Marijuana use among community-dwelling older adults: A population-based study.

OBJECTIVES: There is a paucity of population-level data on marijuana use and mental health and functioning in older adults. METHODS: We analyzed cross-sectional data (n = 910) from a well-characterized cohort, the Monongahela-Youghiogheny Healthy Aging Team (MYHAT) study. MYHAT is an age-stratified random sample of the population age 65 years and older from a small-town in the USA. Half the sample was female and half were over 75 (Mean age = 77). Most participants were non-Hispanic White. Marijuana use was assessed by self-report and symptoms of mood disorders were screened using the modified Centers for Epidemiological Studies-Depression Scale and the Generalized Anxiety Disorder screener. Cognition was assessed by the Mini-Mental State Examination and a neuropsychological test battery; functioning using the OARS Activities of Daily Living and Instrumental Activities of Daily Living; and overall assessment using the Clinical Dementia Rating (CDR®). RESULTS: One in five MYHAT participants had a history of marijuana use and 5% reported recent use, primarily for pain (41%) and recreation/relaxation (37%). Recent use was associated with cigarette and alcohol use, symptoms of depression or anxiety, and impairments in attention. CONCLUSIONS: Twenty-percent of community-dwelling older adults living in a US state where recreational marijuana use is illegal had a history of marijuana use. Recent marijuana use was less common but, consistent with prior research, associated with other substance use and poorer mental health.

Nursing student stress and marijuana use.

ABSTRACT: Nursing students increasingly report being stressed. As a potential treatment, students are using marijuana, according to nursing schools. Currently, there is no standardized guideline for the use of marijuana or marijuana testing for nursing students. This article discusses several concerns about clinical nursing students' use of marijuana for stress and anxiety relief.

Risk factors associated with driving after marijuana use among West Virginia college students during the COVID-19 pandemic.

OBJECTIVES: The purpose of this study was to assess sociodemographic and behavioral risk factors associated with driving after marijuana use (DAMU) among West Virginia college students. METHODS: Participants were recruited from West Virginia University between September and November 2022. The study sample was restricted to students who were ≥18 years of age; reported recently driving; possessed a current, valid driver's license from any US state; and were enrolled for at least one credit hour in the Fall 2022 semester. RESULTS: Among respondents (N = 772), 28.9% reported DAMU. Students who had a GPA of B (adjusted odds ratio [AOR]: 2.17, 95% confidence interval [CI]: 1.06-4.42), smoked or ingested marijuana in the past year (AOR: 26.51, 95% CI: 10.27-68.39), drove after drinking (AOR: 2.38, 95% CI: 1.18-4.79), and used both marijuana and alcohol concurrently and then drove (AOR: 10.39, 95% CI: 2.32-46.54) associated with DAMU. Individuals who felt the behavior was somewhat dangerous or not dangerous or thought their peers approved of DAMU showed significant associations with DAMU. CONCLUSIONS: As DAMU was prevalent, future interventions that raise awareness of the danger and potential consequences of DAMU may be needed to reduce this risky behavior on college campuses.

Increasing lifetime and past 30-day marijuana use among middle school students regardless of recreational marijuana sales.

PURPOSE: This study investigated whether adult use marijuana sales were associated with changes in lifetime and past 30-day (P30D) marijuana use among middle school students in Nevada (NV), which had adult-use marijuana sales during the study period, compared to New Mexico (NM), which did not have adult-use marijuana sales during the study period. METHODS: Data were drawn from the middle school 2017 and 2019 NV Youth Risk Behavior and NM Youth Risk and Resiliency Surveys. Difference-in-difference analyses compare changes in lifetime and P30D marijuana use in NV (adult-use sales implemented July 2017) vs. NM (no adult-use sales during the study period). RESULTS: There was no difference in lifetime (aOR 1.11; 95% CI 0.91,1.36) and P30D (aOR 1.17; 95% CI 0.91,1.51) marijuana use by adult-use sales status. The odds of lifetime and P30D marijuana use increased in both states, particularly among students who were female, older, non-White, or attending a Title 1 school. DISCUSSION: Adult-use sales were not associated with an increase in lifetime or P30D marijuana use. State-level prevention efforts should focus on sub-populations with increasing lifetime and P30D use regardless of adult-use sales status.

Adolescent Δ8-THC and Marijuana Use in the US.

Importance: Gummies, flavored vaping devices, and other cannabis products containing psychoactive hemp-derived Δ8-tetrahydrocannabinol (THC) are increasingly marketed in the US with claims of being federally legal and comparable to marijuana. National data on prevalence and correlates of Δ8-THC use and comparisons to marijuana use among adolescents in the US are lacking. Objective: To estimate the self-reported prevalence of and sociodemographic and policy factors associated with Δ8-THC and marijuana use among US adolescents in the past 12 months. Design, Setting, and Participants: This nationally representative cross-sectional analysis included a randomly selected subset of 12th-grade students in 27 US states who participated in the Monitoring the Future Study in-school survey during February to June 2023. Exposures: Self-reported sex, race, ethnicity, and parental education; census region; state-level adult-use (ie, recreational) marijuana legalization (yes vs no); and state-level Δ8-THC policies (regulated vs not regulated). Main Outcomes and Measures: The primary outcome was self-reported Δ8-THC and marijuana use in the past 12 months (any vs no use and number of occasions used). Results: In the sample of 2186 12th-grade students (mean age, 17.7 years; 1054 [48.9% weighted] were female; 232 [11.1%] were Black, 411 [23.5%] were Hispanic, 1113 [46.1%] were White, and 328 [14.2%] were multiracial), prevalence of self-reported use in the past 12 months was 11.4% (95% CI, 8.6%-14.2%) for Δ8-THC and 30.4% (95% CI, 26.5%-34.4%) for marijuana. Of those 295 participants reporting Δ8-THC use, 35.4% used it at least 10 times in the past 12 months. Prevalence of Δ8-THC use was lower in Western vs Southern census regions (5.0% vs 14.3%; risk difference [RD], -9.4% [95% CI, -15.2% to -3.5%]; adjusted risk ratio [aRR], 0.35 [95% CI, 0.16-0.77]), states in which Δ8-THC was regulated vs not regulated (5.7% vs 14.4%; RD, -8.6% [95% CI, -12.9% to -4.4%]; aRR, 0.42 [95% CI, 0.23-0.74]), and states with vs without legal adult-use marijuana (8.0% vs 14.0%; RD, -6.0% [95% CI, -10.8% to -1.2%]; aRR, 0.56 [95% CI, 0.35-0.91]). Use in the past 12 months was lower among Hispanic than White participants for Δ8-THC (7.3% vs 14.4%; RD, -7.2% [95% CI, -12.2% to -2.1%]; aRR, 0.54 [95% CI, 0.34-0.87]) and marijuana (24.5% vs 33.0%; RD, -8.5% [95% CI, -14.9% to -2.1%]; aRR, 0.74 [95% CI, 0.59-0.94]). Δ8-THC and marijuana use prevalence did not differ by sex or parental education. Conclusions and Relevance: Δ8-THC use prevalence is appreciable among US adolescents and is higher in states without marijuana legalization or existing Δ8-THC regulations. Prioritizing surveillance, policy, and public health efforts addressing adolescent Δ8-THC use may be warranted.

Using publicly available data to predict recreational cannabis legalization at the county-level: A machine learning approach.

BACKGROUND: There is substantial geographic variability in local cannabis policies within states that have legalized recreational cannabis. This study develops an interpretable machine learning model that uses county-level population demographics, sociopolitical factors, and estimates of substance use and mental illness prevalences to predict the legality of recreational cannabis sales within each U.S. county. METHODS: We merged data and selected 14 model inputs from the 2010 Census, 2012 County Presidential Data from the MIT Elections Lab, and Small Area Estimates from the National Surveys on Drug Use and Health (NSDUH) from 2010 to 2012 at the county level. County policies were labeled as having recreational cannabis legal (RCL) if the sale of recreational cannabis was allowed anywhere in the county in 2014, resulting in 92 RCL and 3002 non-RCL counties. We used synthetic data augmentation and minority oversampling techniques to build an ensemble of 1000 logistic regressions on random sub-samples of the data, withholding one state at a time and building models from all remaining states. Performance was evaluated by comparing the predicted policy conditions with the actual outcomes in 2014. RESULTS: When compared to the actual RCL policies in 2014, the ensemble estimated predictions of counties transitioning to RCL had a macro f1 average score of 0.61. The main factors associated with legalizing county-level recreational cannabis sales were the prevalences of past-month cannabis use and past-year cocaine use. CONCLUSION: By leveraging publicly available data from 2010 to 2012, our model was able to achieve appreciable discrimination in predicting counties with legal recreational cannabis sales in 2014, however, there is room for improvement. Having demonstrated model performance in the first handful of states to legalize cannabis, additional testing with more recent data using time to event models is warranted.

Why Are Adolescent Cannabis Use Disorder Treatment Admissions Declining in the US? The Mediated Pathway of State Treatment Admissions Rates before and after Recreational Cannabis Legalization.

Purpose: State-level prevalence data are used to investigate whether recreational cannabis legalization moderates the mediated pathway from the perception of low risk of harm, to cannabis use, to cannabis use disorder (CUD) treatment admissions, among adolescents (age 12-17) in the US. Methods: Annual state prevalence measures of perception of low risk, cannabis use, and CUD treatment admissions between 2008 and 2019 (N = 542 state-year observations) were collected from the National Survey on Drug Use and Health (NSDUH) and the Treatment Episode Dataset - Admissions (TEDS-A). A two-way fixed effects (state and year) moderated mediation model was used to test whether recreational legalization moderated the indirect effect of perception of low risk on treatment admissions via cannabis use. Results: A positive indirect effect of perceiving cannabis as low risk on CUD treatment admissions via cannabis use was observed prior to legalization but not afterwards. After legalization, the positive association of perceiving cannabis as low risk with cannabis use was strengthened, and the positive association of cannabis use with treatment admissions was suppressed, as compared to before legalization. Discussion: Recreational legalization may alter the social acceptability and medical self-administration of cannabis, potentially leading to CUD treatment utilization decline among adolescents even as risk factors for CUD increase. Linking recreational cannabis legalization to advancing awareness of the health risks associated with adolescent cannabis use and promoting adolescent CUD treatment engagement through mHealth approaches and primary care providers are key to addressing potential adolescent health challenges brought about by expanding cannabis legalization.

Distress about social problems and tobacco and cannabis use outcomes among young adults in Los Angeles County.

OBJECTIVE: To examine associations of concern, worry, and stress about discrimination, shootings/violence, and police brutality and exclusive and dual tobacco and cannabis use among young adults. METHODS: A prospective, racially/ethnically diverse cohort of young adults (n = 1960) living in Los Angeles, California completed a baseline survey in 2020 (age range: 19-23) and a follow-up survey in 2021. Exploratory factor analysis (EFA) was employed on nine variables assessing levels of concern, worry, and stress about societal discrimination, societal shootings/violence, and community police brutality at baseline. Past 30-day tobacco and cannabis use at follow-up was categorized as current exclusive tobacco, exclusive cannabis, and dual tobacco and cannabis (vs never/former) use based on eleven use variables. Multinomial logistic regressions estimated adjusted associations between each factor score (translated to standard deviation units) with exclusive and dual tobacco and cannabis use. RESULTS: The EFA produced four factor scores representing concern/worry/stress (i.e., distress) about community police brutality (F1), distress about societal shootings/violence (F2), and distress about societal discrimination (F3), as well as generalized stress about police brutality, shootings/violence, and discrimination (F4). F1, F2, and F3 were associated with subsequent exclusive current cannabis use, with F1 having the strongest association (OR: 1.35, 95% CI: 1.18-1.55), while only F1 (OR: 1.51, 95% CI: 1.27-1.78) was associated with dual tobacco and cannabis use. None of the factors were associated with exclusive tobacco use. CONCLUSIONS: Young adult concern, worry, and/or stress about social problems may increase risk of cannabis use with or without concurrent tobacco use 6-12 months later.

Adverse outcomes of cannabis use in Canada, before and after legalisation of non-medical cannabis: cross-sectional analysis of the International Cannabis Policy Study.

OBJECTIVES: To date, there is little evidence on the extent to which cannabis legalisation affects the prevalence of adverse events from cannabis at the population level. The current study examined trends in the prevalence of adverse events among people who consumed cannabis before and after Canada's legalisation of recreational cannabis. DESIGN: Data come from the first four survey waves of the International Cannabis Policy Study, which were conducted online annually immediately prior to non-medical cannabis legalisation in Canada in October 2018, and in the three following years (2019-2021). PARTICIPANTS: The current analysis included 18 285 Canadian respondents aged 16-65 who reported cannabis use in the past 12 months. OUTCOME MEASURES: Primary outcomes included types of adverse events experienced from cannabis use, medical help-seeking and the types of products used. Weighted logistic regression models examined differences in help-seeking, emergency room usage and the experience of cannabinoid hyperemesis syndrome across survey years. RESULTS: Approximately one-third of people who consume cannabis reported experiencing at least one adverse event within the past 12 months, including 5% of consumers who sought medical help for an adverse event, most commonly for panic attacks, feeling faint/dizzy/passing out, heart/blood pressure problems and nausea/vomiting. The prevalence of seeking help and the types of adverse events were similar before (2018) and after legalisation (2019-2021); however, the proportion of consumers seeking help from emergency rooms increased postlegalisation (F=2.77, p=0.041). Adverse events were associated with various product types, with dried flower and oral oils accounting for the largest proportion of events. Help-seeking associated with cannabis edibles significantly decreased after legalisation (p=0.001). CONCLUSIONS: Substantial proportions of people who consume cannabis report adverse events, suggesting widespread difficulty in 'dosing'. Few changes were observed in the prevalence of adverse events reported by consumers since legalisation; however, the location of medical help-seeking and associated products used have changed postlegalisation.

Marijuana Use and Breastfeeding: A Survey of Newborn Nurseries.

BACKGROUND AND OBJECTIVES: Marijuana use has increased nationally and is the most common federally illicit substance used during pregnancy. This study aimed to describe hospital practices and nursery director knowledge and attitudes regarding marijuana use and breastfeeding and assess the association between breastfeeding restrictions and provider knowledge, geographic region, and state marijuana legalization status. We hypothesized that there would be associations between geography and/or state legalization and hospital practices regarding breastfeeding with perinatal marijuana use. METHODS: A cross-sectional, 31-question survey was sent electronically to the 110 US hospital members of the Academic Pediatric Association's Better Outcomes through Research for Newborns (BORN) network. Survey responses were analyzed using descriptive statistics to report frequencies. For comparisons, χ2 and Fisher exact tests were used to determine statistical significance. RESULTS: Sixty-nine (63%) BORN nursery directors across 38 states completed the survey. For mothers with a positive cannabinoid screen at delivery, 16% of hospitals universally or selectively restrict breastfeeding. Most (96%) nursery directors reported that marijuana use while breastfeeding is "somewhat" (70%) or "very harmful" (26%). The majority was aware of the potential negative impact of prenatal marijuana use on learning and behavior. There were no consistent statistical associations between breastfeeding restrictions and provider marijuana knowledge, geographic region, or state marijuana legalization status. CONCLUSIONS: BORN newborn clinicians report highly variable and unpredictable breastfeeding support practices for mothers with perinatal marijuana use. Further studies are needed to establish evidence-based practices and to promote consistent, equitable care of newborns with perinatal marijuana exposure.

Perceptions and Attitudes Related to Driving after Cannabis Use in Canadian and US Adults.

BACKGROUND: This study examined the risk perceptions related to driving after cannabis use (DACU) among Canadian and US adults who used cannabis in the past six months. METHODS: Perceptions of danger, normative beliefs, perceived likelihood of negative consequences, and other driving-related variables were collected via online surveys in Canadian (n = 158; 50.0% female, 84.8% White, mean age = 32.73 years [SD = 10.61]) and US participants (n = 678; 50.9% female, 73.6% White, mean age = 33.85 years [SD = 10.12]). Driving cognitions and DACU quantity/frequency were compared between samples using univariate analyses of variance, and Spearman's (ρ) correlations were performed to examine associations between driving cognitions and DACU quantity/frequency. RESULTS: The two samples did not significantly differ in self-reported level of cannabis use, lifetime quantity of DACU, or the number of times they drove within two hours of cannabis use in the past three months (Ps > .12). Compared to US participants, Canadians perceived driving within two hours of cannabis use as more dangerous (P < 0.001, ηp2 = 0.013) and reported more of their friends would disapprove of DACU (P = 0.03, ηp2 = 0.006). There were no differences in the number of friends who would refuse to ride with a driver who had used cannabis (P = 0.15) or the perceived likelihood of negative consequences (Ps > 0.07). More favorable perceptions were significantly correlated with greater lifetime DACU and driving within two hours of use (ρ = 0.25-0.53, Ps < 0.01). CONCLUSIONS: These findings reveal differences in distal risk factors for DACU between Canada and the US and may inform prevention efforts focusing on perceptions of risk and social acceptance of DACU.

Age-related patterns in high-risk alcohol and cannabis use and their associations with positive and negative affect in young adulthood.

OBJECTIVE: We examined age-varying associations between young adult simultaneous alcohol and marijuana/cannabis use (SAM) and heavy episodic drinking (HED) and positive and negative affect to inform harm reduction efforts. METHODS: Young adults reporting past-year alcohol use (n = 556; ages 19-25) were recruited in a state where alcohol and nonmedical cannabis use was legal for those 21 +. Participants provided 24 repeated monthly assessments. Among those reporting past-month cannabis use on at least one survey, logistic time-varying effect models estimated (1) the age-varying prevalence of and associations between past-month SAM and HED and (2) age-varying unique associations of affect with SAM and HED. RESULTS: There was a positive age-varying association between HED and SAM over time that was highest at age 19 (OR = 7.56), decreased until age 20.7 (OR = 3.39), increased until age 23.0 (OR = 4.85), and decreased until the association became non-significant by age 25. Negative affect was positively associated with SAM from ages 20.7 to 23.0, peaking at age 21.8 (OR = 1.36). Positive affect was positively associated with HED from ages 19.4 to 20.4 (peak OR = 1.25) and ages 22.5 to 24.5 (peak OR = 1.38). In contrast, positive affect was not uniquely associated with SAM nor negative affect with HED across ages 19-25. CONCLUSIONS: While HED and SAM were positively associated throughout young adulthood and interventions could target them in tandem, their associations with affect suggest differential etiologic processes. Preventive intervention and harm reduction efforts should attend to psychological context in which these behaviors occur.

Associations between Adolescent Marijuana Use, Driving after Marijuana Use and Recreational Retail Sale in Colorado, USA.

OBJECTIVE: We investigated associations between the retail distribution of recreational marijuana in Colorado and (i) past 30-day marijuana use and (ii) driving after marijuana use (DAMU) among a representative sample of public high school students using four waves of data from a state surveillance system. METHODS: Past 30-day marijuana use was assessed among all sampled students (n = 85,336). DAMU was assessed among students 15 years or older who indicated driving (n = 47,518). Modified Poisson regression with robust variance estimates was used to estimate prevalence ratios (PR) comparing the pre-distribution (2013) and post-distribution (2015, 2017, 2019) periods for marijuana-related behaviors. Frequency of behavioral engagement was assessed using a multinomial approach. RESULTS: An estimated 20.3% of students engaged in past 30-day marijuana use and 10.5% of student drivers engaged in DAMU. Retail distribution of recreational marijuana was not significantly associated with the prevalence of any marijuana use or DAMU. However, it was associated with 1.16 (95% CI: 1.04-1.29) times the prevalence of using marijuana one or two times in the last 30 days, 1.27 (1.03, 1.55) times the prevalence of DAMU one time, and 0.82 (0.69, 0.98) times the prevalence of DAMU six or more times. No significant associations were observed for the remaining frequency categories. CONCLUSIONS: Approximately 1 in 10 students who drive reported DAMU. Varying prevalence in the frequency of past 30-day marijuana use and DAMU was observed following the retail distribution of recreational marijuana in Colorado. Care should be taken to properly educate adolescent drivers regarding the dangers of DAMU.

Association Between Marijuana Use and Clinical Outcomes After Coronary Artery Bypass Grafting.

INTRODUCTION: Though marijuana use has been linked to an increase in heart failure admissions, no prior study has explored the association between its use and outcomes after coronary artery bypass grafting (CABG). This study examines the relationship between marijuana use and postoperative outcomes in CABG patients. METHODS: We utilized data from the National Inpatient Sample database from 2008 to 2018 for CABG patients ≥18 y old. Patients were divided into two groups based on marijuana use (abuse/dependency versus nonuse). Primary outcomes include in-hospital mortality, favorable discharge, and length of stay (LOS). Secondary outcomes include acute kidney injury (AKI), acute myocardial infarction (AMI), and transient ischemic attack (TIA)/stroke. A multivariable model, adjusted for confounding variables, was utilized for each outcome. RESULTS: A total of 343,796 patients met inclusion criteria for the study, 590 of which were marijuana users. In both marijuana user and nonuser groups, most patients were male and White with an average age of 56.0 and 66.3 y, respectively. There was a nonsignificant decreased odds of in-hospital mortality among marijuana users (odds ratio [OR] = 0.41, [0.141-1.124]). Marijuana users exhibited significantly decreased odds of home discharge (OR = 1.50, [1.24-1.81]), and increased odds of longer LOS (mean 10.4 d versus 9.8 d; OR = 1.14, [1.09-1.20]), AKI (OR = 1.40, [1.11-1.78]), AMI (OR = 1.56, [1.32-1.84]), and TIA/stroke (OR = 1.64, [1.21-2.22]). CONCLUSIONS: Marijuana use and dependency are associated with increased nonhome discharge, AKI, AMI, TIA/stroke, and longer LOS. Further studies are needed to delineate the pathophysiologic derangements that contribute to these unfavorable post-CABG outcomes.

Marijuana use disorder among adults with functional disabilities-A US population-based cross-sectional study.

BACKGROUND AND OBJECTIVES: Recent studies suggest a growing trend in marijuana use, compared to a stable prevalence of marijuana use disorder among US adults over the first 15 years of the 21st century. This study investigated the recent patterns of marijuana use disorder among people with disabilities (PWD). METHODS: We extracted a nationally representative sample (N = 209,058) from the 2015-2019 National Survey on Drug Use and Health data set and examined associations by functional disability status (any disability, disability by type, and number of disabling limitations) with marijuana use disorder using a series of independent multivariable logistic regression models. We also performed trend analyses during the study period. RESULTS: The prevalence of marijuana use disorder (from 1.7% to 2.3%) increased significantly among PWD between 2015 and 2019 (p-trend < .001). PWD were significantly more likely to report marijuana use disorder (odds ratio [OR], 1.37, 95% confidence interval [CI], 1.24-1.52) than people without disability (PWoD). Those with cognitive limitation only (OR, 1.78, 95% CI, 1.53-2.06) and ≥2 limitations (OR, 1.29, 95% CI, 1.10-1.51) were more likely to report marijuana use disorder than PWoD. DISCUSSION AND CONCLUSIONS: PWD had a consistently higher prevalence of marijuana use disorder than PWoD. Additionally, the level of risk for marijuana use disorder varied by disability type and number of disabling limitations. SCIENTIFIC SIGNIFICANCE: Our study provided new nuance on disparities in marijuana use disorder between PWD and PWoD and further revealed the varied risks for marijuana use disorder across different disability statuses.

Predictors of morning cannabis use among young adults: Between- and within-person associations from 24 consecutive months of data.

Morning cannabis use is associated with heavier, frequent cannabis use and more cannabis-related negative consequences, yet little empirical research has examined its predictors. Using 24 months of longitudinal data, the present study tested demographic, psychosocial, and behavioral predictors of morning cannabis use among young adults at the monthly- and person-levels. Young adults (N = 778) were part of a larger study on substance use and social role transitions; participants completed a baseline survey and up to 24 consecutive monthly surveys. Hypotheses were tested using logistic multilevel models to estimate odds ratios for any vs. no morning use in a given month. At the monthly level, social anxiety motives and cannabis use frequency on a given month were positively associated with morning cannabis use. At the person level, typical coping motives, average cannabis use frequency, and male sex were positively associated with morning cannabis use. Findings advance our understanding of individual and psychosocial predictors of morning cannabis use among young adults. Notably, social anxiety motives may represent a malleable target for intervention efforts that could reduce risky use patterns associated with morning use. Such efforts may be especially prudent for young men, as our findings indicated morning cannabis use probabilities were much higher for men than women.

Limited psychological and social effects of lifetime cannabis use frequency: Evidence from a 30-year community study of 4,078 twins.

BACKGROUND: Cannabis use is associated with outcomes like income, legal problems, and psychopathology. This finding rests largely on correlational research designs, which rely at best on statistical controls for confounding. Here, we control for unmeasured confounders using a longitudinal study of twins. METHOD: In a sample of 4,078 American adult twins first assessed decades ago, we used cotwin control mixed effects models to evaluate the effect of lifetime average frequency of cannabis consumption measured on substance use, psychiatric, and psychosocial outcomes. RESULTS: On average, participants had a lifetime cannabis frequency of about one to two times per month, across adolescence and adulthood. As expected, in individual-level analyses, cannabis use was significantly associated with almost all outcomes in the expected directions. However, when comparing each twin to their cotwin, which inherently controls for shared genes and environments, we observed within-pair differences consistent with possible causality in three of the 22 assessed outcomes: cannabis use disorder symptoms (ßW-Pooled = .15, SE = .02, p = 1.7 × 10-22), frequency of tobacco use (ßW-Pooled = .06, SE = .01, p = 1.2 × 10-5), and illicit drug involvement (ßW-Pooled = .06, SE = .02, p = 1.2 × 10-4). Covariate specification curve analyses indicated that within-pair effects on tobacco and illicit drug use, but not cannabis use disorder, attenuated substantially when covarying for lifetime alcohol and tobacco use. CONCLUSIONS: The cotwin control results suggest that more frequent cannabis use causes small increases in cannabis use disorder symptoms, approximately 1.3 symptoms when going from a once-a-year use to daily use. For other outcomes, our results are more consistent with familial confounding, at least in this community population of twins. (PsycInfo Database Record (c) 2023 APA, all rights reserved).