Cannabis Use Among Young Adults in Washington State After Legalization of Nonmedical Cannabis

Treating young adult cannabis use disorder with text message-delivered peer network counseling

BACKGROUND

Approximately 16.5% of U.S. young adults have a cannabis use disorder (CUD) and are at risk for negative outcomes. Treatment can reduce cannabis use, but young adults are less likely to seek help than older adults. Peer Network Counseling-txt (PNC-txt) is a brief, text-delivered, Motivational Interviewing-informed substance use intervention focusing on peer relations and activity spaces as mechanisms for behavioral change. PNC-txt has shown evidence of reducing tobacco and cannabis use with adolescents and young adults, but it has not been tested in the context of legal cannabis use. The current randomized controlled trial sought to expand the evidence regarding the context of PNC-txt effects, comparing one state in which cannabis is legal (Colorado) and one state in which it is not (Tennessee). We hypothesized that participants randomized to PNC-txt would show significant reductions in cannabis use compared to controls, with larger reductions for females and those in Colorado, and that peer relations and activity space would mediate effects.

METHODS

One thousand, seventy eight 18-25 year olds (CO: 551; TN: 527) who met screening criteria for CUD and biologically-verified cannabis use were randomly assigned to PNC-txt or waitlist control condition. Every other day for 4 weeks, participants assigned to PNC-txt received pre-programmed text conversations, tailored via data from the baseline assessment. Self-report and biological indicators of cannabis use were measured at 1-, 3-, and 6-months.

DISCUSSION

Data analysis is underway. Results will provide evidence regarding whether, and how, PNC-txt reduces cannabis use in young adults with CUD.

TRIAL REGISTRATION

This trial was prospectively registered on September 28, 2020 with ClinicalTrials.gov (NCT04567394).

Prevalence of Cannabis Use around the World: A Systematic Review and Meta-Analysis, 2000-2024

This study aims to perform a systematic review and meta-analysis on the global prevalence of cannabis use to inform drug prevention strategies, policy-making, and resource allocation. This study initially screened 177,843 studies published between January 1, 2000, and January 15, 2024, using peer-reviewed databases including Web of Science, PubMed, Scopus, Embase, and Cochrane Library. Ultimately, 595 studies were identified for data extraction, and 39 of these were selected as country-representative studies. Heterogeneity among the selected studies was assessed using the chi-squared test and I2 statistic, while sensitivity analysis was conducted to evaluate the robustness of the results. The prevalence of cannabis use varied between 0.42% and 43.90% across 33 European countries, 1.40% to 38.12% across 15 North and South American countries, 0.30% to 19.10% across 16 Asian countries, and 1.30% to 48.70% across 18 Oceania and African countries. The pooled prevalence of cannabis use was 12.0% [95% confidence interval (CI): 10.0, 14.3] in countries where cannabis is legalized, compared to 5.4% (95% CI: 4.3, 6.9) in non-legalized countries. Our findings indicate that the prevalence of cannabis use has disproportionately increased in most countries with the implementation of medical or recreational cannabis legalization policies and relevant geographic proximity. Increased efforts are needed to monitor newly cannabis-legalized countries and prevent initial use.

Is the 21st birthday a turning point for alcohol and cannabis use? A monthly study of young adults

BACKGROUND

An important life-course event with respect to alcohol and cannabis use is turning 21 years of age, which may be associated with increases in use of these substances due to celebrations during the month and easier access to them on and following this birthday. We examined the trajectories of alcohol and cannabis use behaviors in the months leading up to, during, and following the 21st birthday month. We also examined whether the use trajectories vary by college status and baseline levels of use.

METHODS

We used data from 203 young adults recruited from the Greater Seattle region who turned 21 during the course of the study. Surveys were administered each month for 24 consecutive months. Measures included the typical number of drinks per week for the past month, the frequency of heavy episodic drinking, the number of cannabis use days, and any simultaneous alcohol and cannabis use. Multilevel spline models were run that estimated linear slopes over time at four intervals: (1) up to 1 month before the 21st birthday month; (2) from 1 month before to the month of the 21st birthday; (3) from the 21st birthday month to 1 month following; and (4) from 1 month following the 21st birthday month through all following months.

RESULTS

Alcohol use, generally, and simultaneous alcohol and cannabis use showed sharp increases from the month before the 21st birthday month to the 21st birthday month and decreases following the 21st birthday month. For cannabis use, there were significant increases in the months leading up to the 21st birthday and no other significant changes during other time intervals. Patterns differed by baseline substance use and college status.

CONCLUSIONS

Findings from the current study have implications for the timing and personalization of prevention and intervention efforts. Event-specific 21st birthday interventions may benefit from incorporating content targeting specific hazardous drinking behaviors in the month prior to the 21st birthday.

Predictors of effective therapy among individuals with Cannabis Use Disorder: a review of the literature

Treatment demand for Cannabis Use Disorder (CUD) has increased in the past decade in almost all European countries, and CUD is currently the most common reason for first-time drug-related treatment admission in the European Union. Even though several therapeutic approaches have been shown to benefit individuals with CUD, there is a lack of knowledge regarding factors associated with effective therapy and the underlying mechanisms of change among individuals with CUD presenting for treatment. The aim of the present paper was to review current knowledge on factors that have been shown to contribute to positive outcomes in CUD treatment. A scoping methodology was used, focusing on empirically evaluated studies that used defined, cannabis-related outcome measures. In eligible studies, factors of investigation were categorized as either 'mediators', i.e., treatment-related factors associated with the processes or mechanisms through which patients benefit from therapy, or 'moderators' which are patient-related characteristics that predict his/her odds to benefit from treatment or patient-related (i.e., moderators). Factors categorized as mediators were then classified 'specific factors' if they were related to a certain technique or treatment modality or 'common factors' if they were assessed beyond treatment modalities. Findings suggest that in CUD treatment, specific mediators include treatment duration, addressing motivation to change, acquiring coping skills, enhancing self-efficacy, and integrating several therapeutic components. Common mediators include therapeutic alliance, empathy, expectations and cultural adaptation. Moderators in CUD treatment include sex, ethnicity, age-related factors and comorbid disorders.

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

OBJECTIVE

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

METHOD

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

RESULTS

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

CONCLUSIONS

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

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.

Behavioral economic analysis of legal and illegal cannabis demand in Spanish young adults with hazardous and non-hazardous cannabis use

BACKGROUND

In October 2021, a legal framework that regulates cannabis for recreational purposes in Spain was proposed, but research on its potential impacts on cannabis use is currently limited. This study examined the reliability and discriminant validity of two Marijuana Purchase Tasks (MPTs) for measuring hypothetical legal and illegal cannabis demand, and to examine differences in demand of both commodities in young adults at hazardous vs. non-hazardous cannabis use risk levels.

METHODS

A total of 171 Spanish young adults [Mage = 19.82 (SD = 1.81)] with past-month cannabis use participated in a cross-sectional study from September to November 2021. Two 27-item MPTs were used to estimate hypothetical demand for legal and illegal cannabis independently. The Cannabis Use Disorder Identification Test (CUDIT-R) was used to assess hazardous cannabis use and test for discriminant validity of the MPTs. Reliability analyses were conducted using Classical Test Theory (Cronbach's alpha) and Item Response Theory (Item Information Functions).

RESULTS

The MPT was reliable for measuring legal (α = 0.94) and illegal (α = 0.90) cannabis demand. Breakpoint (price at which demand ceases), and Pmax (price associated with maximum expenditure) were the most sensitive indicators to discriminate participants with different levels of the cannabis reinforcing trait. No significant differences between legal and illegal cannabis demand in the whole sample were observed, but hazardous vs. non-hazardous users showed higher legal and illegal demand, and decreased Breakpoint and Pmax if cannabis were legal vs illegal.

CONCLUSION

The MPT exhibits robust psychometric validity and may be useful to inform on cannabis regulatory science in Spain.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Cannabis and Alcohol Use by U.S. Young Adults, 2008-2019: Changes in Prevalence After Recreational Cannabis Legalization

INTRODUCTION

Young adults' cannabis and alcohol use patterns have changed after state recreational cannabis legalization according to studies based on college samples but not nationally representative samples. Associations between recreational cannabis legalization and changes in cannabis and alcohol use outcomes among young adults were examined, including differences by college enrollment and minor status (ages 18-20 vs 21-23 years).

METHODS

Repeated cross-sectional data (2008-2019) were collected from college-eligible participants aged 18-23 years in the National Survey on Drug Use and Health. Self-reported past-month cannabis use and frequent use (≥20 days) and a proxy for past-year DSM-5 cannabis use disorder were primary outcomes; past-month frequent alcohol use and binge drinking were secondary outcomes. Multilevel logistic regression models quantified changes in outcome prevalence from the study years before to after recreational cannabis legalization, adjusting for secular trends. Analyses were conducted on March 22, 2022.

RESULTS

Prevalence increased from before to after recreational cannabis legalization for past-month cannabis use (from 21% to 25%) and past-year proxy cannabis use disorder (from 11% to 13%); the increases were statistically significant [adjusted odds ratio (95% CI) = 1.20 (1.08-1.32) and 1.14 (1.003-1.30), respectively]. Increases were detected for young adults who were not in college and who were aged 21-23 years. Recreational cannabis legalization impacts were not detected for secondary outcomes.

CONCLUSIONS

Some young adults appear sensitive to state recreational cannabis legalization, including in terms of cannabis use disorder risk. Additional prevention efforts should be directed to young adults who are not in college and timed to occur before age 21 years.

Pre-Post Cannabis Legalization for Adult Use: A Trend Study of Two Cohorts of Young Adult Cannabis Users in Los Angeles

Cannabis was legalized for adult use in California in 2016 for individuals 21 and older. Among 18-20-years-olds, who can possess cannabis legally as medical cannabis patients (MCP) but not as non-patient cannabis users (NPU), the impact of adult use legalization (AUL) on cannabis and other substance use is unknown. Two cohorts of 18-20-year-old cannabis users (MCP and NPU) were surveyed, one in 2014-15 (n = 172 "pre-AUL") and another in 2019-20 (n = 139 "post-AUL"), using similar data collection methods in Los Angeles, California. Logistic and negative binomial regressions estimated cohort and MCP differences for cannabis and other drug use outcomes based on past 90-day use. In both pre- and post-AUL cohorts, MCP were more likely to self-report medical cannabis use (p < .001) while the post-AUL cohort reported greater use of edibles (p < .01), but fewer mean days of alcohol (p < .05) and cigarette (p < .01) use in multivariate models. Notably, frequency of cannabis use (days or hits per day) did not significantly differ between the pre- and post-AUL cohorts, except for greater use of edibles, despite potentially greater access to cannabis.

Injunctive Norms and Driving Under the Influence and Riding With an Impaired Driver Among Young Adults in Washington State

PURPOSE

Alcohol- and cannabis-impaired driving behaviors remain a public health concern especially among young adults (i.e., ages 18-25). Limited updates to prevention efforts for these behaviors may be due, in part, to limited understanding of malleable psychosocial predictors. The current study assessed associations between perceived injunctive norms (i.e., acceptability) of driving under the influence of alcohol (DUI-A) and cannabis (DUI-C), and riding with a driver under the influence of alcohol (RWI-A) and cannabis (RWI-C) in Washington State young adults.

METHODS

Participants included 1,941 young adults from the 2019 cohort of the Washington Young Adult Health Survey. Weighted logistic regressions assessed the associations between peer injunctive norms and impaired driving-related behaviors.

RESULTS

A weighted total of 11.5% reported DUI-A, 12.4% DUI-C, 10.9% RWI-A, and 20.9% RWI-C at least once in the past 30 days. Overlap between the outcomes was observed, indicating some young adults had engaged in multiple impaired driving-related behaviors. After controlling for substance use frequency, weighted logistic regressions indicated more positive perceived injunctive norms were associated with nearly 2 ½ times higher odds of DUI-A, 8 times higher odds of DUI-C, 4 times higher odds of RWI-A and six and a half times higher odds of RWI-C.

DISCUSSION

Results increase the understanding of how injunctive norms-a potentially malleable psychosocial factor-are associated with four impaired driving-related outcomes. Prevention programs that focus on assessing and addressing the norms of these outcomes individually and collectively, such as normative feedback interventions and media campaigns, may be helpful in reducing these behaviors.

The association between cannabis use and risk of non-medical pain reliever misuse onset among young adults in a legal cannabis context

BACKGROUND

Little is known about the prospective relationship between cannabis use and pain reliever misuse. This study examined associations of non-medical and medical cannabis use with onset of non-medical pain reliever misuse among young adults in Washington State (WA), where non-medical cannabis is legal.

METHODS

Data were from a cohort-sequential study of adults 18-25 residing in WA. Four annual surveys were used from cohorts recruited in 2014, 2015, and 2016. Participants who had not reported non-medical pain reliever misuse at baseline were included in discrete time survival analyses (N = 4,236). Odds ratios (ORs) were estimated for new onset of non-medical pain reliever misuse in any given follow-up year over the course of three years according to baseline non-medical and medical cannabis use.

RESULTS

When included separately in models, non-medical and medical cannabis use at baseline were associated with increased risk of non-medical pain reliever misuse adjusting for demographic characteristics as well as past year cigarette use and alcohol use (non-medical OR = 5.27; 95 % CI: 3.28, 8.48; medical OR = 2.21; 95 % CI: 1.39, 3.52). Including both forms of use in the model, associations of non-medical and medical cannabis use with non-medical pain reliever misuse onset remained (non-medical OR = 4.64; 95 % CI: 2.88, 7.49; medical OR = 1.65; 95 % CI: 1.04, 2.62).

CONCLUSIONS

Despite claims that cannabis use may reduce opioid use and related harms, findings suggest that cannabis use, including medical use, may not be protective, but instead may increase risk for non-medical pain reliever misuse.

Substance-Specific Risk Factors for Cannabis and Alcohol Use Among Young Adults Following Implementation of Nonmedical Cannabis Legalization

Laws regarding cannabis are rapidly changing in the USA as more states legalize nonmedical cannabis for adults aged 21 and older. Previous research has examined whether legalization has led to an increase in cannabis use as well as the use of other substances. The current study examined changes in cannabis- and alcohol-specific risk factors following legalization of nonmedical cannabis. We used 6 years of annual cross-sectional data (2014-2019) from 12,951 young adults age 18 to 25 who resided in Washington state. Risk factors examined include perceiving that use was common among same-age peers, believing use was acceptable, having easy access, and low perceived physical and psychological harm from use. Logistic regression models estimated annual rate of increase in these risk factors. All cannabis-specific risk factors increased among those aged 21+ (range of ORs for annual rate of change: 1.07-1.31) while significant increase in cannabis-related risk factors among those under age 21 was limited to perceptions of cannabis use being common (medical use: OR=1.08, 95% CI: 1.03, 1.12; nonmedical use: OR=1.13, 95% CI: 1.08, 1.18) and low perceived physical harm of occasional use (OR=1.08, 95% CI: 1.03, 1.13). Although descriptive norms for past-year use of alcohol among those aged 21+ increased (OR = 1.09, 95% CI: 1.02, 1.17), other risk factors for alcohol did not change significantly or, in the case of low perceived physical and psychological harm, decreased among both those under age 21 and those aged 21+ (range of ORs = 0.90-0.94). Given these findings show an increase in cannabis-specific risk factors since legalization was implemented, particularly among those young adults aged 21+, preventive interventions correcting risk misperceptions and related risk factors among young adults aged 21+ may prove efficacious in reducing use and resultant negative consequences.

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.

Trends in Alcohol, Cigarette, E-Cigarette, and Nonprescribed Pain Reliever Use Among Young Adults in Washington State After Legalization of Nonmedical Cannabis

PURPOSE

Liberalization of cannabis laws may be accompanied by changes in the use of substances other than cannabis and changes in associations of cannabis use with other types of substance use. This study assessed (1) trends in alcohol, nicotine, and nonprescribed pain reliever use and (2) changes in associations of cannabis use with these other substances among young adults in Washington State after nonmedical cannabis legalization.

METHODS

Regression models stratified by age (18-20 vs. 21-25) were used to analyze six annual waves of cross-sectional survey data from a statewide sample from 2014 through 2019 (N = 12,694).

RESULTS

Prevalence of past-month alcohol use, heavy episodic drinking (HED), and cigarette use and prevalence of past-year pain reliever misuse decreased, while the prevalence of past-month e-cigarette use increased since 2016 (the first year assessed). Across years and age groups, the prevalence of substance use other than cannabis was higher among occasional and frequent cannabis users compared to cannabis nonusers. However, associations between both occasional (1-19 days in the prior month) and frequent (20+ days) cannabis use and pain reliever misuse and between frequent cannabis use and HED weakened over time among individuals ages 21-25.

DISCUSSION

Contrary to concerns about spillover effects, implementation of legalized nonmedical cannabis coincided with decreases in alcohol and cigarette use and pain reliever misuse. The weakening association of cannabis use with the use of other substances among individuals ages 21-25 requires further research but may suggest increased importance of cannabis-specific prevention and treatment efforts.

Associations of cannabis retail outlet availability and neighborhood disadvantage with cannabis use and related risk factors among young adults in Washington State

BACKGROUND

This study examined associations of local cannabis retail outlet availability and neighborhood disadvantage with cannabis use and related risk factors among young adults.

METHODS

Data were from annual cross-sectional surveys administered from 2015 to 2019 to individuals ages 18-25 residing in Washington State (N = 10,009). As outcomes, this study assessed self-reported cannabis use at different margins/frequencies (any past year, at least monthly, at least weekly, at least daily) and perceived ease of access to cannabis and acceptability of cannabis use in the community. Cannabis retail outlet availability was defined as the presence of at least one retail outlet within a 1-kilometer road network buffer of one's residence. Sensitivity analyses explored four other spatial metrics to define outlet availability (any outlet within 0.5-km, 2-km, and the census tract; and census tract density per 1000 residents). Census tract level disadvantage was a composite of five US census variables.

RESULTS

Adjusting for individual- and area-level covariates, living within 1-kilometer of at least one cannabis retail outlet was statistically significantly associated with any past year and at least monthly cannabis use as well as high perceived access to cannabis. Results using a 2-km buffer and census tract-level metrics for retail outlet availability showed similar findings. Neighborhood disadvantage was statistically significantly associated with at least weekly and at least daily cannabis use and with greater perceived acceptability of cannabis use.

CONCLUSIONS

Results may have implications for regulatory and prevention strategies to reduce the population burden of cannabis use and related harms.