Impacts of recreational cannabis legalization on cannabis use: a longitudinal discordant twin study

Mental Health, Substance Use, and Related Factors Associated with Recent Use of Cannabis for Sleep: A Co-Twin Control Study

OBJECTIVES

To examine: 1) cross-sectional associations between past-month use of cannabis for sleep with mental health, substance use, and related factors in adults and 2) the role of genetic and early environmental factors shared by twins (familial confounds) in explaining significant associations.

METHODS

In a population-based sample of adult twins (n = 3,165, Mage36.7) we ran regression (phenotypic) and multilevel (co-twin control) models examining associations between past-month use of cannabis for sleep without comes of interest. We controlled for cannabis frequency and sleep quality except when each was the outcome of interest.

RESULTS

Recent use of cannabis for sleep was associated with multiple mental health, substance use, and related factors in phenotypic models. In co-twincontrol models, within-family effects were significant between using cannabis for sleep with more problems from cannabis use, higher cannabis frequency, worse sleep quality, and more frequent use of alcohol and medication for sleep.

CONCLUSIONS

Familial confounds may explain many, but not all, associations between recent use of cannabis for sleep and mental health, substance use, and related factors. Longitudinal work is needed to clarify the directionality of associations not explained by familial confounds, and whether they are risks of using cannabis for sleep.

Marijuana use and failure of initial surgical management of retinal detachment

In this study, we found that marijuana users had a ∼70% increased rate of failure of initial surgical management of retinal detachment (hazard ratio (HR=1.74; p=0.002). Counseling patients regarding this risk may be beneficial.

The Highs and Lows of Fracture Fixation: Complications After Wrist Fracture Fixation for Users of Cannabis, Tobacco, or Neither Substance

BACKGROUND

We investigated associations of cannabis and tobacco use with complications after open reduction and internal fixation (ORIF) of wrist fractures.

METHODS

We retrospectively analyzed PearlDiver data from 337 538 patients who underwent ORIF for wrist fractures from 2010 to 2022. We identified 5587 patients with a history of cannabis use disorder ("cannabis group"); 12 806 patients with a history of tobacco use and no history of cannabis use disorder ("tobacco group"), and 310 108 patients with no history of cannabis use disorder or tobacco use ("control group"). We excluded patients with a history of using other illicit drugs. Propensity matching was used to control for age, sex, and comorbidity burden. Demographic characteristics, comorbidity profiles, and medical and surgical complications were compared using chi-squared tests. Complications were assessed within 90 days after surgery. Postoperative outcomes were also stratified by fracture location. Alpha = .05.

RESULTS

Compared with the control group, the cannabis group had a significantly higher incidence of all medical complications and of fracture malunion, nerve injury, and tendon, muscle, or fascia injury. Compared with the tobacco group, the cannabis group had significantly lower incidence of sepsis, pneumonia, deep venous thrombosis, urinary tract infection, nerve injury, and wound dehiscence.

CONCLUSIONS

Compared with nonusers of cannabis and tobacco, cannabis users had a higher incidence of several medical and surgical complications after ORIF for wrist fractures. These findings will help physicians better anticipate complications in patients who use cannabis or tobacco.

Co-use of alcohol and cannabis: Do social norms relate to personal use and consequences among college students?

The purpose of the present study was to examine (1) differences in descriptive and injunctive norms for alcohol, cannabis, and co-use, (2) whether descriptive and injunctive norms for alcohol, cannabis, and co-use were associated with co-use frequency, and (3) whether co-use descriptive and injunctive norms were associated with co-use consequences. Participants were 209 college students who were required to have engaged in only alcohol, only cannabis, and co-use in the past year. Participants completed an online survey about their substance use. For Aim 1, participants held the strongest descriptive and injunctive norms for alcohol use. For Aim 2, descriptive norms for co-use were related to greater co-use frequency; injunctive norms were not associated with co-use frequency. For Aim 3, both types of norms were not associated with co-use consequences. In comparison to descriptive norms for alcohol-only and cannabis-only, descriptive norms for co-use were most strongly tied with personal co-use frequency. Findings may inform intervention work focused on college students who engage in co-use by targeting normative perceptions of co-use.

Cannabis Use Among Older Adults

Importance

Little is known about patterns (forms, frequency, and reasons) and factors associated with cannabis use in older veterans (aged ≥65 years).

Objective

To examine factors associated with past 30-day cannabis use and cannabis use disorder (CUD) in older veterans.

Design, Setting, and Participants

In this cross-sectional study, community-dwelling adults aged 65 to 84 years who used Veterans Health Administration care were interviewed between February 5, 2020, and August 29, 2023.

Exposure

Sociodemographic, behavioral, and health-related characteristics.

Main Outcomes and Measures

Past 30-day cannabis use (smoking, vaping, dabbing, or edibles) and any CUD (≥2 criteria based on Diagnostic and Statistical Manual of Mental Disorders [Fifth Edition]) were assessed using weighted multivariable logistic regressions.

Results

Of the 4503 participants (weighted mean age, 73.3 years [95% CI, 73.0-73.5 years]; 85.4% [95% CI, 83.6%-87.2%] men), 58.2% (95% CI, 55.3%-61.0%) had ever used cannabis, 28.9% (95% CI, 26.0%-31.8%) of whom reported using cannabis for medical reasons, most commonly for pain (56.4%; 95% CI, 50.9%-61.9%), mood or mental health (18.4%; 95% CI, 14.7%-22.1%), and sleep (16.0%; 95% CI, 11.9%-20.0%). More than 1 in 10 reported past 30-day cannabis use (10.3%; 95% CI, 8.9%-11.7%), with 52.4% (95% CI, 45.4%-59.4%) of these using cannabis for 20 days or more; smoking (72.4%; 95% CI, 65.4%-79.3%) and edibles (36.9%; 95% CI, 29.8%-43.9%) were the most common forms of use. Characteristics associated with past 30-day use included younger age (65-75 years), economic hardship, tobacco and illicit drug use, and residing in a state with recreationally legal cannabis. Among those with past 30-day cannabis use, 36.3% (95% CI, 30.1%-42.6%) screened positive for CUD, with higher odds among younger respondents, those reporting anxiety, those with 1 or more deficits in activities of daily living, those with illicit drug use, those with frequent cannabis use, and those using cannabis recreationally. Past 30-day inhaled cannabis use, compared with edibles only, was associated with increased odds of any CUD (adjusted odds ratio, 3.56; 95% CI, 1.12-11.26).

Conclusions and Relevance

In this cross-sectional study of cannabis use in older veterans, use was common, and more than one-third who used in the past 30 days had any CUD. The prevalence of past 30-day cannabis use was close to tobacco use prevalence, and risk factors for cannabis use were similar to those observed in other populations. Frequent and inhaled cannabis use was associated with higher odds of any CUD. Routine health screening for cannabis use in Veterans Health Administration clinical settings is necessary to identify older adults with cannabis use.

Effects of legal access versus illegal market cannabis on use and mental health: A randomized controlled trial

AIMS

We measured the effects of public health-oriented cannabis access compared with the illegal market on cannabis use and related mental health outcomes in adult cannabis users.

DESIGN

This was a two-arm, parallel group, open-label, randomized controlled trial. Follow-up outcome measurement took place after 6 months.

SETTING

The study was conducted in Basel-Stadt, Switzerland.

PARTICIPANTS

A total of 378 adult (aged ≥18 years) cannabis users were enrolled and randomized between August 2022 and March 2023, although only 374 users who completed baseline measures could be included.

INTERVENTION AND COMPARATOR

Participants were randomly assigned to the intervention group with public health-oriented recreational cannabis access in pharmacies (regulated cannabis products, safer use information, voluntary counseling, no advertisement; 189/188) or the illegal market control group (continued illicit cannabis sourcing; 189/186).

MEASUREMENTS

The primary outcome was self-reported severity of cannabis misuse after 6 months, as measured by the Cannabis Use Disorders Identification Test - Revised (range 0-32). Secondary outcomes involved depressive, anxiety, and psychotic symptoms, cannabis consumption amount, alcohol, and drug use.

FINDINGS

Ten participants were not followed (2.7%). Primary analysis included those with complete data (182 vs. 182). There was some evidence of a difference in cannabis misuse between the legal cannabis intervention group (mean [M] = 10.1) and the illegal market control group (M = 10.9; β = -0.69, 95% confidence interval [CI] = -1.4 to 0.0, P = 0.052). These results were supported by an intention-to-treat multiple imputation analysis (n = 374). Additional sub-group analysis by whether the participant used other drugs or not suggested that any reduction in cannabis misuse was confined to those in the legal cannabis intervention group who used other drugs (PInteraction < 0.001). We found no statistically significant changes in any of the secondary outcomes.

CONCLUSIONS

Public health-oriented recreational cannabis access may decrease cannabis use and cannabis-related harms, especially among those using other drugs.

Examining dynamic patterns of problematic cannabis use: Results from a multilevel network analysis

Young adults who engage in problematic cannabis use report lower work and interpersonal functioning yet are less likely to seek treatment, necessitating alternative methods for assessing and intervening on problematic cannabis use (e.g., mobile health applications to self-monitor drivers of cannabis use in daily life). However, previous work examining maintenance models of problematic cannabis use has primarily focused on modeling predictors of cannabis use as measured using static retrospective report rather than examining cannabis use as a series of interactions that unfold in everyday life. In this study, we analyzed ecological momentary assessment data (T = 3,230 observations) from 65 young adults who reported problematic cannabis use (Cannabis Use Disorders Identification Test-Revised: M = 10.38, SD = 4.35) and an interest in reducing their use. We used multilevel network analyses to model associations among biopsychosocial factors that aligned with social learning, self-medication, and experiential avoidance theories of substance use. Network models demonstrated consistent associations between socioenvironmental triggers and cannabis cravings, use, and intoxication that were nearly all clinically meaningful in size (bs > 0.10). Results indicated a statistically significant association between negative and positive affect with cannabis use and intoxication, respectively; however, these associations were not clinically meaningful in size. There were no clinically meaningful associations between coping strategies and cannabis use variables. Findings advance our understanding of cannabis use in everyday life, which is critical for refining more dynamic conceptualization of substance use and improving the precision of clinical assessments. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Sleep-Related Cannabis Expectancy Questionnaire (SR-CEQ): Factor Analysis Replication, Internal Reliability, and Construct Validity

Expectancies regarding the sleep-promoting effects of cannabis may exacerbate the propensity to self-medicate sleep problems with cannabis. Given the potential clinical importance of expectancies for the sedative effects of cannabis, Goodhines et al (2020) developed the Sleep-Related Cannabis Expectancies Questionnaire (SR-CEQ). However, concurrent validity of this instrument has not been evaluated. This study aimed to replicate the two-factor structure and internal reliability and explore incremental construct validity of the SR-CEQ. Cross-sectional online survey data were collected from 287 college students (Mage = 19.07 ± 1.44 years, range 18-25; 47% male; 84% non-Hispanic White; 61% lifetime cannabis use). Confirmatory factor analysis replicated an adequate fit of the two-factor model (SRMR = 0.08) with excellent internal consistency within positive (α = .94) and negative (α = .91) subscales. Novel correlates were observed for positive (greater mood, sleep, cannabis risk; rs = .16-.48, ps = .001-.03) and negative (lesser cannabis risk; rs = -.18-.61, ps = .001-.03) subscales. Positive expectancies were greater among students with insomnia (t[285] = 2.70, p < .01; d = .33) and hazardous cannabis use (t[284] = 6.63, p < .001; d = 0.91). No group differences were observed by sex or for negative sleep-related cannabis expectances. This study extends psychometric validation of the SR-CEQ and highlights positive expectancies as a potential risk factor for insomnia and hazardous cannabis use.

The impact of schizophrenia genetic load and heavy cannabis use on the risk of psychotic disorder in the EU-GEI case-control and UK Biobank studies

BACKGROUND

The association between cannabis and psychosis is established, but the role of underlying genetics is unclear. We used data from the EU-GEI case-control study and UK Biobank to examine the independent and combined effect of heavy cannabis use and schizophrenia polygenic risk score (PRS) on risk for psychosis.

METHODS

Genome-wide association study summary statistics from the Psychiatric Genomics Consortium and the Genomic Psychiatry Cohort were used to calculate schizophrenia and cannabis use disorder (CUD) PRS for 1098 participants from the EU-GEI study and 143600 from the UK Biobank. Both datasets had information on cannabis use.

RESULTS

In both samples, schizophrenia PRS and cannabis use independently increased risk of psychosis. Schizophrenia PRS was not associated with patterns of cannabis use in the EU-GEI cases or controls or UK Biobank cases. It was associated with lifetime and daily cannabis use among UK Biobank participants without psychosis, but the effect was substantially reduced when CUD PRS was included in the model. In the EU-GEI sample, regular users of high-potency cannabis had the highest odds of being a case independently of schizophrenia PRS (OR daily use high-potency cannabis adjusted for PRS = 5.09, 95% CI 3.08-8.43, p = 3.21 × 10-10). We found no evidence of interaction between schizophrenia PRS and patterns of cannabis use.

CONCLUSIONS

Regular use of high-potency cannabis remains a strong predictor of psychotic disorder independently of schizophrenia PRS, which does not seem to be associated with heavy cannabis use. These are important findings at a time of increasing use and potency of cannabis worldwide.

Cannabis legalization and changes in cannabis and tobacco/nicotine use and co-use in a national cohort of U.S. adults during 2017-2021

BACKGROUND

Little is known about whether cannabis legalization impacts cannabis use uptake or has spillover effects on co-use of cannabis and tobacco/nicotine (using both in the past 30 days). We determined associations of cannabis legalization with self-reported (1) current (past 30-day) cannabis use; (2) current ("now") tobacco/nicotine use (smoking or electronic cigarette use); and (3) current co-use of cannabis and tobacco/nicotine and how prevalence is changing over time.

METHODS

In this longitudinal study, a web-based survey was administered to a nationally representative, population-based panel of US adults in 2017, 2020, and 2021. We used weighted unadjusted binomial logistic GEE models to assess changes in prevalence of cannabis, tobacco/nicotine use and co-use and weighted, adjusted binary logistic GEE models to assess associations of cannabis legalization with cannabis, tobacco/nicotine use and co-use.

RESULTS

A total of 9003 participants (age range = 18-94, mean age = 47.9 [±17.4 SD] years; 4696 females [weighted 52.0 %]) completed the survey in 2017; 5979/8529 (70.1 %) in 2020 and 5420/7305 (74.2 %) in 2021 from the original cohort who remained available. Current cannabis use significantly increased +3.3 % between 2017 and 2021, while tobacco/nicotine use significantly declined (-1.9 %); co-use of cannabis and tobacco/nicotine did not change significantly (+0.2 %). Both medical and recreational cannabis legalization was associated with increased current cannabis use; the independent effect of recreational cannabis legalization was 1.13 times larger than medical. There were no statistically significant differences in tobacco/nicotine use and co-use prevalence by legalization status.

CONCLUSION

Cannabis legalization increases cannabis use but is not associated with changes in tobacco/nicotine use or co-use. Legalization should be coupled with public health efforts.

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.

Understanding Cannabis-Related Information Needs: An Analysis of Inquiries to the National Cancer Institute's Cancer Information Service

Purpose: Given increased cannabis use for medical and nonmedical purposes alike, there is growing public interest related to the potential risks and benefits of cannabis use, particularly related to cancer. The purpose of this descriptive study was to analyze cannabis inquiries to the National Cancer Institute's Cancer Information Service (CIS). Materials and Methods: From September 2018 to June 2023, 190,070 noncannabis and 425 cannabis inquiries were documented by the CIS. Cannabis inquiries were delineated into two categories: nonmedical cannabis (NMC, n=240) or medical cannabis (MC, n=185). Chi-square tests were performed to determine differences between noncannabis and cannabis inquiries and descriptive analyses were used to identify patterns within cannabis-specific inquiries. Results: Statistically significant differences between noncannabis and cannabis inquiries were observed. In addition, there were variations in MC and NMC inquiries. For example, 73% of MC inquiries originated from cancer survivors and caregivers, whereas almost half of NMC inquiries (48%) were from individuals identifying as tobacco users. MC and NMC inquiries also differed by CIS access channel (e.g., instant chat, telephone), language used (English vs. Spanish), discussions of cancer continuum phases and cancer sites, and referrals provided to individuals for additional information and resources. Conclusion: Cannabis-related information needs of the public-as documented by the CIS-varied by several factors. Health information sources such as the CIS can help address cannabis-related questions and concerns, while noting differences in who is inquiring, how, and why.

A Bivariate Twin Study of Lifetime cannabis Initiation and Lifetime Regular Tobacco Smoking Across Three Different Countries

Regular cigarette smoking and cannabis consumption are strongly positively related to each other, yet few studies explore their underlying variation and covariation. We evaluated the genetic and environmental decomposition of variance and covariance of these two traits in twin data from three countries with different social norms and legislation. Data from the Netherlands Twin Register, FinnTwin12/16, and the Minnesota Center for Twin Family Research (total N = 21,617) were analyzed in bivariate threshold models of lifetime regular smoking initiation (RSI) and lifetime cannabis initiation (CI). We ran unstratified models and models stratified by sex and country. Prevalence of RSI was lowest in the Netherlands and prevalence of CI was highest in Minnesota. In the unstratified model, genetic (A) and common environmental factors (C) contributed substantially to the liabilities of RSI (A = 0.47, C = 0.34) and CI (A = 0.28, C = 0.51). The two liabilities were significantly phenotypically (rP = 0.56), genetically (rA = 0.74), and environmentally correlated in the unstratified model (rC = 0.47and rE = 0.48, representing correlations between common and unique environmental factors). The magnitude of phenotypic correlation between liabilities varied by country but not sex (Minnesota rP ~ 0.70, Netherlands rP ~ 0.59, Finland rP ~ 0.45). Comparisons of decomposed correlations could not be reliably tested in the stratified models. The prevalence and association of RSI and CI vary by sex and country. These two behaviors are correlated because there is genetic and environmental overlap between their underlying latent liabilities. There is heterogeneity in the genetic architecture of these traits across country.

Genetic influences and causal pathways shared between cannabis use disorder and other substance use traits

Cannabis use disorder (CanUD) has increased with the legalization of the use of cannabis. Around 20% of individuals using cannabis develop CanUD, and the number of users has grown with increasing ease of access. CanUD and other substance use disorders (SUDs) are associated phenotypically and genetically. We leveraged new CanUD genomics data to undertake genetically-informed analyses with unprecedented power, to investigate the genetic architecture and causal relationships between CanUD and lifetime cannabis use with risk for developing SUDs and substance use traits. Analyses included calculating local and global genetic correlations, genomic structural equation modeling (genomicSEM), and Mendelian Randomization (MR). Results from the genetic correlation and genomicSEM analyses demonstrated that CanUD and cannabis use differ in their relationships with SUDs and substance use traits. We found significant causal effects of CanUD influencing all the analyzed traits: opioid use disorder (OUD) (Inverse variant weighted, IVW β = 0.925 ± 0.082), problematic alcohol use (PAU) (IVW β = 0.443 ± 0.030), drinks per week (DPW) (IVW β = 0.182 ± 0.025), Fagerström Test for Nicotine Dependence (FTND) (IVW β = 0.183 ± 0.052), cigarettes per day (IVW β = 0.150 ± 0.045), current versus former smokers (IVW β = 0.178 ± 0.052), and smoking initiation (IVW β = 0.405 ± 0.042). We also found evidence of bidirectionality showing that OUD, PAU, smoking initiation, smoking cessation, and DPW all increase risk of developing CanUD. For cannabis use, bidirectional relationships were inferred with PAU, smoking initiation, and DPW; cannabis use was also associated with a higher risk of developing OUD (IVW β = 0.785 ± 0.266). GenomicSEM confirmed that CanUD and cannabis use load onto different genetic factors. We conclude that CanUD and cannabis use can increase the risk of developing other SUDs. This has substantial public health implications; the move towards legalization of cannabis use may be expected to increase other kinds of problematic substance use. These harmful outcomes are in addition to the medical harms associated directly with CanUD.

Probing the Paradox: Investigating the Impact of Affect, Exercise Type, and Cannabis Use on the Alcohol-Exercise Relationship in College Students

Alcohol has previously shown a paradoxical positive relationship with exercise behaviors. However, the relationship has not been explored according to type of exercise (aerobic vs. anaerobic), nor has the research considered other contextual variables that commonly co-occur with alcohol use, such as cannabis and mood. This study sought to expand upon previous research to understand how the alcohol-exercise relationship may vary based on exercise type. Additionally, this study included cannabis use and mood as moderators of the alcohol-exercise association. Cross-sectional survey data was collected from college students (N = 335). Negative binomial regression was used to test associations between exercise and alcohol consumption, cannabis use, positive affect (PA), negative affect (NA), and moderating effects of these factors on the alcohol-exercise relationship. Effect sizes are reported from an Incidence Rate Ratio (IRR). Sex assigned at birth (male = 1, female = 0; IRR = 1.34, p = .017), PA (IRR = 1.57, p = .001), and alcohol consumption (IRR = 1.94, p = .037) exhibited positive relationships with exercise. Significant main effects were not observed for negative affect (IRR = 1.17, p = .230), or cannabis use (IRR = 1.00, p = .988). There was a significant interaction between positive affect and alcohol consumption (IRR = 0.87, p = .044) predicting exercise minutes. Alcohol was positively associated with exercise for those with low positive affect (n = 42, b = 12.61, p = .096) and this effect was attenuated as levels of positive affect increased (mean positive affect: n = 232, b = 0.55, p = .926; high positive affect: n = 61, b = -15.86, p = .146). These findings suggest that low positive affect may contribute to the positive link between alcohol use and exercise (especially aerobic exercise) in young people.

A cross-sectional study of the relationship between frequency of cannabis use and psychiatric symptoms among people seeking mental health and addiction services in Nova Scotia (2019-21)

BACKGROUND

Cannabis use may be a modifiable risk factor for mental health problems; however, the role of cannabis use frequency in population seeking mental health and addiction services remains unclear. This study aimed to: 1) compare the prevalence and functional impact of psychiatric symptoms among frequent, infrequent, and non-users of cannabis; and 2) evaluate the associations between cannabis use frequency and functional impact of psychiatric symptoms in help-seeking individuals.

METHODS

Data from the Mental Health and Addictions (MHA) Central Intake system in Nova Scotia, Canada was used. Participants aged 19-64 who received MHA Intake assessments from September 2019 to December 2021 with complete information about substance use were included (N = 20,611). Cannabis use frequency over past 30 days was categorized into frequent (>4 times a month), infrequent (≤4 times a month), and non-use. Psychiatric symptomatology consists of five domains: mood, anxiety, psychosis, cognition, and externalizing behaviors. Multivariate ordinal logistic regression was used to examine the associations between cannabis use frequency and functional impact of psychiatric symptoms.

RESULTS

Frequent and infrequent cannabis users had a higher prevalence of psychiatric symptoms in each domain than non-users, while no significant differences were found between frequent and infrequent users. Frequent cannabis use was associated with greater functional impact of psychiatric symptoms in each domain compared to non-users, while infrequent use was only associated with greater functional impact of externalizing behaviors.

CONCLUSION

Frequent cannabis use is associated with increased prevalence and functional impact of psychiatric symptoms among adults seeking mental health services.

Most Unusual Twin Pairs: A Look at Uterus Didelphys / Twin Research Reviews: Prenatal Aneuploidy Screening for Twin Pregnancies; Twin Conceptions by Same-Sex Male Couples; Legal Personality of Conjoined Twins; Twin Study of Cannabis Use / Human Interest and Importance: Being Taken for Twins Saved Sisters; Twin Children of Jailed Nobel Prize Winner; British 'Biracial' Twins; Triplets Born at Start of Russian Attack on Ukraine; Twins Born in Different Years

A review of an unusual twin type-twins born to women with two uteri (uterus didelphys)-is presented. This review is followed by summaries of recent research and perspectives concerning prenatal aneuploidy screening for twin pregnancies, twin conceptions by same-sex male couples, legal personality of conjoined twins, and a twin study of cannabis use. Interesting information about twins that has appeared in the media is also presented, namely how being taken for twins saved a pair of sisters; twin children of a jailed Nobel Prize winner, British 'biracial' twins, triplets born at the start of Russia's attack on Ukraine, and twins born in different years.

What impact could the legalisation of recreational cannabis have on the health of the UK? Lessons from the rest of the world

Several jurisdictions across the globe have introduced legislation to legally permit the sale and consumption of recreational cannabis. This editorial considers current evidence from the rest of the world and asks how this might inform the possible consequences of 'legalisation' models in the UK.

Medicinal cannabis use among young adults during California's transition from legalized medical use to adult-use: a longitudinal analysis

Background: In 2016, California transitioned from legalized medical cannabis use to adult-use. Little is known about how this policy change affected medicinal cannabis use among young adults.Objectives: To identify longitudinal groups of medicinal cannabis users and concurrent changes in health- and cannabis use-related characteristics among young adults in Los Angeles between 2014 and 2021.Methods: Cannabis users (210 patients and 156 non-patients; 34% female; ages 18-26 at baseline) were surveyed annually across six waves. Longitudinal latent class analysis derived groups from two factors - cannabis patient status and self-reported medicinal use. Trajectories of health symptoms, cannabis use motives, and cannabis use (daily/near daily use, concentrate use, and problematic use) were estimated across groups.Results: Three longitudinal latent classes emerged: Recreational Users (39.3%) - low self-reported medicinal use and low-to-decreasing patient status; Recreational Patients (40.4%) - low self-reported medicinal use and high-to-decreasing patient status; Medicinal Patients (20.3%) - high self-reported medicinal use and high-to-decreasing patient status. At baseline, Medicinal Patients had higher levels of physical health symptoms and motives than recreational groups (p < .05); both patient groups reported higher level of daily/near daily and concentrate use (p < .01). Over time, mental health symptoms increased in recreational groups (p < .05) and problematic cannabis use increased among Recreational Patients (p < .01).Conclusions: During the transition to legalized adult-use, patterns of medicinal cannabis use varied among young adults. Clinicians should monitor increases in mental health symptoms and cannabis-related problems among young adults who report recreational - but not medicinal - cannabis use.

Associations between simultaneous use of alcohol and cannabis and cannabis-related problems in 2014-2016: evidence from the Washington panel survey

BACKGROUND

To address the research question of how simultaneous users of alcohol and cannabis differ from concurrent users in risk of cannabis use problems after the recreational marijuana legalization in Washington State.

METHODS

We used generalized estimating equations with a Poisson distribution to analyze the association between simultaneous use of alcohol and marijuana (SAM) and cannabis-related problems compared to concurrent use. The data is a longitudinal sample of drinkers and cannabis users (n = 257, 47% female) aged 18 years and older from Washington State in 2014-2016. We adjusted for survey weights to account for differential probability of selection and response rates. The primary outcome is the past-six-month CUDIT problem subscale (ranging from 0 to 28), which is the total score for seven CUDIT problem items, after excluding the three items that covered marijuana use frequency. Covariates include marijuana use frequency (daily/near daily use, regular use, or infrequent use), marijuana daily quantity, alcohol daily volume, panel survey cycle, medical marijuana recommendation, driving time to nearest marijuana outlet, age of marijuana use onset, and other demographics.

RESULTS

After adjusting for covariates, we found that compared to concurrent use, SAM was significantly positively associated with CUDIT problem subscale (IRR = 1.68, 95% CI: 1.25-2.27, p < 0.001); daily/near daily use of marijuana was strongly significantly associated with CUDIT problem subscale compared with infrequent use (IRR = 5.1, 2.71-9.57, p < 0.001) or regular use (IRR = 3.05, 1.91-4.85, p < 0.001). Secondary analyses using CUDIT total score as the outcome also showed a significant positive association with SAM compared to concurrent use (IRR = 1.17, 1.02-1.34, p < 0.05).

CONCLUSIONS

This study highlighted the importance of SAM, in addition to cannabis use frequency for predicting cannabis-related problems.

Risk Factors for Quantity of Cannabis Use Per Day among College Students Who Violated Their University Drug Use Policy

Background

Cannabis use among college students represents a continued public health issue. The objective was to assess risk factors and reasons for cannabis use among students who violated their university's drug use policy, and whether risk factors influenced cannabis use quantity.

Methods

This cross-sectional survey study included 99 college students enrolled at a large U.S. public university. Descriptive statistics were calculated, and an ordinary least squares regression analysis was conducted.

Results

Students reported using cannabis an average of 7.4 (SD = 10.2) days in the past month, with 8% reporting daily use. On average, students consumed slightly over 0.25 (SD = 0.25) grams per day, with 40% reporting greater than one gram per day. The average age of onset of cannabis use was 16.8 (SD = 1.8) years old. The top reasons for cannabis use were to: relax or relieve tension (75.8%), feel good or get high (62.6%), and have a good time with friends (60.6%). Students perceived an average of 47% of their peers engaged in past-month cannabis use and only slight risk was associated with regular use. Students perceived their loved ones would mostly approve of a reduction in their cannabis use. Regression results indicated past-month cannabis frequency (p = .002) and being of racial/ethnic minority descent (p = .05) were positively associated with quantity of cannabis per day, while perceived risk of regular cannabis use (β = -0.21) was negatively associated.

Conclusion

Evidence-based cannabis interventions for students who violate their university's drug use policies are critically needed that aim to reduce cannabis use and mitigate its associated negative consequences.

The impact of recreational cannabinoid legalization on utilization in a pregnant population

Background

Marijuana potency and utilization both continue to increase across the United States. While the overall prevalence of cannabinoid utilization during pregnancy has been surveyed in various studies, the direct impact of changing governmental policies on pregnancy use is less characterized. Thus, we aimed to investigate how the legalization of recreational cannabinoid products impacted use during pregnancy in the state of New Mexico.

Methods

Participants who had a live birth during two study epochs were included: pre-legalization (Epoch 1: 1 January 2019-31 March 2021) and post-legalization (Epoch 2: 1 November 2021-30 November 2022). Participants were further divided into case group [prenatal cannabinoid exposure (PCE)] vs. control (no PCE), with cases being identified by documented self-report or a positive laboratory toxicology test for cannabinoid use during pregnancy.

Results

A total of 1,191 maternal/infant dyads were included in Epoch 1, and 378 maternal/infant dyads were included in Epoch 2. In Epoch 1, 788 dyads were controls with 403 cases, while Epoch 2 had 292 controls and 86 cases. Interestingly there was a significant decrease in self-report or positive laboratory toxicology tests in Epoch 2 compared to Epoch 1. Infants born following PCE in both Epoch groups were more commonly born via Cesarean section, had significantly smaller birth weight, length, and head circumference as well as significantly lower Apgar scores at 1 and 5 min.

Conclusion

The finding of decreased reported cannabinoid use in the post-legalization group is contradictory to previous studies which have shown increased rates of cannabinoid use after legalization. This could be due to multiple factors including changes in screening practices, the COVID-19 pandemic, and lack of commercialization of THC products. Additional studies are needed to further characterize how changing governmental policies impacts utilization during pregnancy.

Legalization and retail availability of recreational marijuana and adolescent use in schools

Legalization of use and retail sales of recreational marijuana in U.S. states and the associated potential increase in access to marijuana and normalization of its use by adults could lead to increased use by adolescents. Studies have found that states with legal recreational marijuana have higher rates of adolescent use and frequency of use compared to states without legal use. We examined changes in student office discipline referrals (ODRs) for substance use offenses in Oregon middle and high schools before and after the legalization of recreational marijuana relative to comparison schools in other states. We found that rates of substance use related ODRs in middle schools increased by 0.14 per 100 students (30% of the mean) with legalization relative to comparison schools. This increase was moderated by the presence of a marijuana outlet within one mile of the school. We found no statistically discernible changes in high school ODRs. Marijuana use in adolescence has been linked to negative health and social consequences, including academic problems, mental health issues, and impaired driving. Potential adverse impact on adolescents and investments in school-based prevention programs could be important considerations for policymakers and public health officials when evaluating marijuana legalization.

Addendum to "Evaluating substance use outcomes of recreational cannabis legalization using a unique co-twin control design"

An earlier version of this article was published in error. Our prior publication was missing reference to a prior study on this topic. Our prior research has not found an association between recreational cannabis legalization (RCL) and negative psychosocial and psychiatric outcomes. We reported significant associations between RCL with greater cannabis frequency and fewer alcohol use disorder symptoms. The current study expands on our previous research by using a cross-sectional design and different measures of problems from cannabis and alcohol use and including additional substance use variables. The current study found similar results to our previous research.

Cannabis industry campaign expenditures in Colorado, 2005-2021

BACKGROUND

The cannabis industry has been described using the commercial determinants of health framework because it seeks to increase sales and profits through efforts to change the political environment. To increase understanding of these cannabis industry's efforts, this study describes cannabis industry campaign contributions in Colorado through an analysis of public records.

METHODS

We reviewed datasets posted online at the Colorado Secretary of State's Transparent in Contribution and Expenditure Reporting (TRACER) Campaign Finance System. We generated descriptive data on cannabis industry contributions to elections and conducted regressions to identify predictors of contributions, and associations between lagged contributions and a legislator's cannabis industry score (how closely aligned lawmaker's legislative history is with the cannabis industry from -1 to 1).

RESULTS

Between 2005-2021, 429 cannabis-affiliated contributors gave $4,658,385 (2021 inflation-adjusted) to 512 electoral committees. Contributions came primarily from non-profits (45%), businesses (27%), and individuals (25%). After recreational legalization in 2012, contributions from non-profit donors with industry ties gave way to contributions from cannabis businesses, business owners, and lobbyists. Cannabis industry contributions to local and state-wide ballot initiative campaigns historically made up the majority of the industry spending, but contributions to candidate committees more than tripled between the 2009-2010 legislative cycle and the 2019-2020 cycle. From 2017-2020, every $10,000 in lagged campaign donations from cannabis industry affiliated contributors was associated with a 0.245-point increase in a legislator's cannabis industry score (p=0.04).

CONCLUSION

Cannabis-affiliated interests made substantial campaign contributions in Colorado. Public health advocates should monitor industry connections to lawmakers and industry tactics used to mask the source of political contributions. Continued surveillance of the cannabis industry is essential to exposing conflicts of interest and preventing undue industry influence.

Chronic Pain, Cannabis Legalization and Cannabis Use Disorder in Veterans Health Administration Patients, 2005 to 2019

Background

The risk for cannabis use disorder (CUD) is elevated among U.S. adults with chronic pain, and CUD rates are disproportionately increasing in this group. Little is known about the role of medical cannabis laws (MCL) and recreational cannabis laws (RCL) in these increases. Among U.S. Veterans Health Administration (VHA) patients, we examined whether MCL and RCL effects on CUD prevalence differed between patients with and without chronic pain.

Methods

Patients with ≥1 primary care, emergency, or mental health visit to the VHA and no hospice/palliative care within a given calendar year, 2005-2019 (yearly n=3,234,382 to 4,579,994) were analyzed using VHA electronic health record (EHR) data. To estimate the role of MCL and RCL enactment in the increases in prevalence of diagnosed CUD and whether this differed between patients with and without chronic pain, staggered-adoption difference-in-difference analyses were used, fitting a linear binomial regression model with fixed effects for state, categorical year, time-varying cannabis law status, state-level sociodemographic covariates, a chronic pain indicator, and patient covariates (age group [18-34, 35-64; 65-75], sex, and race and ethnicity). Pain was categorized using an American Pain Society taxonomy of painful medical conditions.

Outcomes

In patients with chronic pain, enacting MCL led to a 0·14% (95% CI=0·12%-0·15%) absolute increase in CUD prevalence, with 8·4% of the total increase in CUD prevalence in MCL-enacting states attributable to MCL. Enacting RCL led to a 0·19% (95%CI: 0·16%, 0·22%) absolute increase in CUD prevalence, with 11·5% of the total increase in CUD prevalence in RCL-enacting states attributable to RCL. In patients without chronic pain, enacting MCL and RCL led to smaller absolute increases in CUD prevalence (MCL: 0·037% [95%CI: 0·03, 0·05]; RCL: 0·042% [95%CI: 0·02, 0·06]), with 5·7% and 6·0% of the increases in CUD prevalence attributable to MCL and RCL. Overall, MCL and RCL effects were significantly greater in patients with than without chronic pain. By age, MCL and RCL effects were negligible in patients age 18-34 with and without pain. In patients age 35-64 with and without pain, MCL and RCL effects were significant (p<0.001) but small. In patients age 65-75 with pain, absolute increases were 0·10% in MCL-only states and 0·22% in MCL/RCL states, with 9·3% of the increase in CUD prevalence in MCL-only states attributable to MCL, and 19.4% of the increase in RCL states attributable to RCL. In patients age 35-64 and 65-75, MCL and RCL effects were significantly greater in patients with pain.

Interpretation

In patients age 35-75, the role of MCL and RCL in the increasing prevalence of CUD was greater in patients with chronic pain than in those without chronic pain, with particularly pronounced effects in patients with chronic pain age 65-75. Although the VHA offers extensive behavioral and non-opioid pharmaceutical treatments for pain, cannabis may seem a more appealing option given media enthusiasm about cannabis, cannabis commercialization activities, and widespread public beliefs about cannabis efficacy. Cannabis does not have the risk/mortality profile of opioids, but CUD is a clinical condition with considerable impairment and comorbidity. Because cannabis legalization in the U.S. is likely to further increase, increasing CUD prevalence among patients with chronic pain following state legalization is a public health concern. The risk of chronic pain increases as individuals age, and the average age of VHA patients and the U.S. general population is increasing. Therefore, clinical monitoring of cannabis use and discussion of the risk of CUD among patients with chronic pain is warranted, especially among older patients.

Research in Context

Evidence before this study: Only three studies have examined the role of state medical cannabis laws (MCL) and/or recreational cannabis laws (RCL) in the increasing prevalence of cannabis use disorder (CUD) in U.S. adults, finding significant MCL and RCL effects but with modest effect sizes. Effects of MCL and RCL may vary across important subgroups of the population, including individuals with chronic pain. PubMed was searched by DH for publications on U.S. time trends in cannabis legalization, cannabis use disorders (CUD) and pain from database inception until March 15, 2023, without language restrictions. The following search terms were used: (medical cannabis laws) AND (pain) AND (cannabis use disorder); (recreational cannabis laws) AND (pain) AND (cannabis use disorder); (cannabis laws) AND (pain) AND (cannabis use disorder). Only one study was found that had CUD as an outcome, and this study used cross-sectional data from a single year, which cannot be used to determine trends over time. Therefore, evidence has been lacking on whether the role of state medical and recreational cannabis legalization in the increasing US adult prevalence of CUD differed by chronic pain status.Added value of this study: To our knowledge, this is the first study to examine whether the effects of state MCL and RCL on the nationally increasing U.S. rates of adult cannabis use disorder differ by whether individuals experience chronic pain or not. Using electronic medical record data from patients in the Veterans Health Administration (VHA) that included extensive information on medical conditions associated with chronic pain, the study showed that the effects of MCL and RCL on the prevalence of CUD were stronger among individuals with chronic pain age 35-64 and 65-75, an effect that was particularly pronounced in older patients ages 65-75.Implications of all the available evidence: MCL and RCL are likely to influence the prevalence of CUD through commercialization that increases availability and portrays cannabis use as 'normal' and safe, thereby decreasing perception of cannabis risk. In patients with pain, the overall U.S. decline in prescribed opioids may also have contributed to MCL and RCL effects, leading to substitution of cannabis use that expanded the pool of individuals vulnerable to CUD. The VHA offers extensive non-opioid pain programs. However, positive media reports on cannabis, positive online "information" that can sometimes be misleading, and increasing popular beliefs that cannabis is a useful prevention and treatment agent may make cannabis seem preferable to the evidence-based treatments that the VHA offers, and also as an easily accessible option among those not connected to a healthcare system, who may face more barriers than VHA patients in accessing non-opioid pain management. When developing cannabis legislation, unintended consequences should be considered, including increased risk of CUD in large vulnerable subgroups of the population.

"That's Pot Culture Right There": Purchasing Behaviors of People Who Use Cannabis Without a Medical Cannabis Card

Introduction

The legal landscape surrounding purchasing cannabis without a medical cannabis card (i.e., without MCC) is changing rapidly, affecting consumer access and purchasing behaviors. Cannabis purchasing behaviors are related to subsequent use and experiencing greater cannabis-related negative consequences. However, purchasing behaviors of individuals who use cannabis without MCC are understudied.

Methods

The current study analyzed qualitative data from focus groups with adults who use cannabis without MCC (n = 5 groups; 6-7 participants/group; n = 31 total participants). Focus groups followed a semi-structured agenda, and were audio recorded and transcribed. Two coders applied thematic analysis to summarize topics pertaining to cannabis purchasing attitudes and behaviors. Focus groups occurred in 2015 and 2016 in Rhode Island, when purchasing and use of cannabis without MCC was decriminalized but still considered illegal.

Results

On average, participants (72% male) were 26 years old (SD = 7.2) and reported using cannabis 5 days per week (SD = 2.1). Thematic analysis revealed three key themes related to cannabis purchasing behaviors: (1) regular purchasing routines (i.e., frequency, schedule, amount of purchases), (2) economic factors (i.e., financial circumstances), and (3) contextual factors (i.e., quality of cannabis, convenience/availability) were perceived to influence purchasing decisions. Dealers' recommendations affected participants' purchases, who also reported minimal legal concerns. Participants reported saving money and using more cannabis when buying in bulk.

Discussion

Purchasing behaviors were found to vary and were perceived to be affected by individual-level (e.g., routines) and contextual factors (e.g., availability) that, in turn, may impact use patterns. Future research should consider how factors (e.g., availability) that differ across contexts (e.g., location) and demographic groups interact to affect purchasing behaviors.

Alternative hypotheses regarding the association between early engagement in gambling and gambling-like activities and later problem gambling - a commentary on Richard and King (2023)

This issue of the Journal of Child Psychology and Psychiatry includes a systematic review on the emergence of problem gambling from childhood to emerging adulthood (Richard & King, 2023). The importance of understanding the risks for problem gambling earlier in development is clear, given the increasing availability of gambling to minors, especially online gambling.

Revisiting the effect of recreational marijuana on traffic fatalities

BACKGROUND

This study examines the effect of retail recreational marijuana legalization on traffic fatalities using the most current data available and recent advancements in difference-in-difference estimation methods proposed by Callaway and Sant'Anna, (2021).

METHOD

A modified difference-in-difference (CS-DID) is used to estimate the effect of recreational marijuana legalization on traffic fatalities reported in the Fatality Analysis Reporting System (FARS). Difference-in-difference regression models are run at the state-year level, using data from 2007 through 2020, and compared to estimates using traditional two-way-fixed-effects (TWFE) models.

RESULTS

Consistent with past studies, results from conventional TWFE suggest traffic fatalities increase at a rate of 1.2 per billion vehicle miles traveled (BVMT) after retail of recreational marijuana begins. However, using the CS-DID model, we find slightly larger average total treatment effects (∼2.2 fatalities per BVMT). Moreover, the size of the effect changes across time, where cohorts "treated" earlier have substantially higher increases than those who more recently legalized.

CONCLUSION

Traffic fatalities increase by 2.2 per billion miles driven after retail legalization, which may account for as many as 1400 traffic fatalities annually. States who legalized earlier experienced larger traffic fatality increases. TWFE methods are inadequate for policy evaluation and do not capture heterogeneous effects across time.