Why no evidence of medical Cannabis efficiency exists?
Studies have been poorly designed — the evidence is unexplored
Canada legalized Cannabis in October 2018. Health Canada issued a very detailed 266-pages report addressed to Health Care professionals to summarize all the knowns and unknowns of medical and recreational Cannabis consumption for general population.
Medical Cannabis is legal in Canada since 2001, almost twenty years later health care professionals opposed to prescribe or recommend medical cannabis for treating health conditions. Why? Because no studies have confirmed the so-called anecdotal reports. Anecdotal evidence is distinctly different from scientific evidence. Anecdotal reports are not taken seriously by MDs; the medical community requires randomized clinical studies. Otherwise, it’s more like a rumor to doctors, not a shred of real evidence. However, many health professionals are mindful of the existence of anecdotal evidence; the so-called “stories” get published in well-respected medical journals.
Based on anecdotal reports or preclinical studies or animal studies or observational studies or small non-randomized studies, the medical community hypothesizes that medical Cannabis may be useful in approximately 50 common human conditions. Conditions are from devastating Alzheimer’s disease to simple insomnia. ( I wish I knew that when my amazing father was suffering from the quick onset of Alzheimer-like dementia at a relatively young age of 70).
Cannabis is not a medical treatment until Health authorities assign a drug identification number (DIN). Not until the future drug candidate has well-controlled and reproducible properties. And we are back to “a randomized clinical study.” An investigational therapy must succeed in the trial before it becomes a drug with DIN. The experimental drug candidate ideally should be tested in the settings of a control arm. Trial participants must be blinded to the fact of whether they receive an active ingredient or a placebo.
A negative stigma of Cannabis prevented well-designed studies for Cannabis-derived drugs from being offered. The results are less than optimal — no studies — no evidence — no new medicines.
Some limited studies, however, were initiated since 2015; the majority investigators used smokable dry Cannabis, and the exact Tetrahydrocannabinol/Cannabidiol (THC/CBD) profile of the strain was hard to quantify. The dry Cannabis used was usually THC dominant, had low potency, and difficult to reproduce the results; if the next investigator used another strain of dry Cannabis, he/she would need to start testing all over again. Besides the usual THC and CBD, there is more to it: THCV, CBDV, THCA, CBDA, and CINV. All these are different cannabinoids or cannabinoid acids found in full-spectrum phytocannabinoid plant Cannabis. The study participants were ‘sans faute’ very diverse: genetically, gender/age-wise, pre-existing conditions, etc.
Is it safe to say, no worthwhile tests were done up to 2020? I think so.
Why would a company spend millions of dollars to conduct a properly designed study? The company must be interested in making a profit when the drug enters the marketplace. Nexium, for example, is a popular drug sold worldwide to treat heartburn or acid reflux. The global annual sales were surpassing 4 B $, at least until the Nexium’s patent expiration in 2014. Four billion dollars annually is an excellent reason to race such a profitable drug to the market by completing all the studies in a valid, reproducible, and reliable way.
An almost complete absence of well-designed studies is the reason for “no evidence exists for the efficacy of medical Cannabis.” Most of the existing evidence resulted in FDA approved drugs: one cannabis-derived and three cannabis-related drug products.
Bits of evidence we possess today could be described on the spectrum as anecdotal evidence, insufficient evidence, very limited evidence, mixed evidence, complex and conflicting evidence, emerging evidence, limited but increasing evidence. That is what “no evidence” really means. It must be there, but we are unsure and mixed up right now.
Unfortunately, no evidence is going to emerge until well-designed studies are completed in this increasingly emerging and promising medical Cannabis market. Stay tuned.
Read more about the human Endocannabinoid system and the potential medical applications of Cannabis-derived drugs