Bachhuber’s research could not prove that medical cannabis use directly led to fewer opioid overdoses. In addition, the overdose count included both prescription opioids and illegal heroin. But the study opened the eyes of many researchers to a possible relation between marijuana and painkiller use. “I think medical cannabis could fall into the category of alternatives for treating chronic pain so that people don’t use opioids or use a lower dose of opioids than they otherwise would,” Bachhuber says.
Various wide-ranging new studies back him up. As reported in the June issue of the Journal of Pain, researchers at the University of Michigan conducted a retrospective survey of 185 patients who frequented a medical marijuana dispensary in Ann Arbor, Mich. Those patients reported cutting their opioid use by more than half in treating their chronic pain. Meanwhile animal studies have shown that cannabinoid chemical compounds found in marijuana can work synergistically with opioids to mitigate pain.
Medical cannabis was also a hot topic at the 2016 meeting of the American Pain Society, says Simon Haroutounian, chief of clinical research at the Washington University Pain Center in St. Louis. He co-authored a study, published online in February in the Clinical Journal of Pain, that followed a group of 176 chronic pain patients in Israel over seven months and found that 44 percent of them stopped taking prescription opioids within seven months of starting medical cannabis. The research is among several recent observational studies showing an association between medical cannabis use and decreased dependence on opioids.
Each of these analyses has its limitations. Retrospective studies cannot reveal crucial details such as whether overdose deaths involved patients who were using medically prescribed opioids or people who got the drugs illegally and were using them recreationally or to self-medicate. And although Haroutounian’s observational study was carried out in real time, the participants were prescreened for psychiatric conditions and the potential for drug misuse. That means they were less likely to suffer complications from medical cannabis than a general population of chronic pain patients. “We don’t have good data on the long-term effects and in larger populations that are not so carefully selected,” Haroutounian explains.