Cohabitation, Marijuana Use, and Heavy Alcohol Use in Young Adulthood

ABSTRACT

Background: Research on the association between cohabitation and substance use has been inconsistent, with some studies indicating an elevated risk among cohabiters and others finding either no difference in risk or a reduced risk of substance use. However, studies of this association have not utilized a causal modeling empirical framework. Objectives: The purpose of this research was to assess whether cohabitation has a causal effect on two forms of substance use among young adults: marijuana and heavy alcohol use. Methods: Three waves of data from the National Survey of Youth and Religion (n = 2,202; 2002–2008), a representative sample of young adults in the United States, and an augmented inverse probability weighting (AIPW) model designed for multivalued treatment effects estimation, were used to assess the association between cohabitation and substance use. Results: The findings indicated that cohabitation was associated with more frequent marijuana use only among females. Much of the effect of cohabitation, though, was due to previous factors, including substance use, that affected whether young adults cohabit or not. Moreover, there was no evidence that cohabitation had a causal impact on heavy alcohol use. Conclusions/Importance: There is little evidence that cohabitation has a causal impact on substance use in general. However, among young women, those who cohabited reported higher levels of marijuana use than those who remained single. Future research should address why this group is at particular risk of substance use.

KEYWORDS:

• Marijuana use
• heavy alcohol use
• cohabitation
• matching estimators
• NSYR

Acknowledgments

I appreciate the advice provided by Mikaela Dufur, Spencer James, Kevin Shafer, and Steve Bahr. The data used in this study are from the National Survey of Youth and Religion (NSYR; Christian Smith, PI) and were made available through the Association of Religion Data Archives (ARDA) at Penn State University (Roger Finke, PI). Steve Vaisey, Kyle Longest, and Chris Smith kindly shared with me several variables from the NSYR that were not available in the public use files. No direct support was received from the granting agencies that sponsored the NSYR. The author was not financially supported for this research by any organization. All uses of the data, analytic decisions, and interpretations of results are the sole responsibility of the author.

Declaration of Interest

The author reports no conflict of interest. The author alone is responsible for the content and writing of the article.