My recent research (for an article) into the biopsychosocial (the ‘BPS’) approach to pain treatment and management has really surprised me. This approach has been around for quite a long time and in that time it’s come to dominate mainstream treatment and management of pain, so I expected to find a fully developed and thoroughly scrutinised theory; but I found nothing of the sort. Detailed accounts that purport to be about the BPS approach tend to focus on treatment and management strategies rather than the fundamental principles of a properly worked out theory. This has left me wondering if there’s anything more to the BPS approach than a system of classification that categorises the multiple causal influences on and therapeutic approaches to pain as biological, psychological, or social. If this is right, the significance of the BPS approach must be illusory.

I’m fairly sure that many reading this post will immediately reject my tentative conclusion for the obvious reason that theoretical substance is a good explanation for the widespread use of the ‘biopsychosocial’ label to describe theory, as well as treatment and management strategies. My response is that the widespread use of BPS terminology does not amount to theoretical substance. And crucially the use of these terms has an alternative explanation.

The birth of the BPS approach is usually traced back to the psychologist George Engel’s influential paper, “The need for a new medical model: a challenge for biomedicine”, which was published in 1977. This was a response to the highly influential and controversial work of the psychiatrist Thomas Szasz. Even though they appear to have radically different views, Engel and Szasz are in agreement on two points: (1) the mainstream medical model focuses on the diagnosis and treatment of (objective) biological cause of disease; (2) this model neglects the (subjective) psychological and social aspects of disease. Szasz took (1) and (2) as evidence that mental illnesses are not illnesses in the (true) biological sense of bodily illness, and so psychiatry/psychology is pseudo-science (Szasz, 1962, 2001). By contrast, Engel saw (1) and (2) as a failing of the mainstream medical model. His conclusion was that, (3) the psychosocial aspects of disease require greater emphasis in medicine generally. It’s important to note that Engel didn’t present a thoroughly worked out BPS model; it’s more a statement of a general principle (3) and a rallying call.

While Engel’s view of mainstream medicine proved controversial it resonated in some quarters. In the 1970s and 1980s the approach of some front-line practitioners slotted readily into (1), and (2): pain is merely a symptom of injury or disease (of biology); and pains that don’t appear to be causally linked to injury or disease are mysterious, not a proper concern of medicine, and nothing to worry about (because “there’s nothing really wrong”). The solution to this misguided and harmful approach was, of course, better education; an education that emphasised the importance of psychosocial factors (3).

At the same time, the International Society for the Study of Pain (the ‘IASP’), which was founded in 1973, was emerging as the educating force in pain science. Put succinctly the message they were pressing in the early 1980s was that pain is a psychological state with multiple causal influences. As BPS classification appears to naturally accord with this message, the cottage industry of shoe-horning pain’s multiple causal influences into biological, psychological, and social categories quickly developed. Note that the substance of this approach is not categorisation, but the causal influences themselves. This is the multidimensional understanding of pain, which is entirely independent of BPS theory.

Ultimately the issue is whether my doubts about the substance of the BPS approach matter. To my mind, the ‘biological’, ‘psychological’, and ‘social’ labels classify the multiple causal influences on pain in a way that simplified complexity and proved extremely useful. However, that was the past. In this day and age, the biological, psychological, and social categories look crude not simple. They create the impression of distinction where there is no meaningful distinction and consequently they mask considerable causal complexity. To illustrate, pain is a conscious experience so it is a psychological state, but pain also has neurological correlates. The difference between pain as psychological state and pain as biological state is one of different explanatory levels, of different ways of thinking about pain; it is not a substantive metaphysical difference. This is true of all psychological states including those states, like belief and emotion, that have a significant causal effect on pain. Another illustration is that patient behaviour, which is a key aspect of pain assessment and treatment, doesn’t fit in any BPS category. If significant progress is to be made, a more nuanced approach to causation needs to be adopted in pain education, assessment, treatment, and management.

Interestingly, while BPS terminology persists, well-informed theorists, educators and practitioners have moved beyond the naïve constraints of BPS categories to a sophisticated approach that better reflects the causal intricacies of the multidimensional understanding that prevails in pain science.