Chronic Back Pain Flare-Ups May Activate Brain Networks Linked to the Sense of Self

For people with chronic lower back pain, everyday movements such as bending to tie shoelaces or lifting shopping bags can trigger painful flare-ups. New research suggests these episodes may do more than activate the brain’s pain-processing regions: They may also engage networks associated with introspection, autobiographical memories and a person’s sense of self.

In a study of 114 adults with chronic low back pain, exercise-induced pain flare-ups were linked to increased activity in the default mode network — a group of connected brain regions that typically becomes active during mind-wandering and self-focused thought.

The finding surprised researchers because activity in the default mode network usually decreases during acute pain, such as touching a hot stove or hitting a knee against a table.

The study was published on October 5 in the British Journal of Anesthesia. Its results suggest that chronic pain flare-ups may involve brain processes beyond the systems that simply detect painful sensations.

How chronic back pain affects the brain

Chronic lower back pain is generally defined as pain lasting at least three months and is a leading cause of disability worldwide.

When chronic pain develops, a network of brain regions known as the pain neural matrix may become sensitized. As a result, pain can persist even after the original painful stimulus has disappeared. Chronic pain has also been associated with changes in brain activity, although researchers do not yet fully understand what happens when a movement suddenly worsens ongoing pain.

Study links pain flare-ups to the default mode network

Researchers used functional magnetic resonance imaging, or fMRI, to examine participants’ brain activity. The technology measures changes in blood flow and provides an indirect measure of activity in the brain.

After an initial brain scan, researchers helped each participant raise one leg until their back pain worsened. The participant held the position for 10 seconds before lowering the leg. Researchers then scanned the brain immediately afterward and compared the results with previously collected scans.

The movement increased participants’ reported pain intensity by an average of 23%.

As expected, the leg movement increased blood flow in brain regions involved in pain and movement processing. However, the researchers also observed increased activity in important parts of the default mode network.

“We expected to be deactivated so much that we had to triple-check our work to make sure the results were legitimate.”

Fadel Zeidan, neuroscientist at the University of California, San Diego

Acute pain typically reduces activity in the default mode network. Research suggests this may happen because acute pain draws attention away from internal thoughts and toward an external threat.

“When we looked at just the first step of the analysis, we thought, ‘Did we get it right?’” study co-author Morgan Gianola, a postdoctoral researcher at the University of California, San Diego, told Live Science.

Fadel Zeidan, whose research focuses on pain and the brain, said the team did not expect the default mode network to be involved in the response to chronic back pain flare-ups.

Why heat pain produced a different brain response

The researchers also exposed participants’ calves to painful heat, a common method for studying acute pain. Unlike exercise-induced low back pain, the heat stimulus was associated with reduced activity in parts of the default mode network.

The difference suggests that a chronic back pain flare-up caused by movement may involve a different brain mechanism from the temporary pain caused by heat.

Can chronic pain become part of a person’s identity?

Participants who reported more severe chronic back pain had stronger connections between the default mode network and brain regions that process sensations from the back.

The researchers said this finding suggests chronic pain may become intertwined with how people perceive themselves and their bodies.

“This flare of pain has almost become part of who they are from an egocentric perspective,” Zeidan said.

Catherine Martucci, a neuroscientist at Duke University who was not involved in the research, praised the study’s experimental design. Researchers usually avoid movement during brain scans because it can reduce image quality. In this study, the team scanned participants before and after the painful movement to work around that challenge.

However, Martucci noted that the observed activity could also reflect lingering pain or anxiety after the leg raise. The study also could not determine whether the brain changes contribute to chronic pain or develop as a result of it.

What the findings could mean for chronic pain treatment

The researchers believe the findings could eventually help inform treatments that focus not only on the painful sensation itself, but also on how people relate to their pain.

Zeidan, who developed chronic back pain while conducting his research, believes that past experiences and memories of pain may influence brain processes to the point that pain becomes closely connected to a person’s sense of self.

His team is investigating whether approaches such as mindfulness meditation and cognitive behavioral therapy affect the default mode network and help reduce chronic pain. Cognitive behavioral therapy for chronic pain, or CBT-CP, is already among the established treatment options.

Martucci cautioned that it is too early to draw conclusions about how the findings could be used in clinical practice. Still, she said the research provides important evidence about how the brain responds to chronic low back pain flare-ups.

“We now have solid data about how people with chronic low back pain show important changes in their brain responses following pain-causing symptoms,” she said. “Brain imaging data shows that they experience pain in a significant and highly visible way.”

Source: Gianola, M., Dean, J., Chen, C., Barrows, D., Riegner, G., Liu, T. and Zeidan, F. (2026). “Brain mechanisms supporting exercise-induced chronic low back pain: An observational brain imaging study.” British Journal of Anesthesia.