Keep off the grass? Cannabis, cognition and addiction

The Relationship of glutamate signaling to cannabis use and schizophrenia

PURPOSE OF REVIEW

This review examines the literature associating cannabis with schizophrenia, glutamate dysregulation in schizophrenia, and cannabis involvement in glutamate pathways. Cannabis use is widespread among adolescents world-wide and is sold legally in many countries for recreational use in a variety of forms. Most people use it without lasting effects, but a portion of individuals have negative reactions that manifest in acute psychotic symptoms, and in some, symptoms continue even after the use of cannabis has ceased. To date, there is a huge gap in our understanding of why this occurs.

RECENT FINDINGS

Recent studies have focused on abnormalities in the glutamate pathway in schizophrenia, the effect of cannabis on the glutamate system, and the role of glutamate in the brain Default Mode Network.

SUMMARY

Given these observations, we hypothesize that perturbance of glutamate neuronal connectivity by cannabis in the brains of individuals genetically at high risk for psychosis will initiate a schizophrenia-like psychosis. Future studies may tie together these diverse observations by combining magnetic resonance spectroscopy (MRS) and functional magnetic resonance imaging (fMRI) of the default resting state network in patients with new onset schizophrenia who do and do not use cannabis compared with nonpsychotic individuals who do and do not use cannabis.

Value signals guiding choices for cannabis versus non-drug rewards in people who use cannabis near-daily

RATIONALE

Despite the critical role of choice processes in substance use disorders, the neurobehavioral mechanisms guiding human decisions about drugs remain poorly understood.

OBJECTIVES

We aimed to characterize the neural encoding of subjective value (SV) for cannabis versus non-drug rewards (snacks) in people who use cannabis on a near-daily/daily frequency (PWUCF) and assessed the impact of cannabis and snack stimuli ('cues') on SV encoding.

METHODS

Twenty-one non-treatment-seeking PWUCF (≥4 days/week; 1 female) participated in an inpatient, crossover experiment with four counterbalanced conditions: 1. neutral cues/cannabis choices; 2. cannabis cues/cannabis choices; 3. neutral cues/snack choices; and 4. snack cues/snack choices. In each condition, participants were exposed to cues before an fMRI scan during which they repeatedly chose between 0-6 cannabis puffs/snacks and a set monetary amount, with randomly-selected choices implemented. The SV signal was operationalized as the neural correlates of the strength of preference for cannabis/snack choices. fMRI data were analyzed for twenty participants.

RESULTS

Despite equivalent choice behavior, SV signals for cannabis, but not snacks, were observed in regions known to encode SV for various rewards (ventromedial prefrontal cortex, vmPFC; ventral striatum; dorsal posterior cingulate cortex, dPCC). SV encoding in vmPFC was stronger for cannabis than snacks. In the dPCC, the impact of cues on SV signals was moderated by reward type.

CONCLUSIONS

PWUCF had expected neural value encoding for cannabis but disrupted non-drug SV encoding, despite equivalent choice behavior. This provides tentative support for theories that highlight dysregulated neural valuation of non-drug rewards as a hallmark of problematic cannabis use.

Effects of cannabis smoke and oral Δ9THC on cognition in young adult and aged rats

RATIONALE

With increasing legalization of recreational and medical cannabis, use of this drug is growing rapidly among older adults. As cannabis can impair cognition in young adults, it is critically important to understand how its consumption interacts with the cognitive profile of aged subjects, who are already at increased risk of decline.

OBJECTIVES

The current study was designed to determine how cannabis influences multiple forms of cognition in young adult and aged rats of both sexes when delivered via two translationally-relevant routes of administration.

METHODS

Rats were exposed acutely to cannabis smoke or chronically to oral Δ9-tetrahydrocannabinol (Δ9THC), followed by cognitive testing.

RESULTS

Acute cannabis smoke enhanced prefrontal cortex-dependent working memory accuracy in aged males, but impaired accuracy in aged females, while having no effects in young adults of either sex. In contrast, the same cannabis smoke regimen had minimal effects on a hippocampus-dependent trial-unique non-matching to location mnemonic task, irrespective of age or sex. Chronic oral consumption of Δ9THC enhanced working memory in aged rats of both sexes, while having no effects in young adults. In contrast, the same Δ9THC regimen did not affect spatial learning and memory in either age group. Minimal age differences were observed in Δ9THC pharmacokinetics with either route of administration.

CONCLUSIONS

The results show that cannabis and Δ9THC can attenuate working memory impairments that emerge in aging. While these enhancing effects do not extend to hippocampus-dependent cognition, cannabis does not appear to exacerbate age-associated impairments in this cognitive domain.

Spanish versions and validation of a series of rating scales and visual analogue scales to assess the subjective effects of cannabis

Cannabis is being legalized for medical and recreational purposes all around the world. However, the understanding of the psychological effects of cannabis is still limited, and it has been previously linked to mental disorders such as schizophrenia. Lately, new scales have been created and adapted to measure its psychological effects. The aim of this study is to create Spanish versions of some of these scales and test their psychometric characteristics. One hundred sixteen participants were recruited from Cannabis Social Clubs (CSC) in Barcelona, Spain. Participants under the effects of their own cannabis completed the Cannabis Experience Questionnaire-modified version (CEQ-mv), Addiction Research Centre Inventory-18 (ARCI-18), Psychotomimetic States Inventory (PSI) and Visual Analogue Scales (VAS). Questionnaires were completed in the CSC, providing a naturalistic setting for the study. Exploratory factor analysis and internal consistency were analyzed. PSI was reduced from a 6-factor to a 4-factor model with adequate to low reliability, ARCI-18 was reduced from a 3-factor to a 2-factor model with good reliability, and VAS were reduced from a 4-factor to a 3-factor model, also with good reliability. These questionnaires showed adequate reliability and can be used in future studies to test the subjective effects of cannabis in clinical and naturalistic settings.

Cannabinoids in Chronic Pain Management: A Review of the History, Efficacy, Applications, and Risks

Background/Objectives: Chronic pain remains a pervasive and challenging public health issue, often resistant to conventional treatments such as opioids, which carry substantial risks of dependency and adverse effects. Cannabinoids, bioactive compounds derived from the Cannabis sativa plant and their synthetic analogs, have emerged as a potential alternative for pain management, leveraging their interaction with the endocannabinoid system to modulate pain and inflammation. Methods: The current, evolving literature regarding the history, efficacy, applications, and safety of cannabinoids in the treatment of chronic pain was reviewed and summarized to provide the most current review of cannabinoids. Results: Evidence suggests that cannabinoids provide moderate efficacy in managing neuropathic pain, fibromyalgia, cancer-related pain, and multiple sclerosis-related spasticity. Patient-reported outcomes further indicate widespread perceptions of cannabinoids as a safer alternative to opioids, with potential opioid-sparing effects. However, the quality of existing evidence is limited by small sample sizes and methodological inconsistencies. Regulatory barriers, including the classification of cannabis as a Schedule I substance in the United States, continue to hinder robust research and clinical integration. Moreover, the risks associated with cannabinoids, such as psychiatric effects, addiction potential, and drug interactions, necessitate cautious application. Conclusions: Cannabinoids represent a promising, albeit complex, alternative for chronic pain management, particularly given the limitations and risks of traditional therapies such as opioids. However, significant deficiencies remain in the research. While smaller trials and systematic reviews indicate therapeutic potential, the quality of evidence is often low due to limited sample sizes, short study durations, and methodological inconsistencies. Large-scale, randomized controlled trials with long-term follow-up are urgently needed to confirm efficacy and safety across diverse patient populations and pain etiologies.

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.

Adolescent THC impacts on mPFC dopamine-mediated cognitive processes in male and female rats

RATIONALE

Adolescent cannabis use is linked to later-life changes in cognition, learning, and memory. Rodent experimental studies suggest Δ9-tetrahydrocannabinol (THC) influences development of circuits underlying these processes, especially in the prefrontal cortex, which matures during adolescence.

OBJECTIVE

We determined how 14 daily THC injections (5 mg/kg) during adolescence persistently impacts medial prefrontal cortex (mPFC) dopamine-dependent cognition.

METHODS

In adult Long Evans rats treated as adolescents with THC (AdoTHC), we quantify performance on two mPFC dopamine-dependent reward-based tasks-strategy set shifting and probabilistic discounting. We also determined how acute dopamine augmentation with amphetamine (0, 0.25, 0.5 mg/kg), or specific chemogenetic stimulation of ventral tegmental area (VTA) dopamine neurons and their projections to mPFC impact probabilistic discounting.

RESULTS

AdoTHC sex-dependently impacts acquisition of cue-guided instrumental reward seeking, but has minimal effects on set-shifting or probabilistic discounting in either sex. When we challenged dopamine circuits acutely with amphetamine during probabilistic discounting, we found reduced discounting of improbable reward options, with AdoTHC rats being more sensitive to these effects than controls. In contrast, neither acute chemogenetic stimulation of VTA dopamine neurons nor pathway-specific chemogenetic stimulation of their projection to mPFC impacted probabilistic discounting in control rats, although stimulation of this cortical dopamine projection slightly disrupted choices in AdoTHC rats.

CONCLUSIONS

These studies confirm a marked specificity in the cognitive processes impacted by AdoTHC exposure. They also suggest that some persistent AdoTHC effects may alter amphetamine-induced cognitive changes in a manner independent of VTA dopamine neurons or their projections to mPFC.

Exploring Cortical Interneurons in Substance Use Disorder: From Mechanisms to Therapeutic Perspectives

Interneurons (INs) play a crucial role in the regulation of neural activity within the medial prefrontal cortex (mPFC), a brain region critically involved in executive functions and behavioral control. In recent preclinical studies, dysregulation of INs in the mPFC has been implicated in the pathophysiology of substance use disorder, characterized by vulnerability to chronic drug use. Here, we explore the diversity of mPFC INs and their connectivity and roles in vulnerability to addiction. We also discuss how these INs change over time with drug exposure. Finally, we focus on noninvasive brain stimulation as a therapeutic approach for targeting INs in substance use disorder, highlighting its potential to restore neural circuits.

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.

Cannabidiol Plays a Modulatory Function on the Methamphetamine-Induced Reward Through Hippocampal D2-Like Dopamine Receptors

Methamphetamine (METH), a stimulant that is extremely addictive, directly affects the central nervous system. METH's abuse and consumption are directly linked to mental illnesses, psychosis, and behavioral and cognitive impairments. It may disrupt the reward system and dopaminergic transmission. METH's rewarding qualities are associated with a rise in dopamine. Additionally, cannabidiol (CBD), one of the primary cannabinoid components of the cannabis plant, significantly affects dopaminergic transmission and may aid in reward- and addiction-related behaviors. To shed light on the role of the D2-like dopamine receptor (D2R) in the hippocampal dentate gyrus (DG), the present study examined the effects of CBD on the acquisition and expression of the conditioned place preference (CPP) induced by METH. The function of D2R was ascertained by delivering Sulpiride microinjections, as a D2R antagonist Sulpiride (0.25, 1, and 4 μg/0.5 μL DMSO12%) into the DG. Moreover, an intracerebroventricular injection of CBD at a dose of 10 μg/5 μL for CPP acquisition and 50 μg/5 μL for CPP expression was given to rats. According to the current research, CBD dramatically reduced the acquisition and expression of CPP resulting from METH. However, Sulpiride suppressed the effect of CBD on METH-induced CPP acquisition and expression, with a greater impact on expression experiments. Ultimately, this study proposed that the expression experiment of METH-induced CPP appears to be heavily dependent on D2R in the DG.

Exploring the interplay between cannabinoids and thymic functions

Cannabinoids, derived from the Cannabis sativa plant, have garnered increasing attention for their potential therapeutic applications in various diseases. The pharmacologically active compounds in Cannabis, such as delta-9-tetrahydrocannabinol and cannabidiol, exhibit diverse immunomodulatory properties. Although studies have explored the effects of cannabinoids on immune function, their specific interactions with the thymus, a primary immune organ critical for T-cell development and maturation, remain an intriguing area of investigation. As the thymus plays a fundamental role in shaping the immune repertoire, understanding the interplay between cannabinoids and thymic function may shed light on potential benefits or concerns associated with Cannabis-based therapies. This article aims to provide an overview of the current scientific knowledge regarding the impact of medicinal Cannabis on the thymus and its implications for disease treatment and immune health.

Functional Adaptation in the Brain Habenulo-Mesencephalic Pathway During Cannabinoid Withdrawal

The mesolimbic reward system originating from dopamine neurons in the ventral tegmental area (VTA) of the midbrain shows a profound reduction in function during cannabinoid withdrawal. This condition may underlie aversive states that lead to compulsive drug seeking and relapse. The lateral habenula (LHb) exerts negative control over the VTA via the GABA rostromedial tegmental nucleus (RMTg), representing a potential convergence point for drug-induced opponent processes. We hypothesized that the LHb-RMTg pathway might be causally involved in the hypodopaminergic state during cannabinoid withdrawal. To induce Δ9-tetrahydrocannabinol (THC) dependence, adult male Sprague-Dawley rats were treated with THC (15 mg/kg, i.p.) twice daily for 6.5-7 days. Administration of the cannabinoid antagonist rimonabant (5 mg/kg, i.p.) precipitated a robust behavioral withdrawal syndrome, while abrupt THC suspension caused milder signs of abstinence. Extracellular single unit recordings confirmed a marked decrease in the discharge frequency and burst firing of VTA dopamine neurons during THC withdrawal. The duration of RMTg-evoked inhibition was longer in THC withdrawn rats. Additionally, the spontaneous activity of RMTg neurons and of LHb neurons was strongly depressed during cannabinoid withdrawal. These findings support the hypothesis that functional changes in the habenulo-mesencephalic circuit are implicated in the mechanisms underlying substance use disorders.

The Züri Can study: Can regulated cannabis sales promote lower-risk cannabis use? Mini-review and study protocol

BACKGROUND AND AIMS

Recreational use of cannabis is illegal in most countries. Despite this, it is the third most commonly used psychoactive substance worldwide. As a result of this discrepancy, a growing number of countries have begun to reassess their legal approach to cannabis in recent years. While the health risks of cannabis and potential harm reduction measures are increasingly well understood, there are still significant gaps in knowledge about which regulatory and supply models are effective in promoting lower-risk cannabis use. In this paper, we outline the Züri Can study, which implements and evaluates a regulatory framework for cannabis sales in the city of Zurich, Switzerland, between 2023 and 2026. In addition, we illustrate how the study addresses current knowledge gaps to provide further insight into the potential future regulation of cannabis in Switzerland. To embed the study in the present scientific and political context, we first provide a brief overview of the state of knowledge on cannabis-related health risks and means of reducing them, along with lessons learned from other countries that have implemented varying regulatory systems.

DESIGN AND MEASUREMENTS

2,100 participants will be able to legally purchase cannabis either at a pharmacy, a cannabis social club, or the municipal drug information center over a three-year period. As part of this observational study, participants will be evaluated regarding their cannabis use habits and motives, their knowledge of lower-risk use, and their mental and physical health, among other parameters. Established harm reduction strategies are implemented as an integral part of the study design.

COMMENTS

The study will contribute to a better understanding of the impact of different cannabis distribution models on cannabis use patterns and related health outcomes. The results are expected to assist Swiss and international policy makers in developing evidence-based and public health-oriented regulatory frameworks for cannabis.

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.

Clinical Benefits and Safety of Medical Cannabis Products: A Narrative Review on Natural Extracts

Interest in medical cannabis and cannabis-based medicinal products (CBMPs) has increased greatly in recent years. Two cannabinoids are of principal importance; delta-9-tetrahydrocannabinol (∆9-THC), the primary psychoactive component, and also cannabidiol (CBD), considered non-intoxicating. Each has distinct mechanisms of action and different therapeutic potentials. CBMPs differ in their ∆9-THC and CBD components; predominantly ∆9-THC, balanced formulations with equivalent ∆9-THC and CBD elements, and CBD-predominant products. In this narrative review, we evaluate the published evidence for the clinical benefits of CBMPs and overall benefits in well-being. We also review the overall safety profile and discuss the potential for dependence with CBMPs. Evidence can be drawn from a wide range of randomized and other controlled studies and from observational real-world studies. Most data from observational registry studies are supportive of ∆9-THC-based products (∆9-THC-predominant or balanced CBMPs) in the management of chronic neuropathic pain. Balanced products are also effective in reducing spasticity in multiple sclerosis. Most CBMPs show benefit in providing symptomatic benefits in reducing anxiety, nausea, and in improving sleep, but the place of specific products is more subtle, and choice guided by specific circumstances. Symptomatic improvements are accompanied by improved quality of life and well-being. Safety data indicate that CBMPs are generally well tolerated in most patients without specific contraindications. The majority of adverse effects are non-serious, and transient; most are principally associated with ∆9-THC and are dose-dependent. In contrast to recreational cannabis use, there is little evidence from clinical studies that CBMPs have any potential for dependence.

The Development of Cannabinoids as Therapeutic Agents in the United States

Cannabis is one of the oldest and widely used substances in the world. Cannabinoids within the cannabis plant, known as phytocannabinoids, mediate cannabis' effects through interactions with the body's endogenous cannabinoid system. This endogenous system, the endocannabinoid system, has important roles in physical and mental health. These roles point to the potential to develop cannabinoids as therapeutic agents while underscoring the risks related to interfering with the endogenous system during nonmedical use. This scoping narrative review synthesizes the current evidence for both the therapeutic and adverse effects of the major (i.e., Δ9-tetrahydrocannabinol and cannabidiol) and lesser studied minor phytocannabinoids, from nonclinical to clinical research. We pay particular attention to the areas where evidence is well established, including analgesic effects after acute exposures and neurocognitive risks after acute and chronic use. In addition, drug development considerations for cannabinoids as therapeutic agents within the United States are reviewed. The proposed clinical study design considerations encourage methodological standards for greater scientific rigor and reproducibility to ultimately extend our knowledge of the risks and benefits of cannabinoids for patients and providers. SIGNIFICANCE STATEMENT: This work provides a review of prior research related to phytocannabinoids, including therapeutic potential and known risks in the context of drug development within the United States. We also provide study design considerations for future cannabinoid drug development.

Cannabidiol for treatment of Irritability and Aggressive Behavior in Children and Adolescents with ASD: Background and Methods of the CAnnabidiol Study in Children with Autism Spectrum DisordEr (CASCADE) Study

Introduction

Autism spectrum disorder (ASD) is a neurodevelopmental disorder commonly associated with behavioral challenges. There are few evidence based pharmacological interventions available for the treatment of behavioral symptoms associated with ASD. Cannabidiol (CBD), the non-psychoactive component of cannabis, has potential neuroprotective, antiepileptic, anxiolytic, and antipsychotic effects and may be useful in treating the behavioral symptoms of ASD.

Methods

We describe the research methods of a 27-week double-blind placebo-controlled cross-over trial of cannabidiol for the treatment of irritability and aggression associated with ASD, utilizing the irritability subscale of the Aberrant Behavior Checklist-2nd edition (ABC-2) as the primary outcome measure. Adverse effects and safety monitoring protocols are included. Several secondary and exploratory outcomes measures also include anxiety, communication, repetitive behaviors, attention, hyperactivity, autism family experience, and telehealth functional behavior assessment.

Conclusion

There is a significant need for clinical research exploring alternative medications for the treatment of behavioral symptoms of ASD. Cannabidiol (CBD) is being studied for the management of irritability, aggression, and other problem behaviors associated with ASD.

Adolescent THC impacts on mPFC dopamine-mediated cognitive processes in male and female rats

Rationale

Adolescent cannabis use is linked to later-life changes in cognition, learning, and memory. Rodent experimental studies suggest Δ9-tetrahydrocannabinol (THC) influences development of circuits underlying these processes, especially in the prefrontal cortex, which matures during adolescence.

Objective

We determined how 14 daily THC injections (5mg/kg) during adolescence persistently impacts medial prefrontal cortex (mPFC) dopamine-dependent cognition.

Methods

In adult Long Evans rats treated as adolescents with THC (AdoTHC), we quantify performance on two mPFC dopamine-dependent reward-based tasks-strategy set shifting and probabilistic discounting. We also determined how acute dopamine augmentation with amphetamine (0, 0.25, 0.5 mg/kg), or specific chemogenetic stimulation of ventral tegmental area (VTA) dopamine neurons and their projections to mPFC impacts probabilistic discounting.

Results

AdoTHC sex-dependently impacts acquisition of cue-guided instrumental reward seeking, but has minimal effects on set-shifting or probabilistic discounting in either sex. When we challenged dopamine circuits acutely with amphetamine during probabilistic discounting, we found reduced discounting of improbable reward options, with AdoTHC rats being more sensitive to these effects than controls. In contrast, neither acute chemogenetic stimulation of VTA dopamine neurons nor pathway-specific chemogenetic stimulation of their projection to mPFC impacted probabilistic discounting in control rats, although stimulation of this cortical dopamine projection slightly disrupted choices in AdoTHC rats.

Conclusions

These studies confirm a marked specificity in the cognitive processes impacted by AdoTHC exposure. They also suggest that some persistent AdoTHC effects may alter amphetamine-induced cognitive changes in a manner independent of VTA dopamine neurons or their projections to mPFC.

Neurological Complications of Cannabinoids

Cannabinoid use, particularly for recreational purposes, is increasing exponentially across all age groups, especially in younger populations, due to its perceived low risk and legalization. While cannabinoids may be largely considered as safe, there is mounting evidence of increased risk of systemic and neurological complications through their interaction with the poorly understood endocannabinoid receptor network within the central nervous system and other organ systems. Acute cannabinoid exposure can cause neuropsychiatric symptoms in addition to altering cerebral blood flow, leading to cerebrovascular complications such as ischemic stroke, subarachnoid hemorrhage, and reversible cerebral vasoconstriction syndrome (RCVS). Chronic use, particularly among adolescents, may be associated with increased risk of long-term cognitive deficits, schizophrenia, and other neuropsychiatric effects. Synthetic cannabinoids have increased potency, with reports of causing profound neurological complications including coma, seizures, posterior reversible encephalopathy syndrome, and RCVS. Despite increasing evidence, the quality of literature describing neurologic complications with cannabinoids remains limited to case series and retrospective cohort studies, with significant confounding factors such as concomitant use of other illicit drugs, limiting interpretation. In this review, we summarize the effect of cannabinoids on the neurologic system and associated neurological complications.

Exploring causal mechanisms of psychosis risk

Robust epidemiological evidence of risk and protective factors for psychosis is essential to inform preventive interventions. Previous evidence syntheses have classified these risk and protective factors according to their strength of association with psychosis. In this critical review we appraise the distinct and overlapping mechanisms of 25 key environmental risk factors for psychosis, and link these to mechanistic pathways that may contribute to neurochemical alterations hypothesised to underlie psychotic symptoms. We then discuss the implications of our findings for future research, specifically considering interactions between factors, exploring universal and subgroup-specific factors, improving understanding of temporality and risk dynamics, standardising operationalisation and measurement of risk and protective factors, and developing preventive interventions targeting risk and protective factors.

What can we learn from low-THC cannabis growers in Europe? A comparative transnational study of small-scale cannabis growers from Italy and Switzerland

BACKGROUND

A market for cannabis with low levels (LT) of Tetrahydrocannabinol (THC) has recently emerged in Europe alongside an ongoing trend of domestic cannabis cultivation with high-THC content (HT). This phenomenon may have diversified the growers' profile. This study investigates LT growers' (LTG) characteristics (demographics, consumption patterns, growing experience) and growing motivations with a subsequent comparison with HT growers (HTG).

METHODS

Data from 11,479 small-scale growers was collected through an online survey (ICCQ 2) conducted by the Global Cannabis Cultivation Research Consortium (GCCRC) from 2020 to 2021. This exploratory study analyses a subsample of the 1618 respondents residing in Italy and Switzerland. A quantitative approach was used, performing comparative bivariate and multivariate analyses between participants who have only grown HT plants in the previous year (HTG; n = 1303) and those who have either grown LT only or alongside HT (LTG; n = 315).

RESULTS

LTGs differ significantly from HTGs. LTGs are older than HTGs. Growing medical cannabis for oneself and others is more likely among them than HTGs. Compared to HTGs, LTGs have lesser odds to grow for recreational use and to have problematic cannabis use. Growing for legality, pleasure and accessing milder cannabis is more likely for LTGs than HTGs. HTGs have greater experience than HTGs, growing for longer, more extensively and better meeting their consumption needs. There is a wider production of by-products, such as oils and extracts, among LTGs than HTGs. Having been in contact with the police for growing is also more likely among them than HTGs.

CONCLUSION

LTGs reported significantly more growing experience when compared to HTGs and should be considered a distinct group of growers. The results suggest that the emergence of the legal LT market has more likely drawn previous HTGs into growing LT, mainly medically, rather than attracting new individuals toward cannabis cultivation.

Impairments of Sociocognitive Functions in Individuals with Behavioral Addictions: A Review Article

Since little is known about the exact pattern of social cognitive impairments related to behavioral addictions, the aim of the PRISMA-oriented review was to (i) provide an overview of relevant empirical publications, and to (ii) to elucidate which specific aspects of social cognition (i.e., emotion recognition, empathy, and theory of mind (ToM)) are impaired in different types of behavioral addictions. Behavioral addictions have been associated with cognitive deficits which may contribute to impaired social cognitive functioning. More recently, this domain has been investigated in patients with behavioral addictions as impaired social cognition detrimentally affects daily functioning and thus forms a relevant target for treatment. A systematic search in the PubMed and Web of Science databases was performed focusing on social cognitive functions in behavioral addictions. Studies focusing on the same social cognitive component were grouped together, this was done based on the used assessment measures. In total, 18 studies met the specified inclusion criteria. Five studies focusing on emotion recognition concluded that individuals with behavioral addictions show impairments in this domain. As for the 13 studies focusing on empathy and/or ToM, most of them found deficits linked to different types of behavioral addictions. Only two studies, one of which was investigating a distinct population (multiplayer online role-playing gamers) did not link empathy to behavioral addictions. The results show that the majority of studies focusing on social cognition and behavioral addictions found some deficits. Additional research focusing on this topic is urgently needed in behavioral addictions, addressing several methodological issues.

Perceptions, Experiences, and Patterns of Cannabis Use in Individuals with Mood and Anxiety Disorders in the Context of Cannabis Legalization and Medical Cannabis Program in Canada - A Qualitative Study

INTRODUCTION

Perceptions of cannabis as a potential medical treatment for mood and anxiety disorders have been increasing in the context of legalizations, availability, and medical cannabis programs, though current evidence predominately indicates risks and negative effects of cannabis use (CU) on mental health outcomes. This study aims to understand motivations, perceptions, effects, and patterns of CU in individuals with mood and anxiety disorders.

METHODS

Thirty-six adult patients diagnosed with mood or anxiety disorders, obsessive-compulsive disorder, or posttraumatic stress disorder who were currently using cannabis completed an in-depth qualitative interview on individual motivations, perceptions, experiences, effects, and patterns of their CU. The thematic analysis focused on phases of CU and sources of cannabis products and information.

RESULTS

Reported motivations for initiation of CU included curiosity, peer pressure, and dissatisfaction with conventional treatments. Factors such as psychotropic effects and coping with mental health symptoms and insomnia contributed to the continuation of CU. More negative effects, including cognitive dysfunction, worsening of mood, and anxiety symptoms, were acknowledged with ongoing CU. Concerning findings included common initiation of CU before age 18, combined medical and recreational CU, rare consultation of medical professionals on CU, and potential effects and harms.

DISCUSSION

Findings indicate individual complexity of motivations, perceptions, and patterns of CU in the study population. The reported potential beneficial effects of specific cannabis products should be further investigated. Findings emphasize patient-provider dialogue on both CU and conventional treatments. Information from this study can contribute to and inform the development of education, prevention, and intervention strategies.

The risk of cannabis use disorder is mediated by altered brain connectivity: A chronnectome study

The brain mechanisms underlying the risk of cannabis use disorder (CUD) are poorly understood. Several studies have reported changes in functional connectivity (FC) in CUD, although none have focused on the study of time-varying patterns of FC. To fill this important gap of knowledge, 39 individuals at risk for CUD and 55 controls, stratified by their score on a self-screening questionnaire for cannabis-related problems (CUDIT-R), underwent resting-state functional magnetic resonance imaging. Dynamic functional connectivity (dFNC) was estimated using independent component analysis, sliding-time window correlations, cluster states and meta-state indices of global dynamics and were compared among groups. At-risk individuals stayed longer in a cluster state with higher within and reduced between network dFNC for the subcortical, sensory-motor, visual, cognitive-control and default-mode networks, relative to controls. More globally, at-risk individuals had a greater number of meta-states and transitions between them and a longer state span and total distance between meta-states in the state space. Our findings suggest that the risk of CUD is associated with an increased dynamic fluidity and dynamic range of FC. This may result in altered stability and engagement of the brain networks, which can ultimately translate into altered cortical and subcortical function conveying CUD risk. Identifying these changes in brain function can pave the way for early pharmacological and neurostimulation treatment of CUD, as much as they could facilitate the stratification of high-risk individuals.

Cannabis Use Characteristics Associated with Self-Reported Cognitive Function in a Nationally Representative U.S. sample

BACKGROUND

With increases in cannabis use and potency, there is a need to improve our understanding of the impact of use on cognitive function. Previous research indicates long-term cannabis use may have a negative effect on executive function. Few studies have examined persistence of it in protracted abstinence, and there is limited evidence of predictors of worse cognitive function in current and former users. In this study, we aim to evaluate the associations between cannabis use status (current, former, and never use) and self-report cognition. Further, we investigate if cannabis use characteristics predict self-report cognitive function.

METHODS

Cross-sectional cannabis use data from the National Epidemiological Survey on Alcohol and Related Conditions-III (NESARC-III), a national survey (N = 36,309) conducted in the USA between 2012 and 2013 were used alongside the Executive Function Index scales. The data were analyzed by using Ordinary Least Squares regression.

RESULTS

Current (N = 3,681, Female = 37.7%) and former users (N = 7,448, Female = 45.4%) reported poorer cognition than never users (N = 24,956, Female = 56.6%). Self-reported cognition of former users was in-between that of current and never users. Several cannabis use characteristics were associated with self-reported cognition in current and former users.

CONCLUSION

While prospective studies are required to confirm, findings suggest cannabis use is linked to worse cognition. There may be some limited recovery of cognition in former users and some cannabis use characteristics predict impairment. These findings add to our understanding of the cognitive impact of cannabis use. As worse cognitive function may impact relapse, findings have implications for personalization of cannabis use disorder treatment.

Amyotrophic Lateral Sclerosis and Pain: A Narrative Review from Pain Assessment to Therapy

Amyotrophic lateral sclerosis (ALS) is the most frequent neurodegenerative disease of the motor system that affects upper and lower motor neurons, leading to progressive muscle weakness, spasticity, atrophy, and respiratory failure, with a life expectancy of 2-5 years after symptom onset. In addition to motor symptoms, patients with ALS have a multitude of nonmotor symptoms; in fact, it is currently considered a multisystem disease. The purpose of our narrative review is to evaluate the different types of pain, the correlation between pain and the disease's stages, the pain assessment tools in ALS patients, and the available therapies focusing above all on the benefits of cannabis use. Pain is an underestimated and undertreated symptom that, in the last few years, has received more attention from research because it has a strong impact on the quality of life of these patients. The prevalence of pain is between 15% and 85% of ALS patients, and the studies on the type and intensity of pain are controversial. The absence of pain assessment tools validated in the ALS population and the dissimilar study designs influence the knowledge of ALS pain and consequently the pharmacological therapy. Several studies suggest that ALS is associated with changes in the endocannabinoid system, and the use of cannabis could slow the disease progression due to its neuroprotective action and act on pain, spasticity, cramps, sialorrhea, and depression. Our research has shown high patients' satisfaction with the use of cannabis for the treatment of spasticity and related pain. However, especially due to the ethical problems and the lack of interest of pharmaceutical companies, further studies are needed to ensure the most appropriate care for ALS patients.

Effects of Cannabidiol and Delta-9-Tetrahydrocannabinol on Plasma Endocannabinoid Levels in Healthy Volunteers: A Randomized Double-Blind Four-Arm Crossover Study

Background: The effects of cannabis are thought to be mediated by interactions between its constituents and the endocannabinoid system. Delta-9-tetrahydrocannabinol (THC) binds to central cannabinoid receptors, while cannabidiol (CBD) may influence endocannabinoid function without directly acting on cannabinoid receptors. We examined the effects of THC coadministered with different doses of CBD on plasma levels of endocannabinoids in healthy volunteers. Methods: In a randomized, double-blind, four-arm crossover study, healthy volunteers (n=46) inhaled cannabis vapor containing 10 mg THC plus either 0, 10, 20, or 30 mg CBD, in four experimental sessions. The median time between sessions was 14 days (IQR=20). Blood samples were taken precannabis inhalation and at 0-, 5-, 15-, and 90-min postinhalation. Plasma concentrations of THC, CBD, anandamide, 2-arachidonoylglycerol (2-AG), and related noncannabinoid lipids were measured using liquid chromatography-mass spectrometry. Results: Administration of cannabis induced acute increases in plasma concentrations of anandamide (+18.0%, 0.042 ng/mL [95%CI: 0.023-0.062]), and the noncannabinoid ethanolamides, docosatetraenylethanolamide (DEA; +35.8%, 0.012 ng/mL [95%CI: 0.008-0.016]), oleoylethanolamide (+16.1%, 0.184 ng/mL [95%CI: 0.076-0.293]), and N-arachidonoyl-L-serine (+25.1%, 0.011 ng/mL [95%CI: 0.004-0.017]) (p<0.05). CBD had no significant effect on the plasma concentration of anandamide, 2-AG or related noncannabinoid lipids at any of three doses used. Over the four sessions, there were progressive decreases in the preinhalation concentrations of anandamide and DEA, from 0.254 ng/mL [95%CI: 0.223-0.286] to 0.194 ng/mL [95%CI: 0.163-0.226], and from 0.039 ng/mL [95%CI: 0.032-0.045] to 0.027 ng/mL [95%CI: 0.020-0.034] (p<0.05), respectively. Discussion: THC induced acute increases in plasma levels of anandamide and noncannabinoid ethanolamides, but there was no evidence that these effects were influenced by the coadministration of CBD. It is possible that such effects may be evident with higher doses of CBD or after chronic administration. The progressive reduction in pretreatment anandamide and DEA levels across sessions may be related to repeated exposure to THC or participants becoming less anxious about the testing procedure and requires further investigation. The study was registered on clinicaltrials.gov (NCT05170217).

Apathy and Motivation: Biological Basis and Drug Treatment

Apathy is a disabling syndrome associated with poor functional outcomes that is common across a broad range of neurological and psychiatric conditions. Currently, there are no established therapies specifically for the condition, and safe and effective treatments are urgently needed. Advances in the understanding of motivation and goal-directed behavior in humans and animals have shed light on the cognitive and neurobiological mechanisms contributing to apathy, providing an important foundation for the development of new treatments. Here, we review the cognitive components, neural circuitry, and pharmacology of apathy and motivation, highlighting converging evidence of shared transdiagnostic mechanisms. Though no pharmacological treatments have yet been licensed, we summarize trials of existing and novel compounds to date, identifying several promising candidates for clinical use and avenues of future drug development.

The potential for medicinal cannabis to help manage challenging behaviour in people with intellectual disability: A perspective review

BACKGROUND

Around 2% of the population have intellectual disabilities. Over one-third people with intellectual disabilities (PwID) present with 'challenging behaviour', which nosologically and diagnostically is an abstract concept. Challenging behaviour is influenced by a range of bio-psycho-social factors in a population, which is unable to suitably comprehend and/or communicate concerns. This predisposes to poor health and social outcomes. There is no evidence-based treatments for managing challenging behaviour. Cannabidiol (CBD) and tetrahydrocannabinol (THC) are being trialled for a range of disorders, which are over-represented in PwID and provoke challenging behaviours, such as severe epilepsy, spasticity, post-traumatic stress disorder, social phobia, pain, etc.

METHODS

This perspective review explores the different conditions, which benefit from medicinal CBD/THC preparations, by analysing recent literature from neurobiological, pre-clinical and clinical studies related to the topic. The evidence is synthesised to build an argument of the therapeutic benefits and challenges of medicinal cannabis to manage severe challenging behaviour in PwID.

RESULTS

There is developing evidence of medicinal CBD/THC improving psychiatric and behavioural presentations in general. In particular, there is emergent proof in certain key areas of influence of medicinal CBD/THC positively supporting challenging behaviour, for example in children with neurodevelopmental disorders. However, there are significant challenges in employing such treatments in vulnerable populations such as PwID.

CONCLUSION

Further clinical research for the considered use of medicinal CBD/THC for challenging behaviour management in PwID is needed. Strong co-production with experts with lived experience is needed for further testing to be done in this exciting new area.

Current status of Complementary and Alternative Medicine Interventions in the Management of Pancreatic Cancer - An Overview

OPINION STATEMENT

Pancreatic cancer (PC) remains the deadliest cancer worldwide. Most patients are diagnosed at the advanced or metastatic stage, leading to a poor prognosis. Awareness of the limitations of current therapy and accompanying pain, depression, malnutrition, and side effects of chemoradiotherapy may lead patients and physicians towards complementary and alternative medicine (CAM). CAM refers to a diverse set of medical and healthcare practices, products, and systems that are not part of conventional Western medicine. Despite the low-quality evidence supporting the efficacy of these methods, they remain appealing due to patients' beliefs, fear of death, and the slow development of conventional therapy. Hence, the possibility of using natural products for pancreatic cancer is increasing. CAM options such as: medical cannabis, plants, fungi, herbal formulas, and injections, which originate primarily from traditional Chinese or Japanese medicine i.e. Curcuma longa, Panax ginseng, Poria cocos, Hochuekkito, Juzentaihoto, and Rikkunshito, Shi-quan-da-bu-tang/TJ-48, Huang-qin-tang, Shuangbai San, Wen Jing Zhi Tong Fang, Xiang-Sha-Liu-jun-zi-tang, Aidi injection, Brucea javanica oil emulsion/Yadanziyouru injection, Compound Kushen injection, Huachansu injection, Kangai injection and Kanglaite injections are becoming promising candidates for the management of pancreatic cancer. The abovementioned substances/medications are the most popular or potentially effective in PC treatment and consequently CAM-based adjuvant therapy through improving patients' quality of life, might be a useful addition in the treatment of pancreatic cancer patients.

Canadian cannabis education resources to support youth health literacy: A scoping review and environmental scan

Background

The 2018 legalisation of cannabis in Canada sparked concern and conversation about the potential negative impacts of youth cannabis use. It is clear that young people are already engaging in cannabis use for a variety of reasons; therefore, youth cannabis education is desirable to promote harm reduction and reduce the risk of adverse physical and mental health outcomes.

Objective

To identify and categorise Canadian cannabis education resources using a social-ecological approach informed by the youth health literacy framework, considering multiple factors at the micro-, meso- and macro-levels that influence health literacy and impact behaviour.

Methods

In line with scoping review methodology, database searches and an environmental scan of materials were completed. Specific inclusion criteria were identified to encompass all Canadian cannabis education resources directed towards young people aged 9-18 years and adults in contact with youth.

Results

A total of 60 resources were identified and categorised using the youth health literacy framework in terms of their focus on (1) micro influences (resources for youth); (2) meso influences (resources for teachers, parents, mentors); and (3) macro influences (resources for indigenous communities and medical professionals).

Conclusions

While many resources were identified, issues exist with the accessibility, quality and multicultural considerations of such resources, warranting the development of comprehensive, evidence-based and harm reduction-focused cannabis education for youth.

Neuropsychological functioning of patients with major depression or bipolar disorder comorbid to substance use disorders: A systematic review

Major depression disorder (MDD) and bipolar disorder (BD) are usual comorbidities in patients with substance use disorders (SUD), a condition known as dual disorder (DD). MDD, BD and SUD are associated with cognitive impairment, potentially leading to a greater functional impairment in the context of DD.

OBJECTIVES

To review the existing data on the cognitive impairment in DD patients with comorbid MDD or BD, considering the influence of the depressive symptomatology.

METHODS

Following the PRISMA protocol 19 studies were selected from the last 17 years, 13 of which focused on BD, five on MDD and one included both diagnoses.

RESULTS

Studies based in BD+SUD showed that the most affected cognitive domains were attention and executive functions, but not all of them found a greater impairment due to the comorbidity. While fewer studies were found for depression, MDD+SUD works point to a similar impairment cognitive pattern. Furthermore, depression improvement could be associated to better cognitive performance.

LIMITATIONS

More standardized research is needed regarding the influence of depression on cognitive performance of DD patients, especially on those with comorbid MDD. Factors such as main substance, abstinence, or MDD/BD-related variables should be considered. Unstudied factors, like gender or circadian rhythms, are proposed to improve knowledge in this area.

CONCLUSIONS

Current studies suggest that DD could potentiate cognitive impairment in BD, MDD and SUD. However, additional research is needed to improve the understanding of comorbidity to apply more individualized therapies in the treatment of these patients, considering the interference of their neurocognitive functioning.

Acute effects of Δ9-tetrahydrocannabinol (THC) on resting state connectivity networks and impact of COMT genotype: A multi-site pharmacological fMRI study

BACKGROUND

Cannabis produces various acute psychotropic effects, with marked individual differences. Cannabis use is a risk factor for developing psychotic disorders. The main component responsible for these effects is Δ9-tetrahydrocannabinol (THC). Here we investigated the neural basis of acute THC effects and its modulation by catechol-methyl-transferase (COMT) Val158Met genotype.

METHODS

Resting state functional MRI data of healthy occasional cannabis users were combined and re-analyzed from three double-blind, placebo-controlled, within-subject pharmacological functional magnetic resonance imaging studies (total N=87). Functional connectivity after placebo and THC was compared in three functional networks (salience, executive and default mode network) and a network implicated in psychosis (the hippocampus-midbrain-striatum network). COMT genotype modulation of subjective effects and connectivity was examined.

RESULTS

THC reduced connectivity in the salience network, specifically from the right insula to both the left insula and anterior cingulate cortex. We found a trend towards decreased connectivity in the hippocampus-midbrain-striatum network after THC. COMT genotype modulated subjective effects of THC, with strongest dysphoric reactions in Met/Met individuals. In addition, reduced connectivity after THC was demonstrated in the hippocampus-midbrain-striatum network of Met/Met individuals only.

CONCLUSIONS

In this large multisite study we found that THC robustly decreases connectivity in the salience network, involved in processing awareness and salient information. Connectivity changes in the hippocampus-midbrain-striatum network may reflect the acute psychotic-like effects of THC. COMT genotype modulation of THC's impact on subjective effects and functional connectivity provides further evidence for involvement of prefrontal dopamine levels in the acute effects of cannabis.

Associations between regular cannabis use and brain resting-state functional connectivity in adolescents and adults

BACKGROUND/AIM

Cannabis use is highly prevalent in adolescents; however, little is known about its effects on adolescent brain function.

METHOD

Resting-state functional magnetic resonance imaging was used in matched groups of regular cannabis users (N = 70, 35 adolescents: 16-17 years old, 35 adults: 26-29 years old) and non-regular-using controls (N = 70, 35 adolescents/35 adults). Pre-registered analyses examined the connectivity of seven major cortical and sub-cortical brain networks (default mode network, executive control network (ECN), salience network, hippocampal network and three striatal networks) using seed-based analysis methods with cross-sectional comparisons between user groups and age groups.

RESULTS

The regular cannabis use group (across both age groups), relative to controls, showed localised increases in connectivity only in the ECN analysis. All networks showed localised connectivity differences based on age group, with the adolescents generally showing weaker connectivity than adults, consistent with the developmental effects. Mean connectivity across entire network regions of interest (ROIs) was also significantly decreased in the ECN in adolescents. However, there were no significant interactions found between age group and user group in any of the seed-based or ROI analyses. There were also no associations found between cannabis use frequency and any of the derived connectivity measures.

CONCLUSION

Regular cannabis use is associated with changes in connectivity of the ECN, which may reflect allostatic or compensatory changes in response to regular cannabis intoxication. However, these associations were not significantly different in adolescents compared to adults.

Combined exposure to alcohol and cannabis during development: Mechanisms and outcomes

Exposure to substances of abuse during pregnancy can have long-lasting effects on offspring. Alcohol is one of the most widely used substances of abuse that leads to the most severe consequences. Recent studies in the United States, Canada, and the United Kingdom showed that between 1% and 7% of all children exhibit signs and symptoms of fetal alcohol spectrum disorder (FASD). Despite preventive campaigns, the rate of children with FASD has not decreased during recent decades. Alcohol consumption often accompanies exposure to such drugs as tobacco, cocaine, opioids, and cannabis. These interactions can be synergistic and exacerbate the deleterious consequences of developmental alcohol exposure. The present review focuses on interactions between alcohol and cannabis exposure and the potential consequences of these interactions.

Mechanisms of cannabinoid tolerance

Cannabis has been used recreationally and medically for centuries, yet research into understanding the mechanisms of its therapeutic effects has only recently garnered more attention. There is evidence to support the use of cannabinoids for the treatment of chronic pain, muscle spasticity, nausea and vomiting due to chemotherapy, improving weight gain in HIV-related cachexia, emesis, sleep disorders, managing symptoms in Tourette syndrome, and patient-reported muscle spasticity from multiple sclerosis. However, tolerance and the risk for cannabis use disorder are two significant disadvantages for cannabinoid-based therapies in humans. Recent work has revealed prominent sex differences in the acute response and tolerance to cannabinoids in both humans and animal models. This review will discuss evidence demonstrating cannabinoid tolerance in rodents, non-human primates, and humans and our current understanding of the neuroadaptations occurring at the cannabinoid type 1 receptor (CB1R) that are responsible tolerance. CB1R expression is downregulated in tolerant animals and humans while there is strong evidence of CB1R desensitization in cannabinoid tolerant rodent models. Throughout the review, critical knowledge gaps are indicated and discussed, such as the lack of a neuroimaging probe to assess CB1R desensitization in humans. The review discusses the intracellular signaling pathways that are responsible for mediating CB1R desensitization and downregulation including the action of G protein-coupled receptor kinases, β-arrestin2 recruitment, c-Jun N-terminal kinases, protein kinase A, and the intracellular trafficking of CB1R. Finally, the review discusses approaches to reduce cannabinoid tolerance in humans based on our current understanding of the neuroadaptations and mechanisms responsible for this process.

Cannabis use breaks in young adults: The highs and lows of tolerance breaks

BACKGROUND/PURPOSE

Cannabis tolerance breaks, or T-breaks, are believed to benefit persons who use cannabis (PUCs) by decreasing tolerance levels to cannabis. However, no prior research, to our knowledge, has compared the effects of T-breaks and other use breaks on cannabis use patterns and outcomes. The current study examined whether the occurrence of cannabis use breaks (tolerance and other use breaks), or the duration of these breaks, is associated with changes in hazardous cannabis use (CUDIT-R), CUD severity, cannabis use frequency, and withdrawal symptoms over a 6-month follow-up.

METHODS

Young adults, who recreationally use cannabis, (N=170, 55.9% female, Mean age=21 yo) completed baseline and on-time 6-month assessments of hazardous cannabis use (CUDIT-R), CUD severity, cannabis use frequency, and withdrawal symptoms. The occurrence of cannabis use breaks and the duration of these breaks during the intervening period was assessed at 6 months.

RESULTS

Taking a T-break was associated with an increase in hazardous cannabis use and CUD severity at 6 months. When considering cannabis use breaks for other reasons, a longer break was associated with a significant decrease in hazardous cannabis use (CUDIT-R), CUD severity, and cannabis use frequency at 6 months.

CONCLUSION

Findings from our study suggest recreational PUCs who take a T-break may be at greater risk for problematic cannabis use. In addition, taking a longer cannabis use break for other reasons may have beneficial effects on cannabis-related outcomes. The ability to abstain from cannabis for other reasons may be protective while individuals who take T-breaks may be important targets for intervention and prevention.

The Skin and Natural Cannabinoids-Topical and Transdermal Applications

The chemical constituents of the Cannabis plant known as cannabinoids have been extensively researched for their potential therapeutic benefits. The use of cannabinoids applied to the skin as a potential method for both skin-related benefits and systemic administration has attracted increasing interest in recent years. This review aims to present an overview of the most recent scientific research on cannabinoids used topically, including their potential advantages for treating a number of skin conditions like psoriasis, atopic dermatitis, and acne. Additionally, with a focus on the pharmacokinetics and security of this route of administration, we investigate the potential of the transdermal delivery of cannabinoids as a method of systemic administration. The review also discusses the restrictions and difficulties related to the application of cannabinoids on the skin, emphasizing the potential of topical cannabinoids as a promising route for both localized and systemic administration. More studies are required to fully comprehend the efficacy and safety of cannabinoids in various settings.

Attention-deficit/hyperactivity disorder (ADHD) symptoms and their relation to diagnosed ADHD, sociodemographic characteristics, and substance use among patients receiving opioid agonist therapy: a Norwegian cohort study

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) symptoms may challenge sufficient treatment of substance use and mental disorders. The literature on the extent of such symptoms among patients receiving opioid agonist therapy (OAT) is scarce. This study examined ADHD symptoms using the ADHD self-report scale (ASRS) and the association between the 'ASRS-memory' and 'ASRS-attention' scores and substance use and sociodemographic characteristics among patients receiving OAT.

METHODS

We used data from assessment visits of a cohort of patients in Norway. In total, 701 patients were included from May 2017 to March 2022. All patients responded at least once to two ASRS questions assessing memory and attention, respectively. Ordinal regression analyses were performed to investigate whether the two obtained scores were associated with age, sex, frequent substance use, injecting use, housing status, and educational attainment at baseline, i.e., the first assessment, and over time. The results are presented as odds ratios (OR) with 95% confidence intervals (CI). Additionally, a subsample of 225 patients completed an extended interview, including the ASRS-screener and collection of registered mental disorder diagnoses from the medical records. Standard cutoffs were used to define the presence of each ASRS symptom or a positive ASRS-screener ('ASRS-positive').

RESULTS

At baseline, 428 (61%) and 307 (53%) patients scored over the cutoffs on the 'ASRS-memory' and 'ASRS-attention,' respectively. Frequent cannabis use was associated with higher 'ASRS-memory' (OR: 1.7, 95% CI: 1.1-2.6) and 'ASRS-attention' (1.7, 1.1-2.5) scores compared with less or no use at baseline, though reduced score on the 'ASRS-memory' over time (0.7, 0.6-1.0). At baseline, frequent stimulant use (1.8, 1.0-3.2) and low educational attainment (0.1, 0.0-0.8) were associated with higher 'ASRS-memory' scores. In the subsample fulfilling the ASRS-screener, 45% of the patients were 'ASRS-positive,' of whom 13% with a registered ADHD diagnosis.

CONCLUSIONS

Our findings illustrate a relationship between the ASRS-memory and -attention scores and frequent cannabis and stimulant use. Furthermore, nearly half of the subsample was 'ASRS-positive.' Patients receiving OAT might benefit from being further assessed for ADHD, but improved diagnostic methods are required.

Differentiating people who use cannabis heavily through latent class analysis

BACKGROUND

People who use cannabis daily or near-daily vary considerably in their daily dosage and use frequency, impacting both experienced effects and adverse consequences. This study identified heavy cannabis user groups according to consumption patterns and factors associated with class membership.

METHODS

We conducted a cross-sectional study of 380 Spanish residents (61.8% male; average age = 30.3 years) who had used cannabis ≥ 3 days/week throughout the past year. Participants were recruited through chain referral and cannabis social clubs. We applied latent class analysis (LCA) to cluster participants according to use intensity. LCA indicators included frequency of weekly cannabis use, joints smoked each day, cannabis dosage, and if cannabis was consumed throughout the day or only at specific times. Associations between class membership and socio-demographics, use patterns, motives, supply sources, adverse outcomes, and use of other substances were measured using ANOVA and chi-squared tests. Multinomial regression identified the factors associated with latent class membership.

RESULTS

Three latent classes (moderately heavy: 21.8%, heavy: 68.2%, very heavy: 10%) had average weekly cannabis intakes of 2.4, 5.5, and 18.3 g, respectively. Very heavy users were older ([Formula: see text]=17.77, p < 0.01), less educated [Formula: see text]=36.80, p < 0.001), and had used cannabis for longer (F = 4.62, p = 0.01). CAST scores (F = 26.51, p < 0.001) increased across the classes. The prevalence of past-month alcohol use was lower among the heaviest users ([Formula: see text]=5.95, p = 0.05). Cannabis was usually obtained from a club by very heavy users ([Formula: see text]=20.95, p < 0.001).

CONCLUSIONS

People who use cannabis heavily present three groups according to frequency and quantity of cannabis consumption. Use intensity is associated with increased cannabis-related problems. Differences among heavy users must be considered in harm reduction interventions in cannabis clubs and indicated prevention.

Chronic Δ9-tetrahydrocannabinol treatment has dose-dependent effects on open field exploratory behavior and [3H] SR141716A receptor binding in the rat brain

AIMS

Acute and chronic Δ⁹-THC exposure paradigms affect the body differently. More must be known about the impact of chronic Δ⁹-THC on cannabinoid-1 (CB1R) and mu-opioid (MOR) receptor levels in the brain. The present study examined chronic Δ⁹-THC's effects on CB1R and MOR levels and locomotor activity.

MAIN METHODS

Adolescent Sprague-Dawley rats were given daily intraperitoneal injections of Δ⁹-THC [0.75mg/kg (low dose or LD) or 2.0 mg/kg (high dose or HD)] or vehicle for 24 days, and locomotion in the open field was tested after the first and fourth weeks of chronic Δ⁹-THC exposure. Brains were harvested at the end of treatment. [³H] SR141716A and [³H] DAMGO autoradiography assessed CB1R and MOR levels, respectively.

KEY FINDINGS

Relative to each other, chronic HD rats showed reduced vertical plane (VP) entries and time, while LD rats had increased VP entries and time for locomotion, as assessed by open-field testing; no effects were found relative to the control. Autoradiography analyses showed that HD Δ⁹-THC significantly decreased CB1R binding relative to LD Δ⁹-THC in the cingulate (33%), primary motor (42%), secondary motor (33%) somatosensory (38%), rhinal (38%), and auditory (50%) cortices; LD Δ⁹-THC rats displayed elevated binding in the primary motor (33% increase) and hypothalamic (33 % increase) regions compared with controls. No significant differences were observed in MOR binding for the LD or HD compared to the control.

SIGNIFICANCE

These results demonstrate that chronic Δ⁹-THC dose-dependently altered CB1R levels throughout the brain and locomotor activity in the open field.

Different Tokes for Different Folks: Use of Cannabis Products Among a Longitudinal Cohort of People with Heroin Dependence

Co-occurring cannabis use is common among those with opioid use disorder (OUD), but the extent to which it is harmful may be due to its preparation and concentration of various cannabinoids. The current study aimed to examine the prevalence of, and long-term associations with, the use of varying cannabis products among a naturalistic longitudinal cohort of people with heroin dependence. A total of 615 people, most of whom were entering treatment, were recruited to the Australian Treatment Outcome Study (ATOS) in 2001-2002. This analysis focuses on the 401 participants followed up at 18-20 years post baseline. Structured interviews assessed the use of cannabis products, as well as demographic and health covariates. High-potency/indoor-grown cannabis was the most common type ever used (68.8%), and in the past 12 months (80.4%), followed by low potency/outdoor grown (22.4%; 14.4%), and less so for other types of cannabis. After controlling for covariates, older age at baseline was associated with lower odds of high-potency cannabis being used as the primary type in the past 12 months. In contrast to studies of non-opioid dependent populations, common use of high-potency cannabis was not associated with more severe health outcomes.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11469-023-01071-5.

Effects of cannabidiol on anandamide levels in individuals with cannabis use disorder: findings from a randomised clinical trial for the treatment of cannabis use disorder

Cannabidiol (CBD) has shown promise in treating psychiatric disorders, including cannabis use disorder - a major public health burden with no approved pharmacotherapies. However, the mechanisms through which CBD acts are poorly understood. One potential mechanism of CBD is increasing levels of anandamide, which has been implicated in psychiatric disorders including depression and cannabis use disorder. However, there is a lack of placebo-controlled human trials investigating this in psychiatric disorders. We therefore assessed whether CBD affects plasma anandamide levels compared to placebo, within a randomised clinical trial of CBD for the treatment of cannabis use disorder. Individuals meeting criteria for cannabis use disorder and attempting cannabis cessation were randomised to 28-day administration with placebo (n = 23), 400 mg CBD/day (n = 24) or 800 mg CBD/day (n = 23). We estimated the effects of each CBD dose compared to placebo on anandamide levels from baseline to day 28. Analyses were conducted both unadjusted and adjusted for cannabis use during the trial to account for effects of cannabis on the endocannabinoid system. We also investigated whether changes in plasma anandamide levels were associated with clinical outcomes relevant for cannabis use disorder (cannabis use, withdrawal, anxiety, depression). There was an effect of 800 mg CBD compared to placebo on anandamide levels from baseline to day 28 after adjusting for cannabis use. Pairwise comparisons indicated that anandamide levels unexpectedly reduced from baseline to day 28 in the placebo group (-0.048, 95% CI [-0.089, -0.007]), but did not change in the 800 mg CBD group (0.005, 95% CI [-0.036, 0.047]). There was no evidence for an effect of 400 mg CBD compared to placebo. Changes in anandamide levels were not associated with clinical outcomes. In conclusion, this study found preliminary evidence that 28-day treatment with CBD modulates anandamide levels in individuals with cannabis use disorder at doses of 800 mg/day but not 400 mg/day compared to placebo.

Cannabis Use and Endocannabinoid Receptor Genes: A Pilot Study on Their Interaction on Brain Activity in First-Episode Psychosis

The role of both cannabis use and genetic background has been shown in the risk for psychosis. However, the effect of the interplay between cannabis and variability at the endocannabinoid receptor genes on the neurobiological underpinnings of psychosis remains inconclusive. Through a case-only design, including patients with a first-episode of psychosis (n = 40) classified as cannabis users (50%) and non-users (50%), we aimed to evaluate the interaction between cannabis use and common genetic variants at the endocannabinoid receptor genes on brain activity. Genetic variability was assessed by genotyping two Single Nucleotide Polymorphisms (SNP) at the cannabinoid receptor type 1 gene (CNR1; rs1049353) and cannabinoid receptor type 2 gene (CNR2; rs2501431). Functional Magnetic Resonance Imaging (fMRI) data were obtained while performing the n-back task. Gene × cannabis interaction models evidenced a combined effect of CNR1 and CNR2 genotypes and cannabis use on brain activity in different brain areas, such as the caudate nucleus, the cingulate cortex and the orbitofrontal cortex. These findings suggest a joint role of cannabis use and cannabinoid receptor genetic background on brain function in first-episode psychosis, possibly through the impact on brain areas relevant to the reward circuit.

Adolescents and youths' opinions about the factors associated with cannabis use: a qualitative study based on the I-Change model

BACKGROUND

To learn about the experiences and opinions of adolescent non-consumers and regular cannabis users about cannabis use and the factors that determine its use, using the I-Change explanatory model as a basis.

METHODS

Qualitative methodology with a content analysis was used. Focus groups were conducted with adolescents who were non-regular cannabis users (those who had not tried cannabis or had only experimented with it before) and semi-structured interviews were conducted with adolescent and young adult in recovery who were in a detoxification program. A deductive analysis of the audio-recorded and transcribed interviews was performed, using the domains of the I-Change Model as a reference.

RESULTS

Personal problems, social problems or family problems can lead to cannabis use. There was a lack of knowledge and low risk perception about consumption of this drug. There are other factors that influence consumption, the perception of advantages, such as the feeling of freedom and the influence of the peer group. The consumption of this substance in girls is changing, becoming more and more equal to that of boys. The family has an important role to play in preventing drug use.

CONCLUSION

Knowledge of these factors is of vital importance as a prior step to the development of efficient intervention measures adjusted to the needs identified and the characteristics of the population.

Cannabinoids and Multiple Sclerosis: A Critical Analysis of Therapeutic Potentials and Safety Concerns

Multiple sclerosis (MS) is a complicated condition in which the immune system attacks myelinated axons in the central nervous system (CNS), destroying both myelin and axons to varying degrees. Several environmental, genetic, and epigenetic factors influence the risk of developing the disease and how well it responds to treatment. Cannabinoids have recently sparked renewed interest in their therapeutic applications, with growing evidence for their role in symptom control in MS. Cannabinoids exert their roles through the endogenous cannabinoid (ECB) system, with some reports shedding light on the molecular biology of this system and lending credence to some anecdotal medical claims. The double nature of cannabinoids, which cause both positive and negative effects, comes from their actions on the same receptor. Several mechanisms have been adopted to evade this effect. However, there are still numerous limitations to using cannabinoids to treat MS patients. In this review, we will explore and discuss the molecular effect of cannabinoids on the ECB system, the various factors that affect the response to cannabinoids in the body, including the role of gene polymorphism and its relation to dosage, assessing the positive over the adverse effects of cannabinoids in MS, and finally, exploring the possible functional mechanism of cannabinoids in MS and the current and future progress of cannabinoid therapeutics.

Recommendations for Reducing the Risk of Cannabis Use-Related Adverse Psychosis Outcomes: A Public Mental Health-Oriented Evidence Review

Objective: Cannabis use is increasingly normalized; psychosis is a major adverse health outcome. We reviewed evidence on cannabis use-related risk factors for psychosis outcomes at different stages toward recommendations for risk reduction by individuals involved in cannabis use. Methods: We searched primary databases for pertinent literature/data 2016 onward, principally relying on reviews and high-quality studies which were narratively summarized and quality-graded; recommendations were developed by international expert consensus. Results: Genetic risks, and mental health/substance use problem histories elevate the risks for cannabis-related psychosis. Early age-of-use-onset, frequency-of-use, product composition (i.e., THC potency), use mode and other substance co-use all influence psychosis risks; the protective effects of CBD are uncertain. Continuous cannabis use may adversely affect psychosis-related treatment and medication effects. Risk factor combinations further amplify the odds of adverse psychosis outcomes. Conclusions: Reductions in the identified cannabis-related risks factors-short of abstinence-may decrease risks of related adverse psychosis outcomes, and thereby protect cannabis users' health.

Use of non-medical cannabis in epilepsy: A scoping review

Objective

The use of medical cannabis among people with epilepsy (PWE) has been garnering increasing interest. In this scoping review, we aimed to summarize the literature on recreational/non-medical cannabis (NMC) use in PWE, focusing on the experience, habits, and beliefs of PWE regarding NMC.

Methods

Four databases (OVID Medline, OVID Embase, Ovid APA PsycInfo, and Web of Science) were searched for studies describing NMC use in PWE. NMC was defined as cannabis products procured from sources other than by prescription. Studies that consisted in original research and that detailed the experience, habits, and/or beliefs of PWE regarding NMC use were included in the analysis. Data pertaining to study identification, demographics, NMC use, and epilepsy characteristics were extracted. Descriptive statistical analyses and reflexive thematic analyses were performed to map these data.

Results

In total, 3,228 records were screened, and 66 were included for analysis: 45 had mainly adult samples, whereas 21 had mainly pediatric samples. Most studies were published after 2010, originated from the USA, and were cross-sectional. The median number of PWE using cannabis in these studies was 24.5 (1-37,945). No studies showcased elderly PWE, and most had predominantly Caucasian samples. The lifetime prevalence of NMC use in PWE was variable, ranging between 0.69 and 76.8%. Factors frequently associated with NMC use in PWE were male sex, younger adult age, and lower education status. Children with epilepsy took NMC primarily for seizure control, using high CBD/THC ratios, and only orally. Adults with epilepsy took NMC for various reasons including recreationally, using variable CBD/THC ratios, and predominantly through smoking. The majority of PWE across all studies perceived that NMC aided in seizure control. Other aspects pertaining to NMC use in PWE were rarely reported and often conflicting.

Conclusion

The literature on NMC use in PWE is sparse and heterogeneous, with many salient knowledge gaps. Further research is necessary to better understanding the experience, habits, and beliefs of PWE pertaining to NMC.