Quick answer
Why does chronic back pain feel so personal?
A recent study from the University of California San Diego School of Medicine found that movement-triggered flare-ups of low back pain activate a brain network tied to identity and how we think about ourselves. This response—opposite to what happens in acute pain—may help explain why persistent pain feels so personal and why conventional treatments sometimes provide limited relief.
What did the University of California San Diego study find?
Researchers observed that movement-provoked low back pain activates the default mode network, a set of brain regions that typically switches off during acute pain. The team recruited 114 people with chronic low back pain and asked them to perform a leg raise test, a standard procedure that triggers back pain. While they did this, the scientists measured changes in brain blood flow using a functional MRI technique called arterial spin labeling, which does not require a contrast agent. They also applied an uncomfortable but harmless heat stimulus to the calf to compare how the brain responds to acute pain and chronic pain.
The default network and sense of identity
Sometimes called the “self network,” the default mode network consists of areas spread across the frontal, parietal, and temporal parts of the brain. These regions become active when we focus inward, for example while reflecting on past experiences or on our own sense of self. During acute pain, this network normally deactivates so the brain can focus on the external threat. But in movement-triggered low back pain flare-ups, the scientists saw it switch on instead of off. This suggests that chronic pain does not only process physical sensations—it also engages the brain systems that shape our experience of self. Patients with more severe low back pain showed stronger connections between this network and the primary somatosensory cortex, which processes physical signals such as those from the back.
Why chronic pain and acute pain are not processed the same way
The comparison between movement-triggered pain and heat revealed a striking difference: heat reduced default mode network activity, as the brain usually does during acute pain, while the low back pain flare-up increased it. During acute pain, the brain normally shuts down that network to attend to the immediate threat, but in a chronic pain flare-up the opposite happens. Fadel Zeidan, corresponding author and professor in the Department of Anesthesiology, explained that in all previous studies pain deactivates the default mode network; what they observed for the first time is that a pain flare-up turns it on and makes the person identify the experience with their identity. Heart rate measurements during the test also mirrored the severity of the pain flare-up.
New clues for treating chronic low back pain
Because movement-triggered chronic low back pain involves brain networks that differ from those in acute pain, treatments focused only on suppressing the pain signal may not address all the processes that sustain the painful experience. Opioids, for example, act mainly on pain signaling but may not address its emotional and personal dimensions. That is why the researchers suggest looking for treatments that consider not only the sensation of pain but also the relationship a person builds with it. Their work is still at an early stage, and more research is needed to confirm these results. If you live with chronic pain, a doctor can evaluate your whole case.
Frequently asked questions
Is chronic low back pain just a physical signal?
No, the study suggests it also activates brain networks linked to identity and personal memories. That may be why pain can feel so intimate and persistent, and why it is not reduced to a simple damage signal in the back.
What is the difference between acute and chronic pain in the brain?
In acute pain, the default mode network deactivates so the brain can focus on the threat. In movement-triggered chronic low back pain flare-ups, that same network activates, suggesting the brain processes the pain differently.
Does the finding change how chronic low back pain is treated?
Not yet. It is an observational brain imaging study that helps explain why chronic pain feels so personal. The researchers believe it opens the door to treatments that also address that dimension, but more studies are needed.
How many people participated in the study?
A total of 114 people with chronic low back pain participated in the study. All of them completed a leg raise test while researchers observed their brain activity with functional MRI.
Does the study say conventional treatments are useless?
No, it does not say they are useless. It suggests they may be limited because they focus on suppressing the pain signal. The finding suggests that addressing the brain-identity relationship could complement current approaches.