Photo by mari lezhava on Unsplash

There Is Almost No Evidence That Cannabis Will Improve Mental Health Conditions

A recent meta-analysis reveals just how little we know

J. Brandon Lowry
Nov 12, 2019 · 7 min read

Disorders of negative affect, such as depression and anxiety, are among the most common psychiatric illnesses in the United States. According to the Anxiety and Depression Association of America, 40 million adults are affected by anxiety disorders. Not surprisingly, anti-depressants are some of the most frequently prescribed medications in the US. While these drugs undoubtedly help many manage their conditions, they are not without side effects, and often lose efficacy over time, leading the depressed and anxious to turn to other sources of relief.

Increasingly, this takes the form of medical marijuana. A 2016 survey revealed that 58% of medical cannabis consumers in Washington state did so for anxiety relief. Similar numbers were obtained for those seeking to ease their depression. In a separate survey, 12.7% of respondents said they were using cannabis in place of their prescription anti-depressants. Clearly, there is a demand for alternatives, and a belief that marijuana can help.

Unfortunately, there is very little research to suggest that cannabis is effective for this purpose. In fact, there’s a troubling paucity of trustworthy clinical research on this subject, as demonstrated by a new study published in The Lancet Psychiatry. In this paper, the authors examine the evidence showing either a positive or negative effect of cannabis on six different mental disorders. What they found shows just how far we still have to go in investigating the potential of medical marijuana.

What Did They Do?

Citing the increasing popularity of cannabis use for mental disorders, the authors chose six conditions to focus on: Depression, Anxiety, ADHD, Tourette Syndrome, PTSD, and Psychosis. Then they scoured databases of scientific literature searching for any papers mentioning cannabis and any one of these conditions. From there, they filtered out their results based on pre-determined criteria, keeping only the most relevant pieces of evidence. In particular, they focused on Randomized Controlled Trials (RCTs), the so-called “gold standard” in medical research. Using their systematic approach, the authors were able to filter through thousands of research articles and narrow their focus to a much more manageable eighty-three.

The final step in the process was to evaluate each of the remaining papers and grade the strength of the evidence. Under their scheme, an RCT is initially rated as “high quality”, and then downgraded to “moderate”, “low”, or “very low” as befit the situation. With all of their data collected and graded, they grouped the papers together based on the condition being studied and analyzed the results.

What Did They Find?

Anxiety

There was slightly better evidence for studying CBD on its own. A pair of RCTs studied the effect of pharmaceutical grade CBD on those with social anxiety, and found that it had no effect when compared to placebo.

Post-Traumatic Stress Disorder

Psychosis

One RCT investigated the use of a combination of THC-CBD to treat psychosis. There was no change in the Positive symptoms (compared to placebo), but a significant worsening of the Negative symptoms. Further, the researchers found a strong negative effect on cognitive functioning after cannabinoid treatment. CBD on its own did not effect either the Positive or Negative symptoms, but it did significantly improve “global functioning”.

Adverse Events/Study Withdrawals

What Does This Mean?

“To our knowledge, this is the most comprehensive systematic review and meta-analysis examining the available evidence for medicinal cannabinoids in treating mental disorders and symptoms. There is a notable absence of high-quality evidence where mental disorders are the primary target of treatment[…]”

To put it another way, there is almost no evidence that cannabinoids can treat mental health disorders. Now, this does not mean that cannabis can’t treat them. Absence of evidence is not evidence of absence. But given that so many are turning to cannabis and cannabinoids for mental health reasons, we need to understand this much better, and sooner rather than later.

Highlighting this gap in our knowledge is important for several reasons. First, it’s possible that people are putting themselves at risk with little or no chance of reward. Every drug comes with side effects. Often these are negligible, or at the very least they are worth suffering in order to make the original issue go away. But in the case of cannabis and mental disorders, there’s evidence for negative side effects with little or no benefit. Further, cannabis can exacerbate certain conditions, as we saw with the patients with psychosis. This paper demonstrates how little we actually know, and might help sway some people to choose a different path.

This lack of knowledge also impacts policy decisions. Without federal legalization, each state is left to choose which conditions qualify a patient for medical marijuana. As of now, 29 states allow doctors to authorize medical marijuana use for the treatment of PTSD, 8 for the treatment of Tourette, and only 1 for anxiety. Clearly, these decisions were not made based on the strength of the science. It’s impossible to know what harm, if any, will come as a result of these decisions… but that’s exactly my point. We are acting blindly on this issue.

Finally, it arms people against dubious claims. Illegality leads to a lack of regulation. As it stands, there is very little oversight as to what claims can be made in advertising and selling marijuana. Therefore, it’s on the consumer to be educated and understand the risks and rewards before trying a new drug. By making it clear just how little we truly know, consumers can more effectively gauge the messages their receiving and make informed decisions.

More from the No BS Guide:

About the author:

J. Brandon Lowry holds a PhD from the Institute of Molecular Biology at the University of Oregon. A digital nomad and freelance writer, he writes about cannabis, science, health, and travel. He is also editor at Midnight Mosaic Fiction.

The No BS Guide to Medical Cannabis

One nomadic scientist dispelling the myths surrounding the world’s most controversial plant

J. Brandon Lowry

Written by

Nomadic PhD and full-time writer. Topics: Writing, Fiction, and Poetry. Editor at Forge Editing Services: forgeediting.wordpress.com

The No BS Guide to Medical Cannabis

A publication dedicated to translating the science of cannabis research for regular folk. The goal is neither to promote nor demonize marijuana, but to help others make informed decisions using the best research available.

J. Brandon Lowry

Written by

Nomadic PhD and full-time writer. Topics: Writing, Fiction, and Poetry. Editor at Forge Editing Services: forgeediting.wordpress.com

The No BS Guide to Medical Cannabis

A publication dedicated to translating the science of cannabis research for regular folk. The goal is neither to promote nor demonize marijuana, but to help others make informed decisions using the best research available.

Medium is an open platform where 170 million readers come to find insightful and dynamic thinking. Here, expert and undiscovered voices alike dive into the heart of any topic and bring new ideas to the surface. Learn more

Follow the writers, publications, and topics that matter to you, and you’ll see them on your homepage and in your inbox. Explore

If you have a story to tell, knowledge to share, or a perspective to offer — welcome home. It’s easy and free to post your thinking on any topic. Write on Medium

Get the Medium app

A button that says 'Download on the App Store', and if clicked it will lead you to the iOS App store
A button that says 'Get it on, Google Play', and if clicked it will lead you to the Google Play store