By Kathleen Couillard – The Rumor Detector
Agence Science-Presse (www.sciencepresse.qc.ca)
The use of cannabis for medical purposes has been legal in Canada since 2001. Yet over two decades later, its health benefits are hard to measure.
The Origins
It’s not that we doubt the pertinence of using cannabis: on the contrary, the use of cannabis to treat illnesses or relieve symptoms has been documented for more than 4,000 years, researchers from Ecuador pointed out in a 2020 literature review on the subject. And cannabis was officially recognized as medicine in the 19th century, a 2016 document by the Canadian Centre on Substance Use and Addiction (CCSA) reminds us.
Between 1920 and1950, cannabis was made illegal in several countries. It began being partially authorized for medical use in the United States in 1978, then in Ireland in 1998, in Israel in 1999 and in Canada in 2001. France would have to wait until 2013.
How Do Cannabinoids Work?
A cannabis plant contains over a hundred substances called cannabinoids. The most widely known of these are THC and CBD, explains the National Center for Complementary and Integrative Health in the United States. The human body also produces its own cannabinoids, but these have a chemical structure different from THC or CBD.
Many cannabinoid receptors are present in the human brain, especially on the neurons. They are also found on the cells responsible for inflammation and immunity. THC and CBD produce their effects by interacting with those receptors, says a 2022 report by American researchers on the therapeutic potential of cannabis.
Since the endocannabinoid system is involved in several of the human body’s mechanisms, cannabis has the potential to be used to treat many illnesses, according to a 2022 clinical publication on the use of cannabis for therapeutic purposes by the Regroupement de pharmaciens experts en soins palliatifs du Québec (the Quebec group of pharmacists specializing in palliative care).
Difficult to Study
The same pharmacists noted in 2022 that there have been very few rigorous studies on the medical use of cannabis. The sample sizes are small, and patient follow-up is generally short term. Several factors complicate research. For example, the quantity of cannabinoids can fluctuate according to plant variety and the environmental conditions in which a plant is cultivated.
Furthermore, it is possible to use not only the plant itself, but also to purify cannabinoids from cannabis extract. Some can even be synthesized in a laboratory.
Finally, the method of administering cannabis has an influence on the effects felt, we can read on the Medline Plus website, which is associated with one of the world’s largest subsidized health agencies, the National Institutes of Health in the United States. Cannabis can be smoked, mixed into food, vaporized, or take the form of oil or capsules.
Three uses of cannabis are better documented than others, according to the Association des pharmaciens des établissements de santé du Québec (the health institution pharmacists association of Quebec). Nonetheless, even in these cases, cannabis and cannabinoids are considered a treatment of last resort, because of the risks involved.
1) Nausea and Vomiting
According to a 2015 analysis by the non-profit collective Cochrane – which produces systematic health reviews – patients who used cannabinoids were three times more numerous in reporting an absence of symptoms than those who were given a placebo. And cannabinoids are as efficient as conventional treatments. That same year, another analysis by an international team of researchers looking at 28 studies concluded that cannabinoids are more beneficial than a placebo. Nonetheless, this effect is often judged to be weak – in other words, it is not always statistically significant.
Elsewhere, the Cochrane analysis revealed that cannabis and cannabinoids cause more side effects than do conventional treatments. That’s why using them to treat vomiting and nausea is unlikely to become a widespread therapy. But they remain a good option for patients who resist other treatments.
2) Chronic Pain
In Canada, some medications derived from cannabis are approved to treat chronic pain, noted the CCSA in 2016. Adults who were treated with cannabis or cannabinoids were more likely to report a reduction in their symptoms, concluded a 2017 committee on the health effects of cannabis conducted by the National Academies of Sciences, Engineering, and Medicine (NASEM), an American organization.
However, here again, study results have been mixed, concluded the researchers from Ecuador. Out of a total of 20 studies, 9 show benefits, 3 show negative effects and 8 show ambiguous results. Because of the psychoactive effects and the addiction risks, some clinicians believe that the benefits of cannabis are not sufficient to compensate for its negative effects, says the CCSA.
3) Multiple Sclerosis
The use of cannabis seems to improve symptoms of muscular rigidity reported by patients suffering from multiple sclerosis, NASEM noted in 2017. But this improvement is more limited when objectively measured by a physician. This was also the conclusion of a 2014 systematic review by American researchers, as well as a 2018 meta-analysis of 17 studies. According to the authors of this meta-analysis, the placebo effect is an important factor, and it is difficult to hide whether study participants are being given a placebo or cannabis.
Other Benefits?
For other medical conditions the research is promising, but not sufficient to draw conclusions, noted the CCSA in 2016. For example, CB1 receptors present in our brain and spinal cord are also present in the colon. This makes it possible that cannabinoids might be useful in relieving irritable bowel syndrome symptoms. But there have not been enough studies to confirm this.
Otherwise, anxiety is the most common reason invoked to consume cannabis. A small study (24 patients) conducted in 2011 showed that a “single dose” could significantly reduce anxiety among people preparing for an oral presentation who suffer from social anxiety. In their 2022 article, the American researchers mentioned that eight clinical trials were already underway.
These researchers added that certain data suggests that CBD could also have an effect on convultions in epileptic patients. And cannabis might also stimulate appetite in patients with HIV or cancer, says Medline Plus.
Verdict
Cannabis and its components can be beneficial in relieving certain symptoms such as nausea, vomiting, chronic pain and involuntary muscular contractions. But these benefits are accompanied by many side effects. As for the other supposed benefits of cannabis, more research is necessary, because several factors complicate any analysis of the results.
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