Cannabis abuse by US youth with mood disorders linked to self-harm, death

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Heavy use of marijuana by United States teens and young adults with mood disorders – such as depression and bipolar disorder – is linked to an increased risk of self-harm, suicide attempts and death, a study published in JAMA Pediatricshas found, writes Sandee LaMotte for CNN. An independent expert said a causal link had neither been proved nor refuted.

Heavy use of marijuana by teens and young adults with mood disorders – such as depression and bipolar disorder – is linked to an increased risk of self-harm, suicide attempts and death, a study published in JAMA Pediatrics has found, writes Sandee LaMotte for CNN. However an independent expert said a causal link had neither been proved nor refuted.

Unintentional overdoses, suicide and homicide were the three most frequent causes of death, reports the research from Ohio State University, the Abigail Wexner Research Institute and the Rockefeller Neuroscience Institute at West Virginia University, published online by JAMA Pediatrics on 19 January 2021. The CNN article is below:

"The perception is that marijuana is safe to use, but we need to educate parents and kids that there are risks involved, particularly with heavy and high potency cannabis use," said study author Cynthia Fontanella, an assistant professor in the department of psychiatry and behavioural health at Ohio State University's College of Medicine.

"And clinicians need to intervene to identify and treat cannabis use disorder as well as kids with mood disorders," Fontanella said.

Cannabis use disorder

Cannabis use disorder, also known as marijuana use disorder, is associated with dependence on the use of weed. A person is considered dependent on weed when they feel food cravings or a lack of appetite, irritability, restlessness and mood and sleep difficulties after quitting, according to the National Institute on Drug Abuse (NIDA).

"People who begin using marijuana before the age of 18 are four to seven times more likely to develop a marijuana use disorder than adults," NIDA advises. About four million people in the United States met the diagnostic criteria for a marijuana use disorder in 2015, NIDA estimates.

Experts say that number will have grown due to a rise in potency in today's varieties of weed, along with the legalisation of recreational marijuana for adults in 15 American states and medical use in 36 states, writes CNN’s LaMotte.

Studies in adults show a strong association between overuse of weed and suicide attempts and death.

A study of adult same-sex twins found those who were dependent on marijuana were nearly three times more likely to attempt suicide than their twin who was not dependent on weed.

Another study of 1,463 suicides and 7,392 natural death in the United States found a link between any use of marijuana by adults and suicide risk after adjusting for alcohol use, depression and use of mental health services.

And there was an increased risk of suicide for both men and women who were dependent on marijuana, according to a four-year study of 6,445 Danish adults.

First study in children

The CNN article continues: The new study used Ohio Medicare data to identify both cannabis use disorder and self-harm attempts and outcomes in youth between the ages of 10 and 24 years old. The study could only show an association between cannabis dependence and negative outcomes, not a direct cause and effect.

Prior studies show children with mood disorders are highly likely to use and abuse marijuana, Fontanella said, partly because they don't like the side effects of many prescribed medications.

"Mood stabilisers and psychotic medications can cause weight gain, say up to 30 or 40 pounds … stiffness of their neck or eyes … and it can cause sedation," Fontanella said. "So, they may not use their medication and may self-medicate with cannabis to treat the mood disorders."

It could also be that using weed might contribute to the development of mood disorders, however.

"Research shows cannabis use is associated with early onset of mood disorder, psychosis and anxiety disorders, so it can lead to the onset of severe mental illness," Fontanella said.

At this point, however, science is not sure which comes first, partly because few if any studies have been done in teens and young adults, continues LaMotte for CNN.

"Research suggests that marijuana exposure impacts on the brain's ability to process emotion. Could this interact in a deleterious way with the developing brain?" wondered Dr Lucien Gonzalez, who chairs the American Academy of Pediatrics committee on substance use and prevention. Gonzalez was not involved in the study.

"It doesn't prove that using cannabis causes depression or self-harm, but also doesn't definitively refute it," said Gonzalez, an assistant professor of psychiatry and behavioral sciences at the University of Minnesota Medical School.

"Complicated associations appear to be found, and we just don't fully understand them yet," Gonzalez said.

While science sorts out the answers, "family-based models and individual approaches such as cognitive behavioral therapy" have been effective in treating youth with marijuana use disorder, Fontanella and her team said.

They also called for the rollout of a national study to further examine the mortality risks for youths and young adults who struggle with overuse of weed.


Study details

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

An original investigation

Cynthia A Fontanella, Danielle L Steelesmith, Guy Brock, Jeffrey A Bridge, John V Campo and Mary A Fristad

Author affiliations: The Department of Psychiatry and Behavioral Health and the Department of Biomedical Informatics at Ohio State University; Abigail Wexner Research Institute at Nationwide Children’s Hospital in Columbus, Ohio; and the Rockefeller Neuroscience Institute at West Virginia University, United States.

Published online in the journal JAMA Pediatrics on 19 January 2021



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.


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 1 July 2010 and 31 December 2017, who were followed up to 365 days from the index diagnostic claim until the end of enrolment, the self-harm event or death. Statistical analysis was performed from 4 April to 17 July 2020.


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

Non-fatal 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.


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 hospitalisations (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 non-fatal 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, death by unintentional overdose and homicide among youths with mood disorders.

These findings should be considered as US states contemplate legalising medical and recreational marijuana, both of which are associated with increased CUD.


CNN story – Marijuana abuse by youth with mood disorders linked to suicide attempts, self-harm and death, study finds (Open access)


Article in JAMA Pediatrics – Association of Cannabis Use With Self-harm and Mortality Risk Among Youths With Mood Disorders (Restricted access)


See also from MedicalBrief’s archives

Cannabis reduces OCD symptoms by half in the short-term



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