How does persistent pain happen?

While I’ll mostly be using the word pain here, the concepts and mechanisms described apply to many other symptoms, like anxiety, fatigue, etc.

Pain is a protective mechanism - your bodymind doing its best to look after you. It is part of a really sophisticated system that serves to protect our bodyminds. When there is an outside threat (whether that be a threat of physical injury or a threat to our safety, dignity or belonging), or we injure ourselves, our brain sends out pain messages to let us know that there’s something wrong. This allows us to act and try to avoid or repair any damage, such as pulling our hand away from something hot to prevent burning ourselves, resting an injured limb, or choosing to change our behavior to avoid being outcast from our group.

In persistent pain, the brain keeps sending out protection messages, even when there is no tissue damage, after an injury has healed or when there’s no injury at all. This is one of the challenges of pain, there are many situations in which pain does not seem to match the amount of damage to your tissues, but it still really hurts, and it’s still very real.

Here’s a crucial bit of information that might be a surprise: the brain (and nervous system) constructs all pain. Yes, that’s right. The feeling of pain does not come from peripheral structures (like our back or our stomach), but from the brain. While our body is constantly sending messages to the brain, and some of these messages are danger messages, the brain interprets these danger messages, and decides whether or not to create pain in response to keep us safe. The brain takes hundreds of factors into account (remember the biopsychosocial model & the model of complexity) when creating pain in fractions of a second, including whether it’s been primed or sensitized to pain (your threat/fear/pain system has become overactive), and something called predictive processing (also known as predictive coding). Predictive processing is a theory of brain function in which the brain is constantly generating and updating a mental model of the environment, which is then used to generate predictions of sensory input that are compared to actual sensory input. That is, the brain continually generates models of the world around it in order to predict the most plausible explanation for what’s happening in each moment. In other words, we experience, in some sense, the world we expect to experience.

If your brain assesses that a part of your body (or all of you) is in danger or under threat and needs protecting, then it will make part of your body (or all of your body) hurt, and/or it will generate difficult emotional experiences. You will experience pain when your brain concludes that there is more credible evidence of danger than there is credible evidence of safety.

This helps us understand how the expectation of pain (often unconscious) will create pain. And, while we have no say in the moment, we can definitely influence this fascinating process through learning different neural pathways and activating positive bioplasticity.

The concept of neuroception can be useful here. Neuroception is a term coined by Stephen Porges, author of the Polyvagal Theory, to describe the process through neural circuits distinguish whether situations or people are safe, dangerous, or life threatening. Because of our evolution as a species, neuroception takes place in primitive parts of the brain, without our conscious awareness. The detection of a person as safe or dangerous triggers neurobiologically determined prosocial or defensive behaviors. Even though we may not be aware of danger on a cognitive level, on a neurophysiological level, our body has already started a sequence of neural processes that would facilitate adaptive defense behaviors such as fight, flight, freeze, fawn or flop.

If you want to keep learning about this topic, and learn about what we can do to unlearn persistent pain, check out the entry on priming and sensitization or read the full text on bodymind (re)learning for wellbeing and ease.