Pain and the brain

Dr. Benedict Wand is Associate Professor at the School of Health Sciences, University of Notre Dame, Fremantle, Western Australia. He is involved in research on the role of changes in the central nervous system in chronic pain. Here he describes some of the changes in central nervous system activity, and how they might be addressed, in people with chronic pain.


One of the many changes in our understanding of pain over the last few decades has been an increased appreciation that action is an important component of the pain response. Part of what pain does is motivate us to change our behaviour. Often the actions we take are helpful to us, they minimise the risk of further injury and help with recuperation – these are adaptive behaviours. Resting and strapping a painful swollen ankle or putting your thumb in your mouth to cool it down after burning it are sensible and helpful behaviours likely to improve outcome.

Some behaviours are not helpful in driving recovery – they are maladaptive. Importantly, things that are helpful initially do not always remain so. Resting a sore ankle for a few days is a good idea, but the healing process needs movement so resting for a few weeks or months undermines recovery. While putting your burnt thumb in your mouth for a few minutes will help, leaving it there for a few months is definitely not going to optimise the health of the tissue in the area!

These ideas have been discussed for many years, though generally with reference to the effects on injured tissue such as muscles, ligaments and bones and other physical effects such as fitness, strength and flexibility. Recent research suggests the same ideas might apply to the brain – the place where all pain experiences are constructed. Our brains are remarkably plastic and will change and modify depending on our behaviour. London cab drivers have a larger hippocampus from remembering all those street names, Braille users enlarge the area of the brain that receives input from their finger and you probably reorganise your brain a bit every time you pick up a hand tool to use to help make that tool an ‘extension of your body’ – these are all adaptive, helpful changes.

Pain also seems to change the brain. In repeated experimental pain, which the subjects know has a clear cause and will only last a short time, the changes appear to be adaptive. There is measurable thickening of the gray matter in some brain areas and this is related to better tolerance to the pain – which is a handy skill to have. In clinical pain problems there is gathering support for the idea that some of the changes might be maladaptive and contribute to the maintenance of the problem. When pain has been present for a long time the chemical concentrations in some brain areas have been shown to change and there seems to be a (reversible) thinning of some areas of gray matter. These changes might make people more sensitive to – and less tolerant of – painful inputs, less able to disengage from pain and maybe changes the way the sore area is perceived by the brain, so that body part might feel less connected, less easily controlled and maybe even a bit strange and foreign.

While there is still much to be discovered it is likely that what people think about their pain problem and the behaviours they adopt contribute to maladaptive brain changes. Worrying excessively about the pain problem and its outcome, overly focusing on painful input, splinting and guarding the sore area and moving abnormally for long periods are the main things we think influence changes in the brain. These are the kind of behaviours likely to emerge when people have a persistent high perceived need to protect the injured area, exactly the kind of belief that many approaches to managing painful problems promote; particularly low back pain. Scary pictures from MRI, stories of degeneration and fragility or things being out of place and instructions to splint and brace the back and move in quite unnatural ways are all great ways of creating a high perceived need for protection and potentially contributing to maladaptive brain changes. So good accurate information about your pain problem, appropriate graded functional movement that builds confidence and treatment plans that restore hope and reduce fear, vulnerability and confusion are likely to minimise these effects. These are issues that have been talked about a lot on this website and the emerging data on the brain in chronic pain adds further support to this approach.

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