The International Cannabis Toolkit (iCannToolkit): a multidisciplinary expert consensus on minimum standards for measuring cannabis use

Examining Associations Between Cannabis Use Disorder and Measures of Weekly and Within-Day Cannabis Frequency, Quantity, and Potency in College Students

Background: College student cannabis use has increased significantly in recent years, and individuals aged 18-25 are at elevated risk for development of cannabis use disorder (CUD). While weekly cannabis use frequency is a commonly used measure of cannabis consumption, there is increasing scientific interest in exploring more nuanced measures of cannabis use. Currently, limited research exists examining the clinical utility of cannabis quantity, within-day frequency, and potency variables. Methods: We used cross-sectional survey data from a sample of 617 undergraduate students in the state of Colorado. A two-part model-building approach was leveraged to examine whether within-session cannabis quantity and within-day cannabis use frequency were associated with odds of experiencing any CUD symptoms and total number of CUD symptoms endorsed. We also examined whether cannabis flower potency was associated with odds of experiencing any CUD symptoms and total number of CUD symptoms endorsed among a subset (N=288) of the sample who reported knowledge of the cannabinoid content of their most frequently used products. Results: Weekly flower use frequency (odds ratio [OR]=1.27, p<0.001) and weekly concentrate use frequency (OR=1.10, p=0.044) were positively associated with increased odds of experiencing any CUD symptoms, but cannabis quantity and within-day frequency variables were not. In addition, no association was found between flower potency and odds of endorsing any CUD symptoms. Among individuals endorsing at least one symptom, weekly flower use frequency (incident rate ratio [IRR]=1.06, p<0.001) was positively associated with total symptom count, but weekly concentrate use frequency, cannabis quantity variables, and within-day frequency variables were not. Among individuals endorsing symptoms, a positive association was found between flower potency and total symptom count (IRR=1.01, p=0.008). Conclusion: Current methods of assessing within-session cannabis quantity and within-day cannabis use frequency may lack clinical utility in examining college student CUD symptoms over and above weekly cannabis use frequency. Cannabis flower potency may prove useful in assessment of CUD symptom severity, but further research is warranted.

Associations between hair-derived cannabinoid levels, self-reported use, and cannabis-related problems

RATIONALE

As cannabis potency and cannabis use are increasing in newly legalized markets, it is increasingly important to measure and examine the effects of cannabinoid exposure.

OBJECTIVES

The current study aims to assess how hair-derived cannabinoid concentrations - offering insight into three-month cumulative exposure - are associated with common self-report measures of cannabis use and cannabis use-related problems.

METHODS

74 near-daily dependent cannabis users self-reported their quantity of cannabis use, cannabis use-related problems, and estimated cannabis potency. Hair samples were provided to quantify Δ9-THC, CBD, and CBN using LC-MS/MS and THC-consumption was verified by analyzing THC-COOH in hair using GC-MS/MS.

RESULTS

Cannabinoids were detectable in 95.95% of the hair samples from individuals who tested positive on a urine screen for cannabis. Δ9-THC concentrations were positively associated with measures of self-reported potency (relative potency, potency category, and perceived 'high'), but Δ9-THC, CBD, CBN concentrations and THC/CBD ratio were not associated with self-reported quantity of use. Self-reported potency, but not hair-derived concentrations, were associated with withdrawal and craving. Self-reported quantity of cannabis use, but not cannabinoid concentrations, were associated with cannabis use-related problems.

CONCLUSIONS

The use of hair-derived cannabinoid quantification is supported for detecting cannabis use in near-daily users, but the lack of associations between hair-derived cannabinoid concentrations and self-report measures of use does not support the use of hair analyses alone for quantification of cannabinoid exposure. Further research comparing hair-derived cannabinoid concentrations with other biological matrices (e.g. plasma) and self-report is necessary to further evaluate the validity of hair analyses for this purpose.

Persistent increased severity of cannabis use disorder symptoms in adolescents compared to adults: a one-year longitudinal study

Adolescence is a developmental period characterised by increased vulnerability to cannabis use disorder (CUD). However, previous investigations of this vulnerability have relied on cross-sectional comparisons and lack a detailed assessment of cannabis quantity, a potentially important confounding factor. Here, we aimed to investigate the one-year course of CUD in adolescents compared to adults who currently use cannabis, adjusting for a comprehensive measure of cannabis quantity. Data are from a one-year observational longitudinal study (CannTeen) of adolescents and adults who currently used cannabis regularly with five waves of assessment at 3-monthly intervals, based in London, UK. Participants were n = 70 adults (26-29, 45.7% female), who did not regularly use cannabis when they were under age 18, and n = 76 adolescents (16-17, 50.0% female). The exposure was adolescent (compared to adult) frequent cannabis use. The primary outcome was CUD symptoms measured using the cannabis use disorder identification test revised (CUDIT-R) at five time points. Models were adjusted for cannabis quantity using mean weekly standard THC units (one unit = 5 mg THC). Other covariates included gender, and whether each session occurred before or during the COVID-19 pandemic. In models adjusted for pre-registered covariates, adolescents scored 3.7 points higher on the CUDIT-R compared to the adult group across the 5 assessment waves (3.66 95% CIs 1.99, 5.34). There was also evidence of a linear reduction in symptoms over time in both groups (-0.47, 95%CIs -0.67, -0.27). Adolescents had persistently increased CUD symptoms compared to adults across the 12-month period. This association was robust after adjusting for the quantity of cannabis consumed and other covariates.

Greater vulnerability to cannabis dependence among heavy cannabis user French women

BACKGROUND AND OBJECTIVES

Between 1990 and the mid-2010s, France registered a sharp rise in the spread and consumption of cannabis. At the same time, there has been an increase in the concentration of Δ9-tetrahydrocannabinol contained in cannabis. The aims of our study are to measure addictive and psychiatric comorbidities in cannabis users in France, and to compare characteristics between women and men.

METHODS

Three hundred and forty-two heavy cannabis users seen in a cannabis clinic between 2004 and 2014 were assessed during a 2-h clinical interview (DSM-IV, MINI).

RESULTS

83.2% of users are currently cannabis dependent, 10.6% alcohol dependent, and 2.1% cocaine/crack dependent. 37.8% have a current mood disorder, 47.6% have a current anxiety disorder, and 8.8% are psychotic. Women suffer significantly more often than men from major depressive episodes, dysthymia, agoraphobia, social phobia, generalized anxiety disorder and posttraumatic stress disorder (PTSD), both current and lifetime. Logistic regression shows that women have a significantly higher risk than men of suffering from PTSD over their lifetime (odds ratio [OR] = 5.48; p < 10-3). The vast majority of women suffering from PTSD report having been sexually assaulted in the course of their lives. In addition, women are at greater risk of cannabis dependence (OR = 3.87; p < .05) for lower cannabis consumption (grams smoked per week) (OR = 0.96; p < .05).

DISCUSSION AND CONCLUSIONS

French women heavy cannabis users are particularly at risk of PTSD and are more likely than men to be dependent despite consuming fewer.

SCIENTIFIC SIGNIFICANCE

Further studies are needed to clinically quantify cannabis consumption and distinguish its impact on women and men.

Enhanced cannabis timeline followback (EC-TLFB): Comprehensive assessment of cannabis use including standard THC units and validation through biological measures

AIMS

The aims of this study were to present an enhanced cannabis timeline followback (EC-TLFB) enabling comprehensive assessment of cannabis use measures, including standard tetrahydrocannabinol (THC) units, and to validate these against objectively indexed urinary 11-nor-9-carboxy-tetrahydrocannabinol (THC-COOH) concentrations.

DESIGN

We used cross-sectional baseline data from the 'CannTeen' observational longitudinal study.

SETTING

The study was conducted in London, UK.

PARTICIPANTS

A total of 147 participants who used cannabis regularly took part in the study (n = 71 female, n = 76 male; mean age = 21.90, standard deviation = 5.32).

MEASUREMENTS

The EC-TLFB was used to calculate frequency of cannabis use, method of administration, including co-administration with tobacco, amount of cannabis used (measured with unaided self-report and also using pictorial aided self-report) and type of cannabis product (flower, hash) which was used to estimate THC concentration (both from published data on THC concentration of products and analysis of cannabis samples donated by participants in this study). We calculated total weekly standard THC units (i.e. 5 mg THC for all cannabis products and methods of administration) using the EC-TLFB. The outcome variable for validation of past week EC-TLFB assessments was creatinine-normalized carboxy-tetrahydrocannabinol (THC-COOH) in urine.

FINDINGS

All measures of cannabis exposure included in this analysis were positively correlated with levels of THC-COOH in urine (r = 0.41-0.52). Standard THC units, calculated with average concentrations of THC in cannabis in the UK and unaided self-report measures of amount of cannabis used in grams showed the strongest correlation with THC-COOH in urine (r = 0.52, 95% bias-corrected and accelerated = 0.26-0.70).

CONCLUSIONS

The enhanced cannabis timeline followback (EC-TLFB) can provide a valid assessment of a comprehensive set of cannabis use measures including standard tetrahydrocannabinol units as well as and traditional TLFB assessments (e.g. frequency of use and grams of cannabis use).

Typical Hits, Grams, or Joints: Evaluating Cannabis Survey Measurement Strategies for Quantifying Consumption

Aim: Standardized survey measures that capture diverse cannabis consumption patterns are needed to inform public health and policy. Our team is developing a flexible, personalized, low-burden survey item inventory to measure cannabis use patterns and estimate milligrams of THC (mgTHC) consumption in large samples. This study aimed to identify measurement gaps and analysis implications associated with an initial pool of candidate items that assessed use of cannabis flower and concentrate products (smoked and/or vaporized). Methods: Adult cannabis consumers (n=4247) completed an online survey assessing cannabis use frequency, quantity, product types, product potencies (%THC), and methods of administration. Participants chose to report their consumption quantities using one of three units: "hits per day," "grams per week," or "joints per week." Respondents also indicated whether their past 7-day consumption pattern represented their typical pattern. Results: Eighty-one percent had used cannabis daily in the past week. Thirty-two percent, 53%, and 15% chose to report flower and concentrate consumption quantity in hits, grams, and joints, respectively. Approximately 80-90% of responses for the number of hits, grams, and joints consumed were less than the maximum response option-suggesting that response options captured the full range of potential cannabis consumption behaviors. Those who chose grams or joints units were generally more likely to endorse higher risk cannabis use (e.g., morning use, high %THC products) in the past week than those who chose the hits unit (adjusted Odds Ratio range: 1.2-3.9). Among those who reported that the past week represented their typical behavior (83%), past 30-day and past 7-day frequencies were highly correlated (Spearman's Rho=0.77)-supporting the feasibility of using lower burden "typical week" items to extrapolate patterns beyond a 1-week time frame. Conclusion: Results from this online convenience sample of frequent cannabis consumers suggest that the current items yield coherent and expected response patterns. Although additional testing is required, a standardized, flexible survey instrument for large-scale assessment of cannabis patterns and calculation of mgTHC seems within reach.

Cannabis Dependence is Associated with Reduced Hippocampal Subregion Volumes Independently of Sex: Findings from an ENIGMA Addiction Working Group Multi-Country Study

Background: Males and females who consume cannabis can experience different mental health and cognitive problems. Neuroscientific theories of addiction postulate that dependence is underscored by neuroadaptations, but do not account for the contribution of distinct sexes. Further, there is little evidence for sex differences in the neurobiology of cannabis dependence as most neuroimaging studies have been conducted in largely male samples in which cannabis dependence, as opposed to use, is often not ascertained. Methods: We examined subregional hippocampus and amygdala volumetry in a sample of 206 people recruited from the ENIGMA Addiction Working Group. They included 59 people with cannabis dependence (17 females), 49 cannabis users without cannabis dependence (20 females), and 98 controls (33 females). Results: We found no group-by-sex effect on subregional volumetry. The left hippocampal cornu ammonis subfield 1 (CA1) volumes were lower in dependent cannabis users compared with non-dependent cannabis users (p<0.001, d=0.32) and with controls (p=0.022, d=0.18). Further, the left cornu ammonis subfield 3 (CA3) and left dentate gyrus volumes were lower in dependent versus non-dependent cannabis users but not versus controls (p=0.002, d=0.37, and p=0.002, d=0.31, respectively). All models controlled for age, intelligence quotient (IQ), alcohol and tobacco use, and intracranial volume. Amygdala volumetry was not affected by group or group-by-sex, but was smaller in females than males. Conclusions: Our findings suggest that the relationship between cannabis dependence and subregional volumetry was not moderated by sex. Specifically, dependent (rather than non-dependent) cannabis use may be associated with alterations in selected hippocampus subfields high in cannabinoid type 1 (CB1) receptors and implicated in addictive behavior. As these data are cross-sectional, it is plausible that differences predate cannabis dependence onset and contribute to the initiation of cannabis dependence. Longitudinal neuroimaging work is required to examine the time-course of the onset of subregional hippocampal alterations in cannabis dependence, and their progression as cannabis dependence exacerbates or recovers over time.

Meaningfully Characterizing Cannabis Use for Research and Clinical Settings: A Comprehensive Review of Existing Measures and Proposed Future Directions

Cannabis use is increasingly common. There is a need for validated tools to meaningfully assess recreational, medical, and disordered cannabis use in both research and clinical contexts. Cannabis assessments were considered against pre-determined inclusion criteria within a comprehensive review. Measures were categorized as either (i) evaluating use frequency or quantity, (ii) measuring symptoms of disordered use and withdrawal, or (iii) assessing use motives, effects, and perceptions. The applications and validations for each assessment are summarized. Finally, recommendations for refining of existing measures or development of new measures are presented. The literature review resulted in 289 publications that were reviewed in detail, yielding 21 assessments that met inclusion criteria. The applications of these assessments are described here, in addition to the information about the validation studies of each assessment. Based on the complication of these tools, 5 areas of potential development are highlighted to guide future research, including (i) sensitivity to the mode of cannabis administration as well as sensitivity to (ii) potency of cannabis products alongside frequency and quantity, (iii) unit equivalence, (iv) aligning clinical measures consistently with cannabis use disorder (CUD) diagnostic criteria, and (v) creating measures specific to medical users, their motives for use, and their perceptions of therapeutic benefits or side effects. Clinicians and researchers can pragmatically benefit from this summary of validated measures of cannabis use, and future work could improve the study of and clinical care for cannabis use and CUD by pursuing one or more key areas of development described here.

Cross-Substance Associations With Transitions in Cannabis and Nicotine Use in a Statewide Sample of Young Adults in Washington State

OBJECTIVE

Understanding transitions in nicotine and cannabis use has implications for prevention and efforts to reduce harmful use. Focusing on cross-substance associations, we examined how use of one substance was associated with year-to-year transitions in frequency of use of the other among young adults in the context of legalized nonmedical cannabis.

METHOD

A statewide sample from Washington (N = 4,039; ages 18-25 at baseline) provided up to 3 years of annual data on past-month cannabis use and nicotine use (tobacco cigarettes and e-cigarettes/vaping). Manifest Markov models examined how use of each substance was associated with transitions in the other across categories of past-month no use, occasional use (1-19 days), and frequent use (≥20 days).

RESULTS

Occasional and frequent nicotine use (vs. no use) predicted higher probability of transitioning from no cannabis use to occasional or frequent cannabis use and from occasional use to frequent use, whereas associations with cessation and de-escalation were inconsistent in direction, small in magnitude, and not statistically significant. Cannabis use positively predicted onset of nicotine use, and associations of cannabis use with escalation from occasional to frequent nicotine use, de-escalation in use, and cessation in use were small and inconsistent in direction.

CONCLUSIONS

The findings corroborate prior research on cannabis and nicotine use as risk factors to address in prevention efforts. The findings do not provide strong support for prioritization of dual abstinence in efforts to encourage reductions in or cessation of cannabis or nicotine use among young adults.

Brain reward function in people who use cannabis: a systematic review

Rationale

Cannabis is one of the most widely used psychoactive substances globally. Cannabis use can be associated with alterations of reward processing, including affective flattening, apathy, anhedonia, and lower sensitivity to natural rewards in conjunction with higher sensitivity to cannabis-related rewards. Such alterations have been posited to be driven by changes in underlying brain reward pathways, as per prominent neuroscientific theories of addiction. Functional neuroimaging (fMRI) studies have examined brain reward function in cannabis users via the monetary incentive delay (MID) fMRI task; however, this evidence is yet to be systematically synthesised.

Objectives

We aimed to systematically integrate the evidence on brain reward function in cannabis users examined by the MID fMRI task; and in relation to metrics of cannabis exposure (e.g., dosage, frequency) and other behavioural variables.

Method

We pre-registered the review in PROSPERO and reported it using PRISMA guidelines. Literature searches were conducted in PsycINFO, PubMed, Medline, CINAHL, and Scopus.

Results

Nine studies were included, comprising 534 people with mean ages 16-to-28 years, of which 255 were people who use cannabis daily or almost daily, and 279 were controls. The fMRI literature to date led to largely non-significant group differences. A few studies reported group differences in the ventral striatum while participants anticipated rewards and losses; and in the caudate while participants received neutral outcomes. A few studies examined correlations between brain function and withdrawal, dosage, and age of onset; and reported inconsistent findings.

Conclusions

There is emerging but inconsistent evidence of altered brain reward function in cannabis users examined with the MID fMRI task. Future fMRI studies are required to confirm if the brain reward system is altered in vulnerable cannabis users who experience a Cannabis Use Disorder, as postulated by prominent neuroscientific theories of addiction.

Assessing Cannabis Use in People with Psychosis

Introduction: Cannabis use is common in people with psychotic disorders and is associated with the exacerbation of symptoms, poor treatment adherence, and an increased risk of relapse. Accurate assessment of cannabis use is thus critical to the clinical management of psychosis. Discussion: Cannabis use is usually assessed with self-report questionnaires that were originally developed for healthy individuals or people with a cannabis use disorder. Compared to these groups, the pattern of cannabis use and the associated harms in patients with psychosis are quite different. Moreover, in people with psychosis, the accuracy of self-reported use may be impaired by psychotic symptoms, cognitive deficits, and a desire to conceal use when clinicians have advised against it. Although urinary screening for delta-9-tetrahydrocannabinol is sometimes used in the assessment of acute psychotic episodes, it is not used in routinely. Cannabis use could be assessed by measuring the concentration of cannabinoids in urine and blood, but this is rarely done in either clinical settings or research. Conclusion: Using quantitative biological measures could provide a more accurate guide to the effects of use on the disorder than asking patients or using questionnaires.

Changes in Cannabis Use From 2014 to 2019 Among Young Adults in Washington State

INTRODUCTION

Understanding changes in cannabis use in the legalized nonmedical cannabis context is critical. Washington State, one the earliest states to implement legalization, presents a unique opportunity to examine how cannabis use and its consequences changed after the implementation of legalization for adults. With a focus on Washington State young adults, this study conducted in 2022-2023 examined changes in (1) cannabis use by sex and age, (2) preferred mode of use, and (3) cannabis use disorder symptoms.

METHODS

Using repeated cross-sectional data on young adults aged 18-25 years in Washington State from 2014 (premarket opening) to 2019 (N=12,945), logistic regression models assessed trends over time in the prevalence of any and frequent (20+ days) past-month cannabis use. Among individuals reporting use, multinomial logistic regressions estimated trends over time in the preferred mode of use and negative binomial regressions examined trends in the count of cannabis use disorder symptoms.

RESULTS

From 2014 to 2019, the prevalence of cannabis use converged by sex, with females being equally likely as males to report both any and frequent use by 2019. Among young adults reporting past-month use, smoking as the preferred mode of use decreased relative to other modes. Number of cannabis use disorder symptoms reported increased, which was not accounted for by changes in preferred mode of use.

CONCLUSIONS

During the 5-year period following the implementation of legalization, patterns of young adult cannabis use shifted, including particularly sharp increases among females and increases in cannabis use disorder symptoms. Future studies should investigate underlying causes for these important changes.

How much cannabis is used in a joint in Australia? An experimental investigation into use by potency and frequency

INTRODUCTION

Cannabis use is highly prevalent in Australia, yet current survey metrics measure tetrahydrocannabinol (THC) exposure with limited accuracy. Often survey items measure cannabis quantity by assuming specific modes of use (i.e., 'how many joints do you use?'), which fail to capture variations in cannabis use and the diverse modes of use (e.g., joints, cones, spliffs). This study investigated how much cannabis is used in these modes of administration in an Australian sample.

METHODS

Participants (N = 31, Mage  = 25.77; 51% university students) completed the Roll a Joint Paradigm in which they rolled joints, spliffs and packed cones as they would typically, using oregano as 'cannabis.' Participants then prepared each again but with cannabis of higher or lower potency.

RESULTS

The amount of cannabis used across different modes of administration was variable: joints (range 0.10-1.25 g), spliffs (range 0.12-1.21 g) and cones (range 0.03-0.41 g). Participants who used cannabis daily rolled three times the amount of cannabis into a joint.

DISCUSSION AND CONCLUSIONS

The amount of cannabis used in common modes of administration may be highly variable. Daily use may be associated using larger quantities of cannabis. Titration attempts based on potency were not proportional or consistent across modes of administration. The results indicate people may adjust the quantity of cannabis based on perceived potency, however, not proportional to THC concentration. Inconsistency in the amount of cannabis used based on potency and within different modes of administration may represent a problem for self-report metrics which ask participants to report cannabis use in joints.

Support Provided by Stop-Smoking Practitioners to Co-users of Tobacco and Cannabis: A Qualitative Study

INTRODUCTION

Co-use of tobacco and cannabis is highly prevalent among cannabis users and is associated with poorer tobacco cessation outcomes. This study explored the barriers and enablers influencing stop-smoking practitioners' ability to provide optimal support to co-users.

AIMS AND METHODS

Online semi-structured interviews were audio recorded. Interviewees (n = 20) were UK-based certified stop-smoking practitioners. An interview schedule informed by the "capability", "opportunity", "motivation" (COM-B) model was designed to explore participants' perceived barriers and enablers in better supporting co-users to achieve abstinence of both substances or tobacco harm reduction. The transcripts were analyzed using framework analysis.

RESULTS

Capability: Practitioners' lack of knowledge and skills undermines their delivery of smoking cessation interventions to co-users. Interestingly, when cannabis is used for medicinal reasons, practitioners feel unable to provide adequate support. Opportunity: Service recording systems play an important role in screening for co-use and supporting co-users. When responding to clients' specific needs and practitioners' uncertainties, a positive therapeutic relationship and a support network of peers and other healthcare professionals are needed. Motivation: supporting co-users is generally perceived as part of practitioners' roles but there are concerns that co-users are less likely to successfully stop smoking.

CONCLUSIONS

Practitioners are willing to support co-users, but their lack of knowledge and access to an appropriate recording system are barriers to doing so. Having a supportive team and a positive therapeutic relationship is perceived as important. Identified barriers can be mostly addressed with further training to improve tobacco cessation outcomes for co-users.

Health Effects of High-Concentration Cannabis Products: Scoping Review and Evidence Map

Background. The concentration of pharmacologically active tetrahydrocannabinol (THC) in cannabis products has been increasing over the past decade. Concerns about potential harmful health effects of using these increasingly higher-concentration products have led some states to consider regulation of cannabis product THC concentration. We conducted a scoping review of health effects of high-concentration cannabis products to inform policy on whether the THC concentrations of cannabis product should be regulated or limited. Objectives. We conducted a scoping review to (1) identify and describe human studies that explore the relationship of high-concentration cannabis products with any health outcomes in the literature and (2) create an interactive evidence map of the included studies to facilitate further analyses. Search Methods. An experienced medical information specialist designed a comprehensive search strategy of 7 electronic databases. Selection Criteria. We included human studies of any epidemiological design with no restrictions by age, sex, health status, country, or outcome measured that reported THC concentration or included a known high-concentration cannabis product. Data Collection and Analysis. We imported search results into Distiller SR, and trained coders conducted artificial intelligence‒assisted screening. We developed, piloted, and revised data abstraction forms. One person performed data abstraction, and a senior reviewer verified a subset. We provide a tabular description of study characteristics, including exposures and outcomes measured, for each included study. We interrogated the evidence map published in Tableau to answer specific questions and provide the results as text and visual displays. Main Results. We included 452 studies in the scoping review and evidence map. There was incomplete reporting of exposure characteristics including THC concentration, duration and frequency of use, and products used. The evidence map shows considerable heterogeneity among studies in exposures, outcomes, and populations studied. A limited number of reports provided data that would facilitate further quantitative synthesis of the results across studies. Conclusions. This scoping review and evidence map support strong conclusions concerning the utility of the literature for characterizing risks and benefits of the current cannabis marketplace and the research approaches followed in the studies identified. Relevance of the studies to today's products is limited. Public Health Implications. High-quality evidence to address the policy question of whether the THC concentration of cannabis products should be regulated is scarce. The publicly available interactive evidence map is a timely resource for other entities concerned with burgeoning access to high-concentration cannabis. (Am J Public Health. 2023;113(12):1332-1342. https://doi.org/10.2105/AJPH.2023.307414).

A cross-cultural fMRI investigation of cannabis approach bias in individuals with cannabis use disorder

Introduction

As cannabis policies and attitudes become more permissive, it is crucial to examine how the legal and social environment influence neurocognitive mechanisms underlying cannabis use disorder (CUD). The current study aimed to assess whether cannabis approach bias, one of the mechanisms proposed to underlie CUD, differed between environments with distinct recreational cannabis policies (Amsterdam, The Netherlands (NL) and Dallas, Texas, United States of America (TX)) and whether individual differences in cannabis attitudes affect those differences.

Methods

Individuals with CUD (NL-CUD: 64; TX-CUD: 48) and closely matched non-using controls (NL-CON: 50; TX-CON: 36) completed a cannabis approach avoidance task (CAAT) in a 3T MRI. The cannabis culture questionnaire was used to measure cannabis attitudes from three perspectives: personal, family/friends, and state/country attitudes.

Results

Individuals with CUD demonstrated a significant behavioral cannabis-specific approach bias. Individuals with CUD exhibited higher cannabis approach bias-related activity in clusters including the paracingulate gyrus, anterior cingulate cortex, and frontal medial cortex compared to controls, which was no longer significant after controlling for gender. Site-related differences emerged in the association between cannabis use quantity and cannabis approach bias activity in the putamen, amygdala, hippocampus, and insula, with a positive association in the TX-CUD group and a negative association in the NL-CUD group. This was not explained by site differences in cannabis attitudes.

Conclusions

Pinpointing the underlying mechanisms of site-related differences-including, but not limited to, differences in method of administration, cannabis potency, or patterns of substance co-use-is a key challenge for future research.

A remote brief intervention plus social media messaging for cannabis use among emerging adults: A pilot randomized controlled trial in emergency department patients

INTRODUCTION

Interventions addressing cannabis use among emerging adults (ages 18-25) are currently needed to prevent negative outcomes. Emergency Department (ED) visits provide an opportunity to initiate interventions. In this pilot study, we created a brief intervention (BI), extended with private social media messaging for emerging adult ED patients who use cannabis regularly. Study aims were to examine intervention feasibility, acceptability, and descriptive outcomes.

METHODS

We recruited and randomized N = 58 emerging adults (M age 21.5 years, 65.5% female) who used cannabis from an ED in-person and remotely after their ED visit (given COVID-19 restrictions). Participants randomized to the intervention (N = 30) received a Motivational Interviewing-based BI and 4 weeks of health coaching via private social media; control participants received a resource brochure and entertaining social media messaging. Follow-ups occurred at 1-month and 3-months.

RESULTS

Most intervention participants liked the BI (95.8%), found it helpful to discuss cannabis use in the BI (91.7%), and liked interacting with coaches on social media (86.3%). Social media content (e.g., video clips, images/still pictures/memes) were highly rated. Descriptively, the intervention group showed theory-consistent changes in importance of and intentions to change cannabis (increases vs. decrease/stability in control group), whereas findings for cannabis consumption/consequences were mixed.

CONCLUSIONS

This BI paired with social media messaging was acceptable in a sample of emerging adults from an ED who used cannabis regularly. Despite feasibility challenges due to COVID-19, this intervention warrants future investigation with a larger sample and longer follow-up period, with attention to the changing cannabis landscape when measuring outcomes.

Exploring survey methods for measuring consumption quantities of cannabis flower and concentrate products

Background: Researchers need accurate measurements of cannabis consumption quantities to assess risks and benefits. Survey methods for measuring cannabis flower and concentrate quantities remain underdeveloped.Objective: We examined "grams" and "hits" units for measuring flower and concentrate quantities, and calculating milligrams of THC (mgTHC).Methods: Online survey participants (n = 2,381) reported preferred unit (hits or grams), past-week hits and grams for each product, and product %THC. Quantile regression compared mgTHC between unit-preference subgroups. Hits-based mgTHC calculations assumed a universal grams-per-hit ratio (GPHR). To examine individualized GPHRs, we tested a "two-item approach," which divided total grams by total hits, and "one-item approach," which divided 0.5 grams by responses to the question: "How many total hits would it take you to finish 1/2 g of your [product] by [administration method]?"Results: Participants were primarily daily consumers (77%), 50% female sex, mean age 39.0 (SD 16.4), 85% White, 49% employed full-time. Compared to those who preferred the hits unit, those who preferred the grams unit reported consuming more hits and grams, higher %THC products, and consequently, larger median mgTHC (flower-hits mgTHC: 32 vs. 91 (95%CI: 52-67); flower-grams mgTHC: 27 vs. 113 (95%CI: 73-95); concentrate-hits mgTHC: 29 vs. 59 (95%CI: 15-43); concentrate-grams mgTHC: 61 vs. 129 (95%CI: 43-94)). "Two-item" and "one-item" approach GPHRs were similar and frequently 50% larger or smaller than the universal GPHR.Conclusion: Allowing respondents to choose "hits" or "grams" when reporting cannabis quantities does not compromise mgTHC estimates. A low-burden, one-item approach yields individualized "hit sizes" that may improve mgTHC estimates.

A Longitudinal Analysis of Monthly Changes in Substance Use in Relation to Negative Consequences From Alcohol and Cannabis Use in a Community Sample of Young Adults

OBJECTIVE

Experiencing negative substance use consequences may deter future use, alter patterns of substance use (e.g., substituting one substance for another, combining substances), or point to a sustained pattern of engaging in heavy or frequent use. We used monthly data to examine relationships between negative alcohol and cannabis use consequences experienced in one month and changes in use the following month.

METHOD

Data were from 508 individuals (59% female; ages 18-23 years at enrollment) who were surveyed monthly for 2 years and used both alcohol and cannabis during the study period. Multilevel models assessed within-person associations between monthly fluctuations in substance-related negative consequences and the next month's substance use (i.e., typical drinks per week, cannabis use frequency, and simultaneous alcohol and cannabis/marijuana [SAM] use), controlling for the prior month's substance use.

RESULTS

Positive associations were found between alcohol consequences and the following month's alcohol use and between cannabis consequences and subsequent cannabis use, although only the cannabis association was statistically significant. There was little evidence of effects of cannabis consequences on the next month's alcohol use or alcohol consequences on the next month's cannabis use. Cannabis consequences had a positive and statistically significant association with the next month's SAM use. Within-substance positive associations were strongest for physical alcohol consequences and cannabis consequences of low motivation, memory problems, and trouble breathing.

CONCLUSIONS

Experiencing negative cannabis use consequences predicted more frequent cannabis use and greater chance of SAM use 1 month later. Results point to negative consequences, along with prior use, indicating risk for future use.

Measuring cannabis quantities in online surveys: A rapid review and proposals for ways forward

OBJECTIVES

Cannabis use quantities are relevant for determining cannabis-related harms. This research aims to provide an overview of the available methods to assess quantities through self-report.

METHODS

A rapid review of various strategies to collect information on cannabis use quantities through self-report. Two independent literature searches resulted in n = 38 studies included for review.

RESULTS

A total of n = 14 studies employed methods for collecting cannabis use quantities that are not suitable for online surveys (e.g., rolling a fake joint). Of the remaining n = 24 studies with items that are suitable for online surveys, the quantity assessment was performed in three different ways. The data collection was either carried out by asking (a) for the total number of joints (i.e., crude joint method), (b) for the total weight (i.e., crude weight method), or (c) for specific products separately, for example, for the amount of flower and resin (i.e., product-specific method). In only n = 8 studies, cannabis use quantities were ascertained by providing visual aids (e.g., illustration of various amounts of flower).

CONCLUSIONS

The crude joint method and the product-specific method are the two most promising methods to collect information on cannabis use quantities. Using visual aids may potentially improve the accuracy of those methods.

Results of a pilot study examining the effect of positive psychology interventions on cannabis use and related consequences

BACKGROUND

Young adults experience high rates of cannabis use and consequences. Cross-sectional work has linked positive psychological constructs (e.g., savoring) to less cannabis use and consequences, and positive psychological interventions (PPIs) have shown promise in targeting other substance use behaviors. This pilot study sought to provide an initial test of PPIs to reduce young adult cannabis use and consequences.

METHODS

Adults (18-25 years old) who endorsed at least weekly past-month cannabis use (N = 59, 69.6% men, 41.1% White) reported their baseline cannabis use and consequences. Participants were randomized to complete one of three daily exercises (Savoring, Three Good Things, or a control) along with daily text message surveys for two weeks, then completed a follow-up survey at the end of the two weeks.

RESULTS

Paired samples t-tests indicated that participants in the Three Good Things group showed medium to large reductions in frequency of weekly cannabis use (p = .08, gav = -0.57) and cannabis-associated consequences (p = .08, gav = -0.57) from baseline to follow-up. In the Savoring and control groups, there were not significant changes in frequency of weekly cannabis use (Savoring: p = .39, gav = 0.20; Control: p = .96, gav = 0.01) nor cannabis-associated consequences (Savoring: p = .84, gav = 0.05; Control: p = .45, gav = -0.18). Participants in both positive psychology conditions reported the exercises were easy to complete, providing evidence for acceptability.

DISCUSSION

Results provide initial support for the feasibility and potential promise of a text-message based PPI as a harm reduction approach for cannabis users. A larger clinical trial is warranted to test the effects of such interventions with adequate statistical power.

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.

Evaluating cannabis exposure in survey items: Insights, strategies, and remaining challenges identified from cognitive interviewing

Background

The diversity in characteristics of cannabis products and behavior patterns make evaluation of cannabis exposure in population-based, self-report surveys challenging. Accurate identification of cannabis exposure and related outcomes necessitates a thorough understanding of participants' interpretations of survey questions assessing cannabis consumption behaviors.

Objectives

The current study utilized cognitive interviewing to gain insight on participants' interpretation of items in a self-reported survey instrument used to estimate the quantity of THC consumed in population samples.

Methods

Cognitive interviewing was used to evaluate survey items assessing cannabis use frequency, routes of administration, quantity, potency, and perceived "typical patterns" of use. Ten participants ≥18 years (n = 4 cisgender-men; n = 3 cisgender-women; n = 3 non-binary/transgender) who had used cannabis plant material or concentrates in the past week were recruited to take a self-administered questionnaire and subsequently answer a series of scripted probes regarding survey items.

Results

While most items presented no issues with comprehension, participants identified several areas of ambiguity in question or response item wording or in visual cues included in the survey. Generally, participants with irregular use patterns (i.e., non-daily use) reported more difficulty recalling the time or quantity of cannabis use. Findings resulted in several changes to the updated survey, including updated reference images and new quantity/frequency of use items specific to the route of administration.

Conclusion

Incorporating cognitive interviewing into cannabis measurement development among a sample of knowledgeable cannabis consumers led to improvements in assessing cannabis exposure in population surveys, which may otherwise have been missed.

Addressing cannabis consumption among patients with hyperemesis gravidarum

Severe nausea and vomiting of pregnancy and hyperemesis gravidarum affect up to 3% of all pregnant people, causing substantial maternal and neonatal morbidity, suffering, and financial cost. Evidence supports the association of cannabis consumption with symptoms of severe nausea and vomiting of pregnancy or hyperemesis gravidarum as the general public has come to believe that cannabis is a natural, safe antiemetic. Cannabis consumption in pregnancy is discouraged strongly by the Surgeon General of the United States and the American College of Obstetricians and Gynecologists because of evidence of potential harms. Symptoms of intractable, severe nausea and vomiting of pregnancy or hyperemesis gravidarum associated with cannabis consumption may be unrecognized cannabinoid hyperemesis syndrome, and this syndrome may be more common than previously thought. Cannabis consumption is especially detrimental when causing or exacerbating debilitating symptoms such as the intense, persistent, recurrent, or cyclic vomiting and associated dehydration and other sequelae of cannabinoid hyperemesis syndrome. Open discussion of cannabis consumption during pregnancy is very challenging for patients and maternity care providers in our current environment of variable legal status across states and variable degrees of personal and societal acceptance. Evidence-based medical knowledge, guidance, tools, and skills are needed to differentially diagnose and treat cannabinoid hyperemesis syndrome in pregnancy. Researchers, clinicians, and medical specialty organizations must work together to strengthen the evidence base and develop or refine the necessary guidelines and tools for maternity care provider skill development, and to increase public and patient awareness of cannabinoid hyperemesis syndrome, specifically during pregnancy.

High potency cannabis use, mental health symptoms and cannabis dependence: Triangulating the evidence

BACKGROUND

Cannabis potency (concentration of Δ-9-Tetrahydrocannabinol) has been associated with risks of adverse mental health outcomes and addiction but no studies have triangulated evidence from self-report and objective measures of cannabis potency. We hypothesised that users of high potency cannabis would have higher levels of (a) anxiety, (b) depression and (c) psychosis-like symptoms (d) cannabis dependence than users of lower potency cannabis.

METHODS

A cross-sectional study of 410 participants donated a sample of cannabis for analysis of THC concentration and reported their cannabis potency preference. These two exposure measures were investigated for their association with cannabis dependence, depression, anxiety, and psychosis-like symptoms in separate linear/logistic regression models.

RESULTS

High potency cannabis preference was associated with a slight increased risk of cannabis dependence after adjusting for confounding, with the exception of cannabis use frequency (OR = 1.16, 95% CI 1.04-1.28). No association was found between THC concentration in cannabis and cannabis dependence. There was weak evidence of a small association between cannabis potency and depression and anxiety. There was no association between high potency cannabis preference or THC concentration in cannabis and psychosis-like symptoms.

CONCLUSIONS

Users of cannabis who preferred high potency types might be at increased risk of problematic cannabis use. This should be considered with caution as we were not able to triangulate these results with an objective measure of cannabis potency. More research is needed to understand the association between high potency cannabis use and depression and anxiety.

Measuring white matter microstructure in 1,457 cannabis users and 1,441 controls: A systematic review of diffusion-weighted MRI studies

INTRODUCTION

Cannabis is the most widely used regulated substance by youth and adults. Cannabis use has been associated with psychosocial problems, which have been partly ascribed to neurobiological changes. Emerging evidence to date from diffusion-MRI studies shows that cannabis users compared to controls show poorer integrity of white matter fibre tracts, which structurally connect distinct brain regions to facilitate neural communication. However, the most recent evidence from diffusion-MRI studies thus far has yet to be integrated. Therefore, it is unclear if white matter differences in cannabis users are evident consistently in selected locations, in specific diffusion-MRI metrics, and whether these differences in metrics are associated with cannabis exposure levels.

METHODS

We systematically reviewed the results from diffusion-MRI imaging studies that compared white matter differences between cannabis users and controls. We also examined the associations between cannabis exposure and other behavioral variables due to changes in white matter. Our review was pre-registered in PROSPERO (ID: 258250; https://www.crd.york.ac.uk/prospero/).

RESULTS

We identified 30 diffusion-MRI studies including 1,457 cannabis users and 1,441 controls aged 16-to-45 years. All but 6 studies reported group differences in white matter integrity. The most consistent differences between cannabis users and controls were lower fractional anisotropy within the arcuate/superior longitudinal fasciculus (7 studies), and lower fractional anisotropy of the corpus callosum (6 studies) as well as higher mean diffusivity and trace (4 studies). Differences in fractional anisotropy were associated with cannabis use onset (4 studies), especially in the corpus callosum (3 studies).

DISCUSSION

The mechanisms underscoring white matter differences are unclear, and they may include effects of cannabis use onset during youth, neurotoxic effects or neuro adaptations from regular exposure to tetrahydrocannabinol (THC), which exerts its effects by binding to brain receptors, or a neurobiological vulnerability predating the onset of cannabis use. Future multimodal neuroimaging studies, including recently developed advanced diffusion-MRI metrics, can be used to track cannabis users over time and to define with precision when and which region of the brain the white matter changes commence in youth cannabis users, and whether cessation of use recovers white matter differences.

SYSTEMATIC REVIEW REGISTRATION

www.crd.york.ac.uk/prospero/, identifier: 258250.

Nationally Representative Surveys on Cannabis Use Lack Product Details Relevant to Public Health

Objectives

Many annual, nationally representative US surveys that assess cannabis use do not collect information on product characteristics despite varying health risks and benefits. Capitalizing on a rich dataset of primarily medical users, the purpose of this study was to describe the degree of potential misclassification in clinically relevant cannabis use measures when primary mode of use is recorded but not product type.

Methods

Analyses consider user-level data from the Releaf App™ database on product types, consumption modes, and potencies in a non-nationally representative sample of 26,322 cannabis administration sessions occurring in 2018, across 3,258 users. Proportions, means, and 95% confidence intervals were calculated and compared across products and modes.

Results

Primary consumption modes were smoking (47.1%), vaping (36.5%), and eating/drinking (10.4%), with 22.7% of users reporting multiple modes of use. Moreover, mode of use did not signify a single product type: users reported vaping both flower (41.3%) and concentrates (68.7%). Of those who smoked cannabis, 8.1% reported smoking concentrates. Concentrates averaged 3.4 times higher tetrahydrocannabinol (THC) potency and 3.1 times higher cannabidiol (CBD) potency than flower.

Conclusions

Cannabis consumers employ multiple consumption modes, and product type cannot be inferred from mode of use. With THC potencies markedly higher in concentrates, these findings underscore the importance of including information on cannabis product types and mode of use in surveillance surveys. Clinicians and policymakers need these data to inform treatment decisions and assess cannabis policies' implications for population health.

Posttraumatic stress disorder, sleep and medical cannabis treatment: A daily diary study

Despite increasing use of Medical Cannabis (MC) among posttraumatic stress disorder (PTSD) patients, research is lacking on how MC treatment relates to PTSD symptomatology, in particular sleep disturbances. This study examines the time gap between MC use and sleep onset and its association with (1) number of awakenings throughout the night, (2) early awakenings, (3) nightmares. Each morning over a two week period, 77 licensed MC patients suffering from PTSD reported on the timing of previous night MC use and sleep disturbances. Within-person analyses found that shorter time gaps between previous night MC use and sleep start time was associated with lower likelihood of experiencing nightmares throughout the night, but it was not associated with nightly awakenings or waking up too early. Between-person analyses showed that individuals who used MC products with higher CBD concentrations reported fewer early awakenings. These preliminary results indicate that future research should test causal relations between MC use and sleep problems in PTSD patients. Future research is warranted in order to explore causal relationships between MC use, nightmares and insomnia in PTSD patients.

Association of cannabis potency with mental ill health and addiction: a systematic review

Cannabis potency, defined as the concentration of Δ⁹-tetrahydrocannabinol (THC), has increased internationally, which could increase the risk of adverse health outcomes for cannabis users. We present, to our knowledge, the first systematic review of the association of cannabis potency with mental health and addiction (PROSPERO, CRD42021226447). We searched Embase, PsycINFO, and MEDLINE (from database inception to Jan 14, 2021). Included studies were observational studies of human participants comparing the association of high-potency cannabis (products with a higher concentration of THC) and low-potency cannabis (products with a lower concentration of THC), as defined by the studies included, with depression, anxiety, psychosis, or cannabis use disorder (CUD). Of 4171 articles screened, 20 met the eligibility criteria: eight studies focused on psychosis, eight on anxiety, seven on depression, and six on CUD. Overall, use of higher potency cannabis, relative to lower potency cannabis, was associated with an increased risk of psychosis and CUD. Evidence varied for depression and anxiety. The association of cannabis potency with CUD and psychosis highlights its relevance in health-care settings, and for public health guidelines and policies on cannabis sales. Standardisation of exposure measures and longitudinal designs are needed to strengthen the evidence of this association.

Measurement of public health impacts of cannabis legalization in Canada to reflect policy maker priorities: A rapid scoping review of instruments and content domains

BACKGROUND

We were engaged by policy stakeholders to undertake a scoping review of cannabis measurement instruments to inform the evaluation of cannabis legalization impacts. We identified instruments employed in population-based or clinical research to screen and assess cannabis use, including measurement properties. We also identified the content domains included in each instrument and gaps in the measurement of key priority areas as established by policy stakeholders.

METHODS

We followed PRISMA and conducted searches on MEDLINE, PsycINFO, Web of Science, EMBASE, HAPI, Scopus and grey literature. We included publications from the past 15 years that reported the use of an instrument to measure cannabis use. Six study team members calibrated screening and data abstraction, independently identified records and abstracted data.

RESULTS

Across 915 included publications, we identified 187 unique instruments covering seven content domains and 35 subdomains. The most identified instruments were the Composite International Diagnostic Interview, the Timeline Follow-Back and the National Epidemiologic Survey on Alcohol and Related Conditions (109/915; 91/915; 64/915). The Canadian Cannabis Survey addressed the most subdomains (22/35). Frequency of use, prevalence of use, and mental health impacts were the most addressed subdomains (110/187; 94/187; 67/187) and storage, growing cannabis, and second-hand exposure were the least addressed (1/187; 4/187; 6/187).

CONCLUSION

This research identified instruments and domains critical to the assessment of public health impacts of cannabis legalization, which can facilitate the harmonization of measures to inform policy development. Future research should develop new instruments for less commonly-addressed constructs and thoroughly explore psychometric properties of existing instruments.

Prevalence and use of cannabis products and routes of administration among youth and young adults in Canada and the United States: A systematic review

BACKGROUND

The current systematic review aimed to summarize the literature on the prevalence of routes of administration and cannabis products used among youth and young adults in Canada and the United States (US).

METHODS

Five academic databases were searched in April 2020 and February 2021. Peer-reviewed articles were included if they were a population-based quantitative observational study describing the prevalence of a cannabis product or route of administration among youth and young adults in Canada or the US. Risk of bias was assessed using Hoy and colleagues' risk of bias assessment tool. A narrative review was conducted.

RESULTS

Twenty-six studies were identified for the following routes of administration: smoking (n = 16), vaping (n = 21), dabbing (n = 3), oral (n = 13), topical (n = 1); and products: dried flower (n = 2), and concentrates (n = 8). Smoking had the highest prevalence rates among youth and young adults; however, rates of use appeared to reduce over time. Conversely, prevalence of vaping appeared to increase over time. Fewer studies focused on oral or dabbed cannabis but those that did reported prevalence estimates of approximately a third among recent cannabis consumers.

DISCUSSION

The heterogeneity of cannabis routes of administration restricted our ability to collate average prevalence estimates. In jurisdictions where non-medical cannabis is legal, policymakers should provide guidance and education to youth on each type of product and routes of administration.

OTHER

Funding for this study was provided by a Canadian Institutes of Health Research (PJT-153342). The current review was registered with PROSPERO (CRD42020169275).

A network approach to relationships between cannabis use characteristics and psychopathology in the general population

Cannabis use characteristics, such as earlier initiation and frequent use, have been associated with an increased risk for developing psychotic experiences and psychotic disorders. However, little is known how these characteristics relate to specific aspects of sub-clinical psychopathology in the general population. Here, we explore the relationships between cannabis use characteristics and psychopathology in a large general population sample (N = 2,544, mean age 29.2 years, 47% women) by employing a network approach. This allows for the identification of unique associations between two cannabis use characteristics (lifetime cumulative frequency of cannabis use, age of cannabis use initiation), and specific psychotic experiences and affective symptoms, while controlling for early risk factors (childhood trauma, urban upbringing). We found particularly pronounced unique positive associations between frequency of cannabis use and specific delusional experiences (persecutory delusions and thought broadcasting). Age of cannabis use initiation was negatively related to visual hallucinatory experiences and irritability, implying that these experiences become more likely the earlier use is initiated. Earlier initiation, but not lifetime frequency of cannabis use, was related to early risk factors. These findings suggest that cannabis use characteristics may contribute differentially to risk for specific psychotic experiences and affective symptoms in the general population.

The CannTeen study: verbal episodic memory, spatial working memory, and response inhibition in adolescent and adult cannabis users and age-matched controls

BACKGROUND

Preclinical and human studies suggest that adolescent cannabis use may be associated with worse cognitive outcomes than adult cannabis use. We investigated the associations between chronic cannabis use and cognitive function in adolescent and adult cannabis users and controls. We hypothesised user-status would be negatively associated with cognitive function and this relationship would be stronger in adolescents than adults.

METHODS

As part of the 'CannTeen' project, this cross-sectional study assessed cognitive performance in adolescent cannabis users (n = 76; 16-17-year-olds), adolescent controls (n = 63), adult cannabis users (n = 71; 26-29-year-olds) and adult controls (n = 64). Users used cannabis 1-7 days/week. Adolescent and adult cannabis users were matched on cannabis use frequency (4 days/week) and time since last use (2.5 days). Verbal episodic memory (VEM) was assessed using the prose recall task, spatial working memory (SWM) was assessed using the spatial n-back task, and response inhibition was assessed with the stop-signal task. Primary outcome variables were: delayed recall, 3-back discriminability, and stop signal reaction time, respectively.

RESULTS

Users had worse VEM than controls (F(1,268) = 7.423, p = 0.007). There were no significant differences between user-groups on SWM or response inhibition. Null differences were supported by Bayesian analyses. No significant interactions between age-group and user-group were found for VEM, SWM, or response inhibition.

CONCLUSIONS

Consistent with previous research, there was an association between chronic cannabis use and poorer VEM, but chronic cannabis use was not associated with SWM or response inhibition. We did not find evidence for heightened adolescent vulnerability to cannabis-related cognitive impairment.

Cannabis and Alcohol Use and Their Associations with Sleep: A Daily Diary Investigation of Single-Use and Co-Use in College Students

Introduction: Sleep continuity problems are widespread among college students and may be influenced by single-use and co-use of alcohol and cannabis. We examined the within-person associations of alcohol and cannabis use with subsequent sleep experiences in the everyday life of college students. Materials and Methods: A sample of 80 college students reported prior-night alcohol and cannabis use and sleep experiences for 14 consecutive days. Mixed-effects models examined the within-person relationships between alcohol and cannabis use (single- and co-use) and subsequent (1) sleep-onset latency, (2) total sleep time, (3) number of awakenings, and (4) early awakenings that night. Results: Compared to no-use evenings, alcohol and cannabis, used separately or together (co-use), were associated with shorter sleep-onset latency and longer total sleep time. Students reported more nightly awakenings after alcohol-only use compared to no-use and after co-use, and they reported fewer early awakenings after no-use and co-use. Conclusions: In line with previous experimental findings, we found that alcohol and cannabis use in the everyday life of college students were associated with sleep-inducing effects, and that alcohol use was associated with disturbed sleep continuity. The results suggest that cannabis may curb alcohol's detrimental effect on the number of awakenings and may reduce the incidence of early awakenings. Yet, due to lack of control for potentially important confounders (e.g., quantity of cannabis/alcohol consumed, withdrawal) the current results may be best seen as preliminary and further research is needed before causal inferences can be reached.