Believe in your placebo

Optimizing Placebo and Minimizing Nocebo to Reduce Pain, Catastrophizing, and Opioid Use: A Review of the Science and an Evidence-Informed Clinical Toolkit

Pain, a noxious psychosensory experience, motivates escape behavior to assure protection and survival. Psychological factors alter the experience and trajectory of pain, as well as behavior and treatment response. In the context of pain, the placebo effect (expectation for pain relief) releases endogenous opioids and facilitates analgesia from exogenously administered opioids. Nocebo hyperalgesia (expectation for persistent or worsening pain) opposes endogenous opioid analgesia and patient engagement in prescription opioid tapering. Reductions in nocebo hyperalgesia and pain catastrophizing may enhance descending modulation of pain, mediate adaptive structural brain changes and promote patient engagement in opioid tapering. Interventions that minimize nocebo and optimize placebo may adaptively shape the central nervous system toward pain relief and potentially opioid reduction. Here we provide a critical description of catastrophizing and its impact on pain, placebo and nocebo effects. We also consider the importance of minimizing nocebo and optimizing placebo effects during prescription opioid tapering, and offer a clinical toolkit of resources to accomplish these goals clinically.

Placebo Effect: Theory, Mechanisms and Teleological Roots

Why pain can be relieved with placebos is heavily debated. The term "placebo effect," implies that the placebo treatment induces pain relief which is imprecise because it is the mental cueing to the context of treatment and not the placebo itself that can reduce pain. This essay reverts to fundamentals of perception that have been used to explain how context generates predictions that can in turn effect the process of processing, organizing and interpreting of sensory inputs received from the periphery. We reinterpret placebo effect as a neurobiological phenomenon that occurs through the process of reward and aversive learning. The brain uses learnt information to generate predictions. The perceptual processes adjust the experience of pain to fit with the predictions generated from prior information. Placebo effect is thus understandably a result of the expectations and mental states that result from engaging in the process of treatment. These processes have teleological roots in ancient medicine and are the context that produces these responses is transforming with the evolution of modern medicine. Thus, when placebo effect is observed, the potent agent that induces pain reduction is not the placebo itself, but the mental cueing to the context of taking treatment.

Brain imaging tests for chronic pain: medical, legal and ethical issues and recommendations

Chronic pain is the greatest source of disability globally and claims related to chronic pain feature in many insurance and medico-legal cases. Brain imaging (for example, functional MRI, PET, EEG and magnetoencephalography) is widely considered to have potential for diagnosis, prognostication, and prediction of treatment outcome in patients with chronic pain. In this Consensus Statement, a presidential task force of the International Association for the Study of Pain examines the capabilities of brain imaging in the diagnosis of chronic pain, and the ethical and legal implications of its use in this way. The task force emphasizes that the use of brain imaging in this context is in a discovery phase, but has the potential to increase our understanding of the neural underpinnings of chronic pain, inform the development of therapeutic agents, and predict treatment outcomes for use in personalized pain management. The task force proposes standards of evidence that must be satisfied before any brain imaging measure can be considered suitable for clinical or legal purposes. The admissibility of such evidence in legal cases also strongly depends on laws that vary between jurisdictions. For these reasons, the task force concludes that the use of brain imaging findings to support or dispute a claim of chronic pain - effectively as a pain lie detector - is not warranted, but that imaging should be used to further our understanding of the mechanisms underlying pain.

Placebo effects in neurological diseases

There is an imperious need of redefining placebo effect in contemporary times. The effects of sham medical intervention, combined with a careful observation of the natural evolution of a disease, could reveal the true efficiency and impact of active drugs. This interest is not driven only by a scientific curiosity, but also by the pragmatic fact that the standard process of approving new medicines through supportive clinical trials requires a comparison against placebo. A complete understanding of the placebo effect should include both its psychological mechanisms and the underlying neurobiology. In contrast to other type of conditions, neurological disorders could provide specific clues in understanding the placebo effect, since the pathogenic mechanisms of different diseases might interfere with neuronal circuitry involved in the perception of disease symptoms. However, there are ethical considerations dictating the limits of using placebo. This paper reviews recent articles about placebo effect, with an emphasis on its importance in several neurological conditions (Parkinson's disease, neuropathic pain, headache, multiple sclerosis, epilepsy), and intends to offer new insights on this major topic.

Experimental designs and brain mapping approaches for studying the placebo analgesic effect

The placebo effect has intrigued scientists since it was proposed. The debate has now centered on how it works. Significant progress has been made and most of our knowledge about the neurobiological mechanisms comes from the field of pain and analgesia. The appropriateness of the experimental/clinical paradigms is crucial when we want to investigate the mechanisms of the placebo phenomenon. Recently, functional imaging techniques, such as positron emission tomography, magnetic resonance imaging, and electro/magnetoencephalography have also given the opportunity to define the neuroanatomical bases of placebo analgesia. This work systematically reviews the literature that deals with placebo analgesia, emphasizing both the methodological aspects and the neurobiological advances. The understanding of placebo mechanisms is fundamental and necessary to identify ways of accessing and harnessing these mechanisms in clinical practice to the patient's benefit.

Monitoring Brain Oxygen Saturation During Coronary Bypass Surgery: A Randomized, Prospective Study

BACKGROUND

Cerebral deoxygenation is associated with various adverse systemic outcomes. We hypothesized, by using the brain as an index organ, that interventions to improve cerebral oxygenation would have systemic benefits in cardiac surgical patients.

METHODS

Two-hundred coronary artery bypass patients were randomized to either intraoperative cerebral regional oxygen saturation (rSO2) monitoring with active display and treatment intervention protocol (intervention, n = 100), or underwent blinded rSO2 monitoring (control, n = 100). Predefined clinical outcomes were assessed by a blinded observer.

RESULTS

Significantly more patients in the control group demonstrated prolonged cerebral desaturation (P = 0.014) and longer duration in the intensive care unit (P = 0.029) versus intervention patients. There was no difference in overall incidence of adverse complications, but significantly more control patients had major organ morbidity or mortality (death, ventilation >48 h, stroke, myocardial infarction, return for re-exploration) versus intervention group patients (P = 0.048). Patients experiencing major organ morbidity or mortality had lower baseline and mean rSO2, more cerebral desaturations and longer lengths of stay in the intensive care unit and postoperative hospitalization, than patients without such complications. There was a significant (r(2) = 0.29) inverse correlation between intraoperative rSO2 and duration of postoperative hospitalization in patients requiring > or =10 days postoperative length of stay.

CONCLUSION

Monitoring cerebral rSO2 in coronary artery bypass patients avoids profound cerebral desaturation and is associated with significantly fewer incidences of major organ dysfunction.