A review of scientific literature shows that research into the medical potential of marijuana has greatly increased in recent years.

Israeli researchers surveyed scientific databases for papers published from 2000 to 2017 and published a statistical summary of the results in the journal Population Health Management. According to the researchers, during those years “The overall number of scientific publications in PubMed increased 2.5-fold. In contrast, the number of publications on cannabis increased 4.5-fold and the number of publications on medical cannabis increased almost 9-fold. The number of publications on medical cannabis in Web of Science increased even more (10-fold).” This great increase has been especially notable since 2013. The numbers behind the overall 4.5-fold increase are 620 to 2,388, and the numbers behind the almost 9-fold increase in medical studies are 82 to 742. The authors find that “The spike in the number of scientific publications on medical cannabis since 2013 is encouraging.”

As for where the studies were conducted, “More than half of the publications on medical cannabis originated from the United States, followed by Canada.” (According to another recent study, the share of the world’s medical studies conducted in the United States has dropped from 57 percent in 2005 to 44 percent in 2015.)

Conditions under study

The researchers note that the “most significant number of publications was in the field of psychiatry.” Psychiatric conditions for which medical marijuana is often prescribed include anxiety, depression, and PTSD. The results of these studies are mixed, which is why an increase in the number of studies is “encouraging.” The more studies, the clearer and more verifiable our understanding of the psychiatric uses of cannabis is likely to become. As John M. Grohol puts it in a summary of the current research: “I suspect that, in the end, it would come down to an individual’s unique reaction, similar to how each individual reacts differently to different psychiatric medications. Well-done research studies seem to indicate that marijuana would help certain people, while it may not help others.”

Psychiatrists already try different medications to treat mental health symptoms before finding what works with an individual patient. The same process may apply with cannabis medications. A complicating factor, however, is that depression, along with marijuana use, is often chronic, or long-term, with few clear outcomes over time. In one study published in 2016, for example, researchers were unable to determine whether people used marijuana because they were depressed or were depressed because they used marijuana: “Whether or not cannabis use may increase the risk for depression and/or anxiety is not clear. For one thing, it has not been possible to draw a definitive conclusion regarding the direction of causality, i.e. whether cannabis use increases the risk for depression/anxiety or vice versa.”

SEE ALSO: A majority of healthcare professionals now favor legalization.

Not all conditions are as hard to quantify as psychiatric ones, however. For example, when it comes to pain, studies are showing clearer results. For example, one study concludes: “The current systematic review suggests that [cannabis-based medicines] might be effective for chronic pain treatment…primarily for neuropathic pain (NP) patients.” In addition to treating pain, especially neuropathic pain, studies are showing that cannabis can be effective at treating two symptoms associated with chemotherapy: nausea and pain.

Other conditions for which cannabis medicines are being reviewed include epilepsy, HIV, and multiple sclerosis. Many of these show promising results. Recently, for example, the FDA approved a drug that includes CBD as a treatment for two rare and severe types of epilepsy. On the other hand, studies have shown that marijuana use during pregnancy correlates with lower birth weight: expecting mothers should not use.

The authors of the Population Health Management study conclude that given the number of studies now being conducted that show promising results, it is time to remove the legal roadblocks to study of cannabis medicines. Under United Nations conventions and U.S. law, marijuana remains a drug without medical value. Actual medical studies, however, are showing that cannabis medicines are working for some conditions and may be of help with others.

What do you think? Will research take off in Canada? What will additional studies likely confirm? Leave a comment below.

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