Increasing marijuana use trajectories were linked to violent behavior with weapons
Among inner-city youth, trajectories of increasing marijuana use from adolescence to adulthood were associated with over three times the odds of engaging in violence involving weapons.
Quick Facts
What This Study Found
In a longitudinal study of 838 inner-city African American and Puerto Rican participants, researchers identified distinct trajectories of marijuana use from adolescence to adulthood and examined their association with violent behavior. Compared to the no/low use trajectory, the increasing marijuana use trajectory was associated with 3.37 times the odds of engaging in violence involving weapons (shooting or hitting someone).
The moderate use trajectory (AOR = 1.98) and even the "quitter" trajectory (AOR = 1.70) were also associated with increased odds of weapon-related violence compared to no/low use. The analyses controlled for other predictors of violent behavior.
Key Numbers
838 participants. Increasing use trajectory: AOR = 3.37 (P < .001). Moderate use trajectory: AOR = 1.98 (P < .01). Quitter trajectory: AOR = 1.70 (P < .05). All compared to no/low use.
How They Did This
Longitudinal study following 838 inner-city African American and Puerto Rican participants. Growth mixture modeling identified marijuana use trajectories from adolescence to adulthood. Logistic regression examined associations between trajectory group membership and weapon-related violence.
Why This Research Matters
Understanding the association between marijuana use patterns and violent behavior has implications for both public health prevention and criminal justice approaches. The finding that even "quitter" trajectories showed elevated violence risk suggests that exposure history matters beyond current use.
The Bigger Picture
This study does not establish that marijuana causes violence. The association likely reflects shared risk factors in inner-city environments, including poverty, exposure to violence, deviant peer networks, and limited educational opportunity. However, the dose-response pattern (heavier use trajectories = stronger association) warrants attention.
What This Study Doesn't Tell Us
Observational design cannot establish causation. The specific inner-city, minority population limits generalizability. Weapon violence is rare and affected by many contextual factors. Self-reported marijuana use and violence may be subject to reporting bias. Confounders related to socioeconomic conditions and neighborhood exposure were not fully captured.
Questions This Raises
- ?Would these associations hold in different socioeconomic and demographic contexts?
- ?Does marijuana use directly increase aggression, or do shared environmental risk factors explain the association?
- ?Why did even the "quitter" trajectory show elevated risk?
Trust & Context
- Key Stat:
- 3.37x odds of weapon violence in the increasing marijuana use trajectory
- Evidence Grade:
- Longitudinal trajectory analysis with appropriate statistical methods, though limited by observational design and specific population.
- Study Age:
- Published in 2014.
- Original Title:
- Developmental trajectories of marijuana use from adolescence to adulthood: relationship with using weapons including guns.
- Published In:
- Aggressive behavior, 40(3), 229-37 (2014)
- Authors:
- Brook, Judith S, Lee, Jung Yeon, Finch, Stephen J, Brook, David W
- Database ID:
- RTHC-00777
Evidence Hierarchy
Follows a group of people over time to track how outcomes develop.
What do these levels mean? →Frequently Asked Questions
Does marijuana cause violent behavior?
This study found an association between marijuana use trajectories and weapon-related violence, but it cannot establish causation. Shared risk factors in inner-city environments likely contribute to both marijuana use and violence.
Did quitting marijuana reduce violence risk?
Interestingly, even the "quitter" trajectory (those who used and then stopped) showed elevated violence odds compared to no/low use, suggesting that past exposure or the factors that led to use also contribute to risk.
Read More on RethinkTHC
Cite This Study
https://rethinkthc.com/research/RTHC-00777APA
Brook, Judith S; Lee, Jung Yeon; Finch, Stephen J; Brook, David W. (2014). Developmental trajectories of marijuana use from adolescence to adulthood: relationship with using weapons including guns.. Aggressive behavior, 40(3), 229-37. https://doi.org/10.1002/ab.21520
MLA
Brook, Judith S, et al. "Developmental trajectories of marijuana use from adolescence to adulthood: relationship with using weapons including guns.." Aggressive behavior, 2014. https://doi.org/10.1002/ab.21520
RethinkTHC
RethinkTHC Research Database. "Developmental trajectories of marijuana use from adolescence..." RTHC-00777. Retrieved from https://rethinkthc.com/research/brook-2014-developmental-trajectories-of-marijuana
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.