In this post we’ll take our first dive into the medical research on cannabis.
Many people who are hesitant to consider cannabis as a treatment option for various conditions point to a lack of clinical research. That perspective is a bit wrong and a bit right. On the one hand, because cannabis is a Schedule I controlled substance in the US and Schedule II in Canada, research on it has been relatively limited. That being said, there have been tens of thousands of international scientific studies and clinical trials on medical cannabis. Not all research is made equal, and in a future blog post we’ll tackle how to verify research and assess its quality.
Two meta-analyses addressed these problems, analyzing the literature on medical cannabis for its findings and the quality of research: the 2017 National Academies of Sciences, Engineering, and Medicine study and the 2017 University of Calgary School of Medicine and Institute for Public Health ‘Cannabis Evidence Series’ review. The National Academies study is a 487 page peer-reviewed synthesis of 10,000 studies published since 1999, and is led by a team of 16 experts in medical fields (McCormick et al 2017). The Calgary study is a 286 page systematic review of “79 randomized controlled trials, including the Whiting systematic review containing 104 separate trials” (Dowsett et al 2017).
This post will briefly examine the findings of these meta-analysis on the clinical, randomized, double-blind medical benefits of cannabis. A later post will examine the potential adverse effects and risk factors from those studies as well.
Both meta-analyses found strong clinical evidence for the positive effects of medical cannabis on pain, chronic pain, and muscle stiffness, with sustain evidence that patients reported significant reduction in pain symptoms (McCormick et al 2017). As such, medical cannabis has great potential to replace the more dangerous, addictive, and deadly opioids which are frequently prescribed for pain. There was also ‘conclusive evidence’ for the effectiveness of certain oral cannabinoids in preventing and treating nausea and vomiting, particularly those induced by chemotherapy. Combined with the strong clinical evidence for pain management, cannabis has excellent potential as a treatment for cancer patients, particularly those undergoing chemotherapy. Finally, there was strong evidence for patient reported improvement in spasms associated with multiple sclerosis (‘spasticity’) with the short-term use of certain oral cannabinoids (Dowsett et al 2017).
There was moderate evidence for the effectiveness of medical cannabis in improving short-term sleep outcomes for individuals experiencing sleep disturbances associated with obstructive sleep apnea syndrome, fibromyalgia, chronic pain, and multiple sclerosis (McCormick et al 2017; Dowsett et al 2017). There was also moderate evidence for improved cognitive performance among individuals with psychotic disorders, such as improved performance on learning and memory tasks in those with a history of schizophrenia and other psychoses.
There was limited evidence on several outcomes: doctor-reported spasm reduction (associated with multiple sclerosis), appetite stimulation and weight loss hindrance for HIV/AIDS patients, improvement in Tourette syndrome symptoms, improvement in anxiety symptoms in individuals with social anxiety disorders, improvement in PTSD symptoms, and better outcomes after traumatic brain surgery. There was also limited evidence for treatments of glaucoma, dementia, and depressive symptoms in cases of chronic pain and multiple sclerosis (McCormick et al 2017).
Finally, there was sustained anecdotal, but insufficient clinical evidence for direct cancer treatment, cancer-related anorexia, irritable bowel syndrome, epilepsy, spasticity in patients with spinal cord paralysis, amyotrophic lateral sclerosis, Huntington’s disease, Parkinson’s disease, dystonia, drug addiction, and schizophrenia (McCormick et al 2017).
The following list is a composite of the academic and non-academic accounts of the medical effects of cannabis (Dowsett et al 2017; McCormick et al 2017; Greydanus & Merrick 2016; Hand et al 2016; Walsh et al 2003):
It’s important to note that limited evidence or the lack of it is not the same as a lack of correlation or causation. Put differently, we do not know everything there is to know about medical cannabis, and a great deal of what is known is anecdotal (but ubiquitous). You should only pursue medical cannabis in consultation with a physician and a Patient Educator.
As always, if you ever have any questions, the Patient Educators at Hello Cannabis are a phone call or email away. Our entire team is here to help with any questions you have about medical cannabis.
We’ll keep returning to the medicinal benefits of cannabis, but our next post will introduce you to medical cannabis legislation in Canada!
- Dowsett, L.E. et al. 2017. Cannabis Evidence Series: An Evidence Synthesis. Calgary: Government of Alberta.
- Greydanus, D.E., & Merrick, J. 2016. Cannabis or marijuana: A review. Journal of Pain Management, 9(4), 347-373.
- Hand, A., Blake, A., Kerrigan, P., Samuel, P., Friedberg, J. (2016). History of Medical Cannabis. Journal of Pain Management, 9(4), 387-394.
- McCormick, M. et al. (2017). The Health Effects of Cannabis and Cannabinoids: The Current State of Evidence and Recommendations for Research. Washington: The National Academies Press.
- Walsh, D. et al (2003). Established and potential therapeutic applications of cannabinoids in oncology. Supportive Care in Cancer (11), 137-143.