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'Hard To Justify' Medical Cannabis Use For Mental Disorders

Jim Folk author
Written by: Jim Folk.
Medically reviewed by: Marilyn Folk, BScN.
Last updated: October 29, 2019

Hard To Justify Medical Cannabis Use For Mental Disorders image

A new systematic review and meta-analysis finds that there's little evidence to support the use of cannabinoids to treat mental health disorders, such as anxiety disorder, depression, posttraumatic stress disorder, and psychosis.[1]

"Patients who are interested in using cannabinoids for mental disorders should understand that there's limited evidence for it, and if they do choose this intervention, there needs to be monitoring to check that it's helpful and is not causing harm," lead investigator Louisa Degenhardt, PhD, National Drug and Alcohol Research Centre, University of New South Wales, Sydney, Australia, told Medscape Medical News.[2]

However, a large body of evidence has shown that cannabis use can increase anxiety, depression, and psychotic symptoms, and lead to dependence, she added.

"In many ways, we know more about the long-term risks of regular cannabis use than we do about its benefits for people with mental disorders," said Degenhardt. Meanwhile, she added, the trend toward legalization of cannabis has made it widely available on a global scale.

Because many sources claim cannabis can play a therapeutic role in the treatment of mental health disorders, this study sought to find the evidence to support that claim.

The investigators describe their research as "the most comprehensive systematic review and meta-analysis examining the available evidence for medicinal cannabinoids in treating mental disorders and symptoms."

Based on the research summary, the following method was used:

For this systematic review and meta-analysis we searched MEDLINE, Embase, PsycINFO, the Cochrane Central Register of Controlled Clinical Trials, and the Cochrane Database of Systematic Reviews for studies published between Jan 1, 1980, and April 30, 2018. We also searched for unpublished or ongoing studies on ClinicalTrials.gov, the EU Clinical Trials Register, and the Australian and New Zealand Clinical Trials Registry. We considered all studies examining any type and formulation of a medicinal cannabinoid in adults (≥18 years) for treating depression, anxiety, attention-deficit hyperactivity disorder (ADHD), Tourette syndrome, post-traumatic stress disorder, or psychosis, either as the primary condition or secondary to other medical conditions.

We placed no restrictions on language, publication status, or study type (ie, both experimental and observational study designs were included). Primary outcomes were remission from and changes in symptoms of these mental disorders.

The safety of medicinal cannabinoids for these mental disorders was also examined. Evidence from randomised controlled trials was synthesised as odds ratios (ORs) for disorder remission, adverse events, and withdrawals and as standardised mean differences (SMDs) for change in symptoms, via random-effects meta-analyses. The quality of the evidence was assessed with the Cochrane risk of bias tool and Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach. This study is registered with PROSPERO (CRD42017059372, CRD42017059373, CRD42017059376, CRD42017064996, and CRD42018102977).

The researchers concluded:

  • There is scarce evidence to suggest that cannabinoids improve depressive disorders and symptoms, anxiety disorders, attention-deficit hyperactivity disorder, Tourette syndrome, post-traumatic stress disorder, or psychosis.
  • There is very low quality evidence that pharmaceutical THC (with or without CBD) leads to a small improvement in symptoms of anxiety among individuals with other medical conditions.
  • There remains insufficient evidence to provide guidance on the use of cannabinoids for treating mental disorders within a regulatory framework.
  • Further high-quality studies directly examining the effect of cannabinoids on treating mental disorders are needed.

The study was published in Lancet Psychiatry online, Oct 28.

Our research has found that some people find the use of cannabinoids helpful in reducing their anxiety symptoms, some find it provides only marginal symptom reduction, some find that it provides no reduction in symptoms, and some find cannabinoids make their symptoms much worse.

As it stands today, it appears this research holds true for what most people experience from using cannabinoids for mental health disorders and their symptoms.

The combination of good self-help information and working with an experienced anxiety disorder therapist is the most effective way to address anxiety disorder and its many symptoms. Until the core causes of anxiety are addressed - the underlying factors that motivate apprehensive behavior - a struggle with anxiety disorder can return again and again. Identifying and successfully addressing anxiety's underlying factors is the best way to overcome problematic anxiety.

Additional Resources:

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1. Black, Nicola, et al. "Cannabinoids for the treatment of mental disorders and symptoms of mental disorders: a systematic review and meta-analysis." The Lancet - Psychiatry, 28 Oct. 2019.

2. Anderson, Pauline. “Medical Cannabis for Mental Disorders 'Hard to Justify'.” Medscape Medical News, 28 Oct. 2019.