MRIs Reveal Cannabis’ Pain Killing Components
(Ivanhoe Newswire) -- The psychoactive ingredient found in cannabis tends to make the experience of pain more tolerable instead of actually reducing the intensity of pain, according to a recent study at Oxford University.
“We have revealed new information about the neural basis of cannabis-induced pain relief. Our small-scale study, in a controlled setting, involved 12 healthy men and only one of many compounds that can be derived from cannabis. That’s quite different from doing a study with patients. My view is the findings are of interest scientifically but it remains to see how they impact the debate about use of cannabis-based medicines. Understanding cannabis’ effects on clinical outcomes, or the quality of life of those suffering chronic pain, would need research in patients over long time periods,” Dr. Michael Lee at Oxford University’s Centre for Functional Magnetic Resonance Imaging of the Brain, was quoted as saying.
Long-term pain is a complex healthcare problem. Treatment can include medications, physical therapy, psychological support, and physiotherapy. For some patients, cannabis or cannabis related medications are effective when other drugs fail. However, on the other side of the debate, people report very little effect of the drug on pain but experience side-effects.
A series of MRI scans were conducted on 12 of the volunteers involved in the study. Participants were given a 15mg tablet of THC (delta-9-tetrahydrocannabinol) or a placebo before a scan. THC is the active psychotropic compound in cannabis that is responsible for the high that drives recreational use of the drug.
The volunteers had to rub a cream containing 1% capsaicin (ingredient in chili’s that causes a painful burning sensation) or a dummy cream to induce a certain level of pain. Participants then received 4 MRI scans to study each combination of THC or placebo, and chili pain-inducing cream or dummy cream.
“The participants were asked to report the intensity and unpleasantness of the pain: how much it burned and how much it bothered them. We found that with THC, on average people didn’t report any change in the burn, but the pain bothered them less,” Dr. Lee said.
Only six out of 12 participants reported a clear change in how much the pain bothered them. The MRI results substantiate the reports of the participants. The change in discomforting pain was matched with a suppression of activity in the part of the brain called the anterior mid-cingulate cortex. This part of the brain is involved in many functions and has previously been implicated in the emotional aspects of pain.
The most interesting aspect of the experiment for researchers was the strength of the connection in people between their right amydala (the part of the brain known to be primed by pain) and a part of the cortex called the primary sensorimotor area. The connection in individual participants correlated well with THC’s different effects on the pain, suggesting that there may be a way of predicting who would see benefits from taking cannabis for pain relief.
“We may in future be able to predict who will respond to cannabis, but we would need to do studies in patients with chronic pain over longer time periods,” Dr. Lee concluded.
SOURCE: Pain, December 2012