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Original Investigation
January 19, 2021

Association of Cannabis Use With Self-harm and Mortality Risk Among Youths With Mood Disorders

Author Affiliations
  • 1Department of Psychiatry and Behavioral Health, The Ohio State University Wexner Medical Center, Columbus
  • 2Department of Biomedical Informatics, The Ohio State University, Columbus
  • 3Abigail Wexner Research Institute, Nationwide Children’s Hospital, Columbus, Ohio
  • 4Rockefeller Neuroscience Institute, Behavioral Medicine and Psychiatry, West Virginia University, Morgantown
JAMA Pediatr. 2021;175(4):377-384. doi:10.1001/jamapediatrics.2020.5494
Key Points

Question  Is cannabis use disorder associated with heightened risk of self-harm, suicide, and mortality among youths with mood disorders?

Findings  This population-based cohort study of Medicaid-enrolled youths with mood disorders found that the presence of cannabis use disorder was significantly associated with an increased risk of nonfatal self-harm, all-cause mortality, and death by unintentional overdose and homicide.

Meaning  Cannabis use disorder is common among adolescents and young adults with mood disorders and is associated with an elevated risk of self-harm, overall mortality, and death by unintentional overdose and homicide in this already vulnerable population.

Abstract

Importance  Cannabis use and cannabis use disorder (CUD) are common among youths and young adults with mood disorders, but the association of CUD with self-harm, suicide, and overall mortality risk is poorly understood in this already vulnerable population.

Objective  To examine associations of CUD with self-harm, suicide, and overall mortality risk in youths with mood disorders.

Design, Setting, and Participants  A population-based retrospective cohort study was performed using Ohio Medicaid claims data linked with death certificate data. The analysis included 204 780 youths (aged 10-24 years) with a diagnosis of mood disorders between July 1, 2010, and December 31, 2017, who were followed up to 365 days from the index diagnostic claim until the end of enrollment, the self-harm event, or death. Statistical analysis was performed from April 4 to July 17, 2020.

Exposure  Physician-diagnosed CUD defined using outpatient and inpatient claims from 180 days prior to the index mood disorder diagnostic claim through the 365-day follow-up period.

Main Outcomes and Measures  Nonfatal self-harm, all-cause mortality, and deaths by suicide, unintentional overdose, motor vehicle crashes, and homicide. Marginal structural models using inverse probability weights examined associations between CUD and outcomes.

Results  This study included 204 780 youths (133 081 female participants [65.0%]; mean [SD] age at the time of mood disorder diagnosis, 17.2 [4.10] years). Cannabis use disorder was documented for 10.3% of youths with mood disorders (n = 21 040) and was significantly associated with older age (14-18 years vs 10-13 years: adjusted risk ratio [ARR], 9.35; 95% CI, 8.57-10.19; and 19-24 years vs 10-13 years: ARR, 11.22; 95% CI, 10.27-12.26), male sex (ARR, 1.79; 95% CI, 1.74-1.84), Black race (ARR, 1.39; 95% CI, 1.35-1.44), bipolar or other mood disorders (bipolar disorders: ARR, 1.24; 95% CI, 1.21-1.29; other mood disorders: ARR, 1.20; 95% CI, 1.15-1.25), prior history of self-harm (ARR, 1.66; 95% CI, 1.52-1.82), previous mental health outpatient visits (ARR, 1.26; 95% CI, 1.22-1.30), psychiatric hospitalizations (ARR, 1.66; 95% CI, 1.57-1.76), and mental health emergency department visits (ARR, 1.54; 95% CI, 1.47-1.61). Cannabis use disorder was significantly associated with nonfatal self-harm (adjusted hazard ratio [AHR], 3.28; 95% CI, 2.55-4.22) and all-cause mortality (AHR, 1.59; 95% CI, 1.13-2.24), including death by unintentional overdose (AHR, 2.40; 95% CI, 1.39-4.16) and homicide (AHR, 3.23; 95% CI, 1.22-8.59). Although CUD was associated with suicide in the unadjusted model, it was not significantly associated in adjusted models.

Conclusions and Relevance  Cannabis use disorder is a common comorbidity and risk marker for self-harm, all-cause mortality, and death by unintentional overdose and homicide among youths with mood disorders. These findings should be considered as states contemplate legalizing medical and recreational marijuana, both of which are associated with increased CUD.

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    2 Comments for this article
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    Cannabis use, self-harm and mortality among youths with mood disorders
    Tomoyuki Kawada, MD | Nippon Medical School
    Fontanella et al. conducted a retrospective cohort study to examine the associations of cannabis use disorder (CUD) with self-harm, suicide and all-cause mortality in youths with mood disorders. The adjusted hazard ratios (AHRs) (95% confidence intervals [CIs]) of CUD for nonfatal self-harm and all-cause mortality were 3.28 (2.55-4.22) and 1.59 (1.13-2.24), respectively. In contrast, CUD was not significantly associated with suicide. I have a query about their study.

    Gobbi et al. conducted a meta-analysis to evaluate the risk of cannabis use during adolescence for developing subsequent major depression, anxiety, and suicidal behavior. Pooled odds ratios (OR) (95% CI) of
    cannabis use for developing depression, anxiety, suicidal ideation and suicidal attempt were 1.37 (1.16-1.62), 1.18 (0.84-1.67), 1.50 (1.11-2.03), and 3.46 (1.53-7.84), respectively. Although this reported did not evaluate the risk of mortality by cannabis use, consuming cannabis during adolescence had a risk of depression and suicide. Discrepancy regarding the risk of cannabis for depression and anxiety should be specified by further studies. Anyway, screening of CUD in patients with mood disorder is important for preventing suicidal behavior.


    References
    1. Fontanella CA, Steelesmith DL, Brock G, et al. Association of Cannabis Use With Self-harm and Mortality Risk Among Youths With Mood Disorders. JAMA Pediatr 2021 Jan 19. doi: 10.1001/jamapediatrics.2020.5494
    2. Gobbi G, Atkin T, Zytynski T, et al. Association of Cannabis Use in Adolescence and Risk of Depression, Anxiety, and Suicidality in Young Adulthood: A Systematic Review and Meta-analysis. JAMA Psychiatry 2019;76(4):426-434.
    CONFLICT OF INTEREST: None Reported
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    Benefits associated with cannabis?
    Susanne Bejerot, M.D. | Department of Medical Sciences, Örebro University, Örebro, Sweden
    Dear Dr Fontanella,

    With great interest I have read your paper on the association of cannabis use with self-harm and mortality risk in youths with mood disorders. Thank you very much indeed for this very important contribution to the field! However, I was wondering about the conclusion in the paper, I would have expected a stronger warning, considering your findings. You state:

    “…. information about the known risks, including mortality, and benefits associated with cannabis should be readily available to youths and young adults, their parents, health care professionals, and legislators.”

    What benefits associated
    with cannabis use is supposed to be communicated to youths and young adults? How much impact do you believe any information will have on the use of cannabis among youths and young adults? In other words, if cannabis is readily available, do you think warnings about the risks will have any influence on young people?
    CONFLICT OF INTEREST: None Reported
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