Among 480 Spanish undergraduates, 46% used multiple substances, with cannabis-inclusive patterns being most common, and polydrug use was strongly correlated with the substance use of close family and friends.
Read this if you're curious about how your social environment influences substance use patterns.
46% of students used 2+ substances; cannabis patterns most common
What the researchers found
Researchers surveyed 480 Spanish health and sports science undergraduates about their substance use and that of their closest reference persons (parents, siblings, best friend, and partner). Nearly half (46%) reported using two or more substances.
The most common polydrug pattern included cannabis plus alcohol and/or tobacco (50.7% of polydrug users). A smaller group used cannabis plus alcohol, tobacco, and at least one other illegal drug (16.7%). The simplest pattern was alcohol plus tobacco only (29.4%).
The strongest finding was the social correlation: the more a person's close reference persons used multiple substances, the more likely the participant was to be a polydrug user. This held across parents, siblings, best friends, and partners.
Why it matters
Prevention programs often focus on individual decision-making, but this study highlights the powerful influence of social environment. Polydrug use patterns mirror those of close family and friends, suggesting that family and peer-focused interventions may be more effective.
The numbers in context
480 students surveyed. 46% reported polydrug use. Pattern A (alcohol+tobacco): 29.4%. Pattern B (cannabis+alcohol/tobacco): 50.7%. Pattern C (cannabis+alcohol+tobacco+other illegal): 16.7%. Strong correlation between participant and reference person polydrug use.
How the study worked
Cross-sectional survey of 480 Spanish undergraduates (43.7% female, ages 18-36) studying health and sports science. Self-report questionnaire assessed substance use of participants and their closest reference persons. Polydrug patterns classified using European Observatory categories.
What this study cannot tell us
Cross-sectional design cannot determine causal direction. Spanish health/sports science students may not represent all college students. Self-reported data about others' substance use may be inaccurate. Social environment correlations could reflect shared genetics or neighborhood effects.
How to read the evidence
Cross-sectional survey from a single university program. Descriptive findings with social correlation analysis.
When this study was published
Published in 2015 from Spanish university data.
The bigger picture
Substance use does not happen in a vacuum. The social transmission of drug use patterns from family and peers to young adults is one of the most consistent findings in addiction research. Programs that address family and social network dynamics may be more effective than those targeting individuals alone.
Questions still open
- Which reference person has the strongest influence on polydrug patterns? Would family-based interventions reduce polydrug use among college students? Do these social patterns persist after college?
Common questions
How common is polydrug use among college students?
Does family substance use predict student substance use?
Read the original research
Polydrug use and its relationship with the familiar and social context amongst young college students.
Adicciones, 27(3), 205-13
Citation
Hernández-Serrano, Olga; Font-Mayolas, Sílvia; Gras, Maria Eugènia. (2015). Polydrug use and its relationship with the familiar and social context amongst young college students.. Adicciones, 27(3), 205-13.
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