Chronic back pain is linked to physical changes in the brain, according to researchers in Germany.
A team found patients with the condition also had microstructural changes in the pain-processing areas of their brains.
The scientists said the work provided evidence that the condition was real and it could aid treatment research.
They discovered the brains of patients with chronic back pain had a more complex and active microstructure compared with the healthy volunteers' brains.
The changes occurred in regions of the brain associated with pain-processing, emotion and stress response.
However, the researchers said more research would be needed to determine whether the physical changes were a cause or result of the pain.
Co-author Gustav Schelling, from the Department of Anaesthesiology at Munich University, said: "It's difficult to know whether these are pre-existing changes in the brain that predispose an individual to developing chronic pain, whether ongoing pain creates the hyperactivity that actually changes the brain organisation, or if it is some mixture of both.
"DTI may help explain what's happening for some of these patients, and direct therapeutic attention from the spine to the brain."