Low back pain is the single leading cause of disability worldwide, according to the World Health Organization . For people with chronic low back pain (cLBP) lasting more than 12 weeks, a sudden pain flare triggered by movement can often worsen the condition. Pain signals originate in the brain, but scientists still don't fully understand the specific neural circuitry that sparks this movement-based pain.
Now, researchers at UC San Diego School of Medicine have found that the brain region's Default Mode Network (DMN) is turned on when cLBP patients experience sudden pain brought on by movement. The DMN is also referred to as the "self network" because it is associated with interconnected regions of the frontal, parietal and temporal lobes of the brain that become active when we are thinking about ourselves and our identity or reflecting on internal thoughts and feelings — rather than focusing on the outside world.
The study, published on October 5, 2026 in the British Journal of Anaesthesia, could help explain why typical symptom-based treatments are often ineffective and suggests that targeting the brain's DMN may be a better approach to managing cLBP.
The researchers had 114 cLBP patients perform a "leg raise test" — a standard way to trigger a back pain flare — while they measured blood flow in the brain using a specialized functional MRI technique called arterial spin labeling. As a control, they also tested how the patients' brains responded to a harmless but painful heat stimulus on the calf, comparable to accidentally touching a hot stove.
They found that movement-evoked pain activated the DMN, providing the first evidence that the experience of chronic pain is not merely a sensation, but is deeply embedded in the sense of self. In addition:
- Participants who suffered from more severe chronic back pain had stronger connections between the DMN and the primary somatosensory cortex, the area of the brain that processes sensations from the back.
- The more intense the pain was during the leg raise test, the more activity was observed in the brain's sensory and motor regions.
- An increase in heart rate during the leg raise test was a reliable indicator of how intense the pain flare was.
In contrast, when the participants were subjected to the painful heat, their DMN shut down, which is the brain's usual response to acute pain. This allows the brain to focus entirely on the external threat rather than on the self, according to corresponding author Fadel Zeidan, PhD, professor in the Department of anesthesiology, endowed professor at the Sanford Institute for Empathy and Compassion and director of the Pain Health and Mindfulness Laboratory at UC San Diego School of Medicine.
"In every pain study, when you're experiencing pain, the DMN deactivates," said Zeidan. "What we show for the first time ever is that when you have a pain flare, it turns on instead. You start to identify the experience with who you are."
In essence, in cLBP the brain is maladaptively coupling the physical pain with a deep, internal sense of self.
"The moment-to-moment experience is contaminated not only by the feeling of pain, but by the anticipation of it and recovery from it. It's contaminated by past experiences like embarrassment about not being able to participate in normal activities and fear of movement when trying to avoid the pain."
The researchers think that because pain flares evoked by movement in cLBP patients activate different brain networks than typical acute pain, this might be why standard pain treatments like opiates often fail for this type of pain.
"Current pain medicine is fixated on ridding patients of their pain symptoms, but that's not the source of chronic pain. These data suggest that a chronic pain flare also encompasses one's identity."
Recent research by Zeidan's team points to a different route to treatment by using mindfulness meditation and the psychedelic compound psilocybin , helping patients separate the physical experience of chronic pain from their identity, resulting in reductions to pain intensity. These preliminary findings are promising, but more research is needed to validate these early studies.
"These types of mind-body and psychedelic medicine approaches target the whole person," Zeidan said. "Mindfulness is a meditation technique that's about cultivating non-judgmental awareness of the present moment that dramatically reduces pain in a very unique way. Psilocybin seemingly resets the pain system that integrates trauma, past experiences and future worries to facilitate a restart, if you will. They're not a silver bullet — you're not necessarily getting rid of the pain, but you're changing the relationship you have with that pain so it doesn't contaminate your everyday life."
Zeidan's lab is currently conducting several neuroimaging-based clinical trials to further understand how approaches that target self-referential brain processes like mindfulness meditation and psychedelics can rewire the brain to alter the subjective experience of chronic pain.
Link to study: " Brain mechanisms supporting movement-evoked chronic low back pain "
Additional co-authors on the study include: Morgan Gianola, Jon Dean, Conan Chen, Daniel Barrows, Gabriel Reigner and Thomas Liu at UC San Diego School of Medicine.
The study was funded, in part, by the National Institutes of Health's National Center for Complementary and Integrative Health (Grant #R01AT009693) and the UC San Diego Sanford Institute for Empathy and Compassion. The authors declare that they have no conflicts of interest.
