" OR "cognition" OR "education" OR "occupation". Results: Our search detected a total of 2,870 studies, from which we extracted 124 relevant studies from the literature on cannabis effects in the non-clinical population. Effects of cannabis on several behavioral sequelae including cognition, motivation, impulsivity, mood, anxiety, psychosis intelligence, and psychosocial functioning were identified. The preponderance of the evidence suggests that frequency of cannabis use, THC (but not CBD) content, age of onset, and cumulative cannabis exposure can all contribute to these adverse outcomes in individuals without a pre-existing medical condition or psychiatric disorder. The strongest evidence for the negative effects of cannabis are for psychosis and psychosocial functioning. Conclusions: Although more research is needed to determine risk factors for development of adverse behavioral sequelae of cannabis use, these findings underline the importance of understanding vulnerability to the adverse effects of cannabis, which has implications for prevention and treatment of problematic cannabis use.

Effects of Tobacco Smoking Status on Verbal Learning and Memory in Patients With Schizophrenia and Non-Psychiatric Controls

BACKGROUND AND OBJECTIVES

Patients with schizophrenia have higher rates of tobacco smoking compared to the general population. Moreover, these patients have deficits in cognition, including verbal learning and memory. However, it is not clear whether smoking status alters verbal learning and memory in schizophrenia. We examined the effects of smoking abstinence and reinstatement on verbal learning and memory in people with schizophrenia and nonpsychiatric controls and other cognitive domains as exploratory.

METHODS

Smoking participants (N = 28; 14 schizophrenia smokers; 14 nonpsychiatric smokers) were studied under smoking satiated, overnight abstinence and smoking reinstatement conditions. Nonsmokers ( n = 30; 15 schizophrenia nonsmokers; 15 nonpsychiatric nonsmokers) were also studied. A comprehensive cognitive battery was administered including verbal learning and memory using the Hopkins Verbal Learning Test-Revised (HVLT-R).

RESULTS

A 2 (diagnosis) × 2 (smoking status) repeated measures analysis of variance with time (session) as the within-subjects factor and diagnosis and smoking status as the between-subject factors was performed for HVLT-R and other cognitive outcomes. Smoking abstinence produced a decline in verbal memory of the HVLT discrimination index in smokers with schizophrenia that was partially revised by reinstatement, although trends for other HVLT measures were not statistically significant.

CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE

Acute cigarette smoking and abstinence may selectively alter verbal learning and memory deficits in smokers with schizophrenia compared to nonpsychiatric smoking controls and nonsmokers, but additional studies are needed to confirm the preliminary findings in this small sample. (Am J Addict 2019;00:1-9).

Feasibility and effects of galantamine on cognition in humans with cannabis use disorder

BACKGROUND

As long-term use of medicinal and recreational cannabis becomes more common and concentrations of delta-9-tetrahydrocannabinol (THC) in cannabis increase, it is timely to identify strategies to counteract the cognitive effects of cannabinoids.

OBJECTIVE

Galantamine is an acetylcholinesterase inhibitor approved for the treatment of Alzheimer's disease and other dementias. This study aimed to investigate the feasibility of galantamine administration to individuals with cannabis use disorder (CUD), and the effects of galantamine on cognition. We hypothesized galantamine would be well tolerated and would not have procognitive effects in the absence of acute cannabis intoxication.

METHODS

Thirty individuals with CUD (73.5% male, 26.5% female) participated in a randomized, double-blind, parallel-group trial. Participants completed a baseline session followed by a 10-day outpatient treatment period, during which they received either 8 mg/day of galantamine orally or placebo. Cognitive assessments were conducted at three time points and self-reported measures that may impact cognitive performance (cannabis withdrawal, craving, and mood) were completed at six time points.

RESULTS

There were no significant differences in demographic and baseline variables between groups (galantamine vs. placebo). There were no significant adverse effects from galantamine. Cannabis withdrawal and craving continuously decreased over the study. We saw evidence of a modest improvement in cognitive outcomes during the 10-day period, exemplified by a statistically significant increase in measures of response inhibition (increased median reaction time on the Stop Signal Task), and a trend for improvement in measures of attention (increased RVP A'), for both groups. Analyses did not show, however, a significant main effect for treatment or treatment-by-time interactions.

CONCLUSIONS

The findings of this pilot study support the feasibility of the administration of galantamine for individuals with CUD. Adequately powered, randomized, placebo-controlled trials are required to investigate the potential of galantamine to improve cognitive deficits associated with CUD.

Cannabis and mental illness: a review

With the increasing push to legalize cannabis in Western nations, there is a need to gage the potential impact of this policy change on vulnerable populations, such as those with mental illness, including schizophrenia, mood, and anxiety disorders. This is particularly important as there are strong motives in these individuals to seek short-term reward (e.g., "getting high"). Nonetheless, data to support the beneficial effects of cannabis use in psychiatric populations are limited, and potential harms in patients with psychotic and mood disorders have been increasingly documented. This article reviews the effects of cannabis in people with mental illness. Then, we provide a reconciliation of the addiction vulnerability and allostatic hypotheses to explain co-morbidity addiction in mentally ill cannabis users, as well as to further aid in developing a rational framework for the assessment and treatment of problematic cannabis use in these patients.

Therapeutic potential of medicinal marijuana: an educational primer for health care professionals

With the proposed Canadian July 2018 legalization of marijuana through the Cannabis Act, a thorough critical analysis of the current trials on the efficacy of medicinal marijuana (MM) as a treatment option is necessary. This review is particularly important for primary care physicians whose patients may be interested in using MM as an alternative therapy. In response to increased interest in MM, Health Canada released a document in 2013 for general practitioners (GPs) as an educational tool on the efficacy of MM in treating some chronic and acute conditions. Although additional studies have filled in some of the gaps since the release of the Health Canada document, conflicting and inconclusive results continue to pose a challenge for physicians. This review aims to supplement the Health Canada document by providing physicians with a critical yet concise update on the recent advancements made regarding the efficacy of MM as a potential therapeutic option. An update to the literature of 2013 is important given the upcoming changes in legislation on the use of marijuana. Also, we briefly highlight the current recommendations provided by Canadian medical colleges on the parameters that need to be considered prior to authorizing MM use, routes of administration as well as a general overview of the endocannabinoid system as it pertains to cannabis. Lastly, we outline the appropriate medical conditions for which the authorization of MM may present as a practical alternative option in improving patient outcomes as well as individual considerations of which GPs should be mindful. The purpose of this paper is to offer physicians an educational tool that provides a necessary, evidence-based analysis of the therapeutic potential of MM and to ensure physicians are making decisions on the therapeutic use of MM in good faith.

Changes in tobacco consumption in cannabis dependent patients with schizophrenia versus non-psychiatric controls during 28-days of cannabis abstinence

BACKGROUND

Tobacco and cannabis are highly co-morbid in the general population and in patients with schizophrenia. Given the putative causal mechanisms facilitating co-use, it is important to determine how cannabis cessation may influence concurrent tobacco use. Using a 28-day cannabis abstinence paradigm, we prospectively examined changes in tobacco consumption in patients with schizophrenia and controls with cannabis dependence and daily cigarette use.

METHODS

Cannabis dependent patients with schizophrenia (n = 19) and controls (n = 20) completed the study with abstinence rates of 42% and 55%, respectively. Participants completed measures of substance use, withdrawal, and clinical symptoms weekly. Urine samples were collected twice weekly to biochemically verify abstinence.

RESULTS

Patients reported a greater increase in cigarettes smoked per day (CPD) on Day 7 relative to baseline (2.97 cigarette increase for abstinent subgroup, p < .01) compared to controls (.06 cigarette increase for abstinent subgroup, p = .95). Initially, greater reductions in cannabis use related to greater increases in CPD relative to baseline in the patient subsample (simple slope = -2.31, p = .05), but by Day 28, CPD returned to baseline levels independent of cannabis use. CPD changes were unrelated to cannabis withdrawal. Results were similar for changes in caffeine consumption, but not for alcohol.

CONCLUSIONS

Findings suggest transient tobacco substitution for cannabis in patients with schizophrenia. This provides further support for a strong association between cannabis and tobacco in schizophrenia. Future studies should focus on targeting underlying mechanisms that promote co-use to better address potential changes in concurrent substance use during treatment interventions.