Most states in the USA, and many countries across the world have passed legislation that allows the use of marijuana for medical purposes. Some of this legislation is dependent on various claims, many of which appear to be based on weak or nonexistent scientific evidence. Of all of the purported marijuana medical benefits, only a handful are supported by real evidence.
This review, Committee on the Health Effects of Marijuana: An Evidence Review and Research Agenda (pdf, which can be downloaded for free by registering or can be found online here), published by the influential and prestigious National Academies of Science, Engineering, and Medicine, examined more than ten thousand scientific studies that involved cannabis and various medical conditions. The value of such a review is that it examines not only the quantity of evidence supporting a claim but also the quality of such evidence. In the end, it gives much more weight to high-quality evidence.
I know many comments will drop on this article that “you haven’t read that incredible study published in Journal of Weed and Cancer Cures” – that misses the point. The National Academies is a highly respected institution, made up of the most respected scientists in the USA. And the committee that created this review is made up of leading public health, cancer, epidemiology, pharmacology, and psychiatry, all fields germane to understanding clinical and basic scientific research into cannabis.
Moreover, a review like this does two things – it gives more weight to well done clinical trials and pre-clinical studies, and it eliminates poorly done and biased studies. This is how science works – examine ALL of the evidence before coming to a conclusion. Pseudoscience, on the other hand, is to have a conclusion, like “weed cures cancer,” and only seeking evidence that supports that preordained conclusion.
Furthermore, and this cannot be stressed enough, this review is not opinion. It is not belief. It is not cherry picking. It is a critical analysis based on thousands of studies published in peer-reviewed journals. This is not published in a pro-cannabis website that cherry picks, misinterprets, and overrates a one-off study in an obscure journal. The report is over 400 pages long – most of you will not read even a few pages, because it is a dense scientific review written by some of the top scientists in the USA. Before you denigrate the study, I would suggest you read it carefully.
To save you time from reading the 400+ page opus, which I did, I divided up the medical evidence from strong to none of the evidence in support of benefits and of risks from smoking cannabis. Not to bury the lede, but there are only three conditions for which there is strong, overwhelming evidence benefits of marijuana. Just three. Continue reading “Marijuana medical benefits – large review finds very few”