A team of researchers at Syracuse University has found that cannabinoid drugs such as marijuana can have relieving effects on a user’s state of mind but don’t actually diminish pain intensity. 

Doctoral candidates Martin De Vita and Dezarie Moskal, along with professors Stephen Maisto and Emily Ansell, sorted through data from more than 1,800 experimental cannabis studies. Their study is the first systematic review of research on how cannabis affects pain.  

The researchers are all in SU’s department of psychology. Their findings were published on Sept. 19, during Pain Awareness Month. 

Medical marijuana is now legalized in 30 states despite its classification as a Schedule I drug by the United States Drug Enforcement Administration. Experts at SU said cannabis is being used increasingly for pain-related conditions. Research, though, doesn’t fully back up this practice. 

“I think as a whole, popular belief is that cannabinoids reduce pain intensity, and that’s not what we found,” Moskal said. 

De Vita and his team said their analysis clarified the already-existing mixed results in cannabis research and allowed for a better understanding of the kinds of effects cannabis could have on healthy adults. But they also said it raises as many questions as answers. 

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Ansell said the team was surprised that this type of study hadn’t yet been conducted because of the prevalence of medical marijuana. When the results were finalized, she said they were even more surprised to find that cannabinoids don’t really diminish the intensity of pain, which is what they expected given prevailing medical knowledge. 

“In some ways it makes sense, but in some ways it contradicts a lot of the discussion that’s been taking place around the legalization of medical marijuana,” Ansell said of their findings.  

Plant-based cannabis differs from place to place and is “much more complex” than nicotine or alcohol, De Vita said. There are hundreds of cannabinoids in existence, with many different compounds and cannabinoids typically present in plant-based cannabis. THC is the most common cannabinoid in plant-based cannabis, he said. 

About five different types of cannabis were examined in the researchers’ meta-analysis, De Vita said, including synthetic cannabinoids — purified or artificially produced versions of the chemical compounds in organically occurring cannabinoids. 

All the cannabinoids evaluated in the meta-analysis had psychoactive properties, meaning they produce a “high,” including euphoria and changes in cognition. Not every cannabinoid produces psychoactive effects, De Vita added.  

Pain is a multifaceted, biopsychological process affected by both the body and mind, De Vita said. The group’s primary findings indicated that the use of cannabinoids didn’t affect the physical intensity of pain, but it did decrease some of the unpleasant aspects of pain so that people were able to better tolerate it.  

“Pain is complex, and it has all of these different dimensions that can be affected differently,” he said. “If I can make your pain feel less unpleasant but I can’t take away the pain, you still might get some relief out of it.” 

The cannabinoids examined in the study didn’t stop the nervous system from sending pain signals, De Vita said. Therefore, he said, cannabinoid drugs may prevent the onset of pain by increasing a person’s pain threshold but might not necessarily influence the intensity of that pain.  

Another way to put it, Moskal said, is that cannabis use might make pain more tolerable. 

“People were feeling better about being in pain — not necessarily that their pain intensity reduced, but that while in pain they were feeling less unpleasant,” Moskal said. “They were in a better mood than without the cannabinoids.” 

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The team narrowed the initial data down to 18 studies, all conducted in North America and Europe over a 40-year period on healthy adults. All the initial studies had relatively small sample sizes, De Vita said, and with small sample sizes it’s more difficult to get precise estimates. A meta-analysis allows for the creation of one conceptual study with all participants together, increasing both the sample size and precision, he added.  

De Vita said he was surprised that cannabis didn’t affect all pain processes. The public consensus, he said, generally points to science having established concrete health effects of cannabis. But his research found that isn’t actually the case. 

“We still don’t know a lot about the health effects of cannabis, good or bad,” he said. “We need opportunities to actually study these things empirically, and until we do we’re not going to be able to say conclusively that it can go one way or the other.”  

The researchers agreed that their findings are just the beginning.  

Some patients using cannabis for pain treatment don’t use drugs with psychoactive cannabinoids because they interfere with normal brain function, De Vita said. Further research, he added, could investigate whether cannabis affects pain differently when it’s not a psychoactive cannabinoid.  

Other possible research could include investigating if these drugs or substances influence pain processing more significantly with certain conditions. 

 “Having a good understanding of that will help people make a more informed decision about whether cannabis is appropriate in their situation,” Ansell said.

Published on September 25, 2018 at 9:43 pm

Contact Colleen: cefergus@syr.edu | @ColleenEFergus2