In a college residence hall network, peer marijuana and alcohol use were significantly associated with individual use, while peer exercise levels were not, suggesting substance use may be more socially contagious.
Read this if you want to understand how friend groups influence marijuana use on college campuses.
Peer marijuana and alcohol use predicted individual use; peer exercise did not
What the researchers found
Researchers mapped the social network of 129 college students living in one residence hall and examined whether peers' substance use and exercise behaviors were associated with individual behavior. Students nominated an average of 4.1 hall members as important to them, with 53.9% of connections being reciprocal.
Six distinct social clusters emerged within the hall, and these clusters differed significantly on substance use and exercise behaviors. After controlling for demographics, peer alcohol consumption and peer marijuana use were both significantly associated with individual substance use. However, peers' exercise levels showed no association with individual exercise.
The asymmetry between substance use and exercise as socially influenced behaviors suggests that peer-based interventions may be more effective for targeting substance use than physical activity.
Why it matters
Understanding that marijuana use clusters within peer networks helps explain how use spreads among college students and suggests that peer-based prevention programs could be effective targets for intervention.
The numbers in context
129 students, 6 social clusters identified. Average of 4.1 nominated peers. 53.9% reciprocal ties. Peer marijuana and alcohol use were significantly associated with individual use. Peer exercise was not associated with individual exercise.
How the study worked
Cross-sectional social network study of 129 undergraduates (51.9% female) in one residence hall. Web-based survey assessed substance use, exercise, and social connections. Community detection cluster analysis identified peer groupings. Network autocorrelation modeling examined associations between peer and participant behaviors.
What this study cannot tell us
Cross-sectional design cannot determine whether peers influenced each other or whether similar individuals selected each other as friends (selection vs. influence). Limited to one residence hall at one university. Small sample size. Self-reported substance use may be subject to bias.
How to read the evidence
Social network analysis with appropriate statistical methods, but cross-sectional design at a single residence hall limits causal conclusions.
When this study was published
Published in 2014.
The bigger picture
The finding that substance use is more socially contagious than health-promoting behaviors like exercise has practical implications for campus prevention programs. It suggests that peer influence interventions might be particularly well suited for substance use reduction but may need different approaches for promoting healthy behaviors.
Questions still open
- Does changing a few key individuals' behavior in a network reduce overall marijuana use? Would longitudinal tracking distinguish peer influence from friend selection? Do these patterns hold in non-residential college settings?
Common questions
Do your friends' marijuana use predict your own?
Is substance use more socially influenced than exercise?
Read the original research
Peer associations for substance use and exercise in a college student social network.
Health psychology : official journal of the Division of Health Psychology, American Psychological Association, 33(10), 1134-42
Citation
Barnett, Nancy P; Ott, Miles Q; Rogers, Michelle L; Loxley, Michelle; Linkletter, Crystal; Clark, Melissa A. (2014). Peer associations for substance use and exercise in a college student social network.. Health psychology : official journal of the Division of Health Psychology, American Psychological Association, 33(10), 1134-42. https://doi.org/10.1037/a0034687
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