Running in the woods today I was taken back to school days when we would go down to the habitat to learn about nature. Our enthusiastic science teacher, whose laboratory experiments would invariably go wrong, led us down the hill, across the playing fields and into a small wooded area that surrounded a murky pond. This was safer than a bunsen burner, and I do not recall anyone ever falling into the water.
In the habitat we would collect data on flowers, plants and insects. In particular I recall that we should note down the irritability of insects, in other words, how reactive they were to a stimulus — the stimulus being a group of excited kids. Generally they flew away; the insects.
My point here is that whilst running I was taken back by the context of where I was, especially the smell of wild mustard. It was this olfactory experience that evoked a clear memory of the habitat, most likely helped by the fact that I was in a wood.
Recently I was talking to a patient about an experience that he had when visiting a hospital where he had been in ITU. On entering the building and walking the corridors, he was hit with a storm of emotions and memories that triggered a need to escape. He did not understand why this happened.
We are unaware of the vast majority of the things going on around us. Our brain filters and draws our attention to what is important right now. We can only focus on a limited amount of data otherwise it would be impossible to function. You may now be thinking about your right butt cheek, but probably not before I mentioned it. And whatever you do, do not think about a white elephant…
The brain stores memories that can be retrieved when it thinks that a reminder is useful. In the case of re-entering the hospital, although the feelings of panic are unpleasant, it is a useful set of responses to a threatening environment as this is where the brain recorded the events in the first instance. Knowing that this is a normal response allows for control to be re-gained. Not understanding often kick starts further thinking that evokes further protection via the autonomic nervous system — increased heart rate, dilated pupils, sweating etc. This demonstrates the importance of understanding our biology.
In chronic pain the same mechanisms are on alert. As we are multisensory, any of the senses can evoke a protective response. Sounds, smells, touch, taste and sights can all evoke emotional and physical responses. Think of that song, the one that perks you up or brings you down. It is a song, yet it is the meaning that you give to the song that determines how you respond.
Pain being an output from the individual, from the brain, in response to a perceived threat is no different. The more protective the systems, the wider the range of cues that can trigger a pain and stress response. This is equally true in anxiety. Our individual interpretation of a situation or a thought effects the response. We notice butterflies in the stomach (a change in blood flow through the gut) and know that we are anxious before realising what is making us feel anxious; or we have a thought and this leads to feelings of anxiety. It is bi-directional.
From a survival perspective, the brain registering information from all the senses during an experience is useful. Learning is vital. The next time we are in that situation, or one that is similar, the brain will use prior experience to work out if a threat exists, or a potential threat. On concluding that there is something dangerous going on, or about to happen, the brain will initiate protective responses that drive protective behaviours. Whilst this is entirely appropriate in acute pain, on going protection is a problem in chronic pain. Pain is always a normal response to what the brain thinks is going on, but in persisting pain it is often the underlying processes in the nervous and immune systems that are problematic and need targeting for effective treatment.
Memories play a fundamental in how we live and learn. We can actively search our archive but often reminders seemingly just pop into the mind’s eye. There will always be a reason why your brain thinks this is useful but that may not be immediately obvious.
Specialist Pain Physio Clinics, London — for chronic pain and complex pain — 07932 689081