Chronic pain has been in your head all along, and scientists are working on proving it. For the first time, researchers at the University of California San Francisco have made a groundbreaking discovery using electrodes to measure the brain activity of individuals experiencing chronic pain. They've discovered a unique biomarker distinguishing chronic pain from other pain experiences.
A challenging puzzle, chronic pain has a high resistance to treatment. This groundbreaking research could revolutionize our understanding of this leading cause of worldwide disability. “This paper provides the proof of principle that chronic pain can be decoded from the brain in real patients, in the real-world, but there are almost certainly other brain regions that contain important signals that merit future study,” say lead author Prasad Shirvalkar, M.D., Ph.D., an associate professor of anesthesia and neurological surgery at the University of California, San Francisco.
Shirvalkar highlights the significance of these findings. "There is still so much we don't understand about how pain works," he said. "By developing better tools to study and potentially affect pain responses in the brain, we hope to provide options to people living with chronic pain conditions."
Published in the journal Nature Neuroscience, the study investigated the activity in two brain regions that play a central role in processing pain information: the anterior cingulate cortex (ACC) and the orbitofrontal cortex (OFC). While the ACC is known to be involved in experiencing acute pain, the OFC has yet to garner much focus in pain research. However, its reciprocal connections with the ACC and other regions in the functional pain network apparently make it a crucial player in chronic pain perception.
To investigate the neural signatures of chronic pain, four stroke or phantom limb pain patients had electrodes implanted in their ACC and OFC. In their daily lives, the participants activated their implanted brain electrodes to record and then journaled their pain and emotional states. By measuring the general activity of neurons located around the electrodes, they collected what is known as local field potentials. The researchers then compared the activity of the ACC and OFC during various painful experiences.
Machine learning tools revealed brain activity patterns unique to chronic pain. By comparing the features of chronic to acute pain measurements, the machine learning tools determined that local field potential information from the OFC was more critical than the ACC in decoding the severity of chronic pain. These patterns can serve as objective biomarkers, offering valuable insights into the personal experience and tailored treatment approaches.
By studying brain signatures, Dr. Shirvalkar and colleagues hope to better understand how to prevent pain from transitioning from acute to chronic. Walter Koroshetz, M.D., director of the National Institute of Neurological Disorders and Stroke, emphasizes the significance of these preliminary findings. "Building from these preliminary findings could lead to effective, non-addictive pain treatments," he says, emphasizing the potential relevance of this research in developing novel therapeutics that outperform opioid pain management.
While the research is promising, it is essential to note that the biomarkers identified aren't as painless as non-invasive blood sampling. Instead, surgically implanted brain electrodes limit application and highlight the need for less invasive techniques for detecting and monitoring chronic pain biomarkers.