Why chronic back pain may involve more than the brain's usual pain-processing regions
Brain imaging of 114 adults links movement-triggered pain flare-ups to the default mode network, without proving cause.
Why can a seemingly ordinary movement cause a painful flare-up for someone living with chronic lower back pain? A new brain-imaging study suggests that such episodes involve more than the regions usually associated with detecting painful sensations.
Researchers studied 114 adults with chronic lower back pain using a form of functional MRI called arterial spin labelling. This technique measures changes in blood flow as an indirect marker of brain activity. Participants performed a leg-raising manoeuvre intended to provoke their familiar back pain, and researchers examined how blood flow and functional connectivity changed.
The movement increased reported pain intensity by an average of 23% and pain unpleasantness by 26%. As expected, activity increased in regions involved in sensation and pain processing. More unexpectedly, it also increased in parts of the default mode network, including the medial prefrontal and posterior cingulate cortices.
This network is associated with internally directed thought, autobiographical memory and self-related processing. In many experiments involving brief, externally applied painful stimuli, its activity decreases rather than increases. Participants reporting more severe ongoing pain also showed stronger connections between this network and sensory-processing regions.
What does this mean for patients?
The findings may help explain why persistent pain can become intertwined with movement, expectations and everyday experiences. Crucially, this does not mean that chronic pain is imaginary or simply psychological. Pain is a real experience involving complex interactions between the body and nervous system.
This was an observational study. It cannot establish whether these brain changes contribute to chronic pain or develop as a consequence of it. Functional MRI measures blood-flow signals, not pain directly, and the researchers did not test a treatment. We therefore cannot infer that targeting the default mode network would relieve symptoms.
The work is scientifically interesting and may inform future research, but it does not yet change clinical management. Its principal message is that chronic pain involves biological processes extending beyond the immediate detection of painful signals.
Original research
British Journal of Anaesthesia, published online 5 October 2026. Read the original study →