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European Journal of Sport Science Apr 2020Research over the past 15 years on the placebo effect has substantiated its contribution to the efficacy of established treatments for a range of clinical conditions and... (Review)
Review
Research over the past 15 years on the placebo effect has substantiated its contribution to the efficacy of established treatments for a range of clinical conditions and identified its underlying mechanisms. There is also evidence that placebo effects contribute to the performance benefits of many ergogenic aids, and that performance can worsen when dummy treatments are associated with expectations of a harmful outcome (i.e. nocebo effect). Unfortunately, the bulk of sport research involving placebos and nocebos continues to be hampered by outdated definitions and conceptualizations of placebo effects and their mechanisms. This has implications not only for research but also application, as nearly 50% of athletes report experiencing a beneficial placebo effect, and a similar proportion of coaches report providing placebos to their athletes. The objective of this paper is to attempt to stimulate research by presenting updated definitions of placebo and nocebo effects in the context of sport, describing their major mechanisms and, highlighting the importance of the psychosocial context on placebo effects in the sport setting.
Topics: Athletes; Athletic Performance; Humans; Nocebo Effect; Placebo Effect
PubMed: 32023170
DOI: 10.1080/17461391.2020.1727021 -
Brain : a Journal of Neurology Nov 2008Placebo effects are beneficial health outcomes not related to the relatively direct biological effects of an intervention and can be elicited by an agent that, by... (Review)
Review
Placebo effects are beneficial health outcomes not related to the relatively direct biological effects of an intervention and can be elicited by an agent that, by itself, is inert. Understanding these placebo effects will help to improve clinical trial design, especially for interventions such as surgery, CNS-active drugs and behavioural interventions which are often non-blinded. A literature review was performed to retrieve articles discussing placebo implications of clinical trials, the neurobiology of placebo effects and the implications of placebo effect for several disorders of neurological relevance. Recent research in placebo analgesia and other conditions has demonstrated that several neurotransmitter systems, such as opiate and dopamine, are involved with the placebo effect. Brain regions including anterior cingulate cortex, dorsolateral prefrontal cortex and basal ganglia have been activated following administration of placebo. A patient's expectancy of improvement may influence outcomes as much as some active interventions and this effect may be greater for novel interventions and for procedures. Maximizing this expectancy effect is important for clinicians to optimize the health of their patient. There have been many relatively acute placebo studies that are now being extended into clinically relevant models of placebo effect.
Topics: Analgesia; Brain; Controlled Clinical Trials as Topic; Humans; Models, Psychological; Physician-Patient Relations; Placebo Effect; Research Design; Stress, Psychological
PubMed: 18567924
DOI: 10.1093/brain/awn116 -
Alimentary Pharmacology & Therapeutics Jan 2010Randomized, placebo controlled trials are used to assess the efficacy of therapies for Crohn's disease. The placebo response and remission rates vary among studies. (Review)
Review
BACKGROUND
Randomized, placebo controlled trials are used to assess the efficacy of therapies for Crohn's disease. The placebo response and remission rates vary among studies.
AIM
To analyse how the placebo response and remission rates in Crohn's trials have changed over time in the era of parenteral biologic therapies.
METHODS
A search for randomized, placebo-controlled trials of parenteral biologic therapies for active Crohn's disease was conducted using online databases. The placebo response and remission rates and study week of evaluation were recorded for each trial. The placebo response and remission rates were analysed as functions of publication date and study week of evaluation.
RESULTS
The odds of a placebo-induced remission and response significantly increased as the week of evaluation increased. The placebo remission rate increased significantly with year of publication. Adjusted for week of evaluation, this increase in placebo remission rate over time was no longer significant. The increase in the placebo response over this time period was not statistically significant.
CONCLUSION
The observed increase in placebo remission rates over time in trials of parenteral biologic therapies in Crohn's disease is explained by longer times to the primary endpoint in more recent trials.
Topics: Crohn Disease; Enteral Nutrition; Humans; Logistic Models; Placebo Effect; Placebos; Randomized Controlled Trials as Topic; Treatment Outcome
PubMed: 19691670
DOI: 10.1111/j.1365-2036.2009.04125.x -
Psychosomatic Medicine Sep 2011Negative expectations deriving from the clinical encounter can produce negative outcomes, known as nocebo effects. Specifically, research on the nocebo effect indicates... (Review)
Review
Negative expectations deriving from the clinical encounter can produce negative outcomes, known as nocebo effects. Specifically, research on the nocebo effect indicates that information disclosure about potential side effects can itself contribute to producing adverse effects. Neurobiological processes play a role in the nocebo effect, and this article provides a selective review of mechanistic research on the nocebo effect. Comparatively little attention has been directed to clinical studies and their implications for daily clinical practice. The nocebo response is influenced by the content and the way information is presented to patients in clinical trials in both the placebo and active treatment conditions. Nocebo effects adversely influence quality of life and therapy adherence, emphasizing the need for minimizing these responses to the extent possible. Evidence further indicates that the informed consent process in clinical trials may induce nocebo effects. This article concludes with ethical directions for future patient-oriented research and routine practice.
Topics: Anticipation, Psychological; Drug-Related Side Effects and Adverse Reactions; Humans; Informed Consent; Placebo Effect
PubMed: 21862825
DOI: 10.1097/PSY.0b013e3182294a50 -
Cognitive Research: Principles and... Apr 2023Placebo and nocebo effects could influence the perceived, actual, or both postural stabilities. Therefore, this experiment examined whether postural stability is...
Placebo and nocebo effects could influence the perceived, actual, or both postural stabilities. Therefore, this experiment examined whether postural stability is susceptible to placebo and nocebo effects. Driven by expectations, these cognitions could influence the motor stability of people in physical rehabilitation and those with motion instability. We randomly assigned 78 participants to a placebo, nocebo, or control group. Then, we applied a sham sports cream with positive, negative, or neutral instructions about its impact on balance. Next, we tested postural stability with a modified version of the Modified Clinical Test of Sensory Interaction in Balance, including standard, proprioceptive, visual, and vestibular tests before and after the intervention. Further, we measured expected and perceived performance with visual analog scales and assessed trait anxiety, change in state anxiety, optimism, holistic thinking, persistence, and cooperation with questionnaires. The intervention did not affect actual test performances; similarly, trait and state variables and expectations did not have an impact. Furthermore, the experimental manipulation and trait and state variables did not significantly affect perceived performance. However, the association between expectation and perceived performance was strong (ϱ = 0.627, p < 0.001). These findings suggest that postural stability is not susceptible to placebo and nocebo influences. Still, there is a dissociation between objective and subjective performance, showing that expectations impact perceived but not actual performance, which could fuel motivation in rehabilitation settings.
Topics: Humans; Nocebo Effect; Placebo Effect; Cognition; Motivation; Anxiety
PubMed: 37093367
DOI: 10.1186/s41235-023-00476-z -
Medecine Sciences : M/S Mar 2005A placebo is a sham treatment such as pill, liquid, injection, devoid of biological activity and used in pharmacology as a control for the activity of a drug. In many... (Review)
Review
A placebo is a sham treatment such as pill, liquid, injection, devoid of biological activity and used in pharmacology as a control for the activity of a drug. In many cases, this placebo induces biological or psychological effects in the human. Two theories have been proposed to explain the placebo effect: the conditioning theory which states that the placebo effect is a conditioned response, and the mentalistic theory for which the patient expectation is the primary basis of the placebo effect. The mechanisms involved in these processes are beginning to be understood through new techniques of investigation in neuroscience. Dopamine and endorphins have been clearly involved as mediators of the placebo effect. Brain imaging has demonstrated that the placebo effect activates the brain similarly as the active drug and in the same brain area. This is the case for a dopamine placebo in the Parkinson'disease, for analgesic-caffeine- or antidepressor-placebo in the healthy subject. It remains to be understood how conditioning and expectancy are able to activate, in the brain, memory loops that reproduce the expected biological response.
Topics: Animals; Conditioning, Psychological; Humans; Placebo Effect
PubMed: 15745708
DOI: 10.1051/medsci/2005213315 -
Osteoarthritis and Cartilage Sep 2013Administration of a placebo associates with symptomatic improvement in many conditions--the so-called placebo response. In this review we explain the concept of placebo... (Review)
Review
INTRODUCTION
Administration of a placebo associates with symptomatic improvement in many conditions--the so-called placebo response. In this review we explain the concept of placebo response, examine the data that supports existence in osteoarthritis (OA), and discuss its possible mechanisms and determinants.
METHODS
A Pubmed literature search was carried out. Key articles were identified, and their findings discussed in a narrative review.
RESULTS
Pain, stiffness, self-reported function and physician-global assessment in OA clearly improve in response to placebo. However, more objective measures such as quadriceps strength and radiographic progression appear less responsive. Although not directly studied in OA, contextual effects, patient expectation and conditioning are believed to be the main mechanisms. Neurotransmitter changes that mediate placebo-induced analgesia include increased endogenous opioid levels, increased dopamine levels, and reduced levels of cholecystokinin. Almost all parts of the brain involved in pain processing are influenced during placebo-induced analgesia. Determinants of the magnitude of placebo response include the patient-practitioner interaction, treatment response expectancy, knowledge of being treated, patient personality traits and placebo specific factors such as the route and frequency of administration, branding, and treatment costs.
CONCLUSION
Clearer understanding of the neurobiology of placebo response validates its existence as a real phenomenon. Although routine administration of placebo for symptomatic improvement is difficult to justify, contextual factors that enhance treatment response should be employed in the management of chronic painful conditions such as OA where available treatments have only modest efficacy.
Topics: Arthralgia; Brain; Chronic Pain; Humans; Osteoarthritis; Placebo Effect
PubMed: 23973135
DOI: 10.1016/j.joca.2013.04.018 -
Neuron Nov 2014Today we are witnessing a new science of placebo, a complex discipline that encompasses several experimental approaches and translational implications. Modern... (Review)
Review
Today we are witnessing a new science of placebo, a complex discipline that encompasses several experimental approaches and translational implications. Modern neurobiological tools have been used to answer important questions in placebo research, such as the top-down modulation of sensory and motor systems as well as the influence of cognition, emotions, and learning on symptoms, diseases, and responses to treatments. What we have learned is that there is not one single placebo effect, but many. This review highlights the translational implications of this new knowledge, ranging from clinical trial design to medical practice to social and ethical issues.
Topics: Animals; Humans; Mental Disorders; Nervous System Diseases; Neurobiology; Placebo Effect; Translational Research, Biomedical
PubMed: 25442940
DOI: 10.1016/j.neuron.2014.10.023 -
Philosophical Transactions of the Royal... Jun 2011Meta-analyses and re-analyses of trial data have not been able to answer some of the essential questions that would allow prediction of placebo responses in clinical... (Review)
Review
Meta-analyses and re-analyses of trial data have not been able to answer some of the essential questions that would allow prediction of placebo responses in clinical trials. We will confront these questions with current empirical evidence. The most important question asks whether the placebo response rates in the drug arm and in the placebo arm are equal. This 'additive model' is a general assumption in almost all placebo-controlled drug trials but has rarely been tested. Secondly, we would like to address whether the placebo response is a function of the likelihood of receiving drug/placebo. Evidence suggests that the number of study arms in a trial may determine the size of the placebo and the drug response. Thirdly, we ask what the size of the placebo response is in 'comparator' studies with a direct comparison of a (novel) drug against another drug. Meta-analytic and experimental evidence suggests that comparator studies may produce higher placebo response rates when compared with placebo-controlled trials. Finally, we address the placebo response rate outside the laboratory and outside of trials in clinical routine. This question poses a serious challenge whether the drug response in trials can be taken as evidence of drug effects in clinical routine.
Topics: Bioethics; Clinical Trials as Topic; History, 20th Century; History, 21st Century; Humans; Placebo Effect; Publishing; Research Design
PubMed: 21576146
DOI: 10.1098/rstb.2010.0384 -
Journal of Acupuncture and Meridian... Jun 2012The placebo effect has evolved from being thought of as a nuisance in clinical research to a biological phenomenon worthy of scientific investigation. The study of the... (Review)
Review
The placebo effect has evolved from being thought of as a nuisance in clinical research to a biological phenomenon worthy of scientific investigation. The study of the placebo effect and of its evil twin, the nocebo effect, is basically the study of the therapeutic ritual around the patient, and it plays a crucial role in the therapeutic outcome. In recent years, different types of placebo responses have been analyzed with sophisticated biological tools that have uncovered specific mechanisms at the neuroanatomical, neurophysiological, biochemical, and cellular levels. Most of our knowledge about the neurobiological mechanisms of the placebo response comes from pain and Parkinson's disease, whereby the neuronal networks involved in placebo responsiveness have been identified. In the first case, opioid, cannabinoid, and cholecystokinin circuits have been found to be involved. In the second case, dopaminergic activation in the striatum and neuronal changes in basal ganglia have been described. This recent research has revealed that these placebo-induced biochemical and cellular changes in a patient's brain are very similar to those induced by drugs. This new way of thinking may have profound implications in clinical trials and medical practice both for pharmacological interventions and for nonpharmacological treatments such as acupuncture.
Topics: Brain; Ceremonial Behavior; Clinical Trials as Topic; Humans; Placebo Effect; Therapeutics; Treatment Outcome
PubMed: 22682270
DOI: 10.1016/j.jams.2012.03.001