Association between medical cannabis laws and opioid overdose mortality has reversed over time

Medical cannabis has been put forward as a solution to the US opioid overdose crisis since Bachhuber et al. [M. A. Bachhuber, B. Saloner, C. O. Cunningham, C. L. Barry, JAMA Intern. Med. 174,1668–1673] found that from 1999 to 2010 states with medical cannabis laws experienced slower increases in opioid analgesic overdose mortality. This study incorporated the same methods used by Bachhuber et al to extend the analysis through 2017. The findings from the original analysis did not hold over the longer period. Moreover, the association between state medical cannabis laws and opioid overdose mortality reversed direction from −21% to +23% and remained positive after accounting for recreational cannabis laws. There was no evidence that either broader (recreational) or more restrictive (low-THC) cannabis laws were associated with changes in opioid overdose mortality. Research into potential therapeutic use of cannabis should continue, but there is currently no evidence to support the enactment of medical cannabis laws to reduce opioid overdose deaths.

by Chelsea L. Shover, Corey S. Davis, Sanford C. Gordon, and Keith Humphreys

Read the full article at PNAS.org.