Research Review By Dr. Peter Stilwell©

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Date Posted:

July 2020

Study Title:

An enactive approach to pain: beyond the biopsychosocial model

Authors:

Stilwell P & Harman K

Author's Affiliations:

Faculty of Health, Dalhousie University, Nova Scotia, Canada

Publication Information:

Phenomenology and the Cognitive Sciences 2019; 18(4): 637-665.

Background Information:

Everyone has a working understanding or system of ideas (a theory) to explain pain. However, typically we do not reflect upon nor label our theories. Clinicians’ pain theories, whether they realize it or not, shape the way they assess, explain, and treat pain. In this conceptual paper, we started with a critical review of prominent pain theories from Descartes in the 17th century up to the current landscape, involving increasing application of the biopsychosocial model. We then proposed a novel conceptualization of pain to address limitations and gaps in existing theories. In this Review, I will simplify and summarize the key messages in the 29-page paper.

Descartes considered pain to be linear; peripheral tissues are stimulated and then pain is experienced through a direct line to the brain. He is also famous for suggesting that the mind and body are separate (dualism), which initiated centuries of debate as to where pain is experienced; is it in the mind or body? Over the years, new theories developed that suggested that the linear perspective proposed by Descartes was not fully accurate. This included the gate control theory that suggested nociception could be modulated at the spinal cord and that the brain was not passive, as it could exert anti-nociceptive effects. The gate control theory helped explain injury/nociception without pain (think of war or sports where significant injury is sustained, yet the person reports little or no pain). However, this theory did not help to explain the opposite, where pain is experienced yet there is no injury or underlying condition contributing to nociception (e.g. phantom pain in congenitally absent limbs). Unfortunately, during this era, patients were often stigmatized and advised that their pain was in their head/mind when a bodily reason for pain could not be identified.

In the 1980s and '90s, there was an explosion of interest in the brain. With this came the brain-centric neuromatrix theory that helped explain pain in the absence of peripheral tissue injury/dysfunction. Mind-body dualism was thoroughly discredited by this time and people started asserting that “pain is in the brain” rather than in an immaterial or non-physical mind. Unfortunately, this distinction did not do much to reduce patient stigmatization, as pain was still in one’s head – holding negative connotations. Further, brain-centric approaches began to minimize the importance of the rest of the body, the environment, context, and sociocultural factors.

In contemporary times, many have applied George Engel’s biopsychosocial model to pain. With this, proponents have emphasized the need to consider patients’ biological, psychological, and social factors. However, the biopsychosocial model (as applied to pain) is quite vague, lacks strong underlying theory, and does not explicitly incorporate current theoretical advancements pertaining to perception. Therefore, the biopsychosocial model is implemented in a variety of ways and often (unintentionally) ends up resembling thinking from the era of Descartes – which is contrary to Engel’s original intentions. For example, the biopsychosocial model is often split up; if pain cannot be found in the body (reductionist approach), it must be in the mind or “psychogenic” (dualist approach). We are left with problematic remnants of mind-body dualism; this concept of psychogenic pain is still reflected in notes accompanying the current and most widely accepted definition of pain that was put forth by the International Association for the Study of Pain (IASP). A massive issue remaining is how biological, psychological, and social factors relate in the context of perception/experience; this is the so-called integration problem.

Enactive Approach Summary:

The enactive approach, commonly referred to as enactivism, is an emerging theory of perception/experience that begins to solve the integration problem. The enactive approach was formally introduced in 1991 and was built from a strong theoretical foundation in the cognitive sciences and phenomenology (the tradition of studying consciousness / experience). The enactive approach has gained popularity in recent years and is currently being applied across many domains. In our paper, we applied the enactive approach to pain, as it had not yet been done.

The enactive approach to pain safeguards against artificially splitting a person into biological, psychological, and social components. It also explicitly incorporates phenomenological first-person (subjective) experience, which is a central feature of pain and underappreciated in other pain theories. As a starting point, enactivism considers how the body, brain, and environment are inseparable. Enactivists state that to better understand experience, we need to consider the person-environment system rather than starting with artificial categories (e.g. biological and psychological) that can lead to reductionism (e.g. pain can be found in specific body structures or the brain) or dualism (mind and body are separate). Although enactivism has many philosophical components, two key constructs are: 1) relationality and 2) emergence.

1) Relationality suggests that perception/experience is enacted (brought forth) through interaction between the person (with a body and brain) and the environment. In other words, we are action-oriented and perceive in terms of what we can do – which hinges on the relationship between features of both our bodies and the environment. We present supporting experimental evidence: when participants abduct their arms out to their sides, doorways are perceived to be narrower; and hills are perceived to be steeper when carrying a heavy backpack or when standing at the top on a skateboard versus a stable wooden box. It is not just the orientation of our bodies that shapes perception; for example, hills also appear steeper when participants are fatigued. We used the following metaphor adapted from the philosopher Evan Thompson to summarize that pain is an enactive brain-body-environment process that is relational, not something to be found in the body or the brain:
  • Saying that pain is in the brain is like saying flight is in a bird’s wings. A brain is needed to have pain and wings are needed to fly – but to understand pain or flight, one needs to consider the whole picture and the relational nature between things like a person (with a body/brain) and their social/environmental context; or the bird and the atmosphere. It follows that the experience of pain will not be found in the blood, brain, or other bodily tissues. The tissues in the body or the networks in the brain are not the key to pain – instead they are pieces of a larger system...This always involves the environment that we shape and that shapes us.
The following analogy may also help unravel the concept that perception is relational; pain is a perception that cannot be located in a single part, just as the speed of a car is not located in the engine.

2) Emergence, simply put, refers to the idea that the whole is more than its parts, and that changes or differences in organisational structure can give rise to new processes or entities. Consider the simple example where oxygen and two hydrogen atoms combine in a certain way and this produces water. Examining the parts (only oxygen atoms or only hydrogen atoms) will not capture the essence or properties of the whole (water). The whole cannot be reduced to the parts. We suggest this concept also applies to pain; one needs to consider the full person-environment system and the emerging patient experience. This does not negate examination of the parts such as anatomy/physiology (or oxygen and hydrogen in the water example). Anatomy/physiology are still aspects of the person-environment system – we are just zooming in. The essence or experience of pain will not be revealed by only zooming in on particular parts (e.g. anatomy); we also need to take a step back to look at the person-environment system that enacts pain.

Clinical Application & Conclusions:

The enactive approach to pain is a heuristic framework; it offers a way to think about pain that can shape how chiropractors assess, explain, and treat pain. Regarding assessment, enactivism suggests that we take the subjective nature of pain seriously. Patients’ qualitative narratives are the best available way to somewhat understand a patient’s pain experience. Pain is relational, from a concerned perspective of a person with a unique history and expectations; therefore, one cannot observe that individual’s pain from a third-person or objective perspective. Nor is it possible to negate that person’s idiosyncratic pain experience through a clinical exam or laboratory testing.

Regarding explaining pain, if we take the concepts of relationality and emergence seriously, then we cannot say to a patient that their perception of pain stems solely from a structure in the spine, nor can we say that pain is in the brain. Instead, we need to consider how the full person and their interaction in their environment (past and present) produces the emergent experience of pain from their concerned perspective. The importance of considering the person as inseparable from their environment is emphasized in the growing body of literature on placebo and nocebo effects where context, words, and environmental features combine with a patient’s expectations to shape pain, for better (placebo) or worse (nocebo).

Regarding treatment, taking an enactive approach to pain means considering the full person-environment system; this allows for many points of intervention. One can intervene at the person-level (spinal manipulation, soft tissue therapies, etc.) or the environment (increasing social supports, changing work chair, etc.). This is something chiropractors already do! A change in one part of the person-environment system has potential to change other parts and ultimately create a difference at the level of the whole (person experiencing pain in a particular context).

In conclusion, the enactive approach does not mean throwing away the biopsychosocial model; instead, it adds theoretical patches and moves forward Engel’s original intention of integration and person-centered care. As chiropractors often seek to be holistic healthcare providers, the enactive approach may be appealing as it has a robust theoretical base, is truly integrative, and offers a heuristic, flexible framework to better understand and treat people experiencing pain.

Study Methods:

This was a conceptual paper published in a philosophy journal; therefore, it did not contain original research with a methods section.

Study Strengths / Weaknesses:

As this was a philosophy paper, the strengths and weaknesses outlined in the paper focused on theoretical development. A strength is that we provided an umbrella framework by combining contemporary theories of perception with supporting empirical evidence. However, there are ongoing debates and heterogeneity within enactivism. There are different strands of enactivism developing and we present one variety. There is still much theoretical and empirical research to be conducted. Another limitation is that this is a novel approach, therefore, clinical application is in its infancy. Recent application of enactive principles in medicine and physiotherapy are promising, suggesting that chiropractic may also benefit from embracing enactive theory.

About Dr. Peter Stilwell DC, PhD:

Dr. Peter Stilwell holds a Kinesiology (BKin) degree from the University of Calgary, Doctor of Chiropractic (DC) degree from the Canadian Memorial Chiropractic College (CMCC), and graduate degrees (MSc and PhD) from Dalhousie University. He is currently a full-time Postdoctoral Researcher at McGill University. His research interests include pain and patient-clinician communication. Dr. Stilwell would like to acknowledge the Canadian Chiropractic Guideline Initiative (CCGI) who funded clinical research during his PhD that inspired the theoretical work presented in this review.