Psychosocial risk for substance use in 80,000 Mexican undergraduates: mental health and academic strain.

Introduction: In Mexico, evidence on psychosocial risk for substance use among university students is often derived from small or faculty-specific samples, limiting institutional-level comparisons across academic disciplines and sex. University-wide estimates using standardized multi-domain screening tools remain scarce. Methods: We conducted a university-wide cross-sectional study of 80,077 undergraduate students from the Autonomous University of Nuevo León (Northern Mexico). Participants completed the validated Spanish POSIT instrument, which assesses seven psychosocial domains. Psychosocial risk was operationalized as exceeding the POSIT overall risk cut-off (and domain-specific cut-offs where applicable). Group comparisons of continuous POSIT scores were performed using Results: Mean age was 21.0 years (SD = 2.9), and 51% were women. The mean POSIT total score was 13.0 (SD = 9.0), and 15.2% of students exceeded the overall risk cut-off. Domain-level risk was highest for Educative Level (61.2%) and Mental Health (49.7%), followed by Family and Peer Relationships (~40%). Women showed higher burden in Mental Health and Educative Level, while men showed higher risk in Substance Use/Abuse and Aggressive Behavior. Risk profiles differed across academic disciplines: Arts and Humanities students showed the highest overall risk (e.g., Mental Health OR ≈ 2.16 vs. other disciplines), whereas Health Sciences students showed the lowest risk across several domains. Conclusion: In this university-wide sample of 80,077 Mexican undergraduates, psychosocial risk for substance use clustered primarily in academic strain and mental health domains and varied systematically by sex and academic discipline. Findings support discipline-tailored and gender-responsive prevention strategies integrating academic support with mental health and substance-use screening and referral pathways.