Placebo-like Effects Research Articles

The effect of catheter-based sham renal denervation in hypertension: systematic review and meta-analysis

BackgroundRenal denervation (RDN) has emerged in recent years as a possible treatment for hypertension. The first sham-controlled trial showed a small magnitude and non-significant in the blood pressure (BP) lowering effect, also due to a substantial decrease of BP in sham arm. Considering this, we aimed to quantify the magnitude of BP decrease within the sham arm of Randomized Controlled Trials (RCT) with RDN in patients with hypertension.MethodsElectronic databases were searched since inception until January 2022 for randomized sham-controlled trials which assessed the efficacy in lowering BP of the sham intervention for catheter-based RDN in adult patients with hypertension. The outcomes were change in ambulatory/office systolic and diastolic BP.ResultsA total of 9 RCT were included in the analysis enrolling a total of 674 patients. Sham intervention showed a decrease in all evaluated outcomes. Office systolic BP had a reduction of -5.52 mmHg [95%CI -7.91, -3.13] and office diastolic BP of -2.13 mmHg [95%CI -3.08, -1.17]. Sham procedure for RDN also showed a reduction of -3.41 mmHg [95%CI -5.08, -1.75] in ambulatory systolic BP and − 2.44 mmHg [95%CI -3.31, -1.57] in ambulatory diastolic BP.ConclusionDespite recent data indicating that RDN might be an effective treatment for patients with resistant hypertension when compared to a sham intervention, our results indicate that the sham intervention for RDN also has a significant effect on lowering Office and Ambulatory (24-h) Blood Pressure in adult patients with hypertension. This highlights that BP itself might be sensitive to placebo-like effect and also brings further difficulties in establishing the BP lowering efficacy of invasive interventions due to the magnitude of the sham effect.

Conditioning induced placebo-like and nocebo-like effects of thermal discomfort in adults but not in youth.

Conditioning can be used to modulate the perception of pain, in the form of placebo and nocebo effects. Previous studies show inconsistent results as to whether adolescents show similar, weaker, or non-significant conditioned placebo and nocebo effects compared to effects found in adults. There are suggestions that such differences (if any) may dependent on the cues used in the thermal conditioning paradigms. Therefore, in this current study, we utilized novel, neutral 3D-shaped visual cues to implicitly induce conditioned placebo-like and nocebo-like effects in adolescents and adults. During the conditioning paradigm, distinct cues (Fribbles) were paired with low and high temperatures in 24 adults and 20 adolescents (mean age = 25.5years). In the testing phase, these conditioned cues as well as a neutral (unconditioned) cue were presented with moderate temperatures. Thermal discomfort of moderate temperatures was lower when presented with the conditioned low heat cue (placebo-like effect) and higher when thermal stimuli were presented with the high heat cue (nocebo-like effect) compared to the neutral cue. The effects were driven by adults, as neither the placebo-like nor the nocebo-like effect was significant in adolescents. The difference between adolescents and adults was not explained by differences in temperature or discomfort levels, as adults and adolescents had comparable calibrated temperatures and levels of discomfort during heat stimuli. Our findings suggest that thermal perception in adolescents is less influenced by conditioning to an engaging novel visual cue, compared to adults. Our work may have implications for better understanding the scope and limitations of conditioning as a key mechanism of placebo and nocebo effects in youth.

Visual placebo-like effects on subjective assessment of room acoustics: Sound absorption in classrooms

When studying occupants' environmental perception of well-being in indoor spaces, subjective questionnaires are most often used to evaluate indoor comfort domains. When estimating parameters which can be influenced in some way by certain visual aspects, researchers may question if the obtained results could be affected by other issues. In particular, certain aesthetic aspects, such as indoor furnishing or room shape may have impact on occupants’ perceptions.For this reason, this paper focuses on determining the influence of the visual aspect on occupants’ perception of indoor acoustics. Classrooms were chosen as an example of an enclosed environment; we modified the indoor acoustics of a real classroom twice, inserting false and real sound absorbing panels featuring an identical external layout. Following this, using questionnaires, the indoor acoustics perceived by students were analyzed. Results clearly demonstrate that the sight of false absorbers is sufficient to provide the same perceived acoustics as real absorbers. Since only the visual aspect is varied, a placebo-like effect is assessed. Therefore, this issue can bias results when using surveys as a scientific approach in experimental studies.

Pain therapy within the ERAS concept – Creating objectivity in studies on personalized checkpoint acupuncture

Objectives: One of the key points within the ERAS concept is control of pain and PONV syndrome induced by abdominal surgical procedures. Acupuncture (AC) is widely accepted for pain and an FDA-approved therapy for nausea. To integrate AC in ERAS we set three preconditions: (1) rational access to the functional AC diagnostics the basis of ACpoint selection, (2) proof of efficacy and safety and (3) quality control. We are collecting first data to create a study design with enhanced objectivity, measurability and even double blinding in order to exclude suggestive and placebo-like effects.

Blinding in tDCS Studies: Correct End-of-Study Guess Does Not Moderate the Effects on Associative and Working Memory

Transcranial direct current stimulation (tDCS) has become a valuable tool in cognitive neuroscience research as it enables causal inferences about neural underpinnings of cognition. However, studies using tDCS to modulate cognitive functions often yield inconsistent findings. Hence, there is an increasing interest in factors that may moderate the effects, one of which is the participants’ beliefs of the tDCS condition (i.e., real or sham) they received. Namely, whether participants’ correct guessing of sham condition may lead to false-positive tDCS effects. In this study, we aimed to explore if participants’ beliefs about received stimulation type (i.e., the success of blinding) impacted their task performance in tDCS experiments on associative (AM) and working memory (WM). We analyzed data from four within-subject, sham-controlled tDCS memory experiments (N = 83) to check if the correct end-of-study guess of sham condition moderated tDCS effects. We found no evidence that sham guessing moderated post-tDCS memory performance in experiments in which tDCS effects were observed as well as in experiments that showed null effects of tDCS. The results suggest that the correct sham guessing (i.e., placebo-like effect) is unlikely to influence the results in tDCS memory experiments. We discuss the results in light of the growing debate about the relevance and effectiveness of blinding in brain stimulation research.

Operant and classical learning principles underlying mind\u2013body interaction in pain modulation: a pilot fMRI study

The operant conditioning has been less studied than the classical conditioning as a mechanism of placebo-like effect, and two distinct learning mechanisms have never been compared to each other in terms of their neural activities. Twenty-one participants completed cue-learning based pain rating tasks while their brain responses were measured using functional magnetic resonance imaging. After choosing (instrumental) or viewing (classical) one of three predictive cues (low- and high-pain cues with different level of certainty), they received painful stimuli according to the selected cues. Participants completed the same task during the test session, except that they received only a high pain stimulus regardless of the selected cues to identify the effects of two learning paradigms. While receiving a high pain stimulation, low-pain cue significantly reduced pain ratings compared to high-pain cue, and the overall ratings were significantly lower under operant than under classical conditioning. Operant behavior activated the temporoparietal junction significantly more than the passive behavior did, and neural activity in the primary somatosensory cortex was significantly reduced during pain in instrumental as compared with classical conditioning trials. The results suggest that pain modulation can be induced by classical and operant conditioning, and mechanisms of attention and context change are involved in instrumental learning.

Analysis of the placebo response to the therapeutic environment

Placebo is critical for evaluating medical interventions, but it’s also clear that the biology underpinning the placebo effect in humans could have significant clinical and societal impacts. Placebo effects, real responses to false cues, potentially stand at odds with the view that, for adaptive reasons, organisms respond only to true environmental cues. In placebo effects, phenotypic responses are seen in the absence of a biologically active agent. The reason for the increase in the placebo response is largely unknown, but several attempts have been made to overcome this problem. How placebos work is still not quite understood, but it involves a complex neurobiological reaction that includes everything from increases in feel-good neurotransmitters, like endorphins and dopamine, to greater activity in certain brain regions linked to moods, emotional reactions, and self-awareness. All of it can have therapeutic benefit. Reacting to a placebo is not proof that a certain treatment doesn’t work, but rather that another, non-pharmacological mechanism may be present. If placebo responses seen in humans are the result of phenotypic plasticity, then placebo-like effects should be observable in other species—particularly in cases where the environment has been altered to disrupt its reliability. This is the case, and placebo-like effects are seen in a variety of model systems.

Conditioned Placebo- and Nocebo-Like Effects in Adolescents: The Role of Conscious Awareness, Sensory Discrimination, and Executive Function.

Background: Conditioning is a key mechanism of placebo and nocebo effects in adults. Little is known about the underlying mechanisms of placebo and nocebo effects in youth and how they might be influenced by conscious awareness and cognitive abilities. In this study, the role of conditioning on thermal perception in youth was investigated.Methods: Differences in thermal ratings were assessed in response to consciously and non-consciously perceived cues that were conditioned to either low or high heat. Furthermore, we tested whether executive function mediates the effect of conditioning on thermal perception. Thirty-five high-school students (14–17 years) completed an executive function task and underwent a sensory perception paradigm. In a conditioning phase, two distinct neutral faces (conditioned cues) were coupled to either a low or a high temperature stimulus delivered to participants' forearms. In a testing phase, the conditioned cues, and novel faces (non-conditioned control cues), were paired with identical moderate thermal stimuli. In this testing phase, for half of the participants cues were presented consciously (supraliminally) and for the other half non-consciously (subliminally).Results: We found a significant main effect of cue type on thermal ratings (p = 0.003) in spite of identical heat being administered following all cues. Post-hoc analyses indicated that the nocebo-like effect (conditioned high cue compared to control) was significant (p = 0.027); the placebo-like effect (conditioned low cue compared to control) was non-significant. No difference between cues presented supra- vs. subliminally and no significant interaction effects were found. The association between sensory discrimination and the magnitude of the nocebo-like effect was mediated by executive function.Conclusions: To our best knowledge, this is the first study establishing a relationship between thermal perception, nocebo effects, and executive function in youth. Our results may have important implications for understanding cognitive/ learning processes involved in nocebo effects.

Examining the Interactions Between Expectations and tDCS Effects on Motor and Cognitive Performance.

Background: Despite a growing literature and commercial market, the effectiveness of transcranial direct current stimulation (tDCS) remains questionable. Notably, studies rarely examine factors such as expectations of outcomes, which may influence tDCS response through placebo-like effects. Here we sought to determine whether expectations could influence the behavioral outcomes of a tDCS intervention.Methods: Through an initial study and self-replication, we recruited 121 naïve young adults 18–34 years of age (M = 21.14, SD = 3.58; 88 women). We evaluated expectations of tDCS and of motor and cognitive performance at three times: (i) at baseline; (ii) after being primed to have High or Low expectations of outcomes; and (iii) after a single session of sham-controlled anodal tDCS over the left or right motor cortex. Before and after stimulation, participants performed the Grooved Pegboard Test and a choice reaction time task as measures of motor dexterity, response time, and response inhibition.Results: Repeated measures ANOVA revealed that participants had varying, largely uncertain, expectations regarding tDCS effectiveness at baseline. Expectation ratings significantly increased or decreased in response to High or Low priming, respectively, and decreased following the intervention. Response times and accuracy on motor and cognitive measures were largely unaffected by expectation or stimulation conditions. Overall, our analysis revealed no effect attributable to baseline expectations, belief of group assignment, or experimental condition on behavioral outcomes. Subjective experience did not differ based on expectation or stimulation condition.Conclusions: Our results suggest no clear effects of tDCS or of expectations on our performance measures, highlighting the need for further investigations of such stimulation methods.

Ethical Implications for Potential Placebo Effects of Point of Care Ultrasound.

Anecdotally, practitioners of point of care ultrasound (POCUS) describe instances where patients appear to experience a placebo-like response after the examination, also described as a positive care effect. Extensive study of therapeutic ultrasound has yet to reveal differences between intervention and placebo, both of which respond to therapy. Indeed, POCUS is exemplary in incorporating many components known to modulate placebo-like effects. Patient expectations, ritualistic aspects of hands-on care, symbolic power of sophisticated medical instruments, the power of real-time POCUS images, therapeutic practitioner-patient communication, and the effect of cultural and linguistic concordance all have significant potential to modulate positive or negative care effects of POCUS. Drawing from complementary and alternative medicine's discussion of characteristic and incidental factors, this review argues that POCUS should be studied as a complex medical intervention intertwined with and inextricable from diagnostic and care processes in the hospital setting. Since POCUS is a diagnostic tool with care effect potential, its similarity to the physical exam can guide preliminary ethical guidance on disclosure of potential placebo effects or efforts to maximize that potential effect. However, more data is needed to balance the benefits and risks of effective diagnosis and overdiagnosis, respectively.

Expectations may influence the effects of transcranial direct current stimulation

Growing interest surrounds transcranial direct current stimulation (tDCS) as a safe and inexpensive method for improving cognitive functions and mood. Nevertheless, tDCS studies rarely examine psychological factors such as expectations of outcomes, which may influence tDCS responsiveness through placebo-like effects. Here we sought to evaluate the potential influence of expectations on tDCS intervention outcomes. We assessed expectations of tDCS outcomes in 88 healthy young adults on three occasions: i) at baseline; ii) after reading information implying either high or low effectiveness of stimulation; and iii) after a single-session of sham-controlled anodal tDCS applied to the left dorsolateral prefrontal cortex, during working memory (WM) training. Participants were largely uncertain about the effectiveness of stimulation in improving cognitive function at baseline. High or low expectation priming using simple positive or cautionary messages significantly increased or decreased expectation ratings, respectively, but ratings significantly decreased following stimulation in all groups. We found greater improvement in participants who received high compared to low expectation priming. Participants who received active stimulation and low expectation priming exhibited the lowest performance, suggesting that expectation priming and stimulation may have interacted. We did not find a significant effect of baseline expectations, belief of group assignment, or individual characteristics on measures of WM and verbal fluency. However, controlling for baseline expectations revealed greater post-intervention improvement on the executive function measures in participants who received high (compared to low) expectation priming. People randomly assigned to receive high expectation priming reported having a more pleasant experience overall, including greater satisfaction. Our findings suggest that expectations of outcomes should be taken into account in tDCS-based experimental studies and clinical trials.

Smartphone measures of day-to-day behavior changes in children with autism

Smartphones offer a flexible tool to collect data about mental health, but less is known about their effectiveness as a method to assess variability in children’s problem behaviors. Caregivers of children with autism completed daily questions about irritability, anxiety and mood delivered via smartphones across 8-weeks. Smartphone questions were consistent with subscales on standard caregiver questionnaires. Data collection from 7 to 10 days at the beginning and 7 to 10 days at the end of the study were sufficient to capture similar amounts of variance as daily data across 8-weeks. Other significant findings included effects of caregiver socioeconomic status and placebo-like effects from participation even though the study included no specific treatment. Nevertheless, single questions via smartphones collected over relatively brief periods reliably represent subdomains in standardized behavioral questionnaires, thereby decreasing burden on caregivers.

Studying placebo effects in model organisms will help us understand them in humans.

The placebo effect is widely recognized but important questions remain, for example whether the capacity to respond to a placebo is an evolved, and potentially ubiquitous trait, or an unpredictable side effect of another evolved process. Understanding this will determine the degree to which the physiology underlying placebo effects might be manipulated or harnessed to optimize medical treatments. We argue that placebo effects are cases of phenotypic plasticity where once predictable cues are now unpredictable. Importantly, this explains why placebo-like effects are observed in less complex organisms such as worms and flies. Further, this indicates that such species present significant opportunities to test hypotheses that would be ethically or pragmatically impossible in humans. This paradigm also suggests that data informative of human placebo effects pre-exist in studies of model organisms.

Placebo-like response in absence of treatment in children with Autism.

Caregiver report is the most common measure of change in pediatric psychiatry. Yet, placebo response rates pose significant challenges to reliably detect a treatment response. The present study simulated an eight-week clinical trial protocol for Autism Spectrum Disorder (ASD) for the purpose of testing the feasibility and validity of several outcome measures. Twenty caregivers answered questions about their child's behavior on their smartphone each week and completed a battery of paper questionnaires during weeks one and eight. No treatment was administered. Caregivers reported a significant decrease in problem behaviors on the Aberrant Behavior Checklist (ABC) (29% decrease) and general ASD behaviors on the Social Responsiveness Scale (SRS) (7% decrease). There was also a trend of behavior improvement from smartphone questions but no significant changes in clinical ratings of core diagnostic features of ASD. Participation in a comprehensive protocol in the absence of a particular treatment significantly influenced how caregivers perceived the severity of their children's problem behaviors. These placebo-like effects represent substantial challenges for randomized controlled trials (RCTs) that use treatment as usual and have implications for future behavioral and pharmacological treatment trial designs. Autism Res 2017, 10: 1567-1572. © 2017 International Society for Autism Research, Wiley Periodicals, Inc.

Effects of Transcranial Direct Current Stimulation (tDCS) on Chronic Pain in Spinal Cord Injured Patients

Introduction: Pain following spinal cord injury (SCI) is notoriously difficult to manage and often refractory to treatment. Novel approaches, such as non-invasive brain stimulation, targeting central mechanisms associated with chronic pain, have shown early promise as a safe treatment in various patient groups, including spinal cord injury. To date the number of small clinical trials using non-invasive brain stimulation to treat chronic pain in SCI has produced mixed results. We report here the findings of a UK based trial examining the effects of anodal transcranial direct current stimulation (TdCs) administration on pain in spinal injury patients. Methods: Sixteen spinal injury patients from the National Spinal Injury Centre, Stoke Mandeville Hospital, Aylesbury, UK participated in a single centre, double blind randomized control trial. Patients were randomly allocated to either the active (n=8) or sham (n=8) treatment groups. tDCS was administered by electrodes with anode placement over the dominant M1 and the cathode electrode over the contralateral supraorbit scalp area. Subjects received either active (2 mA anodal current) or sham tDCS for 20 min daily treatment for 5 consecutive days with the dose based on previously reported chronic pain studies in spinal cord injury patients. A mixed ANOVA was used to evaluate both tDCS treatment and time effects on validated assessment measures for pain and depression up to 2 weeks following treatment intervention. Results: No adverse effects of the treatment were observed in this study, nor were there any significant differences between groups in rating perception of stimulation. While treatment appeared to have reduced group pain scores on a visual analogue scale [VAS], there were no statistically significant differences between active and sham treatment groups when re-examined in the 2 week follow up. Conclusion: There were some reductions in self-assessed VAS pain score in our small group of SCI patients during treatment in both the sham and active tDCS and at two weeks’ post treatment. However, our study appears to indicate only a placebo-like effect of tDCS on chronic pain in SCI, and not one attributed to the active, anodal stimulation over motor cortex. We also did not observe any significant effects over time or treatment for an assessment of neuropathic pain. We observed some trends of non-significant reduction in some of selfassessed pain scores measures, however, these are inconclusive. Studies of clinical efficacy of pain treatment by tDCS in spinal cord injury should therefore be conducted on a larger scale, and with a longer follow up period to address the limited evidence available.

Safety of oral dronabinol during opioid withdrawal in humans

BackgroundOpioid dependence remains a significant public health problem worldwide with only three FDA-approved treatments, all targeting the mu-opioid receptor. Dronabinol, a cannabinoid (CB) 1 receptor agonist, is currently under investigation as a novel opioid withdrawal treatment. This study reports on safety outcomes of dronabinol among adults in opioid withdrawal. MethodsTwelve adults physically dependent on short-acting opioids participated in this 5-week within-subject, randomized, double blind, placebo-controlled inpatient study. Volunteers were maintained on oral oxycodone 30mgqid. Double-blind placebo substitutions occurred for 21h before each of 7 experimental sessions in order to produce opioid withdrawal. A single oral test dose was administered each session (placebo, oxycodone 30 and 60mg, dronabinol 5, 10, 20, and 30mg [decreased from 40mg]). Heart rate, blood pressure, respiratory outcomes and pupil diameter were assessed repeatedly. ResultsDronabinol 40mg produced sustained sinus tachycardia accompanied by anxiety and panic necessitating dose reduction to 30mg. Sinus tachycardia and anxiety also occurred in one volunteer after dronabinol 20mg. Compared to placebo, dronabinol 20 and 30mg produced significant increases in heart rate beginning 1h after drug administration that lasted approximately 2h (p<0.05). Dronabinol 5 and 10mg produced placebo-like effects. Oxycodone produced prototypic mu-opioid agonist effects (e.g., miosis). ConclusionDronabinol 20mg and higher increased heart rate among healthy adults at rest who were in a state of opioid withdrawal, raising concern about its safety. These results have important implications for future dosing strategies and may limit the utility of dronabinol as a treatment for opioid withdrawal.

The magnitude of placebo analgesia effects depends on how they are conceptualized

ObjectivePlacebo effects are usually calculated as the difference between placebo treatments and no treatments. Recently, placebo-like effects have been investigated using open and hidden administrations of active treatments. The aim of the study was to directly compare the two types of placebo effects and examine how they are influenced by personality traits. MethodsIn a within-subject, randomized, blinded, balanced placebo trial design study with 48 healthy volunteers, we compared placebo and placebo-like effects and tested if expectancy, absorption and suggestibility correlated with these effects. Subjects completed the Tellegen Absorption Scale and the Sensory Suggestibility Scale, and pain was induced by injections of hypertonic saline into the masseter muscle. Participants received four injections of hypertonic saline with lidocaine or matching placebo in randomized order: open treatment, hidden treatment, placebo and control. The placebo effect was defined as the difference in pain between the placebo and the control condition and the placebo-like effect as the difference in pain between the open and hidden condition. ResultsPlacebo effects were significant both in the traditional paradigm: mean placebo effect AUC 1626mm2 (95% CI 958–2293) and the open–hidden paradigm: mean placebo-like effect AUC 801mm2 (95% CI 134–1469), but there was a significant difference between the magnitude of the two effects (p=0.049). Absorption and suggestibility did not predict the placebo or the placebo-like effect. Estimated expected pain relief correlated with placebo effects but not placebo-like effects. ConclusionThe magnitude of placebo effects differs depending on how they are conceptualized and calculated.

An eco-label effect in the built environment: Performance and comfort effects of labeling a light source environmentally friendly

People tend to idealize eco-labeled products, but can eco-labeling have consequences for performance? To address this question, 48 university students were asked to undertake a color discrimination task adjacent to a desktop lamp that was either labeled “environmentally friendly” or “conventional” (although they were identical). The light of the lamp labeled “environmentally friendly” was rated as more comfortable. Notably, task performance was also better when the lamp was labeled “environmentally friendly”. Individual differences in environmental concern, but not pro-environmental consumer behavior and social desirability indexes, were related to the magnitude of the eco-label effect on performance. Whilst some previous studies have shown similar placebo-like effects of eco-labels on subjective ratings, this is the first study to show an eco-label effect for artifacts in the built environment on performance, and the first study to relate this effect to environmental concern. Psychological mechanisms that may underpin the eco-label effects are discussed.

Design challenges facing clinical trials of the effectiveness of new HIV-prevention technologies

Recent successes of antiretroviral pre-exposure prophylaxis (PrEP) in preventing HIV infection have raised questions whether further placebo controlled trials of new HIVprevention technologies are ethically justifiable. A trial with active agent(s) in the comparator group can be designed either as a superiority or non-inferiority trial. In a non-inferiority trial the hypothesis tested is that the intervention is not inferior to, by a predefined clinically relevant amount, or at least as effective as, the comparator. Noninferiority trials pose challenges in data interpretation. Firstly it is possible to show equivalence of two non-effective interventions. If the active comparator intervention is ineffective, the new intervention would be shown to be noninferior to this inactive intervention, while neither intervention is superior to placebo or no intervention. The second challenge is that any effect that dilutes the true efficacy of an intervention in a trial, such as non-adherence, loss to follow-up or protocol violations, makes it easier for the two interventions to be declared equivalent. Nondifferential low adherence is unlikely to lead to the conclusion that an inferior intervention is non-inferior. However, differential adherence between study arms, which is more likely in non-blinded trials, is likely to bias the results and lead to incorrect conclusions. Investigators conducting non-inferiority trials will have to pay special attention to supporting, measuring and maintaining high adherence. The goal in future noninferiority trials should be to maintain similar levels of high adherence in all study arms, but at a minimum to reduce the likelihood of differential adherence across study arms. 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins AIDS 2012, 26:000‐000

The Higher the Price the Better the Result? The Placebo-Like Effects of Price and Brand on Consumer Judgments

This research investigates the placebo effects of price and brand on consumer judgment and focuses on how two psychological moderators, deliberation thinking and self-confidence, influence the placebo-like effects. Two experiments were conducted. The results show that although different prices and brands on the same product would not influence consumers’ taste evaluation, they would affect participants’ grades in the memory test. That means there is a placebo effect on price/brand cues. The results also indicate that the placebo effect of price is more influenced by the discounted price than the regular price when people have low deliberation thinking. Furthermore, the findings show that the effects of brand and self-confidence create an interaction effect. Self-confidence moderates the placebo effect of brand on consumers’ judgment. Theoretical and managerial implications of the findings are provided.