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Psychological Medicine Oct 2020Placebos are not inert, but exert measurable biological effects. The placebo response in psychiatric illness is important and clinically relevant, but remains poorly... (Review)
Review
Placebos are not inert, but exert measurable biological effects. The placebo response in psychiatric illness is important and clinically relevant, but remains poorly understood. In this paper, we review current knowledge about the placebo response in psychiatric medicine and identify research directions for the future. We argue that more research is needed into the placebo response in psychiatric medicine for three broad reasons. First, awareness of factors that cause placebo response, for whom, and when, within clinical trials will allow us to better evidence efficacy of new treatments. Second, by understanding how placebo mechanisms operate in the clinic, we can take advantage of these to optimise the effects of current treatments. Finally, exploring the biological mechanisms of placebo effects might reveal tractable targets for novel treatment development.
Topics: Clinical Trials as Topic; Humans; Mental Disorders; Placebo Effect; Placebos; Psychiatry
PubMed: 33028433
DOI: 10.1017/S0033291720003633 -
PloS One 2019Previous studies have found a positive effect of cosmetics on certain behavioral measures, such as the tip given to waitresses by male patrons. These studies have...
Previous studies have found a positive effect of cosmetics on certain behavioral measures, such as the tip given to waitresses by male patrons. These studies have employed confederates who usually wear cosmetics. We therefore sought to examine whether the positive effect found in these studies could, in part, be explained by a change in behavior. In order to test the possibility of a 'cosmetics placebo effect', we employed a confederate to solicit donations from passersby. On some days our confederate would not have any cosmetics applied to her face (i.e., no cosmetics condition), on some days cosmetics were pretended to be applied to her face (i.e., placebo cosmetics condition), and on other days cosmetics were actually applied to her face (i.e., cosmetics condition). In line with previous research, we found that across conditions men donated significantly more than women to our female solicitor, providing support for the 'showoff hypothesis', in which male generosity serves as a mating tactic. When investigating men's donations in more detail, we found that the highest percentage of donations came in the cosmetics condition, followed by the placebo cosmetics condition, and then by no cosmetics condition. The effect of condition on donation rates, however, was not statistically significant. Our study was limited to one solicitor and one dependent variable (i.e., percentage of people approached who donated) and therefore future research would benefit from using more confederates as well as examining other behavioral measures. Given the influence of cosmetics use on so many real-world outcomes, we believe that further exploration into a possible 'cosmetics placebo effect' would be valuable.
Topics: Beauty; Behavior; Cosmetics; Face; Female; Humans; Male; Men; Placebo Effect; Social Perception
PubMed: 30629657
DOI: 10.1371/journal.pone.0210238 -
Neuroscience and Biobehavioral Reviews Jun 2020Placebo and nocebo effects can influence somatic symptoms such as pain. For itch and other dermatological symptoms these effects have been far less investigated. This... (Review)
Review
Placebo and nocebo effects can influence somatic symptoms such as pain. For itch and other dermatological symptoms these effects have been far less investigated. This review systematically integrates evidence from both animal (mainly rodents) and human trials on placebo and nocebo effects in itch, itch-related symptoms and conditions of the skin and mucous membranes, and related immune outcomes (e.g., histamine). Thirty-one animal studies, and fifty-five human studies (k = 21 healthy participants, k = 34 patients) were included. Overall, studies consistently show that placebo and nocebo effects can be induced by various methods (e.g., suggestions, conditioning and social cues), despite high heterogeneity across studies. Effects of suggestions were found consistently across subjective and behavioral parameters (e.g., itch and scratching in humans), whereas conditioning was likely to impact physiological parameters under certain conditions (e.g., conditioning of histamine levels in stressed rodents). Brain areas responsible for itch processing were associated with nocebo effects. Future research may investigate how variations in methods impact placebo and nocebo effects, and whether all symptoms and conditions can be influenced equally.
Topics: Animals; Cues; Humans; Nocebo Effect; Pain; Placebo Effect; Pruritus; Suggestion
PubMed: 32240668
DOI: 10.1016/j.neubiorev.2020.03.025 -
Pain Physician Jul 2017It is the gold standard to use a placebo treatment as the control group in prospective randomized controlled trials (RCTs). Although placebo-controlled trials can reveal... (Randomized Controlled Trial)
Randomized Controlled Trial
BACKGROUND
It is the gold standard to use a placebo treatment as the control group in prospective randomized controlled trials (RCTs). Although placebo-controlled trials can reveal an effect of an active treatment, the pure effect of a placebo treatment alone has never been presented or evaluated. No evidence-based, placebo-therapeutic options are currently available, and no placebo-controlled trials have been performed to elucidate the pure placebo effect.
OBJECTIVES
To analyze the pure placebo effect on clinical, chronic pain through a blinded RCT.
STUDY DESIGN
A prospective, randomized, placebo-controlled trial.
SETTING
Medical University centers.
METHODS
One-hundred eighty-two patients suffering from chronic plantar heel pain for over 6 months,who failed to respond to conservative treatments, were screened and 106 of these patients were enrolled into this study. The patients were randomly assigned to receive either a blinded placebo shockwave treatment or an unblinded placebo shockwave treatment. The primary outcome measure was the differences in percentage change of visual analogue scale (VAS) scores 6 weeks after the intervention. The secondary outcome measure was the differences in Roles and Maudsley pain score (RMS) 6 weeks after intervention. As an exploratory outcome, 2-sided group comparisons for baseline characteristics between active treatment and controls were done using the Mann-Whitney-U tests for group comparisons; treatment efficiency was calculated by the effect size coefficient and benchmarks for the Mann-Whitney estimator according to the t-test of 2 independent samples for quantitative data, as well as the Fisher's exact test for binary data.
RESULTS
Patients from both groups did not differ with respect to heel pain ratings at baseline, for both the VAS (P = .476) and RMS (P = .810) scores. After 6 weeks, patients receiving the blinded placebo treatment reported less heel pain on both scales (VAS: P = .031; RMS: P = .004). Change scores of pain ratings were significantly higher in the blinded placebo group than in the un-blinded placebo group (VAS: P = .002; RMS: P = .002).
LIMITATIONS
As the study represents the first to use an inverse placebo RCT (IPRCT), further conceptual and methodological issues need to be addressed to describe detailed, underlying mechanisms. Specific contextual, intrapersonal, and interpersonal factors modulating the placebo effects should be addressed in future IPRCTs.
CONCLUSIONS
The present study indicated that true placebo effect sizes can be analyzed through a proper IPRCT design. Instead of treating high numbers of patients with placebos in a RCT, which increases the risk for subjects not receiving the active treatment, the IPRCT technique seems to be much more appropriate to analyze the effect sizes of any active treatment, in accordance with the Good Clinical Practice guidelines and Declarations of Helsinki.
KEY WORDS
Pain, randomized controlled trial, RCT, placebo, effect size, inverse placebo, study, pain therapy.
Topics: Adult; Aged; Chronic Pain; Female; Humans; Male; Middle Aged; Placebo Effect; Research Design
PubMed: 28727701
DOI: No ID Found -
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 -
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 -
European Journal of Sport Science Apr 2020The aim of this review was to determine the magnitude of the placebo and nocebo effect on sport performance. Articles published before March 2019 were located using...
The aim of this review was to determine the magnitude of the placebo and nocebo effect on sport performance. Articles published before March 2019 were located using Medline, Web of Science, PubMed, EBSCO, Science Direct, and Scopus. Studies that examined placebo and nocebo effects of an objective dependent variable on sports performance, which included a control or baseline condition, were included in the analysis. Studies were classified into two categories of ergogenic aids: (1) nutritional and (2) mechanical. Cohen's effect sizes were calculated from 32 studies involving 1513 participants. Small to moderate placebo effects were found for both placebo ( = 0.36) and nocebo ( = 0.37) effects and when separated by nutritional ( = 0.35) and mechanical ( = 0.47) ergogenic aids. The pooled effect size revealed a small to moderate effect size across all studies ( = 0.38). Results suggest that placebo and nocebo effects can exert a small to moderate effect on sports performance.
Topics: Athletic Performance; Dietary Supplements; Humans; Nocebo Effect; Performance-Enhancing Substances; Placebo Effect; Transcutaneous Electric Nerve Stimulation
PubMed: 31414966
DOI: 10.1080/17461391.2019.1655098 -
Brazilian Journal of Medical and... Jul 2016The objective of this study was to perform a systematic review and meta-analysis to assess the effectiveness of proton pump inhibitors (PPI) for reflux disease in adult... (Meta-Analysis)
Meta-Analysis Review
The objective of this study was to perform a systematic review and meta-analysis to assess the effectiveness of proton pump inhibitors (PPI) for reflux disease in adult patients with laryngopharyngeal symptoms. A comprehensive search of Cochrane Library, EMBASE, Ovid EBM Reviews, and PubMed was performed for English-language literature about laryngopharyngeal reflux (LPR), in September 2014. The papers were filtered using pre-defined inclusion and exclusion criteria. Eight papers were identified and included in this meta-analysis. The sample comprised a pooled total of 370 patients, of which 210 and 160 patients took PPIs and placebo, respectively. The difference between PPIs and placebo groups in overall improvement of symptoms in adult patients with LPR was not statistically significant (RR=1.22; 95%CI=0.93-1.58; P=0.149). The difference in cough improvement was also not significant between PPIs and placebo groups (RR=0.65; 95%CI=0.30-1.41; P=0.279).
Topics: 2-Pyridinylmethylsulfinylbenzimidazoles; Adult; Female; Humans; Laryngopharyngeal Reflux; Male; Placebo Effect; Proton Pump Inhibitors; Treatment Outcome
PubMed: 27383119
DOI: 10.1590/1414-431X20165149 -
Proceedings of the National Academy of... May 2021Harnessing placebo and nocebo effects has significant implications for research and medical practice. Placebo analgesia and nocebo hyperalgesia, the most well-studied... (Randomized Controlled Trial)
Randomized Controlled Trial
Harnessing placebo and nocebo effects has significant implications for research and medical practice. Placebo analgesia and nocebo hyperalgesia, the most well-studied placebo and nocebo effects, are thought to initiate from the dorsal lateral prefrontal cortex (DLPFC) and then trigger the brain's descending pain modulatory system and other pain regulation pathways. Combining repeated transcranial direct current stimulation (tDCS), an expectancy manipulation model, and functional MRI, we investigated the modulatory effects of anodal and cathodal tDCS at the right DLPFC on placebo analgesia and nocebo hyperalgesia using a randomized, double-blind and sham-controlled design. We found that compared with sham tDCS, active tDCS could 1) boost placebo and blunt nocebo effects and 2) modulate brain activity and connectivity associated with placebo analgesia and nocebo hyperalgesia. These results provide a basis for mechanistic manipulation of placebo and nocebo effects and may lead to improved clinical outcomes in medical practice.
Topics: Adult; Analgesia; Analysis of Variance; Brain; Double-Blind Method; Female; Humans; Hyperalgesia; Magnetic Resonance Imaging; Male; Nocebo Effect; Pain; Pain Management; Placebo Effect; Prefrontal Cortex; Surveys and Questionnaires; Transcranial Direct Current Stimulation; Young Adult
PubMed: 33941677
DOI: 10.1073/pnas.2101273118 -
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