Monday, April 03, 2017

Roy on the Pros and Cons of Medical Marijuana

Medical marijuana was legalized in Maryland two years ago, and this summer we will be getting our first dispensaries.  Psychiatrists are starting to ask what this means in terms of treating patients.  Roy did a great job summing up some of the research for our colleagues:

Unfortunately, because of the many historical restrictions on research, there is increasing amounts of data available, yet few "facts" to go by ("fact" as in "a thing that is indisputably the case"). These data are often viewed from differing perspectives. Such as absolute vs relative risks. Harm reduction vs harm avoidance. Public health vs criminalization perspectives. Use vs abuse (eg, plenty people use alcohol without abuse it, getting drunk, rotting their liver... same with cannabis).

That being said, the National Academy of Science and Medicine just put out in January a comprehensive (500 pages) report on the health risks of cannabis. I have attached the 3MB pdf file for our MPS readers' enjoyment. They found about 10,000 relevant abstracts to review (leaving out another 10,000 that did not meet their quality review). I was surprised there was that much out there. 

I'll boil it down to the Executive Summary level. Their major conclusion appears to be that, essentially, we need more research. Beyond that, they divided up additional findings based on the strength and quality of the research:

Strongest evidence:
There is conclusive or substantial evidence that cannabis or cannabinoids are effective:
  • For the treatment of chronic pain in adults (cannabis) (4-1)
  • As antiemetics in the treatment of chemotherapy-induced nausea and vomiting (oral cannabinoids) (4-3)
  • For improving patient-reported multiple sclerosis spasticity symptoms (oral cannabinoids) (4-7a)
Moderate evidence for:
  • Improving short-term sleep outcomes in individuals with sleep disturbance associated with obstructive sleep apnea syndrome, fibromyalgia, chronic pain, and multiple sclerosis (cannabinoids, primarily nabiximols) (4-19)
Limited evidence for: 
  • Increasing appetite and decreasing weight loss associated with HIV/AIDS (cannabis and oral cannabinoids) (4-4a)   
  • Improving clinician-measured multiple sclerosis spasticity symptoms (oral cannabinoids) (4-7a)
  • Improving symptoms of Tourette syndrome (THC capsules) (4-8) 
  • Improving anxiety symptoms, as assessed by a public speaking test, in individuals with social anxiety disorders (cannabidiol) (4-17) 
  • Improving symptoms of posttraumatic stress disorder (nabilone; a single, small fair-quality trial) (4-20)
Limited evidence of a statistical association between cannabinoids and: 
  • Better outcomes (i.e., mortality, disability) after a traumatic brain injury or intracranial hemorrhage (4-15)

The above is from the first page of about 10 pages of summary findings, including findings of both benefit and risk that are in the Exec Summary of the document. If still interested, turn to pages 13 to 22 to read the rest. And dive deeper if you are really interested. 

As for patient education, I think one could turn these 10 pages into maybe 2 pages of "here is what we know and here is what we don't know". Of course, where one draws the dividing line is arbitrary, but start with those things that have the strongest evidence, with benefits on the left and risks on the right.

Then people make up their own mind, like anything else... a risk/benefit discussion. Would you risk liver failure for headache relief? Here's two Tylenol (or four or six).

Sorry if you were looking for a simple answer.