As cannabis becomes more widely accepted across the US, researchers are beginning to explore its effects on relationships, especially in combination with alcohol.
A recent study, “Dyadic cannabis use, alcohol use, and relationship satisfaction: A daily diary study,” published in Drug and Alcohol Dependence, reveals the ways cannabis and alcohol use patterns among couples can affect a couple’s well-being.
Complex Connection Between Substance Use and Relationship Health
Historically, research showed that moderate alcohol consumption can promote positive social interactions and even reduce stress, but heavy drinking often leads to dissatisfaction and conflicts. This new study examines how cannabis, mainly when used with alcohol, affects relationship quality.
“Literature on alcohol use and specifically how it manifests its effects among couples is quite established,” explained study author Margy Yumeng Chen, a PhD student at the University of Colorado Boulder. “but cannabis research needs to catch up with that and consider how those previous findings could change once individuals start using cannabis too.”
Daily Diaries of Cannabis and Alcohol Use
To capture day-to-day variations in substance use and relationship fulfillment, researchers use a unique dyadic diary method. Both partners in 33 couplings, most of whom are identified as heterosexual, recorded their cannabis and alcohol use and partnership happiness over 14 days. This method allows researchers to gather detailed data on how partners’ individual and shared use of these substances influences their relationship dynamics.
Chen noted, “I was also really interested in doing a daily diary study, it gives you very rich and extensive data compared to most cross-sectional design.”
Concordant vs. Discordant Substance Use Patterns
The study divided couples into “concordant” or “discordant” groups based on cannabis use patterns. Concordant couples use cannabis together or avoid it entirely, while discordant couples have different habits, with one partner using cannabis more frequently or exclusively.
Couples also completed a baseline survey capturing demographics, mental health indicators, and initial relationship satisfaction. The findings were surprising. For individuals with heavy cannabis use, the combination of cannabis and alcohol within a single day correlated with a decrease in next-day contentment.
However, alcohol use alone boosted satisfaction for both partners in heavy use cases. “I don’t know exactly how to explain this finding, but there are many previous studies that have shown co-use is often more problematic and associated with more negative consequences compared to using one substance alone,” Chen observed.
Light Cannabis Use Tells a Different Story
Interestingly, the study found no significant changes in relational happiness for light cannabis users, regardless of whether they use alcohol or cannabis alone or in combination. This finding suggests the frequency and intensity of cannabis use may play a key role in how substance use affects relationships.
“The main takeaway for the average reader is that substance use within couples isn’t just about personal choices—it affects daily relationship dynamics as well,” Chen said. “These findings encourage couples to consider how specific substance use patterns may impact their daily interactions and overall relationship health.”
Limitations of the Study
While the study offers valuable insights, Chen acknowledges its limitations. The sample consisted mainly of white participants between 30 and 40 in committed, long-term relationships. This demographic may limit the applicability of the findings to couples in different life stages, racial backgrounds, or relationship dynamics.
Additionally, most couples had discordant cannabis use patterns, meaning the study lacks sufficient variance to examine concordant couples.
“While daily patterns give insights into short-term effects, these findings don’t necessarily predict long-term outcomes,” Chen noted.
Prospects for Future Research
With more research, couples might gain insights into managing substance use to nurture fulfillment among couples, particularly as cannabis use becomes more common. As the study highlights, thoughtful consideration of substance habits could be a step toward stronger, more harmonious relationships.
“I hope it helps people understand that, just as with other shared activities, it’s not just what you do but how you do it together that can strengthen or harm a relationship,” Chen states.
