Race/Ethnicity Differences in Trends of Marijuana, Cigarette, and Alcohol Use Among 8th, 10th, and 12th Graders in Washington State, 2004-2016

Lifetime use of alcohol and cannabis among U.S. adolescents across age: Exploring differential patterns by sex and race/ethnicity using the 2019 NSDUH data

Background

Early use of alcohol and cannabis is associated with health and social problems. It is unclear how lifetime use changes for each additional year of age during adolescence, and whether this change varies by sex and race/ethnicity. This study characterized lifetime rates of alcohol and cannabis use by age among 12- to 17-year-old American youth and explored differential patterns by sex and race/ethnicity.

Methods

Data were obtained from the 2019 National Survey on Drug Use and Health. Analyses were restricted to 12-17-year-olds who were non-Hispanic White, non-Hispanic Black, or Hispanic/Latino (n = 11,830). We estimated the increase in lifetime use of alcohol and cannabis by age for the full sample and stratified by sex and race/ethnicity. Slopes of the regression lines were compared to assess differential patterns across groups.

Results

In these cross-sectional analyses, reported lifetime use increased substantially from age 12 to 17 for alcohol (6.4 % to 53.2 %) and cannabis (1.3 % to 35.9 %). The increase in lifetime alcohol use was slightly, but not significantly, steeper among girls than boys (F1,8 = 3.40, p = 0.09). White and Latino youth showed similar rates of increase in lifetime alcohol use, which was significantly flatter among Black youth (F2,12=21.26, p<0.0001). Latino youth had a slightly, but not significantly, steeper increase in lifetime cannabis use than White and Black youth (F2,12=3.17, p = 0.07).

Conclusions

Reports of lifetime alcohol and cannabis use substantially increase from age 12 to 17 and the rates are different according to sex and race/ethnicity, highlighting the need for early and tailored substance use prevention in adolescents.

Health, safety, and socioeconomic impacts of cannabis liberalization laws: An evidence and gap map

Background

Globally, cannabis laws and regulations are rapidly changing. Countries are increasingly permitting access to cannabis under various decriminalization, medicalization, and legalization laws. With strong economic, public health, and social justice incentives driving these domestic cannabis policy reforms, liberalization trends are bound to continue. However, despite a large and growing body of interdisciplinary research addressing the policy-relevant health, safety, and socioeconomic consequences of cannabis liberalization, there is a lack of robust primary and systematic research that comprehensively investigates the consequences of these reforms.

Objectives

This evidence and gap map (EGM) summarizes the empirical evidence on cannabis liberalization policies. Primary objectives were to develop a conceptual framework linking cannabis liberalization policies to relevant outcomes, descriptively summarize the empirical evidence, and identify areas of evidence concentration and gaps.

Search Methods

We comprehensively searched for eligible English-language empirical studies published across 23 academic databases and 11 gray literature sources through August 2020. Additions to the pool of potentially eligible studies from supplemental sources were made through November 2020.

Selection Criteria

The conceptual framework for this EGM draws upon a legal epidemiological perspective highlighting the causal effects of law and policy on population-level outcomes. Eligible interventions include policies that create or expand access to a legal or decriminalized supply of cannabis: comprehensive medical cannabis laws (MCLs), limited medical cannabidiol laws (CBDLs), recreational cannabis laws (RCLs), industrial hemp laws (IHLs), and decriminalization of cultivations laws (DCLs). Eligible outcomes include intermediate responses (i.e., attitudes/behaviors and markets/environments) and longer-term consequences (health, safety, and socioeconomic outcomes) of these laws.

Data Collection and Analysis

Both dual screening and dual data extraction were performed with third person deconfliction. Primary studies were appraised using the Maryland Scientific Methods Scale and systematic reviews were assessed using AMSTAR 2.

Main Results

The EGM includes 447 studies, comprising 438 primary studies and nine systematic reviews. Most research derives from the United States, with little research from other countries. By far, most cannabis liberalization research focuses on the effects of MCLs and RCLs. Studies targeting other laws-including CBDLs, IHLs, and DCLs-are relatively rare. Of the 113 distinct outcomes we documented, cannabis use was the single most frequently investigated. More than half these outcomes were addressed by three or fewer studies, highlighting substantial evidence gaps in the literature. The systematic evidence base is relatively small, comprising just seven completed reviews on cannabis use (3), opioid-related harms (3), and alcohol-related outcomes (1). Moreover, we have limited confidence in the reviews, as five were appraised as minimal quality and two as low quality.

Authors’ Conclusions

More primary and systematic research is needed to better understand the effects of cannabis liberalization laws on longer-term-and arguably more salient-health, safety, and socioeconomic outcomes. Since most research concerns MCLs and RCLs, there is a critical need for research on the societal impacts of industrial hemp production, medical CBD products, and decriminalized cannabis cultivation. Future research should also prioritize understanding the heterogeneous effects of these laws given differences in specific provisions and implementation across jurisdictions.

Classification of Students by Race and Hispanic/Latino/a/x Ethnicity Impacts Estimates of the Prevalence of Substance Use

Multiracial and Hispanic/Latino/a/x youth are rapidly growing populations in the United States. When considered in substance use studies, they are often treated as homogeneous groups despite important demographic and cultural differences. The current study explores how substance use prevalence may differ depending on how precisely race and ethnicity groups are categorized. Data are from the 2018 High School Maryland Youth Risk Behavior Survey (n = 41,091, 48.4% female). We estimate prevalence of past 30-day substance use (i.e., alcohol, combustible tobacco, e-cigarettes, and marijuana) for all combinations of race and Hispanic/Latino/a/x ethnicity. Substance use prevalence across the specific Multiracial and Hispanic/Latino/a/x categories showed a wider range of estimates than within the traditional CDC racial and ethnic categories. Findings from this study suggest that state- and national-level surveillance of adolescent risk behavior should add further measures of race and ethnic identity to improve researchers' ability to increase precision of substance use prevalence estimates.

"What Do You Consider Use?" Perspectives of Black Youth on Cannabis Use

PURPOSE

Adolescent health surveillance systems are critical for understanding patterns of cannabis use; however, their limitations underscore the need for studies that generate new insights, particularly from individuals who are most impacted by negative outcomes. Our objectives were to learn about youths' cannabis use and their perceptions of their peers' cannabis use; their perspectives about trajectories of cannabis use over time and factors that influence trajectories; and perceived risks and benefits associated with cannabis use.

METHODS

A group model building approach was used to gather data about cannabis use from a sample of urban, Black youth. Information about participants' cannabis use was assessed on eligibility screener, enrollment survey, and through structured activities over the course of four group model building workshops.

RESULTS

Participants [(n = 20) mean age 18; 35% male and 95% Black] exclusively used the terms weed and blunts for cannabis. Youth who consume peers' blunts would not characterize themselves as cannabis users. Collectively, youth estimated the majority of Baltimore youth used cannabis by age 16 and that most used daily. Youth described cannabis as more beneficial than harmful. There were no gender differences in prevalence of use, but there were gender dynamics to shared use.

DISCUSSION

Participatory research with urban, Black youth suggests youths' perceptions are misaligned with the ways that researchers conceptualize cannabis use. To better understand the scope of youth cannabis use and its harms, it is critical to leverage input from youth with lived experience to ensure survey tools adequately capture the way youth see themselves using cannabis.

In harm's way: Do college students' beliefs about cannabis put them at risk for use?

Objective: This study describes beliefs held by college students about cannabis use and examines the association between three specific cannabis beliefs and likelihood of use. Participants: 3,720 undergraduate students ages 18 to 25 attending ten colleges in one state. Methods: Data were gathered via online survey. Results: The majority (80%) of the sample was unsure or believed that cannabis was an effective way to reduce stress; 67% were unsure or believed that cannabis was not related to an increased risk for mental health problems; and 62% were unsure or believed that students who use cannabis are not more academically disengaged. Holding these beliefs, which are not supported by scientific evidence, was associated with a greater likelihood of cannabis use, even after statistically adjusting for covariates. Conclusions: These findings suggest that beliefs unsupported by scientific evidence are widespread among college students. Dispelling misinformation about cannabis might hold promise for reducing use.

Substance Use Behaviors Among LGBTQ+ Youth of Color: Identification of the Populations Bearing the Greatest Burden in Three Large Samples

PURPOSE

Research has identified persistent disparities in alcohol, e-cigarette, and marijuana use, by sexual orientation, gender identity, and race/ethnicity. Using an intersectionality framework, the present study analyzes three large datasets to identify intersecting social positions bearing the highest burden of substance use.

METHODS

Data from adolescents in grades 9-12 in three samples (2019 Minnesota Student Survey, 2017-2019 California Healthy Kids Survey, and 2017 National Teen Survey) were harmonized for an analysis (N = 602,470). A Chi-squared Automatic Interaction Detection analysis compared the prevalence of four types of substance use across all combinations of four social positions (six racial/ethnic identities, five sexual orientations, three gender identities, and two sexes assigned at birth). For each substance, 10 intersectional groups with the highest prevalence of use were examined.

RESULTS

In the full sample, 12%-14% of participants reported past 30-day alcohol, e-cigarette, or marijuana use and 7% reported past 30-day binge drinking. Several intersecting marginalized social positions were consistently found to bear a high burden of substance use. For example, transgender and gender diverse (TGD) Latina/x/o young people, particularly those assigned male at birth, were in the high prevalence groups for alcohol use, binge drinking, and marijuana use. Black TGD or gender-questioning youth were commonly in the high prevalence groups.

DISCUSSION

Findings suggest that support, resources, and structural changes specifically tailored to youth with multiple marginalized identities (especially TGD) may be needed. The results argue for intersectional efforts that explicitly address racial/ethnic and cultural differences, while also integrating awareness and understanding of sexual and gender diversity.

Prospective Associations of Discrimination, Race, and Sexual Orientation with Substance Use in Adolescents

Objective: Adolescents are at high risk for alcohol and cannabis use. Emerging evidence suggests that discrimination exposure is prospectively associated with risk for alcohol use among adolescents of marginalized race, sexual orientation, or gender identity. However, it is unknown whether prospective discrimination-substance use associations among marginalized adolescents are also present for cannabis use. This study examined prospective associations of race, sexual orientation, and discrimination exposure with alcohol and cannabis use over one year. Methods: Data were drawn from a two-wave longitudinal health survey study of 9-11^th graders (n = 350 for the current analyses; Year 1 M_age=15.95 [SD = 1.07, range = 13-19]; 44% male; 44% Black, 22% White, 18% Asian, 16% Multiracial; 16% LGB; 10% Hispanic/Latinx ethnicity) at an urban high school. Two multinomial logistic regressions examined associations of Year 1 race, sexual orientation, and discrimination experiences with Year 2 alcohol and cannabis consumption separately. Results: Year 1 Discrimination exposure was associated with increased risk for Year 2 past-year alcohol use among Asian (OR = 1.34) and past-month alcohol use among Multiracial (OR = 1.30) adolescents, but not Black or LGB adolescents. Discrimination exposure was not associated with any cannabis use pattern in any group. Independent of discrimination, LGB adolescents were at greater risk for monthly alcohol (OR = 3.48) and cannabis use (OR = 4.07) at Year 2. Conclusions: Discrimination exposure is prospectively associated with risk for alcohol use among adolescents of understudied (Asian, Multiracial) racial backgrounds, and should be considered in alcohol prevention and intervention strategies. Risk factors for alcohol and cannabis use among LGB adolescents should continue to be explored.

Cannabis Legalization and Adolescent Use of Electronic Vapor Products, Cannabis, and Cigarettes

OBJECTIVES

Cannabis legalization may have unintended consequences, such as effects on prevalence of adolescent use of other substances. We hypothesize that in states that have legalized recreational cannabis (RCL states), electronic vapor product use ("vaping"), cannabis, and cigarette use among adolescents is more prevalent than in states that have only legalized medical cannabis (MCL states) and states that have neither legalized recreational nor medical cannabis (NL states).

METHODS

Data are from the Center for Disease Control's 2017 Youth Risk Behavior Surveillance Survey (n = 107,665), a nationally representative survey of US high school students. We categorized student responses by cannabis legalization status of the state in which they lived at time of survey, then tested associations between cannabis legalization status and adolescent vaping, cannabis, and cigarette use, using logistic regressions.

RESULTS

Students in RCL states were significantly more likely to report current vaping behaviors compared to NL students [odds ratios (OR's) 2.07-2.21]. Students in cannabis-legal states were significantly more likely to report ever or currently using cannabis compared to NL students (OR's 1.27-1.40). MCL students were significantly less likely to report current cigarette smoking (OR = 0.86) compared to NL students.

CONCLUSIONS

Adolescents in cannabis-legal states were more likely to report vaping and cannabis use compared to adolescents in NL states. Public health officials, policymakers, and clinicians should consider the associations between cannabis legalization and adolescent vaping, cigarette, and cannabis use patterns.

Adolescents' Marijuana Use Following Recreational Marijuana Legalization in Alaska and Hawaii

Alaska and Hawaii, the only two noncontiguous states in the United States, have different marijuana policy environments. Alaska enacted recreational marijuana legalization (RML) in 2014, whereas recreational marijuana is still illegal in Hawaii. This study analyzed how RML affects adolescents' marijuana use (MU) by comparing two states. We used data from 2 states (Alaska and Hawaii) from the Youth Risk Behavior Survey, 2009 to 2019 years (N = 35 467). The trends of lifetime MU and current MU were examined. Using difference-in-differences analysis models, this study investigated whether RML increased lifetime and current MU in Alaska compared with Hawaii after adjusting for socioeconomic characteristics. Both lifetime and current MU prevalence among adolescents in Alaska increased after RML, while both rates in Hawaii gradually decreased. The rate of lifetime MU in Alaska was significantly increased after RML (odds ratio [OR] = 1.29) compared with Hawaii. Similarly, the current MU among adolescents in Alaska was significantly increased compared with that in Hawaii (OR = 1.34). Both lifetime and current MU were increased following RML in Alaska, suggesting that RML may affect the increase of MU among adolescents.

Race/ethnicity differences in risk and protective factors for marijuana use among U.S. adolescents

BACKGROUND

Little is known about how race and ethnicity influence marijuana-specific risk and protective factors in U.S. adolescents. We examined differences in risk and protective factors of marijuana use (MU) and their associations with MU by race/ethnicity.

METHODS

The present study used data from the 2015-2019 National Survey on Drug Use and Health. A total of 68,263 adolescents (aged 12 to 17 years) were divided into seven subgroups by race/ethnicity (White, Hispanic, Black, Asian, Native American, Native Hawaiian/Pacific Islander (NH/PI), and mixed race). Marijuana-specific risk and protective factors (RPFs) were examined, including perceived availability of marijuana, adolescents' perceived risk of MU and perceived disapproval of parents, peers, and close friends. Past-month, past-year, and lifetime MU were used as MU outcomes to examine the associations with RPFs as well as with race/ethnicity.

RESULTS

Overall, 6.85, 12.67, and 15.52% of the sample reported past-month, past-year, and lifetime MU respectively. Weighted adjusted logistic regression analyses revealed that mixed race adolescents reported the greatest perceived availability of marijuana, whereas Black and Asian adolescents had less access compared to White adolescents. The adolescents' perception of parental disapproval of MU was the lowest for Native American adolescents and highest for Asian adolescents. Mixed race adolescents experienced lower peer and close friend disapproval of MU while Black and Asian adolescents had higher. The MU risk perception was lower in most groups including Black, Hispanic, Native American, and mixed race adolescents, but not in Asian adolescents. Native American adolescents scored the highest on all MU outcomes, whereas Asian adolescents scored the lowest. Perceived availability of marijuana was associated with higher MU in all MU outcomes. Lower disapproval MU perceptions and lower MU risk perceptions were also associated with greater MU.

CONCLUSION

These findings suggest there is considerable heterogeneity of marijuana risk and protective factors and MU across race/ethnicity among U.S. adolescents.

Post-legalization changes in marijuana use in a sample of young California adults

INTRODUCTION

Increasing marijuana use among young adults is a concern due to substantial acute and chronic health risks. More widespread use of marijuana may also lead to increased use of nicotine and tobacco products. California legalized commercial sales of marijuana for recreational use as of January 2018. To our knowledge no studies to date have examined subsequent changes in marijuana use. The goal of this study was to test the hypothesis that marijuana use frequency increased following legalization of recreational sales. We also hypothesized that increased marijuana frequency would predict greater frequency of nicotine/tobacco consumption.

METHODS

The study was a secondary analysis of a longitudinal study of tobacco use among non-daily cigarette smokers. Participants were 563 young adults (aged 18-24) enrolled in 2015-16 and followed quarterly for 3 years.

RESULTS

A piecewise multilevel regression model indicated that marijuana use frequency did not change over time, including following legalization. More frequent use was associated with younger age and identifying as white (ps < 0.001, which did not change after legalization. Marijuana frequency was moderated by sex (p < .001), with women reporting increasing and men decreasing use over time. It was also associated with tobacco use, and particularly with e-cigarette use following legalization (ps < 0.05).

CONCLUSIONS

Findings suggest legalization of recreational marijuana sales had a negligible overall impact on days of use among young adults, but may have prompted increased interest in marijuana among some, particularly women and e-cigarette users. The continuously evolving landscape around these products indicates that ongoing surveillance is critical.

Has Cannabis Use Among Youth Increased After Changes in Its Legal Status? A Commentary on Use of Monitoring the Future for Analyses of Changes in State Cannabis Laws

As US states move toward various forms of adult access to cannabis, there has been a great interest in measuring the impact of such changes on adolescent cannabis use. Two recent prominent analyses have used Monitoring the Future (MTF), a nationally representative survey of students, to examine the effects. We compared MTF data for California and for Washington State with other survey data on use by adolescents in those states. In both studies, findings based on MTF were different from those using other larger, state-representative surveys. The discrepancy reflects the high within-state variation in prevalence rates and the small number of schools in MTF state samples. Using the Washington Health Youth Survey, we estimate that after recreational cannabis legalization past 30-day cannabis use prevalence in grade 8 decreased by 22.0%, in grade 10 prevalence decreased by 12.7%, and no effect in grade 12. These trends are consistent with those in states without recreational cannabis laws, suggesting that legalization did not impact adolescent use prevalence. Long-term trends in MTF are consistent with other data, but year-to-year volatility in state-level series undermines the survey's suitability for evaluation of state cannabis policy changes. Survey-based analyses at the state level need to be cross-validated with findings from other data sources. When findings are disparate and methodological rigor is equivalent, analyses of data sources specifically designed to describe state-level phenomena are more credible.

Marijuana Legalization and Youth Marijuana, Alcohol, and Cigarette Use and Norms

INTRODUCTION

Rates of adolescent substance use have decreased in recent years. Knowing whether nonmedical marijuana legalization for adults is linked to increases or slows desirable decreases in marijuana and other drug use or pro-marijuana attitudes among teens is of critical interest to inform policy and promote public health. This study tests whether nonmedical marijuana legalization predicts a higher likelihood of teen marijuana, alcohol, or cigarette use or lower perceived harm from marijuana use in a longitudinal sample of youth aged 10-20 years.

METHODS

Data were drawn from the Seattle Social Development Project-The Intergenerational Project, an accelerated longitudinal study of youth followed both before (2002-2011) and after nonmedical marijuana legalization (2015-2018). Analyses included 281 youth surveyed up to 10 times and living in a state with nonmedical marijuana legalization between 2015 and 2018 (51% female; 33% white, 17% African American, 10% Asian/Pacific Islander, and 40% mixed race or other).

RESULTS

Multilevel modeling in 2019 showed that nonmedical marijuana legalization predicted a higher likelihood of self-reported past-year marijuana (AOR=6.85, p=0.001) and alcohol use (AOR 3.38, p=0.034) among youth when controlling birth cohort, sex, race, and parent education. Nonmedical marijuana legalization was not significantly related to past-year cigarette use (AOR=2.43, p=0.279) or low perceived harm from marijuana use (AOR=1.50, p=0.236) across youth aged 10-20 years.

CONCLUSIONS

It is important to consider recent broad declines in youth substance use when evaluating the impact of nonmedical marijuana legalization. States that legalize nonmedical marijuana for adults should increase resources for the prevention of underage marijuana and alcohol use.

Are national antitobacco campaigns reaching high-risk adolescents? A cross-sectional analysis from PATH Wave 2

Smoking education and prevention campaigns have had marked success in reducing rates of tobacco use among adolescents, however, disparities in use continue to exist. It is critical to assess if adolescents at risk for tobacco use are being exposed to antitobacco campaigns. We used data from Wave 2 of the Population Assessment of Tobacco and Health Study to assess the relationship between exposure to three antitobacco campaigns and key characteristics related to higher risk of cigarette use using full-sample weights and Poisson regression models with robust variance. Adjusted models identified that exposure to antitobacco campaigns was more common among racial and sexual minority adolescents and adolescents who: reported exposure to tobacco marketing, spent more time using media and had household income greater than $25 000. While some high-risk youth are more likely to report exposure to campaigns, there are some priority groups that are not being reached by current efforts compared with non-priority groups, including youth living in households with income below the poverty line and adolescents who are susceptible to cigarette smoking. Future campaigns should consider targeting these groups specifically in order to reduce tobacco use disparities.

A Decline in Propensity Toward Risk Behaviors Among U.S. Adolescents

PURPOSE

Over the past two decades, substance use, delinquent behaviors, and promiscuous sexual activity have declined substantially among U.S. adolescents. We aimed to determine the extent to which these trends represent declines in a general propensity to engage in risk behaviors (i.e., declines in a latent factor).

METHODS

We used Youth Risk Behavior Survey data (1999-2017) (n = 147,800) and examined trends in substance use (e.g., alcohol), delinquency (e.g., fighting), and sexual activity (e.g., number of partners). We conducted two types of analyses stratified by grade (9th/10th vs. 11th/12th) and sex: (1) estimation of year-specific prevalence of each behavior and modeled prevalence changes over time and (2) factor analysis and application of alignment methods to determine changes in the mean of the latent factor over time while correcting for measurement noninvariance.

RESULTS

A single factor explained 53% (girls 11th/12th grade) to 62% (boys 9th/10th grade) of the variance in risk behaviors. Average relative annual declines in the prevalence of each behavior-except for weapon carrying-ranged from 1% to 6%. The structure of the latent factor was mostly unchanged over time, with notable exceptions related to differential changes in prevalence for cigarette and cannabis use. Between 1999 and 2017, the mean of the latent factor declined by between .54 and .73 standard deviations.

CONCLUSIONS

Results suggest that much of the decline in the prevalence of substance use, delinquent, and sexual behaviors among American youth from 1999 to 2017 reflect an approximately two-thirds standard deviation decline in the mean of a latent risk behavior factor.

Trends in Single, Dual, and Poly Use of Alcohol, Cigarettes, and Marijuana Among US High-School Students: 1991-2017

Objectives. To evaluate trends in patterns (single, dual, or poly) of current use of alcohol, cigarettes, and marijuana (ACM) among youths in the United States. Methods. I used data from the 1991-2017 Youth Risk Behavior Surveys (n = 203 663) to report average annual percentage change (AAPC) and linear trends of single, dual, and poly use of ACM among youths. Results. From 1991 to 2017, the prevalence of marijuana-only use increased from 0.6% to 6.3% (AAPC = 7.4) while the prevalence of use of alcohol only or cigarettes only significantly declined. Dual use of alcohol and marijuana increased from 3.6% to 7.6% (AAPC = 2.4), while dual use of alcohol and cigarettes declined from 11.8% to 1.7% (AAPC = -7.5). The prevalence of poly use of ACM declined from 9.4% to 4.4%. There is an enlarged disparity in use of marijuana only by race/ethnicity with an increase of 11.5% among non-Hispanic Blacks and an increase of 8.1% among Hispanics, compared with an increase of 3.4% among non-Hispanic Whites. Conclusions. The use patterns of ACM among youths have changed with a surge in use of marijuana only, especially among racial/ethnic minorities.

Adolescent Marijuana Use, Marijuana-Related Perceptions, and Use of Other Substances Before and After Initiation of Retail Marijuana Sales in Colorado (2013-2015)

Due to the recentness of changes to marijuana policies in a number of states, the effect on adolescent use and perceptions is not yet well understood. This study examines change in adolescent marijuana use and related perceptions in Colorado, before and after the implementation of legal commercial sale of recreational marijuana for adults starting on January 1, 2014. The data are from a repeated cross-sectional survey of a representative sample of Colorado high school students, with separately drawn samples surveyed in fall 2013 (prior to implementation) and fall 2015 (18 months after implementation). We examined change in the prevalence of adolescent marijuana use, measured by lifetime use, past 30-day use, frequent use, and use on school property. To consider the possibility of heterogeneity in the change in marijuana use, we examined change in past 30-day marijuana use by demographic characteristics (sex, grade, race/ethnicity), school characteristics (poverty, percent minority), urbanicity of the school district, and whether the city or county permitted retail marijuana stores. There was an absence of significant effects for change in lifetime or past 30-day marijuana use. Among those reporting past 30-day use, frequent use and use on school property declined. There was a significant decline in the perceived harm associated with marijuana use, but we did not find a significant effect for perceived wrongfulness, perceived ease of access, or perceived parental disapproval. We did not find significant variability in past 30-day use by demographic characteristics or by school and community factors from 2013 to 2015. We did not find a significant effect associated with the introduction of legal sales of recreational marijuana to adults in Colorado on adolescent (illegal) use, but ongoing monitoring is warranted, including consideration of heterogeneity in the effects of marijuana policies.

Historical trends in the grade of onset and sequence of cigarette, alcohol, and marijuana use among adolescents from 1976-2016: Implications for "Gateway" patterns in adolescence

INTRODUCTION

In the past decade, marijuana use prevalence among adolescents has remained relatively steady while cigarette and alcohol prevalence has declined. We examined historical trends in: average grade of onset of marijuana, alcohol, and cigarette use by 12^th grade; proportion who try alcohol/cigarettes before first marijuana use, among those who use by 12^th grade; and conditional probability of marijuana use by 12^th grade after trying alcohol/cigarettes.

METHODS

Data were drawn from 40 yearly, cross-sectional surveys of 12^th grade US adolescents. A subset of students (N = 246,050) were asked when they first used each substance. We reconstructed cohorts of substance use from grade-of-onset to determine sequence of drug use, as well as probability of marijuana use in the same or later grade.

RESULTS

Average grade of first alcohol and cigarette use by 12^th grade increased across time; e.g., first cigarette increased from grade 7.9 in 1986 to 9.0 by 2016 (β=0.04, SE = 0.001, p < 0.01). The proportion of 12^th grade adolescents who smoke cigarettes before marijuana fell below 50% in 2006. Each one-year increase was associated with 1.11 times increased odds of first cigarette in a grade after first marijuana (95% C.I. 1.11-1.12). Among those who initiate alcohol/cigarettes prior to marijuana by 12^th grade, the probability of subsequent marijuana use is increasing.

CONCLUSION

Marijuana is increasingly the first substance in the sequence of adolescent drug use. Reducing adolescent smoking has been a remarkable achievement of the past 20 years; those who continue to smoke are at higher risk for progression to marijuana use.