Review Questions Effectiveness of Cannabis for Mental Health
Alongside chronic pain, mental health issues rank among the leading reasons individuals seek to use marijuana for medical purposes. Nonetheless, a comprehensive analysis spanning 45 years of cannabis research reveals minimal to no high-quality evidence supporting its effectiveness.
The findings, published in The Lancet Psychiatry, illustrate a significant gap between public enthusiasm for cannabis and the available scientific research. This review is noted as the most extensive attempt to evaluate data from randomized-controlled trials related to cannabis and mental health. The study included over 50 clinical trials, assessing various conditions and formulations of cannabinoids.
Surprisingly, the review found no substantiated evidence that cannabis alleviates symptoms associated with anxiety, PTSD, or depression—conditions frequently cited by users of medical marijuana as their reason for using the drug. Interestingly, insomnia, autism, and tic disorders had slightly more supporting data, but even that was considered “low quality” by the researchers.
Jack Wilson, the lead author and a postdoctoral research fellow at the Matilda Centre for Research in Mental Health and Substance Use at the University of Sydney, emphasized the need for further research. He suggested that without robust evidence, using medical cannabis for mental health disorders should be approached with caution.
The findings may not be shocking to those experienced in cannabis research, where challenges in conducting rigorous studies are well-known. For over five decades, cannabis has been classified as a Schedule 1 drug by the DEA; however, recent signals from the federal government suggest a potential reclassification may be on the horizon.
Despite many states moving toward legalizing marijuana for both medical and recreational use, there has been inadequate investment in high-quality studies needed to validate treatments. Given the stringent criteria for studies included in the Lancet Psychiatry paper, only data from around 2,500 patients were considered, and in some cases, no trials existed for conditions like depression.
Ryan Vandrey, a professor at Johns Hopkins University, lamented the lack of data collection regarding cannabis, given its widespread availability as a treatment. He remarked that aggregating data from various products and excluding long-term studies complicates the ability to draw definitive conclusions.
Additionally, a recent review in JAMA Internal Medicine echoed similar sentiments, revealing a lack of evidence for utilizing cannabis in treating mental health conditions while also highlighting the significant risks it poses for vulnerable populations, including adolescents, individuals with a history of substance abuse, or pre-existing psychiatric disorders.
Dr. Devan Kansagara pointed out the complexity of cannabis as a substance, urging healthcare providers to engage in discussions with patients using it, acknowledging both its potential benefits and the knowledge gaps that remain.
As for dosing, it appears that products containing high levels of THC—like gummies and concentrates—may carry the greatest risks, particularly for those with serious mental health issues. Kansagara recommends considering lower-dose alternatives to strike a better balance between potential benefits and harms.
On a more nuanced note, while cannabinoids broadly have shown little promise for anxiety, certain specific compounds—like CBD—demonstrate more favorable outcomes. Vandrey noted that some individuals with anxiety or depression experience significant relief using cannabis, while others may find no advantage or even negative effects. This variability underscores the importance of personalized discussions regarding cannabis use.
