'Talking' brain creates the pain
Pain, it seems, is really all in the mind. A new study by Northwestern University's Feinberg School of Medicine shows for the first time that chronic pain develops when two sections of the brain - related to emotional and motivational behaviour - talk to each other. The more communication between the frontal cortex and nucleus accumbens, the greater the chance a patient will develop chronic pain.
'For the first time we can explain why people who may have the exact same initial pain either go on to recover or develop chronic pain,' says A. Vania Apkarian, professor of physiology at Northwestern and senior author of the paper published in the journal Nature Neuroscience.
'The injury by itself is not enough to explain the ongoing pain. It has to do with the injury combined with the state of the brain. This finding is the result of 10 years of research.'
The study involved 40 participants who had an episode of back pain, diagnosed by a clinician, that lasted four to 16 weeks - but with no prior history of back pain. Brain scans were conducted on each participant at the beginning of the study and for three additional visits during one year.
The researchers were able to predict, with 85 per cent accuracy at the start of the study, which participants would go on to develop chronic pain based on the level of interaction between the frontal cortex and nucleus accumbens.
The latter is an important centre for teaching the rest of the brain how to evaluate and react to the outside world, Apkarian says, and it may use the pain signal to teach the rest of the brain to develop chronic pain. The more emotionally the brain reacts to the initial injury, the more likely the pain will persist after the injury has healed.
Based on this work, researchers hope to develop new therapies for chronic pain treatment.