The longitudinal association of cumulative depression with cannabis use disorder among young adults.

OBJECTIVE: This study examined whether the cumulative experience of elevated depressive symptoms from age 19 to 23 was associated with cannabis use disorder (CUD) at age 26, and whether the association varied by perceived ease of access to cannabis and perceived risk for harms from cannabis use. METHOD: Data were from 4407 young adults participating in the Community Youth Development Study. Cumulative experience of elevated depressive symptoms was calculated by summing the number of times a participant scored 10+ on the 9-item Patient Health Questionnaire across three biennial survey waves (age 19 to 23). To assess CUD, the Diagnostic Interview Schedule was used. Participants also self-reported their ease of access to cannabis and the perceived harm of regular cannabis use at the age 19, 21, and 23 waves. Marginal structural modeling was used to account for multiple time-varying and time-fixed covariates through use of inverse probability weights. RESULTS: In final weighted models, a greater number of time points (i.e., study waves) showing elevated depressive symptoms was associated with an increased likelihood of CUD at age 26 (Prevalence Ratio = 1.46; 95% CI: 1.20, 1.77). There was no strong evidence for moderation of this association by perceived ease of access or perceived risk for harms due to regular cannabis use. CONCLUSIONS: Persistent experience of elevated depressive symptoms may place young adults at risk for cannabis use disorder. Strategies to reduce the burden of depressive symptoms among young adults may lead to downstream effects such as reducing the prevalence of cannabis-related problems.

Young adults with a history of substance use disorder experienced more negative mental health, social and economic outcomes during the COVID-19 pandemic period.

BACKGROUND AND AIMS: For young adults, the disruptions brought by the COVID-19 pandemic to work, social relationships and health-care probably impacted normative life stage transitions. Disaster research shows that negative effects of these events can persist for years after the acute crisis ends. Pandemic-related disruptions may have been especially consequential for young adults with a history of substance use disorder (SUD). The current work aimed to measure the broad impact of the COVID-19 pandemic on young adults with and without a history of SUD. DESIGN, SETTING AND PARTICIPANTS: Data were from a longitudinal panel of n = 4407 young adults across the United States surveyed repeatedly from 2014 to 2019 (aged 19-26 years, pre-pandemic) and again in 2021 (aged 28 years, mid-pandemic). MEASUREMENTS: We fitted multi-level models to understand the association between SUD history and pandemic outcomes, controlling for potential confounders (socio-demographic and health measures). Outcomes included overall life disruption; mental health, social and economic impacts; substance use; and physical health. FINDINGS: Young adults with a history of SUD reported greater life disruption (standardized ß = 0.13-0.15, Ps < 0.015) and negative mental health impacts (standardized ß = 0.12-0.14, Ps < 0.012), experienced approximately 20% more work-related stressors (relative risks = 1.18-1.22, Ps < 0.002) and 50% more home-related stressors (relative risks = 1.40-1.51, Ps < 0.001), and had two to three times the odds of increased substance use during the pandemic (odds ratios = 2.07-3.23, Ps < 0.001). Findings generally did not differ between those with a recent SUD diagnosis and those in recovery from SUD before the pandemic began. CONCLUSIONS: United States young adults with a history of substance use disorder (SUD) reported more life disruption and greater negative physical and mental health, social and economic impacts during the COVID mid-pandemic period than young adults with no history of SUD.

Young Adult Alcohol and Cannabis Impaired Driving After the Opening of Cannabis Retail Stores in Washington State.

Motor vehicle crashes are a leading cause of death for young adults (YA) in the USA, and driving under the influence of alcohol (DUIA), cannabis (DUIC), and simultaneous use of both substances (DUIAC) are prominent risk factors. Trends in YA impaired driving behaviors after opening of cannabis retail stores have been understudied. We examined YA trends in DUIA, DUIC, and DUIAC from immediately prior through 5 years following the opening of cannabis retail outlets in Washington State (2014-2019). Differences in trends were assessed across age, sex, and urbanicity. Weighted logistic regressions assessed yearly change in prevalence of DUIA, DUIC, and DUIAC from 2014 to 2019, using annual statewide data from the Washington Young Adult Health Survey (n = 12,963; ages 18-25). Moderation of trends by age, sex, and urbanicity was assessed. Prevalence of DUIA decreased overall (AOR = 0.93, 95% CI 0.90, 0.97) and among drinkers (AOR = 0.95, 95% CI 0.91, 0.99) but remained at concerning levels in 2019 (10% overall; 16% among drinkers). Overall DUIC did not change significantly (AOR = 0.99, 95% CI 0.96, 1.03; 11% by 2019) but decreased among those who used cannabis (AOR = 0.91, 95% CI 0.86, 0.96; 33% by 2019). DUIAC decreased but not significantly (overall: AOR = 0.89, 95% CI 0.78, 1.01; those who used alcohol and cannabis: AOR = 0.84, 95% CI 0.74, 1.04). Prevalence of YA DUI remained concerning. Trends may reflect some success in reducing DUI, but additional detection and prevention are needed.

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.

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.

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.

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.

Tobacco Use Patterns From Adolescence to Young Adulthood Among Latinx Youth From Rural Communities.

PURPOSE: To examine patterns in adolescent and young adult tobacco use, comparing Latinx foreign-born children and children of foreign-born parents (i.e., children of immigrants(COI)) to Latinx US-born children of US-born parents (i.e., children of nonimmigrants,(CONI)) and to CONI White youth who grew up in small and rural towns. METHODS: Data were from youth who lived in control communities that participated in a community-randomized trial of the Communities That Care prevention system. We compared Latinx CONI (n = 154) with Latinx COI (n = 316) and with non-Latinx White CONI (n = 918). We examined tobacco use in adolescence (any adolescent use, early onset, and chronic use) and young adulthood (any past-year tobacco use, any daily smoking, any nicotine dependence symptoms) with mixed-effects logistic regressions. RESULTS: In adolescence, Latinx CONI had a higher prevalence of any and chronic tobacco use relative to Latinx COI, and of any and early onset tobacco use relative to non-Latinx White CONI. In young adulthood, Latinx CONI were more likely to report tobacco use in the past year, any symptoms of nicotine dependence, and daily smoking relative to Latinx COI; and more likely to report daily smoking relative to non-Latinx White CONI. Generation differences in young adult tobacco use were explained by chronic tobacco use in adolescence. DISCUSSION: The study suggests targeting chronic tobacco use in adolescence to prevent disparities in tobacco outcomes among Latinx young adults from rural communities.

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.

Daily level predictors of impaired driving behaviors in young adults: Protocol design for utilizing daily assessments.

BACKGROUND: Motor vehicle crashes remain a leading cause of death among young adults (ages 18-25) in the United States. Many drivers implicated in these crashes are under the influence of alcohol, cannabis, or the simultaneous use of alcohol and cannabis. Extremely limited research has assessed impaired driving behaviors and their predictors at the daily level. Perceived norms and motives to use substances have empirical support suggesting they may impact impaired driving-related behavior. Novel approaches to assess these associations at the daily level are needed and may inform future intervention and prevention programs. OBJECTIVE: The goal of the current study is to utilize electronic daily assessments to assess driving under the influence of alcohol, cannabis, or simultaneous use and riding with a driver impaired by these substances to assess variability and predictors of these impaired driving-related behaviors at the daily level. This present manuscript details a protocol, measures, and a plan of analyses to assess how within-person differences in perceived norms and motives to use are associated with the likelihood of engaging in impaired driving-related behaviors. METHODS: Participants include young adults in Washington State who report simultaneous use in the past month and either driving under the influence of alcohol, cannabis, or simultaneous use, or riding with a driver under the influence of both substances in the past 6 months. Individuals who verify their identity and meet eligibility requirements will complete a baseline assessment after which they will be scheduled for training on the daily assessment procedure via Zoom. Next, they will be invited to complete daily surveys on Thursday, Friday, Saturday, and Sunday every other week for 6 months and a 6-month follow up assessment. Analyses will utilize multilevel models with days nested within individuals. RESULTS: The study is currently recruiting participants. A total of 192 participants have been recruited and 100 have completed the study protocol. Data collection is expected to be completed in Fall 2022. CONCLUSIONS: This study utilizes a novel design to assess impaired driving and predictors at the daily level among young adults at high risk of impaired driving-related behaviors. Findings will provide unique data that will shape the knowledge base in the field of social science and public health substance use research and that may be helpful for future prevention and intervention efforts on impaired driving.

Substance-Specific Risk Factors among Young Adults: Potential Prevention Targets across Cannabis-Permissive Environments.

PURPOSE: This study examined levels of substance-specific risk factors such as perception of harm from substance use among young adults in a range of cannabis-permissive environments. The main objective was to inform future preventive interventions aimed at reducing cannabis use in the context of increasingly permissive environments. METHODS: Data came from the Community Youth Development Study (CYDS) collected in 2016 when participants were about 23 years old (n = 1,722 participants residing in 46 U.S. states). Young adults self-reported their perceptions about the harms related to cannabis, alcohol, and cigarette use; attitudes about and ease of access to cannabis and other substances; and perceived wrongfulness and social acceptability of cannabis, alcohol, and cigarette use and of selling of cannabis and other illegal drugs. RESULTS: Young adults in more permissive cannabis contexts reported higher levels of all cannabis-specific risk factors (e.g., greater access to and more favorable attitudes about cannabis use), except for perception of harm from regular cannabis use. However, permissiveness of the cannabis environment was not associated with heightened levels of risk factors for other substance use (such as alcohol, cigarettes, and opioids). CONCLUSIONS: Future preventive interventions for young adults living in more permissive cannabis contexts may need to focus on cannabis-specific risk factors in particular and go beyond considerations of harm from regular use. Future studies should replicate these findings with other samples.

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.

Cumulative Neighborhood Risk and Subsequent Internalizing Behavior among Asian American Adolescents.

Neighborhood disadvantage is a developmental context that may contribute to Asian American adolescent internalizing problems, yet there is a dearth of longitudinal studies as well as examination of cultural protective factors. Co-ethnic density, or the proportion of individuals of the same racial/ethnic background in the neighborhood that is often cited as a protective factor for racial/ethnic minority groups, has not been adequately examined in Asian American youth. This study examined the longitudinal association between cumulative neighborhood risk and internalizing behavior, and the moderating role of sex and co-ethnic density using an Asian American subsample (N = 177; 45.2% female; ages 10-12, 14-15; Cambodian, Chinese, Filipino, Hmong, Japanese, Korean, Laotian, Samoan, Vietnamese, and other ethnic backgrounds) of a longitudinal panel study over a span of 6 years. Cumulative neighborhood risk during early adolescence (ages 10-14) was significantly associated with internalizing behavior at mid-adolescence (age 15) controlling for prior levels of internalizing behavior. There was no evidence of moderation by co-ethnic density or sex, indicating that reducing neighborhood disadvantage may be a promising preventive measure to address mental health problems for both sexes of Asian American adolescents.

Retail cannabis environment and adolescent use: The role of advertising and retailers near home and school.

Youth cannabis use is influenced by overlapping environmental contexts. We examined the associations between proximity to cannabis retailers and seeing cannabis advertisements and cannabis use behaviors in Oregon, a state with adult cannabis legalization. We used 2017 anonymous survey data from 24,154 Oregon 8th and 11th grade students. After adjustments for student and school district characteristics, advertising for 8th graders and presence of a retailer within a mile from school for 11th graders were associated with cannabis use and perceived harm. Additional policy efforts may further reduce youth exposure to cannabis.

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

Objectives. To examine changes in prevalence of cannabis use and of cannabis use disorder symptomatology among young adults from 2014 to 2019 in Washington State, where nonmedical (or "recreational") cannabis was legalized in 2012 and retail stores opened in July 2014. Methods. We used 6 years of cross-sectional data collected annually from 2014 (premarket opening) to 2019 from 12 963 (∼2000 per year) young adults aged 18 to 25 years residing in Washington. Logistic regression models estimated yearly change in prevalence of cannabis use at different margins and related outcomes. Results. Prevalence of past-year, at least monthly, at least weekly, and daily use of cannabis increased for young adults, although increases were driven by changes among those aged 21 to 25 years. There was also a statistically significant increase in prevalence of endorsing at least 2 of 5 possible symptoms associated with cannabis use disorder. Conclusions. Among young adults in Washington, particularly those of legal age, prevalences of cannabis use and cannabis use disorder symptomatology have increased since legalization. This trend may require continued monitoring as the nonmedical cannabis market continues to evolve. (Am J Public Health. 2022;112(4):638-645. https://doi.org/10.2105/AJPH.2021.306641).

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.

Simultaneous use of marijuana and alcohol: Potential prevention targets among young adults who use alcohol.

Simultaneous alcohol and marijuana use (SAM) such that their effects overlap has emerged as a behavior that is riskier than using either substance separately. It has been associated with high-risk binge drinking and driving while intoxicated during young adulthood, and it has been demonstrated to cause greater physical and mental impairment than use of alcohol or marijuana separately. To identify intervention and prevention targets specific to SAM, we examined the relationships between alcohol- and marijuana-specific beliefs and attitudes (risk factors) and self-reported SAM compared to non-simultaneous co-use (CAM) and alcohol use only in the past 30 days in a sample of young adults (n = 1,023, mean age = 23.17; SD = 0.43). Of those who reported drinking alcohol in the past 30 days, 20.7% reported SAM, 12.6% reported CAM, and 66.6% reported using only alcohol. Results from multinomial logistic regression analyses indicated that some marijuana-specific risk factors (e.g., belief that it is not at all wrong for someone their age to use marijuana) differentiated SAM or CAM from alcohol use only, but alcohol-specific risk factors generally did not. However, the perceptions that parents approved of their using marijuana or frequently drinking heavily were associated with a greater likelihood of SAM compared to CAM (OR ranged from 2.25 to 3.53). Findings point to the salience of individuals' attitudes and beliefs around marijuana use and their perception of parental approval of heavy drinking and marijuana use as potential targets for prevention programs targeting risk reduction among young adults.

Young adult simultaneous alcohol and marijuana use: Between- and within-person associations with negative alcohol-related consequences, mental health, and general health across two-years.

BACKGROUND: Simultaneous alcohol and marijuana use (SAM) may be linked to both short- and longer-term problems for young adults. Across two years of longitudinal data, we examined between- and monthly within-person associations of alcohol and marijuana use patterns, including SAM, with negative alcohol-related consequences, depressive symptoms, and general health. METHODS: 773 young adults (aged 18-23 at screening; 56% women) who used alcohol in the year prior to study enrollment were surveyed monthly for 24 months. Multilevel models assessed associations of alcohol and marijuana use patterns with outcomes. RESULTS: Individuals who reported a higher proportion of SAM months had more negative alcohol-related consequences (Rate Ratio [RR] = 1.49, 95% CI: 1.17,1.89). At the within-person level, participants experienced more alcohol-related consequences on months when SAM was reported compared to months of alcohol-only (RR = 1.17, 95% CI: 1.10,1.25) and months of concurrent alcohol and marijuana use without simultaneous use (CAM; RR = 1.20, 95% CI: 1.11,1.29). Compared to alcohol-only, SAM was associated with more depressive symptoms and poorer general health at the between-person level and with more depressive symptoms at the monthly within-person level; however, SAM did not differ substantially from using neither alcohol nor marijuana or CAM for these outcomes at either the between- or within-person level. CONCLUSIONS: SAM use may indicate risk for negative alcohol-related consequences, both within months of SAM use and across more extended time periods. Individuals who engage in SAM may experience worse mental and physical health than individuals who use alcohol exclusively.

Dual trajectories of cannabis and alcohol use among young adults in a state with legal nonmedical cannabis.

BACKGROUND: Understanding the nature of the association between cannabis and alcohol use within individuals over time in the era of legalized cannabis is of crucial importance for assessing the public health consequences of increasing cannabis use. An important unanswered question is whether cannabis and alcohol use substitute for one another. Specifically, is greater use of one substance associated with less use of the other substance (i.e., a negative association) or are the substances complementary and their association positive? METHODS: We used 24 consecutive months of data on a young adult sample (n = 774; 56% female, age 18-25 during the study) who drank alcohol in the year prior to enrollment. The sample was recruited in Washington State in 2015/2016 (after legalization of nonmedical cannabis) using media advertisements and community flyers and outreach. Using parallel process latent growth curve models, we assessed three types of association between cannabis and alcohol use across the 24-month period: (1) an association between average levels of cannabis and alcohol use; (2) an association between rates of change in cannabis and alcohol use; and (3) correlations between shorter-term deviations/fluctuations off of longer-term trajectories of level and change in cannabis and alcohol use. RESULTS: We found a positive association between the average frequency of cannabis and alcohol use; individuals who used cannabis more frequently on average also drank alcohol more frequently on average. Change over time in cannabis use was positively associated with change in alcohol use. There was also a contemporaneous positive association between fluctuations in cannabis and alcohol use. CONCLUSIONS: Overall, we found no evidence of substitution. Rather, the results suggest a complementary relationship between cannabis and alcohol use, such that the use of cannabis and alcohol rises and falls together.