One of the chief arguments for the legalization of medicinal marijuana is its usefulness as a pain reliever. For many cancer and AIDS patients across the 19 states where medicinal use of the drug has been legalized, it has proven to be a valuable tool in managing chronic pain—in some cases working for patients for which conventional painkillers are ineffective.
To determine exactly how cannabis relieves pain, a group of Oxford researchers used healthy volunteers, an MRI machine and doses of THC, the active ingredient in marijuana. Their findings, published today in the journal Pain, suggest something counterintuitive: that the drug doesn’t so much reduce pain as make the same level of pain more bearable.
“Cannabis does not seem to act like a conventional pain medicine,” Michael Lee, an Oxford neuroscientist and lead author of the paper, said in a statement. “Brain imaging shows little reduction in the brain regions that code for the sensation of pain, which is what we tend to see with drugs like opiates. Instead, cannabis appears to mainly affect the emotional reaction to pain in a highly variable way.”
As part of the study, Lee and colleagues recruited 12 healthy volunteers who said they’d never used marijuana before and gave each one either a THC tablet or a placebo. Then, to trigger a consistent level of pain, they rubbed a cream on the volunteers’ legs that included 1% capsaicin, the compound found that makes chili peppers spicy; in this case, it caused a burning sensation on the skin.
( via blogs.smithsonianmag.com )