For example, in cancer patients, when an initial dose of chemotherapy causes nausea and vomiting, up to 30% of patients go on to suffer anticipatory nausea and vomiting for the remainder of the chemotherapy course (Roscoe et al 2011). Aside from being clearly distressing GDC-0068 and debilitating, such a learned

protective perception introduces a potent barrier to potentially life-saving therapy. Notably, in this situation, current management of anticipatory nausea advocates preventing nausea and vomiting with the first exposure to chemotherapy, ie, avoid the sensory experience in the first place. How common are these disorders of hyper-protection? In the general population, chronic pain and dyspnoea have a prevalence of 20% (Blyth et al 2001) and 9% (Currow et al 2009), respectively. Not surprisingly, chronic pain and refractory dyspnoea have much in common. Both motivate immediate and persistent behaviours that lead

to secondary physical, psychological, and social health consequences. Although the detector mechanisms that most often trigger pain (nociceptors) or dyspnoea (noci-, chemo- and mechanoreceptors) might differ, their cortical substrates are remarkably similar (Parshall et al 2012, von Leupoldt et al 2005, von Leupoldt et al 2009). In neither are there consistent associations between the severity of the structural or physiological abnormality and the severity of the impairment caused by the sensation. Finally, neither has a clear and clearly effective treatment approach. As physiotherapists, we have an enviable history of developing effective management strategies for ‘signs’ (the things we can observe and objectively measure) with the inference that, find more where interventions (education, exercise, training etc) are effective, there will be an improvement in ‘symptoms’ (the perceptions our patients experience). Where the symptoms are acute, this seems a reasonable mechanistic sequence. In many acute conditions, both signs

and symptoms else do improve with physiotherapy intervention (Reeve et al 2010, Dean et al 2010, Høsøien et al 2010). However, where the symptoms are chronic, they may have a more tenuous relationship with signs and targeting the latter might be expected to have little effect on the former (Chien et al 2011). There is a tendency, however, to hang on to more tissue-based paradigms, even if they do not fit. That is, we tend to collect any instances that confirm a tissue-based paradigm, and though there may be contrary instances, we either do not notice them or we reject them, perhaps in order that our opinions will remain unshaken (Bacon 1620). Our opinions are changing, however slowly. Enough is now known about these survival perceptions to be sure that they all serve to protect us from a situation that the brain perceives to be dangerous, whether or not the situation truly is dangerous. Broadening our view of why a survival perception persists brings into sight potentially important treatment targets.