Recreational Marijuana Legalization and Use Among California Adolescents: Findings From a Statewide Survey

Getting "The whole picture": A review of international research on the outcomes of regulated cannabis supply

BACKGROUND

Several jurisdictions have pursued reforms that regulate cannabis production and/or sale for adult (non-medical) use. Looking at outcomes of such reforms across multiple jurisdictions may help to identify outcomes that are inherent to non-criminal cannabis supply, as well as provide insight into the outcomes of specific regulation models.

METHODS

We identified nine indicators of cannabis policy outcomes and aggregated them into three domains (social outcomes, outcomes in cannabis use, health-related outcomes). We assessed these outcomes across five jurisdictions with different models of regulating cannabis supply (Netherlands, Spain, U.S. states that legalized cannabis, Uruguay, and Canada). We used a three-level systematic literature review, prioritising studies with quasi-experimental design (i.e. comparative and longitudinal). We categorised the studies according to their design and the type of outcome (increase, decrease, or no outcome).

RESULTS

Across long-standing as well as recent cannabis supply regimes, and across different models of cannabis supply, our review identified common outcomes: a decrease in cannabis-related arrests, an increase in adult (but not adolescent) cannabis use, and increase in healthcare utilization (not traffic-related). Negative health-related outcomes were most consistently found for the U.S. states that legalised cannabis for adult non-medicinal use (there were limitations to nuancing cannabis supply models across U.S. states). In the remaining jurisdictions (the Netherlands, Spain, Canada, Uruguay), the design or time-frame of the identified studies was limited, and studies on certain outcomes were lacking.

CONCLUSIONS

Regulating cannabis supply may be associated with benefits in the social area and with potential harms regarding public health; there may though be trade-offs depending on the choice of a cannabis regulation model. Jurisdictions may attempt to mix and match the present models of cannabis regulation to achieve the best ratio of benefits and harms. More research into the specific parameters influencing cannabis policy outcomes is needed.

Recreational Marijuana Laws and suicide deaths in the US

OBJECTIVES

This study aimed to examine the association between Recreational Marijuana Laws (RMLs) and age-adjusted suicide rates in the U.S. population from 2000 to 2022.

METHODS

Suicide rate data were obtained from the Centers for Disease Control and Prevention's (CDC) Multiple Cause of Death Files at the state and year level. Information on RML status and years of legalization was sourced from the National Organization for the Reform of Marijuana Laws (NORML). Using a staggered difference-in-differences (DiD) framework, we assessed the relationship between RMLs and age-adjusted suicide rates.

RESULTS

RMLs were associated with an increase of 0.68 suicide deaths per 100,000 population (p-value < 0.05). This increase was primarily driven by states that implemented RMLs in 2018 (Maine, Vermont, and Michigan) and 2019 (Illinois). In contrast, states that enacted RMLs in 2015 (Alaska, Oregon, and Washington, D.C.) experienced a decline in suicide deaths post-legalization.

CONCLUSION

This study adds to the growing body of literature on RMLs and suicidality by underscoring the potential role of state-specific factors-such as demographic characteristics, implementation strategies, or contextual differences-in shaping the direction and magnitude of this association. These findings highlight the need for further research to better understand the mechanisms underlying these divergent outcomes.

The Impact of Recreational Cannabis Markets on Cannabis Use Among Adolescents and Adults: A Synthetic Control Analysis

Objective

To assess the longer-term impacts of recreational cannabis markets on cannabis use among adolescents and adults across five U.S. states.

Method

Drawing on state-level data from the National Survey on Drug Use and Health, this study uses a novel method of causal inference called the synthetic control method with staggered treatment adoption to estimate the pooled effect of recreational markets on prevalence and initiation of use in Colorado, Washington, Oregon, Alaska, and Nevada. Three separate models were used for those 12-17, 18-25, and 26 and older. Pre-treatment state-level characteristics and trends in cannabis use were used to generate synthetic control weights. Confidence intervals were constructed using a leave-one-out jackknifing method.

Results

Synthetic controls and treated states were similar in terms of sociodemographic characteristics, prevalence of other drug use, and trends in cannabis use prior to the implementation of recreational markets. The study results revealed moderate increases in prevalence and initiation of use among adolescents aged 12-17 (11% and 13%, respectively), and large increases in prevalence and initiation of use among young adults aged 18-25 (17% and 33%, respectively) and older adults aged 26 and older (33% and 82%, respectively) 2-4 years after dispensaries became operational.

Conclusions

The findings of this study suggest recreational cannabis markets have increased prevalence and initiation of cannabis use among adolescents and adults. These increases may lead to adverse health outcomes depending on factors such as frequency of use and characteristics of users.

Age-Gating and Marketing Differences Between Storefront and Non-Storefront Cannabis Retailers

Objective

The study investigated whether California storefront and non-storefront cannabis retailers are adhering to online age-gating requirements and whether differences in website marketing practices exist.

Methods

Websites of 134 storefront and 115 non-storefront licensed retailers were randomly selected. Bivariate associations were tested between retailer type and website marketing, age-gating methods, and presence of age-gating at various purchase stages.

Results

Among the 200 (80.3%) websites with age-gating when entering, 182 (91%) employed an ineffective method where users click either "Yes" or "No" to confirm their age. Moreover, 49 (19.68%) websites lacked age-gating when entering. Amongst those requiring photo identification during checkout (n = 100, 40.16%), 97% allowed users to proceed after uploading an irrelevant image. Significantly more storefront retailers employed combined age-gating at entry, mandatory account registration, and age-gating during checkout than non-storefront retailers, X 2 (1, N = 249) = 7.69, p < .01. Retailer websites frequently displayed "clean" labels (n = 200, 80.32%), followed by positive state claims (n = 198, 79.52%), physical health claims (n = 166, 66.67%), and mental health claims (n = 146, 58.63%). Significantly more storefront retailers displayed physical health claims, X 2 (1, N = 249) = 7.52, p < .01, and health warnings than non-storefront retailers, X 2 (1, N = 249) = 4.13, p = .04.

Conclusions

Most cannabis retailers comply with age-gating requirements; however, methods employed are easily circumvented. Youths' easy and unrestricted access to cannabis retailer websites may increase positive attitudes about cannabis and encourage use.

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.

Is legalization of recreational cannabis associated with levels of use and cannabis use disorder among youth in the United States? A rapid systematic review

Cannabis legalization policies are rapidly changing in the United States. While there are concerns that recreational legalization will negatively affect young people, previous reviews have not provided clear indication of such effects. The purpose of this rapid systematic review was to examine whether recreational legalization was associated with increases in prevalence of cannabis use and use disorder among adolescents and young adults. PubMed/MEDLINE, Embase, Scopus, PsycInfo, Web of Science, Dissertations & Theses Global, the Trip Database, and OpenGrey were searched from date of inception through Marcy 17, 2022 to retrieve all relevant records. English language and human subject filters were applied. Two reviewers screened abstracts and titles, assessed full text articles, and coded the final included articles. Studies including primarily 10- to 19-year-olds were classified as adolescent, and those between 18 and 26 years as young adult. Our search identified 33 research reports (22 with adolescent samples; 14 young adult). For adolescents, ten studies reported no change in use prevalence associated with legalization, six reported a decrease, and seven reported an increase. Among young adults, most studies (8) showed an increase in at least one prevalence measure, four showed no change, and one showed a decrease. Only two adolescent and one young adult study examined cannabis use disorder, both adolescent studies showed an increase, and the young adult showed no change. The majority of studies had risk of bias. Recreational legalization may be associated with increases in prevalence of cannabis use in young adults while results for adolescents are mixed. Policymakers and practitioners should consider appropriate prevention and treatment options for young people.Trial Registration: PROSPERO #CRD42021276984.

Association Between Marijuana Laws and Suicide Among 12- to 25-Year-Olds in the United States From 2000 to 2019

OBJECTIVE

Cannabis use is associated with suicide-related outcomes in both adolescents and adults, and may be increasing amid shifting cannabis policies. However, little is known about the impact of medical marijuana legalization (MML) and recreational marijuana legalization (RML) policies on youth suicide. Using 20 years of national data, we examined associations between MML, RML, and suicide-related mortality among US individuals aged 12 to 25 years, and assessed whether they varied based on age and sex.

METHOD

Suicide deaths (N = 113,512) from the 2000-2019 National Vital Statistics System Multiple Cause of Death files for age groups 12 to 13, 14 to 16, 17 to 19, 20 to 22, and 23 to 25 years were examined in relation to time-varying cannabis law status using a staggered adoption difference-in-difference (DiD) approach with a negative binomial regression to determine associations between MML, RML, and suicide rates, controlling for individual- and state-level covariates and accounting for the varying effective dates of MML and RML by state.

RESULTS

The overall unadjusted annual suicide rate was 10.93/100,000, varying from 9.76 (states without marijuana laws (ML)) to 12.78 (MML states) to 16.68 (RML states). In multivariable analysis, both MML (incidence rate ratio [IRR] = 1.10, 95% CI: 1.05-1.15) and RML (IRR = 1.16, 95% CI: 1.06-1.27) were associated with higher suicide rates among female youth compared to those in states without ML. Youth aged 14 to 16 years had higher rates of suicide in states with RML compared to states with MML (IRR = 1.14, 95% CI: 1.00-1.30) and states without ML (IRR = 1.09, 95% CI: 1.00-1.20). Findings were consistent across sensitivity analyses.

CONCLUSION

MML and RML were associated with increased suicide-related mortality in female youth and 14- to- 16-year-old individuals of both sexes. Mechanisms through which cannabis policies are related to increased youth suicide warrant further study and should inform legislative reform.

Youth Exposure to Recreational Cannabis Legalization: Moderation of Effects by Sex and Parental Cannabis Use during Adolescence

OBJECTIVE

Few studies of recreational cannabis legalization (RCL) have assessed adolescents both before and after RCL or considered moderators of RCL effects. The present study tested whether RCL was more strongly associated with cannabis use for girls and among youth whose parents had a history of cannabis use during adolescence.

METHOD

Data were pooled from 940 adolescents from three intergenerational studies that began in Washington (where RCL was enacted in 2012), Oregon (RCL year = 2015), and New York (RCL year = 2021). Youth were assessed repeatedly from ages 13 to 18 years (k = 3,650 person-years) from 1999 to 2020 (prior to RCL in New York). Parent cannabis use at or before age 18 years (yes/no) was assessed prospectively during the parent's adolescence. Multilevel models focused on the between-subjects effects of years of youth exposure to RCL on adolescents' mean cannabis use likelihood, and interactions with child sex and parent use history.

RESULTS

Child exposure to RCL was associated with a higher likelihood of cannabis use if their parents had a history of adolescent use, (Estimate [SE] = 0.67 [0.25], p = 0.008), versus no such history (Estimate [SE] = -0.05 [0.28], p = 0.855). RCL effects were not moderated by child sex.

CONCLUSIONS

The effects of RCL on adolescents' cannabis use may depend on their parents' history of using the drug. Identifying other moderators of RCL effects, and understanding the mechanisms of these risks and the ways that parents and communities can offset them, are prevention priorities.

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.

Recreational marijuana legalization and marijuana and alcohol co-use among adolescents: Differential associations among racial and ethnic groups

We examined associations of the 2016 legalization of recreational marijuana (RML) in California with marijuana and alcohol co-use among race/ethnic groups using successive cross-sections from 7th, 9th, and 11th graders (N = 3,319,329) in the 2010-11 to 2018-19 California Healthy Kids Surveys. Multilevel logistic regressions indicated a stronger positive association between RML and co-use among non-Hispanic/Latine White youth (OR = 1.21) relative to Hispanic/Latine (OR = 1.02) or Black youth (OR = 0.85). Among drinkers who had not consumed five or more drinks on any occasion in the past 30-days (non-heavy drinkers), the positive association between RML and co-use was stronger among American Indian/Alaska Native youth (OR = 2.19) compared to non-Hispanic/Latine Whites (OR = 1.56). For heavier drinkers it was stronger for Native Hawaiian/Pacific Islanders (OR = 1.47). Among marijuana users, there was a stronger inverse association between RML and co-use among Black youth (OR = 0.72) compared to non-Hispanic/Latine White youth (OR = 0.84). RML may increase the risk of co-use to a greater extent among non-Hispanic/Latine White youth than other race/ethnic groups in California, but broadly increases the risk among youth who engage in alcohol use or heavy drinking.

Consequences of adolescent drug use

Substance use in adolescence is a known risk factor for the development of neuropsychiatric and substance use disorders in adulthood. This is in part due to the fact that critical aspects of brain development occur during adolescence, which can be altered by drug use. Despite concerted efforts to educate youth about the potential negative consequences of substance use, initiation remains common amongst adolescents world-wide. Additionally, though there has been substantial research on the topic, many questions remain about the predictors and the consequences of adolescent drug use. In the following review, we will highlight some of the most recent literature on the neurobiological and behavioral effects of adolescent drug use in rodents, non-human primates, and humans, with a specific focus on alcohol, cannabis, nicotine, and the interactions between these substances. Overall, consumption of these substances during adolescence can produce long-lasting changes across a variety of structures and networks which can have enduring effects on behavior, emotion, and cognition.

Adolescent Advertising Exposure to Cannabis Products in Rural Oklahoma via Medical Dispensaries

OBJECTIVE

We assess cannabis advertising exposure among adolescents in rural Oklahoma from medical dispensaries.

METHOD

Our mixed-methods study identified medical dispensaries within a 15-minute drive time of rural Oklahoma high schools. Study staff completed observational data collection forms and took photographs of each dispensary. Quantitative data from the forms and qualitative coding of photographs were used to describe dispensary characteristics and likely advertising exposure for adolescents.

RESULTS

Ninety-two dispensaries were identified across 20 rural communities. The majority presented as retail spaces (n = 71). Product (n = 22) and price promotions (n = 27) were common. Coding of dispensary photographs found that product promotions advertised cannabis use modalities, with cannabis flower being the most common (n = 15), followed by edibles (n = 9) and concentrates (n = 9). Among dispensaries with price promotions, discounts (n = 19) and prices under $10 (n = 14) were common.

CONCLUSIONS

Sampled rural medical dispensaries present as retail spaces and are a likely source of adolescent cannabis advertising exposure.

Recreational Marijuana Legalization, Local Retail Availability, and Alcohol and Marijuana Use and Co-Use Among California High School Students

OBJECTIVE

This study examined whether recreational marijuana legalization (RML) and local retail availability were associated with marijuana and alcohol use and co-use among adolescents.

METHOD

We investigated associations between RML and past-30-day marijuana and alcohol use and co-use, and moderating effects of retail availability of marijuana and alcohol, using data from the 2010-2011 to 2018-2019 California Healthy Kids Surveys (CHKS) of 9th and 11th grade students in 38 California cities. Multilevel mixed-effects logistic regression analyses were conducted, controlling for secular trends and student and city demographics. Additional analyses examined associations of RML and retail availability with co-use among subgroups of drinkers and marijuana users.

RESULTS

For the full sample, RML was inversely associated with alcohol use but was not significantly associated with marijuana use or co-use with alcohol. However, significant interactions between RML and marijuana outlet density showed that there were increases in marijuana and alcohol co-use and alcohol following legalization in cities with higher densities of marijuana outlets. RML was positively associated with co-use among non-heavy and heavy drinkers, but inversely related to co-use among occasional and frequent marijuana users. A significant positive interaction between RML and marijuana outlet density indicated that RML was associated with increases in co-use for occasional marijuana users in cities with higher densities of marijuana outlets.

CONCLUSIONS

RML was associated with increases in marijuana and alcohol co-use and alcohol use among California high school students, particularly those in cities with higher densities of retail cannabis stores, although this varied across alcohol and marijuana use subgroups.

Recreational Cannabis Legalization and Proximity to Cannabis Retailers as Risk Factors for Adolescents' Cannabis Use

Within-person studies are lacking regarding how recreational cannabis legalization (RCL) and the numbers of neighborhood cannabis retailers relate to adolescents' cannabis use. Study participants were 146 offspring (55% girls; 77% White non-Latinx) of men recruited in childhood from neighborhoods with high delinquency rates. Youth were assessed for past-year cannabis and alcohol use one or more times from ages 13 to 20 years (age M[SD] = 16.4 [2.1] years across 422 observations), while they were living in Oregon or Washington from 2005 to 2019 (where cannabis retail stores opened to adults ages 21 years and older in 2014 and 2015, respectively). We calculated distances between addresses of licensed cannabis retailers and participants' homes. Multilevel models that accounted for effects of age on cannabis use did not support that the number of retail stores within 2-, 5-, 10-, or 20-mile radii of adolescents' homes increased likelihood of past-year cannabis use at the within- or between-subjects levels. Likewise, primary models did not support a greater likelihood of cannabis use among youth whose adolescence coincided more fully with the post-RCL period. A secondary model suggested that after adjusting for adolescents' concurrent alcohol use as a marker of general substance use risk, RCL was associated with cannabis use (between-subjects B [95% CI] = .35 [.05-.66], p = .024). Further research is needed with larger prospective samples, at-risk subgroups, and as cannabis markets mature.

Effects of Smoking Marijuana on the Respiratory System: A Systematic Review

BACKGROUND

The prevalence of marijuana use and its derivatives has surged over the past century, largely due to increasing legalization globally. Despite arguments advocating its benefits, marijuana smoking exposes the lungs to harmful combustion byproducts, leading to various respiratory issues such as asthma, pneumonia, emphysema, and chronic obstructive pulmonary disease.

METHODS

We embarked on an extensive literature search, utilizing PubMed/Medline, Scopus, Web of Science, and Google Scholar databases, identifying 200 studies. After the elimination of duplicates, and meticulous review of abstracts and full texts, 55 studies were included in our analysis.

RESULTS

Current literature demonstrates that marijuana use negatively impacts lung function, triggering symptoms like chronic cough, sputum production, and wheezing, and diminishing FEV1/FVC ratio in spirometry tests. Moreover, prolonged or chronic marijuana use augments the risk of respiratory function impairment. While the carcinogenic effects of marijuana are still contested, a weak correlation between marijuana use and lung cancer has been observed in some studies. Additionally, instances of other pathologies linked to marijuana use have been reported, including the development of COPD, pulmonary bullae, spontaneous pneumothorax, pleuritic pain, chronic pulmonary aspergillosis, hemoptysis, and pulmonary Langerhans cell histiocytosis.

CONCLUSIONS

The evidence underscores that marijuana use is detrimental to respiratory health. In light of the escalating trend of marijuana use, particularly among the youth, it is imperative to advocate public health messages discouraging its consumption.

Latent Classes of Tobacco and Cannabis Use among Youth and Young Adults in the United States

Background: Research characterizing patterns of tobacco and cannabis use by product type and route of administration among youth and young adults (YAs) is limited. Methods: We conducted latent class analysis of tobacco and cannabis use (i.e., cigarettes, electronic nicotine delivery systems (ENDS), cigars, blunts, cannabis vaping, and other cannabis use (without blunting/vaping)) among youth (ages 15-17) and YAs (ages 18-24) who used at least one product in the past 30 days, using data from the Population Assessment of Tobacco and Health Study (Wave 4, 2016-2017). We used multinomial logistic regression models to examine associations between sociodemographic characteristics and use classes. Results: The latent use classes for youth included cigarettes (2.5%), ENDS (2.6%), blunts (2.5%), other cannabis (6.3%), ENDS + cannabis vaping (2.7%), and cigarettes + cigars + other cannabis (1.5%), while the latent use classes for YAs included cigarettes (11.7%), ENDS (3.9%), blunts (5.3%), other cannabis (7.0%), cigarettes + cigars (8.2%), and cigarettes + ENDS + cannabis vaping (4.9%). We compared use classes to never/former use for youth (82.0%) and YAs (59.0%) and found that they differed by each sociodemographic characteristic. For example, non-Hispanic Black YAs had higher odds of cigarettes + cigar use compared to non-Hispanic White YAs, whereas racial/ethnic minority youth and YAs had lower odds of other dual/poly use groups compared to their non-Hispanic White counterparts. Conclusions: We observed differences in use classes by sociodemographic characteristics for youth and YAs. Health professionals must consider tobacco and cannabis use patterns when implementing prevention and cessation interventions.

The Impact of Cannabis Use on Adolescent Neurodevelopment and Clinical Outcomes Amidst Changing State Policies

Cannabis is the most common illicit substance used by adolescents and the third most common psychoactive substance after alcohol and nicotine. Cannabis use during adolescence interrupts a critical period of brain development and leads to inappropriate activation of the reward pathway. Because the prefrontal cortex, which is responsible for impulse control and other executive functions, is not fully mature until the mid-twenties, the adolescent brain is especially vulnerable to damage from substance use. Although cannabis remains illegal at the federal level, recent changes in state policies have been associated with increased availability of a wide variety of cannabis products. As new products, formulations, and delivery devices that can deliver higher and faster peak doses of tetrahydrocannabinol enter the market, there is an even greater potential for cannabis to have negative clinical impacts on adolescent health. This article reviews the current literature on the impact of cannabis on adolescent health, including the neurobiology of the adolescent brain, potential clinical outcomes in adolescents who use cannabis, and the effects of changing state policies regarding cannabis on the increased availability of unregulated products.

Assessing the Impact of Recreational Cannabis Legalization on Cannabis Use Disorder and Admissions to Treatment in the United States

Purpose of Review

Policy implications from changes in recreational cannabis laws (RCLs) have raised public health concerns. While numerous studies have examined the impact of RCLs on cannabis use, there is less research on the risk of developing cannabis use disorder (CUD). This review summarizes the latest research on the effects of RCLs on CUD prevalence and cannabis treatment admissions.

Recent Findings

Nine studies were published between 2016 - 2022 that examined RCLs and CUD or treatment. Findings generally indicate an increase in CUD prevalence associated with legalization, but effects differ by age group. There was no significant association between legalization and CUD treatment admissions, and CUD admissions decreased overall during the study periods.

Summary

To improve policy, prevention, and treatment services, policymakers should monitor RCLs' effects on adverse public health outcomes and researchers should consider the effects on individual and community-level characteristics. We discuss methodological challenges in conducting state-level research and provide suggestions for future studies.

Impacts of recreational cannabis legalization on use and harms: A narrative review of sex/gender differences

Legalization of cannabis use for non-medical (recreational) purposes is changing the global cannabis landscape. As attitudes toward cannabis use become more positive and prevalence of use increases in complex ways, concerns emerge about the potential for increased cannabis-attributable harms. Understanding the who, why, and when of this likely increase in cannabis-attributable harms is thus an important public health priority. Both sex and gender contribute to variability in the use, effects, and harms of cannabis and thus sex/gender considerations are important when evaluating the impacts of cannabis legalization. The goal of this narrative review is to broadly discuss sex/gender differences in attitudes toward and prevalence of cannabis use, whether there are sex/gender differences in the impacts of cannabis legalization, and why these sex/gender differences might exist. One of our strongest conclusions is that men have always been more likely to use cannabis than women, yet the sex/gender gap in prevalence of cannabis use has narrowed over time, and this might be partly due to cannabis legalization. The existing evidence suggests that there have also been sex/gender differences in the impacts of legalization on cannabis-attributable harms such as cannabis-involved motor vehicle collisions and hospitalizations, though these results are more variable. The body of literature reviewed has focused almost exclusively on samples of cisgender research participants, and thus future research should encourage inclusion of transgender and gender-diverse participants. More consideration of sex- and gender-based analysis in research evaluating long-term impacts of cannabis legalization is a clear research priority.

Effects of Cannabis Legalization on Adolescent Cannabis Use Across 3 Studies

INTRODUCTION

Canada, Uruguay, and 18 states in the U.S. have legalized the use of nonmedical (recreational) cannabis for adults, yet the impact of legalization on adolescent cannabis use remains unclear. This study examined whether cannabis legalization for adults predicted changes in the probability of cannabis use among adolescents aged 13-18 years.

METHODS

Data were drawn from 3 longitudinal studies of youth (spanning 1999-2020) centered in 3 U.S. states: Oregon, New York, and Washington. During this time, Oregon (2015) and Washington (2012) passed cannabis legalization; New York did not. In each study, youth average age was 15 years (total N=940; 49%-56% female, 11%-81% Black/African American and/or Latinx). Multilevel modeling (in 2021) of repeated measures tested whether legalization predicted within- or between-person change in past-year cannabis use or use frequency over time.

RESULTS

Change in legalization status across adolescence was not significantly related to within-person change in the probability or frequency of self-reported past-year cannabis use. At the between-person level, youth who spent more of their adolescence under legalization were no more or less likely to have used cannabis at age 15 years than adolescents who spent little or no time under legalization.

CONCLUSIONS

This study addresses several limitations of repeated cross-sectional studies of the impact of cannabis legalization on adolescent cannabis use. Findings are not consistent with changes in the prevalence or frequency of adolescent cannabis use after legalization. Ongoing surveillance and analyses of subpopulations are recommended.

The impact of recreational cannabis markets on motor vehicle accident, suicide, and opioid overdose fatalities

In the U.S., an increasing number of states are legalizing regulated commercial markets for recreational cannabis, which allows private industry to produce, distribute, and sell marijuana to those 21 and older. The health impacts of these markets are not fully understood. Preliminary evidence suggests recreational markets may be associated with increased use among adults, which indicates there may be downstream health impacts on outcomes related to cannabis use. Three causes of death that are linked to cannabis use are motor vehicle accidents, suicide, and opioid overdose. Drawing on data from U.S. death certificates from 2009 to 2019, we conducted a difference-in-differences analysis to estimate the impact of recreational markets on fatalities from motor vehicle accidents, suicide, and opioid overdose in seven states: Colorado, Washington, Oregon, Alaska, Nevada, California, and Massachusetts. States with comprehensive medical cannabis programs with similar pre-trends in deaths were used as comparisons. For each outcome, a pooled estimate was generated with a meta-analysis using random effects models. The results revealed substantial increases in crash fatalities in Colorado, Oregon, Alaska, and California of 16%, 22%, 20%, and 14%, respectively. Based on estimates from all seven states, recreational markets were associated with a 10% increase in motor vehicle accident deaths, on average. This study found no evidence that recreational markets impacted suicides. Most states saw a relative reduction in opioid overdose death that ranged between 3 and 28%. On average, recreational markets were associated with an 11% reduction in opioid overdose fatalities.

Flavored Tobacco Sales Restrictions and Teen E-cigarette Use: Quasi-experimental Evidence From California

INTRODUCTION

Flavored tobacco sales restrictions (FTSRs) are implemented to reduce access to flavored tobacco products. We examined the association between seven cities with local FTSRs implemented in 2018/2019 and e-cigarette use among high school students in the California Bay Area.

AIMS AND METHODS

We analyzed data from the California Healthy Kids Survey using a difference-in-differences (D-I-D) strategy. We compared pre- and post-policy changes one year after implementation in current and ever e-cigarette use among students attending school in a city with a FTSR (exposed) (n = 20 832) versus without (unexposed) (n = 66 126). Other outcomes included ever marijuana use in an e-cigarette and ease of access to e-cigarettes.

RESULTS

Pre- to post-policy, the adjusted odds of current and ever e-cigarette use did not significantly change among students exposed and unexposed to a FTSR. In the adjusted D-I-D analysis, the odds of current (aOR: 1.25, 95% CI: 0.95, 1.65) and ever e-cigarette use (aOR: 1.06, 95% CI: 0.89, 1.26) did not significantly change by exposure group. However, one year post-implementation, the odds of ease of access to e-cigarettes significantly increased among exposed (aOR: 1.57, 95% CI: 1.27, 1.95) and unexposed students (aOR: 1.54, 95% CI: 1.39, 1.70). Similarly, the odds of ever using marijuana in an e-cigarette significantly increased among exposed (aOR: 1.35, 95% CI: 1.19, 1.53) and unexposed students (aOR: 1.29, 95% CI: 1.20, 1.39).

CONCLUSIONS

Local FTSRs in the California Bay Area were not associated with a change in e-cigarette use one year post-implementation. Increased ease of access and marijuana use may be explanatory factors.

IMPLICATIONS

FTSRs were not associated with a decrease in current or ever e-cigarette use among high school students in the California Bay Area one-year post-implementation. Potential explanatory factors are that ease of access to e-cigarettes and using marijuana in an e-cigarette increased. More research is needed to understand the influence of these factors on youth access and behaviors. To address the youth e-cigarette epidemic, a comprehensive approach is needed, including policies, media campaigns, education programs, and cessation tools targeted to youth.

What is the likelihood that underage youth can obtain marijuana from licensed recreational marijuana outlets in California, a state where recreational marijuana is legal?

OBJECTIVE

Since 2012, 19 states and the District of Columbia have legalized the recreational use of marijuana for adults ages 21 and older. Marijuana use at any level can impair driving performance. Prior research on enforcement of the minimum legal marijuana use age of 21 (MLMU-21) laws is limited. The objective of the current study was to assess the ease of access to marijuana by underage patrons at recreational marijuana outlets in California, where recreational marijuana was legalized in 2016.

METHOD

Pseudo-underage patrons were sent to 50 randomly selected licensed recreational marijuana outlets in the state to see if they could enter the outlet without showing a valid identification of their age.

RESULTS

Pseudo-underage patrons were required to show age identification to enter in 100% of the licensed recreational marijuana outlets visited.

CONCLUSIONS

It appears that licensed California recreational marijuana outlets avoid selling marijuana to underage customers. One reason could be a strong incentive for recreational marijuana outlet owners and managers to avoid being shut down for an illegal activity.

PRACTICAL APPLICATION

Underage youth are not obtaining marijuana at licensed recreational outlets. Future studies and cannabis enforcement agencies should investigate whether underage patrons attempt to use fake IDs at licensed marijuana outlets and whether youth are obtaining marijuana from illicit dispensaries or from social sources.

Estimating the effects of legalizing recreational cannabis on newly incident cannabis use

Liberalized state-level recreational cannabis policies in the United States (US) fostered important policy evaluations with a focus on epidemiological parameters such as proportions [e.g., active cannabis use prevalence; cannabis use disorder (CUD) prevalence]. This cannabis policy evaluation project adds novel evidence on a neglected parameter–namely, estimated occurrence of newly incident cannabis use for underage (<21 years) versus older adults. The project’s study populations were specified to yield nationally representative estimates for all 51 major US jurisdictions, with probability sample totals of 819,543 non-institutionalized US civilian residents between 2008 and 2019. Standardized items to measure cannabis onsets are from audio computer-assisted self-interviews. Policy effect estimates are from event study difference-in-difference (DiD) models that allow for causal inference when policy implementation is staggered. The evidence indicates no policy-associated changes in the occurrence of newly incident cannabis onsets for underage persons, but an increased occurrence of newly onset cannabis use among older adults (i.e., >21 years). We offer a tentative conclusion of public health importance: Legalized cannabis retail sales might be followed by the increased occurrence of cannabis onsets for older adults, but not for underage persons who cannot buy cannabis products in a retail outlet. Cannabis policy research does not yet qualify as a mature science. We argue that modeling newly incident cannabis use might be more informative than the modeling of prevalences when evaluating policy effects and provide evidence of the advantages of the event study model over regression methods that seek to adjust for confounding factors.

A difference-in-difference approach to examining the impact of cannabis legalization on disparities in the use of cigarettes and cannabis in the United States, 2004-17

AIMS

To estimate the impact of recreational and medical cannabis laws (RCL, MCL) on the use of cannabis and cigarettes in the United States.

DESIGN

A difference-in-difference approach was applied to data from the 2004-17 National Survey on Drug Use and Health (NSDUH).

SETTING

United States.

PARTICIPANTS

Nationally representative cross-sectional survey of Americans aged 12 years and older (combined analytical sample for 2004-17, n = 783 663).

MEASUREMENTS

Data on past-month use of (1) cigarettes and (2) cannabis were used to classify respondents into four groups: cigarette and cannabis co-use, cigarette-only use, cannabis-only use or no cigarette or cannabis use. State of residence was measured by self-report. MCL/RCL status came from state government websites.

FINDINGS

Difference-in-difference analyses suggest that MCL was associated with an increase in cigarette-cannabis co-use overall [adjusted odds ratio (aOR) = 1.09; 95% confidence interval (CI) = 1.02-1.16], with the greatest increases among those aged 50 years and above (aOR = 1.60; CI = 1.39-1.84), married (aOR = 1.19; CI = 1.07-1.31), non-Hispanic (NH) black (aOR = 1.14; CI = 1.02-1.07) and with a college degree or above (aOR = 1.15; CI = 1.06-1.24). MCL was associated with increases in cigarette-only use among those aged 50 years and above (aOR = 1.07; CI = 1.01-1.14) and NH black (aOR = 1.16; CI = 1.06-1.27) and increases in cannabis-only use among those aged 50 years and above (aOR = 1.24; CI = 1.07-1.44) and widowed/divorced/separated (aOR = 1.18; CI = 1.01-1.37). RCL was associated with an increase in cannabis-only use overall (aOR = 1.21; 95% CI = 1.09-1.34), a decline in cigarette-only use overall (aOR = 0.89; 95% CI = 0.81-0.97) and increases in co-use among those who were married (aOR = 1.24; CI = 1.02-1.50) and aged 50 years and above (aOR = 1.37; CI = 1.03-1.84).

CONCLUSIONS

Recreational and medical cannabis legalization have had a varying impact on the use, and co-use, of cannabis and cigarettes in the United States.

A Systematic Review and Narrative Synthesis of the Evolution of Adolescent and Young Adult Cannabis Consumption Before and After Legalization

PURPOSE

To systematically review evidence assessing the evolution of cannabis consumption before and after the implementation of non-medical cannabis legislation.

METHODS

MEDLINE, PubMED, PsycINFO, Scopus, and Web of Science were systematically searched for studies that examined change in cannabis consumption before and after nonmedical cannabis legislation. Data were tabulated by study design, levels of consumption, and individual subgroups. Data were analyzed using a narrative synthesis approach, considering study quality.

RESULTS

32 studies were included (11 higher quality and 21 lower quality). 40% of higher quality evidence supported an increase in postlegalization consumption (55% did not report a change and 5% reported a decrease). The increase was most evident for young adults (42% of higher quality evidence) and in the consumption in the past month (37% of higher quality evidence). There was limited supporting evidence for new users having grown in response to legalization. Based on subgroup analysis, the increase in postlegalization consumption was higher among women and those who engage in binge-drinking.

CONCLUSIONS

Higher quality evidence suggests an increase in adolescent past-month consumption of cannabis following legalization in several geographical jurisdictions. Consumption evolution prelegalization and postlegalization differed by age group and for young women and for binge drinkers. Consumption evolution differences suggest a variety of strategies might be required in efforts to lower public health impacts of cannabis consumption following legalization.

Sociodemographic differences in patterns of nicotine and cannabis vaping among US adults

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About half (54.2%) of adults who used electronic vapor products (EVPs) vaped nicotine only.

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Only 7.4% of adults who used EVPs vaped cannabis only, while one-fourth (23.8%) vaped nicotine and cannabis.

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Patterns of nicotine and cannabis vaping differed by age, race/ethnicity, education, and sexual orientation.

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Vaping nicotine and cannabis and cannabis only was more common among young adults.

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Vaping cannabis only was more common among Hispanic and non-Hispanic Black adults.

Nicotine and cannabis vaping has increased over the past several years. While patterns of cigarette and cannabis co-use are well-documented, less is known about the intersection between nicotine and cannabis vaping, especially among adults. Thus, we categorized nicotine and cannabis vaping among adults (18+) who currently (past 30-day) used electronic vapor products (EVPs) from Wave 4 of the Population Assessment of Tobacco and Health Study (n = 3795) as: 1) nicotine only, 2) cannabis only, 3) nicotine and cannabis, and 4) non-nicotine/non-cannabis e-liquid. We calculated vaping pattern proportions overall and by sociodemographic characteristics. Adjusted multinomial logistic regression models assessed associations between sociodemographic characteristics and vaping categories relative to nicotine-only vaping. Approximately half (54.2%) of adults who currently used EVPs vaped nicotine only, 7.4% vaped cannabis only, 23.8% vaped nicotine and cannabis, and 14.6% vaped non-nicotine/non-cannabis e-liquid. Young adults (aged 18–24) (vs. adults aged 35+) had at least three-fold greater odds of vaping cannabis only, nicotine and cannabis, and non-nicotine/non-cannabis e-liquid, compared to nicotine only. Hispanic and non-Hispanic Black (vs. non-Hispanic White) adults had 2.5–3 times greater odds of vaping cannabis only and non-nicotine/non-cannabis e-liquid, compared to nicotine only. Sexual minority adults (vs. heterosexual adults) had 1.5 times greater odds of vaping nicotine and cannabis, compared to nicotine only. Nearly half of adults who vaped EVPs consumed something other than nicotine only, and nicotine/cannabis vaping patterns differed by sociodemographic groups. Vaping and nicotine reduction efforts must recognize that adults who currently vape may be vaping cannabis, or neither nicotine nor cannabis.

Impact of recreational cannabis legalization on cannabis use, other substance use, and drug-related offending among justice-system-involved youth

The present study assessed whether cannabis use, other types of substance use, and drug-related offending changed among 1216 justice-system-involved youth after recreational cannabis legalization. Using generalized estimating equation population-averaged models, we compared youth in California, where recreational cannabis is legalized, and Pennsylvania, where recreational use is still prohibited. Results indicated that cannabis use, cannabis selling, and driving under the influences (DUIs) increased more among Pennsylvanian than Californian youth. We found no changes in alcohol or noncannabis drug use after legalization. Cigarette use did not change significantly among Pennsylvanian youth, but Californian youth exhibited decreased cigarette use after legalization. Although not directly tested in the present analysis, it is possible that changes in state-level recreational cannabis policies throughout the U.S. may contribute to more permissive attitudes toward cannabis, which leads to higher use and use-related outcomes. Future research should continue to consider the potential impacts of legalization on other types of risky and illegal behavior.

Societal Costs and Outcomes of Medical and Recreational Marijuana Policies in the United States: A Systematic Review

Significant support exists in the United States for legalization of marijuana/cannabis. As of 2021, 36 states and four territories approved the legalization of medical cannabis via medical marijuana laws (MMLs), and 15 states and District of Columbia (DC) have adopted recreational marijuana laws (RMLs). We performed structured and systematic searches of articles published from 2010 through September 2021. We assess the literature pertaining to adolescent marijuana use; opioid use and opioid-related outcomes; alcohol use; tobacco use; illicit and other drug use; marijuana growing and cultivation; employment, earnings, and other workplace outcomes; academic achievement and performance; criminal activity; perceived harmfulness; traffic and road safety; and suicide and sexual activity. Overall, 113 articles satisfied our inclusion criteria. Except for opioids, studies on use of other substances (illicit drugs, tobacco, and alcohol) were inconclusive. MMLs and RMLs do not generate negative outcomes in the labor market, lead to greater criminal activity, or reduce traffic and road safety.

Recreational Marijuana Legalization and Co-use With Alcohol Among Adolescents

INTRODUCTION

Little is known about the possible impacts of recreational marijuana legalization on alcohol and marijuana co-use among underage youth. This study examines the association between recreational marijuana legalization in California in 2016 and alcohol and marijuana co-use among adolescents. Additional analyses investigate the associations between recreational marijuana legalization and co-use among past 30-day drinkers and marijuana users and the frequency of alcohol and marijuana use among co-users.

METHODS

This study used annual cross-sectional data from 7th, 9th, and 11th graders (N=3,319,329) who participated in the California Healthy Kids Survey from 2010-2011 to 2018-2019. Measures included past 30-day alcohol and marijuana use and student demographic characteristics, survey year, pre-post recreational marijuana legalization, and urbanicity. Multilevel regression analyses were conducted in 2021.

RESULTS

Recreational marijuana legalization was associated with greater odds of past 30-day alcohol and marijuana co-use in the total sample (OR=1.06, 95% CI=1.05, 1.07). Recreational marijuana legalization was more strongly associated with co-use among adolescents who reported past 30-day alcohol use (OR=1.58, 95% CI=1.52, 1.62) and heavy drinking (OR=1.25, 95% CI=1.21, 1.29) but was inversely related to co-use among past 30-day marijuana users (OR=0.76, 95% CI=0.74, 0.78). Among past 30-day co-users, there was a positive association with the frequency of marijuana use (β=0.36, SE=0.07).

CONCLUSIONS

Recreational marijuana legalization may increase the risk of alcohol and marijuana co-use among adolescents. Greater restrictions on the numbers of alcohol and marijuana retail outlets and hours of operation and advertising and higher taxes on alcohol and marijuana products may help reduce the availability of these substances to adolescents.

Changes in alcohol use by cannabis use status among adolescents and young adults in the United States: Emerging evidence for both substitution and complementarity

BACKGROUND

The majority of adolescents and young adults (AYA) who use cannabis also use alcohol. Although cannabis use is increasing in the United States (US), it is not known whether the increase contributes to either increased co-use of alcohol and cannabis (e.g., complementarity) or replacement of alcohol with cannabis (e.g., substitution). The current study estimated the prevalence of alcohol use by cannabis use status among US AYA ages 12 to 25 in 2018 and trends in alcohol use by cannabis use status from 2002 to 2018.

METHODS

Data were drawn from the 2002 to 2018 National Survey on Drug Use and Health public use data files. The analytic sample included AYA ages 12 to 25 (2018 sample, n = 26,924; total combined sample 2002 to 2018, n = 576,053). Linear and logistic regression models were used to estimate past-month alcohol use, daily alcohol use, and average quantity of alcohol consumed among AYA with and without past-month cannabis use from 2002 to 2018.

RESULTS

In 2018, any alcohol use and daily alcohol use were significantly more common among AYA who used cannabis use than those who did not use cannabis. Overall, any alcohol use, daily alcohol use, and average drinks per day declined from 2002 to 2018 among AYA irrespective of recent cannabis use. However, the decline in any alcohol use, daily alcohol use, and average alcohol drinks per day was more rapid among AYA who used cannabis (daily and nondaily) than those who did not use cannabis. The rate of decline in average alcohol drinks per day was also higher among AYA with daily compared to nondaily cannabis use.

CONCLUSIONS

Even with declines in alcohol use over time, drinking is much more common among AYA who report cannabis than those without recent cannabis use, which is consistent with complementarity. Yet, because the decline in alcohol use has been more rapid among AYA who use cannabis, there is also evidence of substitution. Thus, the current data on alcohol and cannabis use are consistent with both complementarity and substitution. However, these relationships may change as cannabis legalization expands over time.

Persistent Exposure to Δ9-Tetrahydrocannabinol during Adolescence Does Not Affect Nociceptive Responding in Adult Mice

Evidence suggests that Δ9-tetrahydrocannabinol (Δ9-THC), the intoxicating component of cannabis, causes enduring changes in the structure and function of adolescent brain circuits implicated in nociceptive responding. However, whether such changes might persistently disrupt nociceptive behaviors remains unknown. In the present study, we subjected C57BL6/J mice of both sexes to once-daily injections of Δ9-THC (5 mg-kg-1, i.p.) or vehicle throughout adolescence (PND 30-43) and, when the animals had reached adulthood (PND 70), assessed nociceptive behavior using the formalin and chronic constriction injury tests. We also investigated, using the tail immersion test, the antinociceptive effects of morphine and the development of tolerance to such effects. The results show that adolescent Δ9-THC exposure does not significantly impair nociceptive responding or morphine-related antinociception and tolerance. The findings suggest that frequent exposure to a moderate dose of Δ9-THC during adolescence does not permanently alter nociceptive circuits in male or female mice. SIGNIFICANCE STATEMENT: The endocannabinoid system serves critical functions in the central and peripheral nervous systems, including regulation of pain, and can be modified by prolonged exposure to the intoxicating constituent of cannabis, Δ9-tetrahydrocannabinol (Δ9-THC). This raises the possibility that regular use of Δ9-THC-containing cannabis during adolescence might cause changes in nociception that persist into adulthood. This study found that frequent early-life exposure to a moderate dose of Δ9-THC does not permanently alter nociceptive function in male or female mice.