Simultaneous Alcohol and Marijuana Use Among Young Adults: A Scoping Review of Prevalence, Patterns, Psychosocial Correlates, and Consequences.

BACKGROUND: Alcohol and marijuana are commonly used by young adults, and use of both substances, particularly at the same time, is prevalent among this population. Understanding the prevalence, patterns, correlates, and consequences of simultaneous alcohol and marijuana (SAM) use is important to inform interventions. However, this literature is complicated by myriad terms used to describe SAM use, including use with overlapping effects and same-day co-use. OBJECTIVES: This scoping review identifies and describes the peer-reviewed literature focused on SAM use by young adults and distinguishes simultaneous use from same-day co-use of alcohol and marijuana. This review also provides a narrative summary of the prevalence of SAM use, patterns of SAM and other substance use, psychosocial correlates, and consequences of SAM use. ELIGIBILITY CRITERIA: This review is limited to papers written in English and published in peer-reviewed journals between January 2000 and August 2021. It includes papers assessing simultaneous use or same-day co-use of alcohol and marijuana among young adults ages 18 to 30. Review papers, qualitative interviews, experimental lab studies, policy work, toxicology or medical reports, and papers focused on neurological outcomes are excluded. SOURCES OF EVIDENCE: PubMed, PsycINFO, and Web of Science databases were searched. Databases were selected and the search strategy developed in consultation with an information specialist. CHARTING METHODS: A data charting form was utilized to specify which information would be extracted from included papers. Eight categories of data were extracted: (1) research questions and hypotheses; (2) sample characteristics; (3) study procedures; (4) definition of SAM use; (5) prevalence of SAM use; (6) patterns of SAM and other substance use; (7) psychosocial correlates of SAM use; and (8) consequences of SAM use. RESULTS: A total of 1,282 papers were identified through initial search terms. Through double-blind title/abstract screening and full-text review, the review was narrowed to 74 papers that met review inclusion criteria. Review of these papers demonstrated that SAM use was prevalent among young adults, particularly among those who reported heavier quantities and more frequent use of alcohol and marijuana. Enhancement-related motives for use were consistently positively associated with SAM use. SAM use was associated with greater perceived positive and negative consequences of alcohol and/or marijuana use. Inconsistencies in prevalence, patterns, correlates, and consequences were found between studies, which may be due to large variations in measurement of SAM use, populations studied, methodological design (e.g., cross-sectional vs. intensive longitudinal), and the covariates included in models. CONCLUSIONS: The literature on simultaneous use and same-day co-use of alcohol and marijuana has expanded rapidly. Of the 74 included papers (61 on SAM use; 13 on same-day co-use), 60 papers (47 on SAM use; 13 on same-day co-use) were published within the last 5 years. Future research focusing on the ways in which SAM use confers acute risk, above and beyond the risks associated with separate consumption of alcohol and marijuana, is needed for understanding potential targets for intervention.

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.

Intoxicated driving and riding with impaired drivers: Comparing days with alcohol, marijuana, and simultaneous use.

BACKGROUND: Young adults who engage in simultaneous alcohol and marijuana (SAM) use may be more likely to engage in unsafe behaviors including riding with impaired drivers and driving after alcohol and/or marijuana use. METHODS: Young adult SAM users (N = 408) self-reported their behavior for five 14-day bursts, yielding daily-level responses on a total of 14,675 substance use days. Adjusted odds ratios (AOR) estimated the likelihood of riding with an impaired driver and of driving after use on SAM use days compared to alcohol- or marijuana-only use days. RESULTS: More frequent SAM users were more likely to ride with an impaired driver and to drive after use than less frequent SAM users (between-persons). On SAM use days, there were greater odds of riding with an impaired driver, compared to alcohol-only days (AOR = 1.28) and marijuana-only days (AOR = 2.22), and of driving after use, compared to marijuana-only days (AOR = 1.25). Driving after use was more likely on days with non-simultaneous alcohol and marijuana use compared to SAM use (AOR = 1.59). CONCLUSIONS: Riding with an impaired driver is common among young adult substance users, and more likely following simultaneous use of alcohol and marijuana compared to other types of alcohol and marijuana use. Driving after use is more likely after SAM use than marijuana-only use days, but most likely on days when both alcohol and marijuana were used but not simultaneously. Future research on situation-level predictors of riding and driving-related risks among young adults is warranted.

What's the Harm in Getting High? Evaluating Associations Between Marijuana and Harm as Predictors of Concurrent and Prospective Marijuana Use and Misuse.

OBJECTIVE: Substantial research has demonstrated the importance of implicit cognitive processes underlying substance use. However, there is a scarcity of research on implicit processes related to marijuana use. We adapted and tested the predictive validity (concurrent and prospective) of an implicit measure evaluating the strength of associations between marijuana and harm based on research demonstrating less marijuana use among individuals who report stronger explicit attitudes of marijuana's harms. METHOD: A community sample of 187 U.S. young adults living in a state with legal recreational marijuana use completed an Implicit Association Test (IAT) evaluating marijuana-harm associations and measures of marijuana use and risk of cannabis use disorder (CUD) over time. RESULTS: The marijuana-harm IAT had good internal consistency, and scores did not vary as a function of biological sex, legal age status for recreational marijuana use, or college student status. Scores did vary as a function of lifetime and recent use such that lifetime and current abstainers had stronger marijuana-harm associations. Zero-inflated negative binomial regression models demonstrated that marijuana-harm IAT scores significantly predicted concurrent risk of CUD and use such that stronger marijuana-harm associations were associated with less use and risk of CUD. Results evaluating outcomes longitudinally found limited support for IAT scores predicting increases in use over time and no support for predicting changes in risk of CUD over time. CONCLUSIONS: Findings provide preliminary evidence that stronger marijuana-harm associations may act as a protective factor against marijuana use and risk of CUD.

Patterns of Young Adult Social Roles Transitions Across 24 Months and Subsequent Substance Use and Mental Health.

Young adults experience social role transitions across multiple life domains, and a deeper understanding of the ways in which these simultaneous transition experiences are associated with substance use and mental health will inform targeted interventions for this population. Data from the current study include24 repeated monthly assessments of young adults (N = 778; 56% female; age range 18 to 24 at baseline; 60% White, 18% Asian, 12% Multiracial, 5% Black or African American, 1% American Indian, 1% Pacific Islander, 3% Other, 9% Latinx) and outcomes 6 months later. Monthly assessments across 2 years were used to identify latent classes of frequency of social role transitions in four key domains (education, residential, employment, and romantic relationships) and associations between these classes and later outcomes. Three classes of social role transitions were identified: Infrequent Transitions (30.4%), Transitions except in Relationships (38.5%), and Frequent Transitions (31.1%). Compared to the Infrequent Transitions class, the other classes had greater typical drinking and hazardous alcohol use six months later; the Frequent Transitions class also had more hazardous cannabis use, depressive symptoms, and anxiety symptoms. Young adults experiencing frequent transitions across multiple domains appear to be at risk for substance use and mental health problems and may benefit from targeted intervention to address substance use and mental health issues.

Descriptive and Prospective Analysis of Young Adult Alcohol Use and Romantic Relationships: Disentangling between- and within-Person Associations Using Monthly Assessments.

BACKGROUND: Prior research on romantic relationships and alcohol use among young adults has not distinguished between differences in patterns of relationship status over extended periods of time and within-person changes in status that only occur for some individuals. OBJECTIVES: This study captured between-person differences in relationship patterns, assessed associations between relationship patterns and alcohol use, and examined within-person associations between alcohol use and relationship status changes. In addition, age and sex differences in between- and within-person associations were tested. METHODS: We used multilevel modeling of monthly data collected over one year on alcohol use and romantic relationship status from a Seattle area community sample of 620 young adults (ages 18-24). RESULTS: Participants were coded into six relationship pattern groups: (1) single-not-dating (16%), (2) stable-in-a-relationship (30%), (3) single-dating (10%), (4) ended-a-relationship (14%), (5) started-a-relationship (13%), and (6) ended-and-started-a-relationship (18%). Single-not-dating and stable-in-a-relationship groups reported the least drinking across the entire year; the single-dating, ended-a-relationship, and ended-and-started-a-relationship groups reported higher levels of drinking. Examining within-person changes in groups 3-6 revealed increases in drinking associated with months of dating among the single-dating group, months postbreakup among the ended-a-relationship group, and months of breaking up and starting a new relationship among the ended-and-started-a-relationship group. Few differences by age or sex were found for between- or within-person associations. CONCLUSIONS: The findings point to heterogeneity in patterns of relationship status over time, differences in relationship patterns associated with variations in drinking, and particular time points of elevated risk for young adults who experience changes in status.

Condom-Insistence Conflict in Women's Alcohol-Involved Sexual Encounters with a New Male Partner.

First-time sexual intercourse with a new male partner, relative to other sexual encounters, is associated with heightened risk to women for contracting sexually transmitted infections. Little is known, however, about women's condom-related decision-making processes during these first-time sexual encounters. In the present study, we surveyed a community sample of 179 women aged 18-30 about their alcohol consumption, desire to use a condom, perception of their partner's desire to use a condom, condom-insistence conflict, and condom-decision abdication and use during their most recent alcohol-involved first-time sexual encounter with a new partner. With structural equation modeling we tested a cognitive mediation model with various configurations of alcohol effects on abdication and condom use (direct, indirect, moderator). A moderated mediation model fit the data best. Women experienced elevated condom-insistence conflict when they wanted to use a condom and perceived their partner did not; conflict, in turn, was associated with higher likelihood of abdication and lower likelihood of condom use. Higher alcohol intoxication attenuated the associations of desire to use a condom, and perceived partner's desire to use a condom, with conflict. Results support an alcohol myopia-conflict inhibition-reduction model and emphasize the importance of sex education programs that teach young women not only about condom-related assertiveness and the effects of alcohol, but also prepare them to respond to experiences of conflict that arise during sexual encounters.

Longitudinal Change in Women's Sexual Victimization Experiences as a Function of Alcohol Consumption and Sexual Victimization History: A Latent Transition Analysis.

OBJECTIVE: Women's alcohol consumption and vulnerability to sexual victimization (SV) are linked, but findings regarding the nature and direction of the association are mixed. Some studies have found support for the self-medication hypothesis (i.e., victimized women drink more to alleviate SV-related distress); others have supported routine activity theory (i.e., drinking increases SV vulnerability). In this study, we aimed to clarify the interplay between women's prior SV, typical drinking, and SV experiences prospectively over one year. METHOD: Participants (N = 530) completed a baseline survey and weekly follow-up surveys across Months 3, 6, 9, and 12. RESULTS: Latent class analysis (LCA) suggested that women could be classified as victimized or non-victimized at each assessment month; 28% of participants were classified as victimized at one or more assessment months. Latent transition analysis (LTA) revealed that childhood sexual abuse and adult SV history each predicted greater likelihood of being victimized during the year. Typical drinking during a given assessment month was associated with (1) greater likelihood of victimized status at that assessment month and (2) greater likelihood of having transitioned into (or remained in) the victimized status since the previous assessment month. Furthermore, victimized status at a given assessment month predicted a higher quantity of subsequent drinking. CONCLUSION: These findings indicate a reciprocal relationship between typical drinking and SV, supporting both the self-medication hypothesis and routine activity theory, and suggesting that hazardous drinking levels may be one important target for both SV vulnerability reduction and interventions for women who have been sexually victimized.

Partner Type, Sexual Double Standard Endorsement, and Ambivalence Predict Abdication and Unprotected Sex Intentions in a Community Sample of Young Women.

In-the-moment ambivalence about having sex may influence sexual decisions but has rarely been examined. We investigated how ambivalence about sex might be related to intentions to abdicate sexual decisions to a male partner and to engage in unprotected sex in a community sample of young women. Predictors of abdication and unprotected sex intentions included partner type (new casual versus previous relationship), sexual double standard (SDS) endorsement, and two types of ambivalence. After completing a SDS endorsement measure, women (N = 360) projected themselves into a hypothetical sexual situation and completed dependent measures. In the new casual partner condition, SDS endorsement indirectly negatively predicted unprotected sex intentions through its associations with ambivalence and abdication. In both partner conditions SDS endorsement positively predicted abdication, which then positively predicted unprotected sex intentions. Ambivalence indirectly predicted unprotected sex intentions through its negative association with abdication intentions. Results suggest the importance of ambivalence for sexual decisions and the complexity of understanding the sexual decision making processes for women who endorse the SDS.

Influences of acute alcohol consumption, sexual precedence, and relationship motivation on women's relationship and sex appraisals and unprotected sex intentions.

Guided by the cognitive mediation model of sexual decision making (Norris, Masters, & Zawacki, 2004. Cognitive mediation of women's sexual decision making: The influence of alcohol, contextual factors, and background variables. Annual Review of Sex Research, 15, 258-296), we examined female social drinkers' (N = 162) in-the-moment risky sexual decision making by testing how individual differences (relationship motivation) and situational factors (alcohol consumption and sexual precedence conditions) influenced cognitive appraisals and sexual outcomes in a hypothetical sexual scenario. In a path model, acute intoxication, sexual precedence, and relationship motivation interactively predicted primary relationship appraisals and independently predicted primary sex appraisals. Primary appraisals predicted secondary appraisals related to relationship and unprotected sex, which predicted unprotected sex intentions. Sexual precedence directly increased unprotected sex intentions. Findings support the cognitive mediation model and suggest that sexual risk reduction interventions should address alcohol, relationship, sexual, and cognitive factors.

How Do Alcohol and Relationship Type Affect Women's Risk Judgment of Partners with Differing Risk Histories?

Understanding how women judge male partners' sexual risk is important to developing risk reduction programs. Applying a cognitive mediation model of sexual decision making, our study investigated effects of alcohol consumption (control, low dose, high dose) and relationship type (disrupted vs. new) on women's risk judgments of a male sexual partner in three sexual risk conditions (low, unknown, high). After random assignment to an experimental condition, 328 participants projected themselves into a story depicting a sexual interaction. The story was paused to assess primary appraisals of sexual and relationship potential and secondary appraisals of pleasure, health, and relationship concerns, followed by sexual risk judgments. In all risk conditions, alcohol and disrupted relationship increased sexual potential whereas disrupted relationship increased relationship potential in the low- and high-risk conditions. In the unknown-risk condition, women in the no-alcohol, new relationship condition had the lowest primary sexual appraisals. In all conditions, sexual appraisals predicted all secondary appraisals, but primary relationship appraisals predicted only secondary relationship appraisals. Secondary health appraisals led to increased risk judgments whereas relationship appraisals predicted lower risk judgments. Possible intervention points include helping women to re-evaluate their safety beliefs about past partners, as well as to develop behavioral strategies for decreasing hazardous drinking.

Patterns of alcohol use and expectancies predict sexual risk taking among non-problem drinking women.

OBJECTIVE: Although alcohol consumption and sexual risk taking are associated, not everyone who drinks alcohol engages in risky sexual behavior. The purposes of the present study were to identify patterns of alcohol use behaviors and alcohol expectancies among women who are non-problem drinkers and to examine how these patterns are associated with indices of sexual risk. METHOD: Data from 758 non-problem drinking women who have sex with men and were not in committed relationships were analyzed using latent profile analysis to determine patterns of alcohol use and alcohol-related expectancies. RESULTS: Of the four patterns observed, three classes had similar alcohol-related expectancies but differed with respect to drinking behavior (moderate drinking, regular heavy episodes, and frequent heavy episodes), and the fourth class consisted of moderate drinkers with low expectancies (low expectancies). Results revealed that those in the frequent heavy episodes class had the greatest number of sexual partners in the past year and drank the most alcohol before having sex compared with the other women. Both the regular and frequent heavy episodes classes reported greater likelihood of having unprotected sex in the future, more positive beliefs about casual sex, and greater subjective intoxication before having sex than women in the moderate drinking or low expectancies classes. Women in the low expectancies class reported less positive beliefs about condoms than those in the moderate drinking and regular heavy episodes classes. CONCLUSIONS: Results suggest that different patterns of expectancies and drinking behaviors are associated with different indices of sexual risk taking and highlight the importance of individually tailored programs for prevention of sexually transmitted infections.