by Professor Chris Ponting

A guide to the Biopsychosocial model recently put out by Long Covid Advocacy ultimately brought me to a 2005 book chapter, written by Professor George Davey Smith, entitled The biopsychosocial approach: a note of caution in Biopsychosocial Medicine: An Integrated Approach to Understanding Illness, edited by Peter White and published by Oxford University Press. The chapter is available from a University of Bristol website. I thought the divergence of opinion between Profs Davey Smith and Wessely was sufficiently interesting to write this short commentary.

In the book chapter, Davey Smith asked the question “what is the evidence that psychosocial factors are direct aetiological factors in chronic diseases, acting through psychoneuroendocrinological (or other currently fashionable) mediating mechanisms?” Using examples of peptic ulcer and ischaemic heart disease, he ultimately concluded that “When interventional studies have been used to examine the efficacy of a psychosocial approach the results have been disappointing.”

He quoted Susan Sontag’s 1978 book Illness as a metaphor: “Theories that diseases are caused by mental state and can be cured by willpower are always an index of how much is not understood about the physical basis of the disease.” He further commented that “Her reason for being sceptical of the BPS model was that she saw it as a way of putting blame for disease on the people with disease.”

Davey Smith started his peptic ulcer story by saying that decades-long epidemiological research suggested that the cause of peptic ulcer was stress: a specific personality type – those who were worriers, over-conscientious and over-active – tended to get more peptic ulcers. Despite psychological treatments that sought to reduce stress, many died after gastroduodenal bleeding. Davey Smith wrote that “Of course the usual claims for dramatic success were made, but properly conducted randomized controlled trials demonstrated no benefit of such time-consuming and expensive treatments.” We know now that peptic ulcer is not caused by stress but by Helicobacter pylori infection or long-term use of pain relief medication.

Despite George Davey Smith not once referring to myalgic encephalomyelitis / chronic fatigue syndrome (ME/CFS) in his book chapter, the evident parallels between peptic ulcer and ME/CFS, and the lack of efficacy of psychological treatments for both of these diseases, were not lost on one of the book chapter commentators, Professor Simon Wessely (Institute of Psychiatry, King’s College London). Prof Wessely commented “That was a powerful and uncomfortable paper” before continuing that “There will undoubtedly be many people, including, for example, those who one might call ‘CFS activists’, who would have loved every word you were saying.”

The first comment reveals how Wessely is discomfited by Davey Smith saying that the BPS model is not aetiologically important.

Wessely’s last comment admits two further matters. First, that Davey Smith’s discussion of bias, especially in observational studies, closely follows the logical arguments often made by BPS model dissenters. Second, it implies that anyone disagreeing with Wessely’s view of the BPS model’s aetiological relevance should immediately be discredited as an ‘activist’, a needlessly pejorative term. The implicit exception is Davey Smith, due to his status as a distinguished Professor of Clinical Epidemiology. Wessely’s tactic was to shift focus from possible valid objections and onto whether the critic has status, leaving the main issue open.

Davey Smith described the results of BPS interventional studies as ‘disappointing.’ This anticipated the results of the PACE trial (2011), whose patient recruitment started just as this book was published. The trial’s investigators reported that two interventions (cognitive behavioural therapy [CBT] and graded exercise therapy [GET]) were “moderately” effective at treating ME/CFS. However, later analysis under the original study protocol failed to find significant effects.

The evidence for the benefit of GET and CBT was later deemed to be of “low or very low certainty” by the National Institute for Health and Care Excellence (NICE) guideline (2021). A year later, Peter White, Michael Sharpe, and Trudie Chalder (the three principal investigators of the PACE trial), with Simon Wessely and others, objected to this guideline. George Davey Smith’s book chapter can be read to anticipate their arguments. He said: “Authors choose to cite the studies that support their hypothesis, ignoring those that run in the exactly opposite direction.”

Chris P Ponting, August 10, 2026