jueves, 3 de agosto de 2017


Agosto 3, 2017. No. 2769


Un condicionamiento clásico sin sugerencias verbales provoca analgesia placebo e hiperalgesia nocebo.
A Classical conditioning without verbal suggestions elicits placebo analgesia and nocebo hyperalgesia.
PLoS One. 2017 Jul 27;12(7):e0181856. doi: 10.1371/journal.pone.0181856. eCollection 2017.
The aim of this study was to examine the relationships among classical conditioning, expectancy, and fear in placebo analgesia and nocebo hyperalgesia. A total of 42 healthy volunteers were randomly assigned to three groups: placebo, nocebo, and control. They received 96 electrical stimuli, preceded by either orange or blue lights. A hidden conditioning procedure, in which participants were not informed about the meaning of coloured lights, was performed in the placebo and nocebo groups. Light of one colour was paired with pain stimuli of moderate intensity (control stimuli), and light of the other colour was paired with either nonpainful stimuli (in the placebo group) or painful stimuli of high intensity (in the nocebo group). In the control group, both colour lights were followed by control stimuli of moderate intensity without any conditioning procedure. Participants rated pain intensity, expectancy of pain intensity, and fear. In the testing phase, when both of the coloured lights were followed by identical moderate pain stimuli, we found a significant analgesic effect in the placebo group, and a significant hyperalgesic effect in the nocebo group. Neither expectancy nor fear ratings predicted placebo analgesia or nocebo hyperalgesia. It appears that a hidden conditioning procedure, without any explicit verbal suggestions, elicits placebo and nocebo effects, however we found no evidence that these effects are predicted by either expectancy or fear. These results suggest that classical conditioning may be a distinct mechanism for placebo and nocebo effects.

Papel terapéutico del placebo: evolución de un nuevo paradigma en la comprensión de la investigación y la práctica clínica
Therapeutic Role of Placebo: Evolution of a New Paradigm in Understanding Research and Clinical Practice.
Pain Physician. 2017 Jul;20(5):363-386.
Research into interventional techniques in managing chronic spinal pain continues to be challenging, mystifying, confusing, and biased. Insight, or lack thereof, into placebo and nocebo phenomena contributes mightily to these difficulties. Unfortunately, placebo-nocebo responses are the subject of numerous controversies and challenges from not only a research perspective, but also clinical perspective. While interventionalists consider the biggest threat to interventional pain management research is inappropriate and outdated interpretation of the data, a greater problem is the misuse of the placebo response in research, with the declaration that all and everything as a placebo effect: with a misinterpretation of the nature of the placebo the, associated conclusions can be inaccurate. Researchers have been aware of placeboand nocebo effects for decades, even though misunderstandings and misgivings continue to be seen in scientific studies. In simplistic terms, placebo and nocebo had been understood to indicate improving or worsening of symptoms that occur during treatment with placebo/nocebo drugs or modalities. However, research has demonstrated that such terminology does not necessarily reflect "true" placebo effect or nocebo response. These effects are based on numerous factors, including natural course of a disease, spontaneous remission, regression to the mean, and a multitude of other conceptual, explanatory, and moral challenges. In modern clinical research, a neutral substance called placebo has been mainly used as a comparison factor rather than being studied itself, while the nocebo response has only been minimally studied.A major misconception involves active placebo, a concept that has been extended beyond the administration of inert substances. The definition of active placebo of an active agent given to a patient, even though the pharmacologic action of the active agent is not known to be beneficial, has been converted to conveniently change many of the treatments which are effective on their own to be defined as placebos, often leading to conclusions that none of the interventions are effective. This review focuses on a multitude of controversies surrounding placebo and nocebo phenomena in research and clinical applications. The discussion includes a focus on unsolved, forgotten, and ignored features of placebo responses in medicine, and provides an appropriate understanding of placebo and nocebo phenomena in interventional pain management. To that effect, this review also describes therapeutic placebos, research with open placebos, and improvements in understanding clinical applications of present interventional pain management research.
KEYWORDS: Placebo effect; active control trials active placebos.; interventional techniques; nocebo response; placebo analgesia

Los mecanismos moleculares de las respuestas al placebo en la analgesia
Alberto Porras, Alberto del Arco, Gregorio Segovia y Rodrigo Martínez
El Comité Ejecutivo de la IASP insta a Venezuela a centrarse en el acceso a medicamentos para el dolor a la luz de escasez crítica
IASP Executive Committee Urges Venezuela to Focus on Access to Pain Medications in Light of Critical Shortages
As the leading global organization that brings together scientists, clinicians, health-care providers, and policymakers to stimulate and support the study of pain with the goal of improved pain relief worldwide, the International Association for the Study of Pain (IASP) has been made aware that difficult conditions in Venezuela have resulted in inadequate access to pain treatment.
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