The Short-Term Change in Knowledge of Cannabis-Related Risks After a Brief Curriculum-Integrated School Intervention Among Adolescents: A Quasi-Experimental Pre–Post Study

Purpose: The purpose of this study was to estimate the short-term pre–post change in cannabis risk knowledge after a brief curriculum-integrated school intervention delivered under routine educational conditions. Methods: This was a quasi-experimental single-group pre–post study without a control group in a secondary education setting (n = 151; ages 15–17). Intervention: Three standardized 1 h classroom sessions delivered by health professionals, focused on health literacy, risk perception, myth debunking, and peer pressure. Primary outcome: Pre–post change in a knowledge scale (0–15). Analysis: Wilcoxon signed-rank test; effect size r. Results: Knowledge scores increased from a median of 8 (IQR 7–10) at pretest to 13 (IQR 12–14.5) at posttest. The median paired change was +5 points (IQR 3–6; Hodges–Lehmann estimate 5.0, 95% CI 4.5 to 5.0), with improvement observed in 96.7% of students (146/151); the effect size was large (r = 0.867). Associations with family and clinical variables were considered exploratory due to low subgroup frequencies. Discussion: In this single-group pre–post study, the intervention was associated with short-term improvement in cannabis risk knowledge. These findings should be interpreted as evidence of short-term within-subject change in a proximal cognitive outcome under uncontrolled conditions, not as evidence of intervention effectiveness, sustained learning, behavioral change, or broader practical impact. Conclusions: Brief curriculum-integrated cannabis education may be a feasible format for generating short-term gains in risk knowledge, but controlled studies with longer follow-up, psychometrically stronger outcome measures, and implementation data are needed to assess the durability and behavioral relevance of these changes.