Cannabis Use and Suicidal Thinking Were Reciprocally Linked Over Time in Teens and Young Adults

At the within-person level, cannabis use and suicidal ideation were positively and reciprocally related over time (ages 15-20). Bullying at age 15 predicted increases in depressive symptoms and suicidal ideation at age 17 directly, but not through cannabis use, depression, or anxiety as mediators. Cannabis and tobacco use at 17 predicted increases in bullying victimization at 20.

Longitudinal cohort study using three waves of data from the normative z-proso study (N=1,465; 51.7% male) at ages 15, 17, and 20. Random intercept cross-lagged panel models tested within-person mediation effects while controlling for between-person confounds.

The reciprocal relationship between cannabis use and suicidal ideation suggests a potential vicious cycle: cannabis use may increase suicidal thinking, which may in turn increase cannabis use. This bidirectional finding is important for both prevention and clinical intervention.

Suicide is a leading cause of death among young people, and cannabis use is increasing in this population. Understanding that these two problems may fuel each other over time provides a stronger rationale for addressing both simultaneously in prevention and treatment programs.

Three time points across five years may miss shorter-term dynamics. Self-reported measures may be subject to reporting bias. The study cannot establish causation despite using within-person models. Sample was from Zurich, Switzerland, which may have different cannabis norms than other settings.