What is the Placebo Effect?
- HomeWhat is the Placebo Effect?
Just mentioning the placebo effect can cause many health professionals to get quite defensive. There is good reason for this- the placebo has had a long and coloured history, including many snake oil salesmen exploiting this phenomenon. It is only within the last 60 years that it has been studied, and only within the last few decades that it has been recognized as an important, inseparable component of the medical encounter. Whether looking at a medical assessment, a simple x-ray, or open heart surgery[i], the placebo (or nocebo) effect comes in to play. If we choose to ignore it, we do so at the patient’s peril, because what you say, how you say it, how you dress, and even the decor of your clinic can either have positive or negative effects on clinical outcomes.
Many arguments around the placebo effect involve semantics and turf wars. However, whether one uses terms such as non-specific effects, contextual effects, psychosocial factors, or placebo effect, you are largely speaking about the same thing. The mind has the ability to up-regulate, or down-regulate existing biological pathways. What we are really talking about when examining this subject is the fact that psychosocial factors surrounding the clinical encounter have been shown to affect your client’s course of healing, and their perception of pain. This idea is gaining so much traction as a clinical model that you now see the concept of biopsychosocial model emerging as a more complete way of understanding pain, injury and healing. This new model does not discount the important biological factors at play, but there were too many disparities in the biological model for it to provide a complete explanation. The more that structural abnormality was examined, the more tenuous the connection became between structural issues and pain or dysfunction. [ii] This is only one of many reasons why the biopsychosocial model is a more inclusive manner of not just understanding, but treating injury, pain and dysfunction.
Essence of the Placebo Response[iii]
A graphic representation of what appears to be going on with the placebo effect can be seen below.
A psychosocial trigger can up-regulate or down-regulate a biological pathway, which then creates an effect. We see subjective effects such as changes in pain perception and patient descriptions of wellness states, but also objective changes as well. Some of these changes are temporary, but some can last the entire duration of the study.
Several systematic reviews in recent years have looked at the role of this phenomenon in manual therapy and authors have overwhelmingly concluded that these effects are ubiquitous. Furthermore, conclusions from these analyses recommend that therapists should acquaint themselves with the psychosocial factors that trigger this effect, firstly to enhance clinical outcomes, but secondly to avoid producing unintended nocebo responses. In the citations below you can find three of the most current reviews[iv] on this topic.
What you need to know is that what you say, and how you say it is extremely important. If we look at your manual treatments as being the practice of the science of manual therapy, then managing the contextual factors would be described as the ‘art’ of manual therapy. Becoming an excellent therapist means becoming proficient in both the science and the art of your profession.
[i] Wolf, B.R., Buckwalter, J.A. Randomized Surgical Trials and “Sham” Surgery: Relevance to Modern Orthopaedics and Minimally Invasive Surgery. Iowa Orthop J. 2006. 26: 107–111.
[ii] Brinjikji, W, Luetmer, P.H., Comstock, B. Et al. Systematic literature review of imaging features of spinal degeneration in asymptomatic populations. AJNR Am J Neuroradiol. 2015 Apr;36(4):811-6. doi: 10.3174/ajnr.A4173.
[iii] Fulton, B. Placebo Effect in Manual Therapy. Improving Clinical Outcomes in Your Practice. Edinburgh, United Kingdom. Handspring Publishing, 2015.
[iv] Testa M, Rossettini G. (2016) Enhance placebo, avoid nocebo: How contextual factors affect physiotherapy outcomes. Man Ther. Aug;24:65-74.
Bialosky JE, Bishop MD, George SZ, Robinson ME. (2011) Placebo response to manual therapy: something out of nothing? J Man Manip Ther. Feb;19(1):11-9.
Bronfort, G., Haas, M., Evans, R. et al. (2010) Effectiveness of manual therapies: the UK evidence report. Chiropr Osteopat. 18: 3.