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Study breakdown

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

Longitudinal CohortModerate evidence
The takeaway

In a longitudinal study of 1,465 young people, cannabis use and suicidal ideation were positively and reciprocally related from ages 15 to 20, though bullying victimization did not lead to suicidal thinking through cannabis use or depression as mediators.

Parents, clinicians, and prevention specialists concerned about youth cannabis use and suicide risk

1,465 participants, ages 15 to 20

What the researchers found

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.

Why it matters

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.

The numbers in context

1,465 participants; 51.7% male; assessed at ages 15, 17, and 20; cannabis use and suicidal ideation reciprocally related at within-person level; bullying at 15 predicted depression and suicidal ideation at 17; substance use at 17 predicted victimization at 20

How the study worked

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.

What this study cannot tell us

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.

How to read the evidence

Well-designed longitudinal study with within-person modeling, though limited time points and self-report measures

When this study was published

2022 study

The bigger picture

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.

Questions still open

  • What drives the reciprocal relationship between cannabis use and suicidal ideation? Would more frequent assessment time points reveal different mediation patterns? Could treating cannabis use disorder reduce suicidal ideation in at-risk youth?

Common questions

Does cannabis cause suicidal thoughts in teenagers?
This study found cannabis use and suicidal ideation were reciprocally related over time, meaning each predicted increases in the other. This suggests a bidirectional relationship rather than simple one-way causation.
Does being bullied lead to cannabis use?
Interestingly, this study found the opposite direction was stronger: cannabis and tobacco use at age 17 predicted increases in bullying victimization at age 20, rather than bullying driving substance use.

Read the original research

Developmental Relations Between Bullying Victimization and Suicidal Ideation in Middle Adolescence and Emerging Adulthood: Do Internalizing Problems and Substance Use Mediate Their Links?

Journal of youth and adolescence, 51(9), 1745-1759

Citation

Zhu, Xinxin; Griffiths, Helen; Eisner, Manuel; Hepp, Urs; Ribeaud, Denis; Murray, Aja Louise. (2022). Developmental Relations Between Bullying Victimization and Suicidal Ideation in Middle Adolescence and Emerging Adulthood: Do Internalizing Problems and Substance Use Mediate Their Links?. Journal of youth and adolescence, 51(9), 1745-1759. https://doi.org/10.1007/s10964-022-01630-4

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