Medicinal Cannabinoids Not All They Are Cracked Up To Be

Medicinal cannabinoids, which includes CBD, THC, as well as pharmaceutical cannabinoids and their synthetic derivatives, seems to be the next big health craze. From depression and anxiety to chronic pain and poor immunity, we are told cannabinoids are the answer. These are increasingly being made available for medicinal purposes (e.g. in the United States, Australia, and Canada), including for the treatment of mental health disorders, and in response, sales of CBD have grown astronomically.

But is CBD really all it promises?

In the most comprehensive analysis of medicinal cannabinoids and their impact on six mental health disorders to date – combining 83 studies including 3,000 people – Professor Louisa Degenhardt of the National Drug and Alcohol Research Centre (NDARC) at UNSW Sydney, Australia, and her team set out to examine the available evidence for all types of medicinal cannabinoids. They included all study designs and investigated the impact on remission from and symptoms of six mental health disorders in adults: depression, anxiety, attention-deficit hyperactivity disorder (ADHD), Tourette syndrome, post-traumatic stress disorder (PTSD), and psychosis.

Included in the meta-analysis were published and unpublished studies between 1980 and 2018 which totaled 83 eligible studies, 40 of which were randomized controlled trials (RCTs) (the others were open-label trials, where participants knew which treatment they were taking). Of the 83 studies, 42 looked at depression (including 23 RCTs), 31 looked at anxiety (17 RCTs), eight looked at Tourette syndrome (two RCTs), three were on ADHD (one RCT), 12 were on PTSD (one RCT), and 11 were on psychosis (six RCTs).

In most RCTs examining depression and anxiety, the primary reason for cannabinoid use was for another medical condition such as chronic non-cancer pain or multiple sclerosis. In the studies looking at the other four disorders, the cannabinoid was used to treat the mental health disorder.

What the study revealed should have us all rethinking cannabinoids. According to Degenhardt and her team, the use of cannabinoids for mental health conditions cannot be justified based on the current evidence. This is due to a lack of evidence for their effectiveness, and because of the known risks of cannabinoids (Black et. al., 2019).

Even more, the study found a large body of evidence indicating that non-medicinal cannabis use can increase the occurrence of depression, anxiety, and psychotic symptoms. Pharmaceutical THC (with or without CBD) worsened negative symptoms of psychosis (one study, 24 people) and did not significantly affect any other primary outcomes for the mental health disorders examined. It also increased the number of people who had adverse events (ten studies; 1,495 people) and withdrawals due to adverse events (11 studies; 1,621 people) compared with placebo across all mental health disorders examined (Black et. al., 2019).

Degenhardt explains the results, “Our findings have important implications in countries where cannabis and cannabinoids are being made available for medical use. There is a notable absence of high-quality evidence to properly assess the effectiveness and safety of medicinal cannabinoids compared with placebo, and until evidence from randomized controlled trials is available, clinical guidelines cannot be drawn up around their use in mental health disorders.”

The study sheds light on the limited evidence and the low quality of the evidence that exists around using cannabinoids for treatment of mental health conditions. Degenhardt again: “In countries where medicinal cannabinoids are already legal, doctors and patients must be aware of the limitations of existing evidence and the risks of cannabinoids. These must be weighed when considering use to treat symptoms of common mental health disorders. Those who decide to proceed should be carefully monitored for positive and negative mental health effects of using medicinal cannabinoids.”

As cannabinoids are often advocated as a treatment for various mental health conditions, clinicians and consumers need to be aware of the low quality and quantity of evidence for the effectiveness of medicinal cannabinoids in treating mental health disorders and the potential risk of adverse events. Further, as Professor Deepak Cyril D'Souza of Yale University School of Medicine, USA, points out, “The process of drug development in modern medicine is to first demonstrate efficacy and safety in clinical trials before using the drug clinically. With cannabinoids, it seems that the cart (use) is before the horse (evidence). For cannabinoids to be used in the treatment of psychiatric disorders they should be tested in RCTs and subjected to the same regulatory approval process as other prescription medications.”

It is true we are all probably looking for that one drug, supplement, or additive that will dramatically improve our health. However, studies like this one remind us of the importance of self-control – especially when it comes to new treatments for mental health disorders.

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