Cannabis Use Disorder Linked to Psychiatric Risks in Youths with Mood Disorders

Cynthia Fontanella, PhD

Findings from a new study show that cannabis use disorder is largely associated with self-harm, all-cause mortality, and death by unintentional overdose and homicide among youths with mood disorders.

Previous research has indicated that cannabis use disorder is prevalent among individuals with psychiatric disorders, such as depression and bipolar disorder.

However, given that prevalence of cannabis use disorder—as well as suicide—is high among youths, the association between mood disorders, suicide, and cannabis use among this population is critical for suicide preventions efforts.

Therefore, a team led by Cynthia Fontanella, PhD, Department of Psychiatry and Behavioral Health, The Ohio State University Wexner Medical Center, examined these associations through a retrospective cohort study.

“To our knowledge, no studies to date have examined the association of cannabis use disorder with overall mortality risk and nonfatal self-harm in the vulnerable population of youths with mood disorders,” the team wrote.

The Psychiatric Associations of Cannabis Use Disorder

In their study, the investigators included a total of 204,780 youths—a majority (65.0%) of whom were female. The mean age at the time of a mood disorder diagnosis was 17.2 years.

Fontanella and team identified physician-diagnosed cannabis use disorder through utilization of outpatient and inpatient claims from 180 days before mood disorder diagnosis through the 365-day follow-up period.

Patient data was obtained largely from the Ohio Medicaid claims data and death certificate files, Ohio’s Department of Job and Family Services, and the state’s Department of Health.

As such, they documented a total of 21,040 (10.3%) youths with cannabis use disorder.

Further, the disorder was significantly associated with older age—defined as 14-18 years (Adjusted risk ratio [ARR], 11.22; 95% CI, 10.27-12.26), male sex (ARR, 1.79; 95% CI, 1.74-1.84), and black race (ARR, 1.39; 95% CI, 1.35-1.44).

Other risk factors noted by the investigators included bipolar disorder (ARR, 1.24; 95% CI, 1.21-1.29) or 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).

Similarly, those diagnosed with cannabis use disorder typically presented with behaviors related to non-fatal self-harm (HR, 3.28; 95% CI, 2.55-4.22).

These patients also had higher all-cause mortality (HR, 1.59; 95% CI, 1.13-2.24), which included death by unintentional overdose (HR, 2.40; 95% CI, 1.39-4.16) and homicide (AHR, 3.23; 95% CI, 1.22-8.59).

Nevertheless, the investigators reported that suicide was not associated with cannabis use disorder in adjusted models.

Important Considerations

These findings underscore the importance of being attentive to the vulnerability of those with or at-risk for cannabis use disorder.

Nonetheless, Fontanella and colleagues acknowledged that causality or underlying mechanisms cannot be inferred or extracted from their results.

“Youths with mood disorders of greater severity and intractability might be more inclined to use cannabis than youths with less severe mood disorders, and cannabis use can also exacerbate symptoms of mood disorders and interfere with the successful treatment of youths already with depression or bipolar disorder,” they wrote.

Furthermore, in light of legislation to legalize recreational and medical marijuana across the United States, information about known risks (juxtaposed to be potential benefits) related to cannabis use should be used for consideration in the implementatino of policies.

This information should thus be readily available for youths, young adults, parents, health care professionals, and legislators.

The study, “Association of Cannabis Use With Self-harm and Mortality Risk Among Youths With Mood Disorders,” in JAMA Pediatrics.