It’s all to do with our senses
By Jenny Cook
It is estimated that roughly 42% of the UK and 9.4% of the world’s population suffer with some form of back pain, but a new study suggests that – for many people – such discomfort may simply be a figment of the imagination.
Buoyed by previous evidence showing that amputees can continue to feel pain in a limb they no longer have, Australian researchers set out to investigate the neuroscience behind clinical pain. The team recruited a small sample of 15 people with self-reported symptoms of chronic lower back pain (described as pain that ‘does not ease for 12 weeks or more’) alongside an additional 15 healthy participants of the same age to act as a control group.
Over the course of the study, three experiments were conducted – the first of which used a device that applies pressure to the spine in order to objectively measure the resulting stiffness. The measurements were then compared to how the participants said they felt. Secondly, participants were told that they were about to receive an applied force before being asked to estimate the magnitude of the force they had received.
For the final experiment, the researchers looked at whether or not adding sounds to the application of pressure would change the perceived stiffness. From this, it was found that feelings could be modulated using different sounds. For example, the feeling of stiffness was worse with creaky door sounds and less with gentle whooshing sounds. It was then concluded that “feeling stiff may represent a protective perceptual construct. Lead researcher Dr Tasha Stanton said:
“People with chronic back pain and stiffness overestimated how much force was being applied to their backs – they were more protective of their back. How much they overestimated this force related to how stiff their backs felt – the stiffer [it] felt, the more they overestimated force. This suggests that feelings of stiffness are a protective response, likely to avoid movement.”
“In theory, people who feel back stiffness should have a stiffer spine than those who do not. We found this was not the case in reality. Instead, we found that that the amount they protected their back was a better predictor of how stiff their back felt.”
It is clear that more research needs to be carried out on larger sample groups before anything concrete can be drawn from this, but Dr Stanton says she thinks her team’s discovery could pave the way for a future treatment that clinically targets stiffness using a variety of senses, without necessarily focussing on the joint itself.
“The brain uses information from numerous different sources including sound, touch, and vision, to create feelings such as stiffness. If we can manipulate those sources of information, we then potentially have the ability to manipulate feelings of stiffness. This opens the door for new treatment possibilities, which is incredibly exciting.”
The study was published in the journal Scientific Reports.