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Published in final edited form as: Emerg Adulthood. 2023 Jan 7;11(3):698–703. doi: 10.1177/21676968221149079

Alcohol and Cannabis Use Within Emerging Adults’ Committed Romantic Relationships: Associations with Relationship Functioning and Quality of Life

Joan S Tucker 1, Wendy M Troxel 1, Anthony Rodriguez 1, Rachana Seelam 1, Elizabeth J D’Amico 1
PMCID: PMC12381653  NIHMSID: NIHMS2089582  PMID: 40880904

Abstract

This study examines alcohol and cannabis use within emerging adults’ committed romantic relationships and its association with relationship functioning (satisfaction, stability) and well-being (life satisfaction, anxiety, depression). Participants completed surveys in 2020 and 2021 (N=1,214). Latent profile analysis identified four classes of couples’ substance use patterns: concordant (similar) infrequent use (81.9% of sample), near-daily partner cannabis use (6.0%), near-daily respondent cannabis use (6.5%), and concordant moderate alcohol and near-daily cannabis use (5.5%). Cross-sectionally, respondents who reported concordant infrequent use had significantly higher well-being than those who reported concordant heavier use; there were no class differences involving the two types of discordant couples. In general, class membership did not predict changes in well-being or relationship functioning over a one-year period. Results provide new insights into patterns of both alcohol and cannabis use within committed romantic relationships of emerging adults that may have implications for well-being during this developmental period.

Keywords: alcohol, cannabis, relationship functioning, quality of life, emerging adults

Introduction

Heavy alcohol use and cannabis use tend to peak during emerging adulthood (Schulenberg et al., 2021) and have been associated with lower well-being and worse functioning (D’Amico et al., 2022; Tucker et al., 2021). For emerging adults in a committed romantic relationship, their well-being may not only be affected by their own substance use, but also their partner’s substance use (Muyingo et al., 2020; Rodriguez et al., 2014). For example, studies tend to find better relationship functioning among partners with more similar alcohol and cannabis use (Crane et al., 2007; Testa et al., 2018; Torvik et al., 2015). One common explanation is that shared substance use (or non-use) is reflective of the partner’s shared values, interests, and activities (Fischer & Wiersma, 2012). For example, partners with similar use may spend more leisure time together, resulting in better relationship functioning, compared to couples in which one partner engages in heavy use and the other does not. Consistent with this idea, diary studies show that drinking or using cannabis together appears to promote intimacy in couples where both partners use the substance regularly (Testa et al., 2019a. 2019b).

Studies have primarily focused on either alcohol or (to a lesser degree) cannabis use, rarely examining both substances. One of the few studies assessing both alcohol and cannabis use found that discordant (but not concordant) heavy drinking newlyweds were more likely to divorce than non-heavy drinking newlyweds, whereas risk of divorce associated with concordant and discordant cannabis use weakened to non-significance when controlling for alcohol and tobacco use (Leonard et al., 2014). These results indicate a need for more research assessing both alcohol and cannabis use to gain a clearer understanding of their relative effects on relationship functioning, including studies of younger unmarried couples. Further, Leonard et al. (2014) examined effects of alcohol and cannabis use separately, controlling for use of the other, rather than explicitly examining how patterns of alcohol and cannabis co-use within couples are associated with relationship functioning. As such, virtually nothing is currently known about how relationship functioning may differ for couples who are discordant in their use of both substances, only one substance, or neither substance.

The present study significantly extends the existing literature by addressing three aims using data from a large and racially/ethnically diverse cohort of emerging adults. First, it uses latent profile analysis to identify patterns of past month alcohol and cannabis use frequency within committed romantic relationships of emerging adults. Second, it compares these relationship classes on two important and interrelated domains of functioning expected to be affected by a couple’s pattern of substance use: current relationship functioning and respondent well-being (i.e., life satisfaction, anxiety, and depression). Finally, it uses longitudinal data to examine whether these relationship classes differ in terms of changes in relationship stability, relationship functioning, and respondent well-being over a one-year period.

Method

Participants and Procedures

Participants were from two cohorts of 6th and 7th grade students enrolled in 2008 (wave 1: mean age 11.5) recruited from 16 middle schools across three school districts in Southern California as part of an evaluation of a prevention program (CHOICE) that took place in 2008–2009 (D’Amico et al., 2012). Participants completed waves 1–5 (wave 1: Fall 2008; wave 2: Spring 2009; wave 3: Fall 2009; wave 4: Spring 2010; wave 5: Spring 2011) through paper-pencil surveys during PE class. Following wave 5, participants transitioned to over 200 high schools, were re-contacted and re-consented to complete annual web-based surveys. Wave-to-wave retention rates average 85% across all 13 waves, and 90% from age 18 forward (waves 8–13). Participants who do not complete a particular survey do not “drop out” of the study; rather, we field the full sample at every wave so that all participants can participate in each individual survey. Current analyses use data from waves 12 and 13 (collected in 2019–2020 and 2020–2021, heretofore referred to as T1 and T2, respectively). At wave 12, 88.7% of the sample resided in California, where cannabis was legalized for recreational use in 2016. Fifty-two percent of the T1 sample was selected out as they were not in a committed relationship, resulting in an analytic sample of 1,214 at T1. Committed relationship was defined as being married (5.75% of analytic sample at T1), engaged (5.09%), living with their partner (0.90%), or dating their partner exclusively (88.25%). There were no significant differences between individuals who were and were not selected out based on relationship status on covariates or substance use variables with one exception: males were more likely than females to select out based on their report of not being in a committed relationship. At T1, the analytic sample was age 22.5 on average, 37% male, and racially/ethnically diverse (48% Hispanic, 22% non-Hispanic White, 23% Asian, 2% Black, and 4% multiracial/other). All study materials and procedures were approved by the study’s IRB.

Measures

Covariates.

Analyses comparing emergent classes on outcomes controlled for demographic characteristics that may be associated with substance use and outcomes of interest: sex assigned at birth (male, female), sexual orientation (heterosexual/straight vs. lesbian, gay, bisexual, questioning, or asexual), mother’s education (as a proxy for socioeconomic status; college graduate vs. not), and race/ethnicity. For race/ethnicity, participants were classified as non-Hispanic White (reference group), non-Hispanic Black, Hispanic, Asian, and Multi-ethnic/Other. We also controlled for CHOICE intervention status, although the program was conducted over 12 years ago and did not show intervention effects beyond one year.

Substance use by respondent and partner at T1.

Respondents reported on number of days of alcohol and cannabis use in the past month for themselves and their partner (0–30 days). These four items were used in a latent profile analysis to identify substance use relationship types.

Relationship characteristics at T1 and T2.

Relationship quality was assessed with the 7-item Quality of Marriage Index (Norton, 1983; α=.83). Items are rated on a scale from 1=not much to 5=very much, reverse scored (as appropriate), and averaged. We also assessed relationship stability between wave 12 and 13. Respondents were assumed to be in the same relationship over the one-year period between waves if, at wave 13, they reported being married, engaged, or had dated their current partner for more than a year.

Well-being at T1 and T2.

We assessed overall life satisfaction with the 5-item Satisfaction with Life Scale (Diener et al., 1985; α=0.92), rated from 1=strongly disagree to 7=strongly agree and summed (range=5–35, mean=23.10, SD=7.64). Two other measures assessed mental health symptoms in the past two weeks on a scale from 0=not at all to 3=nearly every day. The Patient Health Questionnaire-8 item (PHQ-8; Kroenke et al., 2009; α=0.91) assessed depression (range=0–24, mean=5.35, SD=.38) and the Generalized Anxiety Disorder-7 item (GAD-7; Spitzer et al., 2006; α=0.95) assessed anxiety (range=0–21, mean=5.12, SD=5.46).

Analytic Plan

We used latent profile analysis (LPA) to extract heterogeneity in couples’ substance use patterns. LPA identifies heterogeneity within a sample (or groups) and classifies individuals based on patterns of class-specific means. We used four items (i.e., frequency of past month alcohol and cannabis use by respondent and partner) in our LPA. Models were estimated in Mplus v8.1 using the default method with equal variances across classes assumed. We fit models ranging from one to five classes and examined fit statistics to determine if adding an additional class improved model fit. To assess model fit, we used decreases in the negative two log likelihood (−2LL), Akaike Information Criteria (AIC), Bayesian Information Criteria (BIC), and the sample size adjusted Bayesian Information Criteria (aBIC). Further, we used non-significant Vuong-Lo-Mendell-Rubin Likelihood Ratio Test (VLMRT) and the Lo-Mendell-Rubin adjusted likelihood ratio test (LMRT) to indicate that a k–1 class solution (e.g., 4 vs 3 class) is a better fit to the data. We then used generalized linear models to compare the extracted classes on relationship functioning and well-being, controlling for background covariates.

Results

Class Enumeration

Model fitting results for the LPA are shown in Table 1. Across information criteria indexes values decreased with each sequential solution; however, VLRT and LMRT values were not significant for the 5-class solution, indicating that the 4-class solution may fit the data best. Classes were named according to type of substance use reported in that class. Emergent classes are presented in Figure 1. The “Concordant Infrequent Use” class represented 81.9% (n=994) of the sample, reflecting relationships characterized by less than 5 days of alcohol use and little to no cannabis use by both partners. Two other classes emerged reflecting “Near-Daily Respondent Cannabis Use” (6.5%; n=79) and “Near-Daily Partner Cannabis Use” (6.0%; n=74), with otherwise low levels of alcohol and cannabis use in the relationship. Finally, 5.5% (n=67) of the sample was represented by the Concordant Moderate Alcohol and Near-Daily Cannabis Use class, reflecting relationships in which both partners engaged in, on average, 10 days per month of alcohol use and > 25 days per month of cannabis use.

Table 1.

Model Fit Indices for Substance Use Latent Profile Analysis

Number of classes −2 LL AIC BIC aBIC Entropy VMLRT p LRT p
1 class 32396.90 32412.90 32453.72 32428.30
2 class 30261.14 30287.14 30353.47 30312.17 0.991 2135.76 <.001 2077.26 <.001
3 class 29538.05 29574.05 29665.88 29608.71 0.986 723.09 .016 703.29 .014
4 class 28662.44 28708.44 28825.78 28752.73 0.992 869.60 <.001 845.78 <.001
5 class 28166.26 28222.26 28365.11 28276.17 0.990 496.19 .377 482.59 .370
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Figure 1.

Figure 1.

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Days of Past Month Alcohol and Cannabis Use by Respondent (R) and Their Partners (P) at T1 by Class Membership

Class 1: Near-daily partner cannabis use (n=74; 6.0%).

Alcohol-R: M=5.20 (95% CI: 3.93, 6.47), SD=5.56; Alcohol-P: M=6.93 (95% CI: 5.59, 8.27), SD=5.83;

Cannabis-R: M=5.65 (95% CI: 4.30, 7.00), SD=5.93; Cannabis-P: M=23.16 (95% CI: 21.74, 24.58), SD=6.62

Class 2: Near-daily respondent cannabis use (n=79; 6.5%).

Alcohol-R: M=7.89 (95% CI: 6.38, 9.40), SD=6.84; Alcohol-P: M=5.04 (95% CI: 3.48, 6.60), SD=7.08;

Cannabis-R: M=24.81 (95% CI: 23.59, 26.03), SD=5.52; Cannabis-P: M=3.86 (95% CI: 2.89, 4.83), SD=4.38

Class 3: Concordant infrequent use (n=994; 81.9%).

Alcohol-R: M=3.76 (95% CI: 3.44, 4.08), SD=5.16; Alcohol-P: M=3.48 (95% CI: 3.17, 3.79), SD=4.98;

Cannabis-R: M=0.89 (95% CI: 0.75, 1.03), SD = 2.20; Cannabis-P: M=0.80 (95% CI: 0.67, 0.93), SD=2.13

Class 4: Concordant moderate alcohol and near-daily cannabis use (n=67; 5.5%).

Alcohol-R: M=9.22 (95% CI: 7.26, 11.18), SD=8.20; Alcohol-P: M=10.37 (95% CI: 8.20, 12.54), SD=9.08;

Cannabis-R: M=26.99 (95% CI: 25.92, 28.06), SD=4.45; Cannabis-P: M=27.79 (95% CI: 26.87, 28.71), SD=3.82

Comparisons on Relationship Functioning and Well-Being

Cross-sectional analyses (Table 2, top) indicated no significant class differences on relationship satisfaction. For well-being, the Concordant Infrequent Use class reported significantly higher life satisfaction, lower anxiety, and lower depression compared to the Concordant Moderate Alcohol and Near-Daily Cannabis Use class. There were no other significant differences. In the longitudinal analysis, 76% of the sample was classified as being in the same relationship at T1 and T2. Logistic regression analysis predicting relationship stability at T2 by relationship alcohol and cannabis use class membership at T1 (reference group: Class 3) found no significant class differences. Other longitudinal analyses (Table 2, bottom) indicated no significant class differences on change in relationship satisfaction for respondents who remained in the same relationship at both time points. For anxiety, there was a non-significant increase in anxiety from T1 to T2 for the Near-Daily Respondent Cannabis Use class and a non-significant decrease in anxiety for the Concordant Moderate Alcohol and Near-Daily Cannabis Use class. This directional difference between classes was statistically significant. No other class differences in well-being were found.

Table 2.

Class Differences at T1 (Cross-sectional; Full Sample) and in Change from T1-T2 (Longitudinal; Respondents Who Remained in Same Relationship)

Class
1
Near-daily partner cannabis use		 2
Near-daily respondent cannabis use		 3
Concordant infrequent use		 4
Concordant moderate alcohol and near-daily cannabis use		 Significant pairwise comparisons
M (SD) M (SD) M (SD) M (SD)
T1
Relationship satisfaction 4.34 (0.59) 4.27 (0.77) 4.38 (0.66) 4.34 (0.62)
Life satisfaction 22.04 (7.84) 21.44 (7.88) 23.46 (7.57) 20.88 (7.70) 3>4
Depression 5.80 (5.19) 5.85 (5.51) 5.14 (5.31) 7.46 (6.06) 3<4
Anxiety 5.66 (5.09) 5.47 (5.38) 4.89 (5.38) 7.51 (6.58) 3<4
N = 74 79 994 67
Change from T1-T2
Relationship satisfaction 0.02 (0.57) 0.10 (0.72) −0.02 (0.65) −0.21 (0.59)
Life satisfaction 0.37 (5.53) 0.74 (5.87) −0.20 (6.25) 1.47 (6.91)
Depression 0.25 (3.65) 0.48 (5.45) 0.06 (4.69) −1.21 (5.98)
Anxiety 0.68 (5.16) 1.13 (5.41) 0.03 (4.55) −0.84 (6.52) 2 vs. 4
N = 57 46 652 38
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Note. Due to missing data Ns range from 1,208–1,210 across cross-sectional models and 789–791 across longitudinal models. Table reports unadjusted differences. Significance tests are from analyses that control for covariates (sex at birth, sexual orientation, race/ethnicity, mother’s education, CHOICE condition). Change scores were computed as T2 minus T1. Positive change scores indicate higher scores at T2 and negative scores indicate lower scores at T2.

Discussion

Despite widespread use of alcohol and cannabis among emerging adults (Schulenberg et al., 2021), this study shows that infrequent use by both partners is the normative pattern among those in committed romantic relationships. Further, a key finding from this study is that the remaining three classes were all characterized by near-daily cannabis use – either by the respondent, the partner, or both – whereas alcohol use never exceeded moderate frequency. This may be at least partly due to declining perceptions in this age group of the harmfulness of regular cannabis use (Schulenberg et al., 2021), combined with legal access to recreational cannabis in this largely California sample. Results highlight the importance of simultaneously examining alcohol and cannabis use within the same study to gain a more complete understanding of heterogeneity in patterns of use among emerging adults and their romantic partners.

Prior studies have tended to find better relationship functioning among partners with more similar substance use (Crane et al., 2007; Testa et al., 2018; Torvik et al., 2015). However, we found similar levels of concurrent relationship satisfaction and rates of stability over time among couples in which both partners used infrequently, couples who were concordant in their use, and couples who were discordant in that one partner engaged in near-daily cannabis use and the other did not. This lack of differences on relationship functioning may be due to partner classes largely being defined by the use of cannabis rather than alcohol (e.g., the former may be relatively less impairing in the context of a relationship). This interpretation would be consistent with results from the only other study examining both substances whereby discordant drinking was more predictive of relationship functioning than cannabis use (Leonard et al., 2014). Given the dearth of studies examining couples’ use of multiple substances, research is needed before definitive conclusions can be drawn about similarities and differences in distinct patterns of co-use in terms of relationship functioning and stability. This is particularly important as more than one-third of the US population lives in states that have passed laws allowing retail sales of cannabis for adults (aged 21+ years) for nonmedical purposes, and cannabis use is much more normalized than drinking (Schulenberg et al., 2021).

Regarding class differences on well-being, emerging adults in concordant relationships where both partners engaged in near-daily cannabis use and moderate drinking initially reported greater anxiety (as well as depression and lower life satisfaction) compared to those in relationships characterized by infrequent use. However, of note, over time this concordant group trended towards a decrease in anxiety, whereas emerging adults in relationships where only the respondent engaged in near-daily cannabis use trended towards an increase in anxiety. Findings are complex, but raise interesting hypotheses for future longitudinal studies. For example, it may be that emerging adults with poorer mental health are at higher risk for alcohol and cannabis use, and thus tend to seek partners with similar patterns of regular use; however, over time, this pattern of concordant regular use is less of a risk factor for increased mental health problems than being in a relationship where your own substance use is much heavier than that of your partner.

Two study limitations are worth noting. First, it was beyond the scope of the study to recruit partners for these surveys; thus, relationship classes are based solely on data provided by the respondent. However, it is also the case that an individual’s perception of their partner’s use may be as important (or even more important) than actual use in terms of the outcomes examined in this study. Second, results are based on emerging adults predominantly residing in California, where recreational cannabis use is legal for adults age 21 and older; thus, results may not generalize to other age groups or emerging adults in other geographic locations. In conclusion, findings provide new insights into patterns of both alcohol and cannabis use within the romantic relationships of emerging adults. That three of the classes, or 18% of the sample, were characterized by near daily cannabis use by one or both partners indicate how frequent cannabis use is common among this age group. For example, recent data from Monitoring the Future indicate that 11% of young adults age 23–24 report past month daily cannabis use (Schulenberg et al., 2021). Yet emerging adults still report numerous problems from use (D’Amico et al., 2022), including higher rates of cannabis use disorder (CUD) than other age groups (Hasin et al., 2015), but are the least likely to obtain treatment for CUD (Wu et al., 2017). Thus, future work must continue to examine both alcohol and cannabis use among couples during this important developmental period, particularly longitudinal research to understand how couples’ patterns of use affect their trajectories of individual well-being, relationship stability, and related functional outcomes during and beyond the transition to young adulthood.

Acknowledgments

This research was supported by grants from the National Institute of Alcohol Abuse and Alcoholism (R01AA016577, R01AA020883, R01AA025848; PI: D’Amico). We would like to thank Jen Parker and the RAND Survey Research Group for overseeing the data collection.

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