Combining Alcohol and Cannabis Sharply Increased Self-Harm Risk in Hospitalized Teens
Among 71 adolescents hospitalized for suicide risk, neither cannabis nor alcohol alone predicted self-harm on a given day, but using both together increased the odds by over 30-fold.
Quick Facts
What This Study Found
While neither cannabis nor alcohol use independently predicted nonsuicidal self-injury (NSSI) on a daily level, co-occurring alcohol and cannabis use on the same day increased the odds of NSSI by 30.5 times (OR=30.5, p<0.05) in the 90 days prior to hospitalization.
Key Numbers
71 adolescents; 75% female; mean age 15.79; suicide planning OR=4.47 for NSSI; suicidal ideation OR=10.09 for NSSI; co-occurring alcohol+cannabis use OR=30.5 for NSSI (p<0.05); neither substance independently significant.
How They Did This
Mixed effect models analyzing daily trajectories of alcohol use, cannabis use, suicide planning, and NSSI over the 90 days prior to psychiatric hospitalization in 71 adolescents (75% female, mean age 15.79).
Why This Research Matters
The dramatic interaction between alcohol and cannabis for self-harm risk suggests that polysubstance use, not either substance alone, may be a critical warning sign in suicidal adolescents.
The Bigger Picture
This finding shifts the focus from individual substances to their combination as a risk factor, suggesting that screening for polysubstance use in suicidal adolescents may be more informative than asking about each substance separately.
What This Study Doesn't Tell Us
Small sample size (71 adolescents); all participants had used alcohol, limiting generalizability; retrospective daily recall subject to memory bias; hospitalized sample may not represent community adolescents.
Questions This Raises
- ?What biological or psychological mechanism drives the interaction between alcohol and cannabis for self-harm?
- ?Would polysubstance screening tools in psychiatric settings improve risk assessment?
Trust & Context
- Key Stat:
- Co-occurring alcohol and cannabis use increased same-day self-harm odds by 30.5 times
- Evidence Grade:
- Small longitudinal study with daily-level analysis of high-risk adolescents, limited by sample size and retrospective recall.
- Study Age:
- Study of adolescents hospitalized for suicide risk.
- Original Title:
- The relationship between alcohol and cannabis use with nonsuicidal self-injury among adolescent inpatients: Examining the 90 days prior to psychiatric hospitalization.
- Published In:
- Addictive behaviors, 114, 106759 (2021)
- Authors:
- Sellers, Christina M, Díaz-Valdés, Antonia, Oliver, Michelle M, Simon, Kevin M, O'Brien, Kimberly H McManama
- Database ID:
- RTHC-03509
Evidence Hierarchy
Follows a group of people over time to track how outcomes develop.
What do these levels mean? →Frequently Asked Questions
Does cannabis use increase self-harm risk in teenagers?
In this study, cannabis use alone did not independently predict self-harm. However, when adolescents used both cannabis and alcohol on the same day, the odds of self-harm increased dramatically (over 30-fold).
Why is the combination more dangerous than either substance alone?
The study did not determine the mechanism, but the sharp increase in risk with combined use suggests that alcohol and cannabis together may lower inhibitions and intensify emotional distress in ways that neither substance does on its own.
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Cite This Study
https://rethinkthc.com/research/RTHC-03509APA
Sellers, Christina M; Díaz-Valdés, Antonia; Oliver, Michelle M; Simon, Kevin M; O'Brien, Kimberly H McManama. (2021). The relationship between alcohol and cannabis use with nonsuicidal self-injury among adolescent inpatients: Examining the 90 days prior to psychiatric hospitalization.. Addictive behaviors, 114, 106759. https://doi.org/10.1016/j.addbeh.2020.106759
MLA
Sellers, Christina M, et al. "The relationship between alcohol and cannabis use with nonsuicidal self-injury among adolescent inpatients: Examining the 90 days prior to psychiatric hospitalization.." Addictive behaviors, 2021. https://doi.org/10.1016/j.addbeh.2020.106759
RethinkTHC
RethinkTHC Research Database. "The relationship between alcohol and cannabis use with nonsu..." RTHC-03509. Retrieved from https://rethinkthc.com/research/sellers-2021-the-relationship-between-alcohol
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.