Earlier First Use of Any Substance Predicted More Polysubstance Use Among 22,000 Mexican University Students | Research

The takeaway

Among 22,224 Mexican university students, earlier initiation of alcohol, tobacco, or marijuana was significantly associated with current use of the same substance and with polysubstance use, with males far more likely to use marijuana.

Parents and educators interested in age of first substance use as a risk factor.

Earlier initiation of any substance predicted current polysubstance use among 22,224 students

What the researchers found

In this large cross-sectional survey of first-year university students in Mexico City, most students initiated alcohol at age 15, tobacco at 15-16, and marijuana at 16-17.

Earlier initiation of alcohol and tobacco was associated with continued current use of those substances. Gender differences in alcohol and tobacco were small, but males were significantly more likely than females to use marijuana and to be polysubstance users.

Family substance use was associated with earlier onset across substances. Most importantly, there was a significant association between the earliest age of initiating any of the three substances and current polysubstance use, suggesting that early substance exposure, regardless of the specific substance, increases vulnerability to broader substance use patterns.

Why it matters

Mexico has unique cultural factors around substance use (legal drinking age, attitudes toward marijuana, family dynamics) that influence initiation patterns. This large study demonstrates that the age-of-onset principle, earlier use predicting more problematic use patterns, holds across cultural contexts.

The numbers in context

22,224 students aged 17-20. Most common initiation ages: alcohol 15, tobacco 15-16, marijuana 16-17. Males significantly more likely to use marijuana and be polysubstance users. Family substance use predicted earlier onset. Earlier age of any substance initiation predicted polysubstance use.

How the study worked

Cross-sectional survey of 22,224 first-year university students in Mexico City in 2012. Chi-square tests and logistic regression examined associations between gender, age of onset, order of onset, family substance use, and current polysubstance use.

What this study cannot tell us

Cross-sectional design captures only one time point. University students are not representative of all Mexican young people. Self-report may underestimate substance use. The study cannot determine whether early onset causes polysubstance use or whether both share common risk factors.

How to read the evidence

Moderate evidence from a very large cross-sectional survey, limited by self-report and cross-sectional design.

When this study was published

Published in 2017, using 2012 survey data from Mexico City.

The bigger picture

Prevention science consistently identifies early substance initiation as a risk factor for later problems. This Mexican study confirms the pattern in a non-U.S. context and adds that family substance use is a key predictor of early onset, suggesting that family-based prevention programs could be particularly effective.

Questions still open

Would delaying first substance use reduce polysubstance use later? Are family-based prevention programs more effective in Mexican cultural contexts? How do gender differences in marijuana use map onto Mexican cultural norms?

Common questions

Does using substances earlier make you more likely to develop problems?

This study found that earlier initiation of alcohol, tobacco, or marijuana was associated with both continued use and polysubstance use. While the cross-sectional design cannot prove causation, the finding is consistent with a large body of research linking early substance exposure to greater later risk.

Are there gender differences in marijuana use among Mexican youth?

Yes. Males were significantly more likely than females to use marijuana and to be polysubstance users. Gender differences for alcohol and tobacco were much smaller, suggesting cultural factors specifically discourage female marijuana use in this population.

Read the original research

Age of Onset, Current Use of Alcohol, Tobacco or Marijuana and Current Polysubstance Use Among Male and Female Mexican Students.

Alcohol and alcoholism (Oxford, Oxfordshire), 52(5), 564-571

View on PubMed ↗Publisher’s paper ↗

Citation

Strunin, Lee; Díaz-Martínez, Alejandro; Díaz-Martínez, L Rosa; Heeren, Timothy; Chen, Clara; Winter, Michael; Kuranz, Seth; Hernández-Ávila, Carlos A; Fernández-Varela, Héctor; Solís-Torres, Cuauhtémoc. (2017). Age of Onset, Current Use of Alcohol, Tobacco or Marijuana and Current Polysubstance Use Among Male and Female Mexican Students.. Alcohol and alcoholism (Oxford, Oxfordshire), 52(5), 564-571. https://doi.org/10.1093/alcalc/agx027