A new study conducted by Northwestern University scientists found that the same region in the brain that regulates our feelings of sadness, happiness and addictions can be remodeled by chronic pain. A new treatment strategy is currently being developed that restores this region and, in turn, decreases pain symptoms, although this has only been demonstrated in an animal model thus far.
The new treatment utilizes L-dopa, a Parkinson's drug, and a non-steroidal anti-inflammatory drug, which when combined work on brain circuits in the nucleus accumbens and eliminate chronic pain symptoms when administered to rodents experiencing these symptoms. The findings are pushing scientists to pursue a clinical trial on human subjects.
"It was surprising to us that chronic pain actually rewires the part of the brain controlling whether you feel happy or sad," said James Surmeier, who oversaw the research, in a press release. "By understanding what was causing these changes, we were able to design a corrective therapy that worked remarkably well in the models. The question now is whether it will work in humans."
"The study shows you can think of chronic pain as the brain getting addicted to pain," said A. Vania Apkarian, co-author of the study. "The brain circuit that has to do with addiction has gotten involved in the pain process itself."
The study found that in rodents experiencing chronic pain, a group of neurons linked to negative emotions were hyper-sensitive and more strongly connected to regions of the brain linked to feeling bad shorty after an injury, which is likely connected to chronic pain behavior. These changes were linked to a drop in the neurotransmitter dopamine, something that the administration of the L-dopa drug reversed.
"These results establish chronic pain cannot be viewed as a purely sensory phenomenon but instead is closely related to emotions," said Apkarian.
Further research and clinical trials will examine the benefits of supplementing non-steroidal, anti-inflammatory drugs with medication that raises dopamine to help those experiencing chronic pain.
The findings were published in the Dec. 21 issue of Nature Neuroscience.
