Last week I discussed case formulation as one way of using a biopsychosocial framework in pain management, and I reviewed Benedetti’s description of the process of becoming aware that something’s wrong, seeking relief from that discomfort, then the “meet the therapist moment”, and finally the “receiving the therapy” steps along the way. Benedetti considers this within a neurobiological model (Benedetti, 2013), while Engel (1977) used general systems theory to frame his critique of the original biomedical model.
This week I want to look at a behavioural model. I do this partly because I think it’s been a long time since this model was brought into our discussions about pain and pain behaviour, and I do it because I think we can understand a great deal about why different people respond differently to their pain when we look at behaviour alone – before we even begin to look at beliefs or attitudes about pain.
Let’s do a little revision (Psych 101). In a behavioural model, we’re looking at two main forms of conditioning: Pavlovian or classical conditioning, and operant or instrumental conditioning. In the case of pain, we also need to revisit the distinction made between the experience (pain), and our behavioural response to that experience (pain behaviours). Pain behaviours are typically filtered or influenced by what we think is going on (judgements about the meaning of pain – eg super-scary crumbling back, or I just did too much gardening), what we’ve learned to do, and the context in which we’re experiencing pain. That context can be current (eg I’m in Church and it’s very quiet so I’d better not swear as I hit my toe against the pew!), or past (eg last time I kicked my toe against the pew and swore, everyone looked at me – how embarrassing!), or even future (eg if I swear when I kick my toe against the pew, I’ll never be able to show my face here again!). It’s the learned part I want to discuss today.
Pain behaviours range from reflex withdrawal responses (lifting the foot up while straightening the other leg to support me when I stand on a tack), to quite complex behaviours we’ve learned are relevant in our environment (filling out a claim form for compensation and treatment).
We probably developed pain behaviours as part of our evolutionary development: the reflex withdrawal behaviours don’t require conscious thought, so they begin in infancy (actually, before), and rely on spinal mechanisms (eg Rohrbach, Zeiter, Andersen, Wieling & Spadavecchia, 2014), with various parts of the brain becoming involved as part of strategies to avoid threat (see Damasio and Damasio (2016) for some insights into evolutionary aspects of withdrawal reflex). But because we have a developed cortex, we’ve learned ways of suppressing our responses, depending on social context – and on responses from others around us.
Reflexive responses are those associated with classical conditioning – and lead us to learn relationships between previously non-threatening stimuli and both withdrawal responses and the physiological arousal that goes with them. For example, if I bend over to make the bed and OUCH! my back suddenly gets really sore. I straighten up very carefully – and I’ve learned something: next time I bend over to make the bed, I’ll be remembering and preparing for that OUCH! to happen once again. The bed and bending forward movement become associated, in my mind, with that OUCH! Of course, for most of us, once we make the bed a few more times (make that many times), we’ll learn that OUCH! doesn’t inevitably follow the bend, so we gain confidence to repeat that movement without preparing for the OUCH! Now what do you think might happen if I never had an opportunity to make the bed again? Say, if I have a really protective person in my life who stopped me every time I go to do it – will that association I have in my mind persist, or will it reduce? This is, in essence, what is thought to happen when someone develops so-called “fear avoidance”.Note: the experience of pain does not have to re-occur for me to avoid bending and begin to rev my nervous system up. What needs to happen is for the first instance to be pretty strong, and for me to not test my belief again. It’s the behaviour that persists (avoidance) because by avoiding something I believe will be OUCH! I avoid experiencing OUCH! And by avoiding that experience, I never test whether OUCH! happens every time, or just that once.
Let’s look at the other really powerful learning mechanism: operant conditioning. In this situation, the likelihood of me repeating my behaviour is increased or reduced, depending on responses in the environment. So, let’s take my bending forward and experiencing OUCH! If my partner (bless him) then decided to fuss over me, make me a cup of tea and tell me not to worry about making the bed ever again – AND if I liked that idea – my response is likely to be to avoid making the bed. I might even go as far as wincing a bit when walking, so he makes me another cup of tea and fusses over me. I might talk about my back pain because he’s so concerned about me (or I really want him to be concerned about me) and if he carries on fussing, I’m likely to carry on with these behaviours. Now picture that in a two-year-old kid – every time the kid trips and cries, some concerned parent comes picks him up, something the kid likes, it’s probable that kid will learn that this is normal, and something to do when he hurts. For more on learning theory, Johan Vlaeyen summarises the state of play in a review paper from 2015 (Vlaeyen, 2015).
We’re smart, us humans. We learn to predict and remember patterns even from imprecise data – it doesn’t take much for us to put two and two together, particularly when it’s something relevant to surviving! Whenever I’m listening to someone telling me their story about why they’re presenting in this way at this time, and what is maintaining their situation, I keep thinking about the various learning mechanisms involved. Social context and the people around us and how they respond to us exert a powerful force on what we do – and many times we’re not even aware of why we do what we do. Knowing this stuff means that when I’m listening to someone’s story I try very hard to factor in those things that may have influenced what the person does, rather than just thinking the person is aware of doing all they are doing.
Benedetti, F. (2013). Placebo and the new physiology of the doctor-patient relationship. Physiological Reviews, 93(3), 1207-1246. doi:10.1152/physrev.00043.2012
Engel, G. L. (1977). The need for a new medical model: A challenge for biomedicine. Science, 196(4286), 129-136.