Unravelling how the brain associates safe sensations with threat and pain
Affecting more than 20 % of the global population, chronic pain is a major source of personal suffering as well as a socio-economic burden. This is particularly true for those living with complex regional pain syndrome (CRPS), a rare chronic condition that can turn harmless physical touch into a painful and threatening experience. “For some people with CRPS, even gentle contact – such as clothing brushing against the skin or touch – can cause pain and distress,” explains Iris Coppieters, a research professor at the Vrije Universiteit Brussel(opens in new window), a member of the Pain in Motion consortium(opens in new window). Coppieters is also a postdoctoral researcher at Maastricht University(opens in new window) in the experimental health psychology research group. While the pain that these patients feel is very real, the underlying brain and sensory mechanisms are not fully understood. As a result, many individuals living with CRPS experience functional limitations, while the lack of awareness and understanding surrounding the condition can contribute to stigma and inadequate support. Helping to address this knowledge gap is FABrIC, an EU-funded project focused on providing a deeper understanding of pain-related fear in conditions such as CRPS. “By exploring how the brain can learn and unlearn to associate safe, everyday sensations with threat and pain, we hope to advance the development of new, non-pharmacological approaches to treating this chronic condition,” adds Coppieters.
Evidence of how fear of painful touch develops, spreads and fades
To study how fear of touch develops, spreads and eventually fades, the Marie Skłodowska-Curie Actions(opens in new window) supported project compared individuals with CRPS experiencing chronic pain with healthy, pain-free participants. This was done by combining behavioural experiments with functional MRI brain scans, detailed sensory testing and psychological and pain questionnaires. The project also used a dedicated functional MRI finger-mapping paradigm to look at how fear of painful touch relates to changes in the brain’s representation of the body. With this multimodal framework in hand, researchers found that participants who experienced non-painful touch on the fingers also showed indications of changes in their sensory and emotional brain regions. “This suggests that fear responses can extend beyond the original site of learning, causing otherwise harmless touch to be processed as potentially threatening,” says Coppieters. Researchers also observed changes in brain activity during the extinction phase, when the expected pain no longer occurs. These changes corresponded to reductions in a participant’s reported fear and expectations of pain. “These findings provide the first valuable neuroimaging evidence of how fear of painful touch can be acquired, generalised and potentially reduced – offering a neurobiological understanding of how threat learning can alter sensory processing,” notes Coppieters.
Towards a more personalised approach to treating chronic pain
While the FABrIC project has successfully shown that fear of touch involves a complex neurobiological and sensory process that can shape how the brain interprets otherwise safe physical contact, there’s still more work to be done. That’s why the research team is now exploring how individual vulnerability and resilience factors influence fear learning. “Our ultimate goal is to deliver more personalised, mechanism-based approaches to chronic pain treatment,” concludes Coppieters.
