Sorting out the deluge of new publications on cannabis can be challenging, given that opinions far exceed the scientific evidence for this complex substance and its impact on individuals and society. For those of you who are interested in digging into details and do not want to be misled by questionable publications, I have two good ones to recommend.
An excellent comprehensive summary of the health effects of cannabis – both therapeutic and problematic – was released this year by the National Academies of Sciences, Engineering, and Medicine. The Health Effects of Cannabis and Cannabinoids: The Current State of Evidence and Recommendations for Research reviews all the recent scientific research published in English and classifies the evidence by degrees of conclusiveness. It is available for purchase as a book or for free as an online download at http://www.nap.edu/24625. For those who want to cut to the chase and not wade through all 440 pages, a concise summary of the conclusions can be found on pages 27 to 33. Among the highlights of the report are:
- The strongest evidence for medical benefits exists, at a modest level, for chronic pain, chemotherapy-induced nausea and vomiting, and patient reports of spasticity resulting from multiple sclerosis. Although much interest exists regarding its usefulness for conditions such as seizures, anxiety, insomnia, irritable bowel syndrome, and PTSD, insufficient high-quality studies exist to be able to draw conclusions about them at this time.
- Increased motor vehicle accidents are associated with cannabis use. There is no consensus data about safe levels of cannabis use.
- Substantial barriers to legitimate research exist in this country. These need to be reduced so that some of the controversy surrounding cannabis can be resolved.
Policy issues, including legalization and enforcement of conflicting state and Federal laws, are changing constantly. A good review of these is available in a new edition of an excellent book, Marijuana Legalization: What Everyone Needs to Know®. 2nd Edition by Jonathan P. Caulkins, Beau Kilmer, Mark A.R. Kleiman, 2016. For those of you wanting to keep track of new developments as they occur, good online resources are ProCon and interviews with Mark Kleiman.