Reconsidering the role of personality in placebo effects: dispositional optimism, situational expectations, and the placebo response

Caffeine Expectancy Does Not Influence the Physical Working Capacity at the Fatigue Threshold

ABSTRACT

Ambrozy, CA, Hawes, NE, Hayden, OL, Sortzi, I, and Malek, MH. Caffeine expectancy does not influence the physical working capacity at the fatigue threshold. J Strength Cond Res 38(6): 1056-1062, 2024-The placebo effect occurs when a desired outcome is experienced due to the belief that a treatment is effective, even in the absence of an active ingredient. One explanation for this effect is based on a person's expectations of a drug or supplement. Although caffeine's effects on sports performance have been studied, little is known about how expectations of caffeine affect neuromuscular fatigue during continuous muscle action. The physical working capacity at the fatigue threshold (PWCFT) can be used to assess neuromuscular fatigue noninvasively using surface electromyography. Thus, the purpose of this study was to investigate whether caffeine expectancy influences PWCFT. We hypothesized that regardless of expectancy, caffeine consumption would delay neuromuscular fatigue. The study involved 8 healthy college-aged men (mean ± SEM: age, 25.6 ± 1.0 years) who visited the laboratory on 4 occasions, each separated by 7 days. The subjects completed 4 experimental conditions, in random order, where they were told that they were consuming caffeine or placebo and either received caffeine or placebo. After consuming the drink, the subjects remained in the laboratory for an hour and then performed an incremental exercise test. The results showed that the condition where subjects were told that they were consuming caffeine and received caffeine had significantly higher mean values for maximal power output (F(3, 21) = 11.75; p < 0.001), PWCFT (F(3, 21) = 12.28; p < 0.001), PWCFT (%maximal power output; F(3, 21) = 8.75; p < 0.001), and heart rate at end exercise (%predicted; F(3, 21) = 3.83; p = 0.025) compared with the 2 conditions where placebo was received. However, no statistically significant mean differences were found from the condition where subjects were told that they were consuming placebo but consuming caffeine. This suggests that a person's expectancy and potential somatic response may serve as a cue for how an ergogenic aid or placebo could affect subsequent performance.

Expectations Come True: The Placebo Effect of Exercise on Affective Responses

Objective: This study investigated the placebo and nocebo effects of habitual and induced expectations. Methods: In Study 1, 95 participants (Mage = 19.65 ± 2.21 years, MBMI = 21.94 ± 2.55) were grouped according to habitual expectations (positive, neutral, or negative) and completed a 30-min moderate-intensity aerobic exercise, and their affective response, rating of perceived exertion (RPE), and heart rate variability (HRV) were measured before, during, and after the exercise. In Study 2, the participants from Study 1 were grouped according to induced expectations (control, positive, or negative) and completed a 30-min moderate-intensity aerobic exercise. Affective response, RPE, and HRV were measured before, during, and after exercise. Results: In Study 1, positive habitual expectations increased affective response during and after exercise [F(2, 92) = 2.959, p = .057, ηp2 = .060], and negative habitual expectations increased RPE during exercise [F(2, 92) = 5.174, p = .007, ηp2 = .101]. In Study 2, positive induced expectation increased affective response during [F(2, 86) = 5.492, p = .006, ηp2 = .113] and after exercise [F(2, 86) = 6.096, p = .003, ηp2 = .124] and was not affected by habitual expectation. Conclusion: The affective response during and after exercise is influenced by habitual and induced expectations. Positive expectations enhance affective benefits, while negative expectations reduce affective benefits.

To respond or not to respond: exploring empathy-related psychological and structural brain differences between placebo analgesia responders and non-responders

Introduction

Placebo responsiveness is highly variable across individuals. In the domain of pain, it may range from pronounced hypoalgesia to no response at all. Which factors predict such variation awaits clarification, as the available literature is characterized by mixed and inconclusive results. Particularly interesting in this case are social factors such as empathy or prosocial behavior, as prior work has stressed the connection between feeling pain yourself and empathizing with pain observed in others.

Methods

In a mixed confirmatory and exploratory approach, this study investigated potential psychological and structural brain differences between placebo responders and non-responders in the domain of pain. We aggregated data of four behavioral and neuroimaging studies that had been designed to investigate the effects of placebo analgesia on empathy.

Results

Analyses comparing groups of placebo responders and non-responders showed significant group differences in trait characteristics, with responders reporting increased helping behavior and lower psychopathic traits compared to non-responders. Uncorrected results further showed higher pain-related empathic concern in responders vs. non-responders. These results were accompaniedby tentative group differences in brain structure: placebo analgesia non-responders exhibited increased gray matter volume in left inferior temporal and parietal supramarginal cortical areas, and an increased cortical surface area in bilateral middle temporal cortex.

Discussion

Together, our findings suggest that modifiability of one's pain perception by means of placebo effects is linked to personality traits characterizing social emotions and behavior. They also hint that these psychological as well as brain structural characteristics might be beneficial for the identification of placebo responders. At the same time, they stress the importance of considering contextual factors such as the study setting or paradigm when investigating the association between individual characteristics and placebo responding.

Placebo response of sham acupuncture in patients with primary dysmenorrhea: A meta-analysis

BACKGROUND

The placebo response of sham acupuncture in patients with primary dysmenorrhea is a substantial factor associated with analgesia. However, the magnitude of the placebo response is unclear.

OBJECTIVE

This meta-analysis assessed the effects of sham acupuncture in patients with primary dysmenorrhea and the factors contributing to these effects.

SEARCH STRATEGY

PubMed, Embase, Web of Science, and Cochrane CENTRAL databases were searched from inception up to August 20, 2022.

INCLUSION CRITERIA

Randomized controlled trials (RCTs) using sham acupuncture as a control for female patients of reproductive age with primary dysmenorrhea were included.

DATA EXTRACTION AND ANALYSIS

Pain intensity, retrospective symptom scale, and health-related quality of life were outcome measures used in these trials. Placebo response was defined as the change in the outcome of interest from baseline to endpoint. We used standardized mean difference (SMD) to estimate the effect size of the placebo response.

RESULTS

Thirteen RCTs were included. The pooled placebo response size for pain intensity was the largest (SMD = -0.99; 95% confidence interval [CI], -1.31 to -0.68), followed by the retrospective symptom scale (Total frequency rating score: SMD = -0.20; 95% CI, -0.80 to -0.39. Average severity score: SMD = -0.35; 95% CI, -0.90 to -0.20) and physical component of SF-36 (SMD = 0.27; 95% CI, -0.17 to 0.72). Studies using blunt-tip needles, single-center trials, studies with a low risk of bias, studies in which patients had a longer disease course, studies in which clinicians had < 5 years of experience, and trials conducted outside Asia were more likely to have a lower placebo response.

CONCLUSION

Strong placebo response and some relative factors were found in patients with primary dysmenorrhea. PROSPERO registration number: CRD42022304215. Please cite this article as: Sun CY, Xiong ZY, Sun CY, Ma PH, Liu XY, Sun CY, Xin ZY, Liu BY, Liu CZ, Yan SY. Placebo response of sham acupuncture in patients with primary dysmenorrhea: A meta-analysis. J Integr Med. 2023; 21(5): 455-463.

Association between personality traits and placebo effects: a preregistered systematic review and meta-analysis

ABSTRACT

Placebo effects are ubiquitous yet highly variable between individuals and therefore strongly affect clinical trial outcomes such as pain relief. It is unclear whether dispositional psychological traits influence responsiveness to placebo. This preregistered meta-analysis and systematic review synthesized the literature investigating the association between personality traits and placebo effects. Based on 21 studies with 798 participants, we performed formal meta-analyses for 10 different personality traits, including behavioral inhibition, fun seeking, goal-drive persistence, reward responsiveness, empathic concern, empathic fantasy, perspective-taking, personal distress, optimism, and anxiety. We did not find evidence of associations between any of these traits and magnitude of placebo effects, which was supported by equivalence tests. Furthermore, we did not find evidence for moderating factors such as placebo manipulation type (conditioning or nonconditioning) or condition (pain or nonpain). These findings challenge the notion that personality influences responsiveness to placebos and contradict its utility for identifying placebo "responders" and "nonresponders."

Expectation effects in working memory training

There is a growing body of research focused on developing and evaluating behavioral training paradigms meant to induce enhancements in cognitive function. It has recently been proposed that one mechanism through which such performance gains could be induced involves participants' expectations of improvement. However, no work to date has evaluated whether it is possible to cause changes in cognitive function in a long-term behavioral training study by manipulating expectations. In this study, positive or negative expectations about cognitive training were both explicitly and associatively induced before either a working memory training intervention or a control intervention. Consistent with previous work, a main effect of the training condition was found, with individuals trained on the working memory task showing larger gains in cognitive function than those trained on the control task. Interestingly, a main effect of expectation was also found, with individuals given positive expectations showing larger cognitive gains than those who were given negative expectations (regardless of training condition). No interaction effect between training and expectations was found. Exploratory analyses suggest that certain individual characteristics (e.g., personality, motivation) moderate the size of the expectation effect. These results highlight aspects of methodology that can inform future behavioral interventions and suggest that participant expectations could be capitalized on to maximize training outcomes.

Systematic review and meta-analysis of the placebo effect in panic disorder: Implications for research and clinical practice

OBJECTIVE

This review aimed to measure the degree of placebo response in panic disorder.

DATA SOURCES

We searched major databases up to 31 January 2021, for randomized pharmacotherapy trials published in English.

STUDY SELECTION

A total of 43 studies met inclusion criteria to be in the analysis (with 174 separate outcome measurements).

DATA EXTRACTION

Changes in outcome measures from baseline in the placebo group were used to estimate modified Cohen's d effect size.

RESULTS

A total of 43 trials (2392 subjects, 174 outcomes using 27 rating scales) were included in the meta-analysis. Overall placebo effect size was 0.57 (95% confidence interval = [0.50, 0.64]), heterogeneity (I²: 96.3%). Higher placebo effect size was observed among clinician-rated scales compared to patient reports (0.75 vs 0.35) and among general symptom and anxiety scales compared to panic symptoms and depression scales (0.92 and 0.64 vs 0.56 and 0.54, respectively). There was an upward trend in effect size over the publication period (r = 0.02, p = 0.002) that was only significant among clinician-rated scales (r = 0.02, p = 0.011). There was no significant publication bias, Egger's test (p = 0.08).

CONCLUSION

We observed a substantial placebo effect size in panic disorder. This effect was more prominent for some aspects of panic disorder psychopathology than for others and was correlated with the source of the assessment and publication year. This finding has implications both for research design, to address the heterogeneity and diversity in placebo responses, and for clinical practice to ensure optimal quality of care.

SYSTEMATIC REVIEW REGISTRATION NUMBER

PROSPERO, CRD42019125979.

Placebo: a brief updated review

Our aims were to provide updated information on placebo/nocebo effect and the potential use of placebo in clinical practice. This article can only provide a rough overview on the placebo and nocebo effect and is intended to serve as a starting point for the reader to go deeper into the corresponding literature. The placebo effect has been observed in multiple medical conditions, after oral administration, with manual therapies as well as with surgery and invasive procedures. The use of placebo in clinical trials is fundamental, although the ethics of its use is under discussion. The placebo may behave like a drug from the pharmacokinetic and pharmacodynamic point of view and can also be associated with adverse events (nocebo effect). Placebo can modify treatment by increasing or decreasing the effects of drugs. The factors associated with the occurrence of placebo effect are multiple, but in addition to those that depend on the placebo itself, the doctor-patient relationship would be the most important. As a result of findings that were published in the last two decades, the psycho-neurobiological basis of placebo is becoming better understood, although further studies are needed. In conclusion, the placebo effect in the clinic exhibits weak to moderate intensity. Placebo, in addition to its use in the clinical trial, should be considered another therapeutic remedy either as stand alone or in association with treatment, and could be useful in certain circumstances. The use of placebo should be regulated by the European health authorities through a guide in clinical practice that will improve patient care.

How substitute scarcity appeals effect on experiential gift’s purchase intention?

Purpose

The purpose of this study is to explore the substitute scarcity appeals (unit scarcity or option scarcity) effect on experiential gift’s purchase intention, based on difference in gift attribute (hedonic or utilitarian gift) and difference in the types of givers (close or distant giver), which is a new consideration.

Design/methodology/approach

This study was conducted with two experiments and examined four hypotheses in total. These hypotheses were examined using a 2 × 2 between-subjects designs, and a two-factorial covariance analysis was conducted.

Findings

Empirical results show that unit scarcity produces greater purchase intention than the option scarcity of close givers. For hedonic gifts, unit scarcity produced greater purchase intention than the option scarcity.

Originality/value

The originality of this study is to explore the substitute scarcity appeals effect on experiential gift’s purchase intention based on different types of givers and different types of gifts. The result serves as the gift marketing strategy of online platform operators and the future reference for marketers to create more value and purchase intention.

The Temporal Modulation of Nocebo Hyperalgesia in a Model of Sustained Pain

BACKGROUND

The direction and the magnitude of verbal suggestions have been shown to be strong modulators of nocebo hyperalgesia, while little attention has been given to the role of their temporal content. Here, we investigate whether temporal suggestions modulate the timing of nocebo hyperalgesia in an experimental model of sustained pain.

METHODS

Fifty-one healthy participants were allocated to one of three groups. Participants received an inert cream and were instructed that the agent had either hyperalgesic properties setting in after 5 (Nocebo 5, N5) or 30 (Nocebo 30, N30) minutes from cream application, or hydrating properties (No Expectation Group, NE). Pain was induced by the Cold Pressure Test (CPT) which was repeated before cream application (baseline) and after 10 (Test10) and 35 (Test35) minutes. Changes in pain tolerance and in HR at each test point in respect to baseline were compared between the three groups.

RESULTS

Tolerance change at Test 10 (Δ10) was greater in N5 (MED = -36.8; IQR = 20.9) compared to NE (MED = -5.3; IQR = 22.4; p < 0.001) and N30 (MED = 0.0; IQR = 23.1; p < 0.001), showing that hyperalgesia was only present in the group that expected the effect of the cream to set in early. Tolerance change at Test 35 (Δ35) was greater in N5 (MED = -36.3; IQR = 35.3; p = 0.002) and in N30 (MED = -33.3; IQR = 34.8; p = 0.009) compared to NE, indicating delayed onset of hyperalgesia in N30, and sustained hyperalgesia in N5. No group differences were found for HR.

CONCLUSIONS

Our study demonstrated that temporal expectations shift nocebo response onset in a model of sustained pain.

Associations Between Interindividual Differences, Expectations and Placebo and Nocebo Effects in Itch

Introduction: Placebo and nocebo effects are positive and negative health outcomes that can be elicited by the psychosocial context. They can be mediated by expectations, and may emerge in somatic symptoms even when people are aware of these effects. Interindividual differences (e.g., in personality, affective states) could impact placebo and nocebo responding, but findings are inconsistent. Methods: The current work examined expectation as a mediator of the association between verbal placebo and nocebo suggestions (VSs) and histamine-induced itch across three experimental studies. Moreover, we examined whether interindividual differences (e.g., in optimism, neuroticism, behavioral activation system (BAS), body ignorance) modulated: (1) the direct association between VSs and itch (direct moderation), and (2) the indirect, expectation-mediated association between VSs and itch (moderated mediation). Positive VSs were compared to neutral instructions (Study 1; n = 92) or negative VSs (Studies 2+3; n = 203) in an open-label (i.e., explaining placebo and nocebo effects) or closed-label (concealed) context using PROCESS. First, mediation of VSs effects on itch by expectations was tested. Next, moderation by individual traits was explored using conditional process analyses. Results: The effects of VSs on itch were significantly mediated by expectation in Study 1 and in the open-label (but not closed-label) contexts of Studies 2 and 3. Ignorance of bodily signals marginally moderated the direct effects of VSs on itch when closed-label suggestions were given: at low levels of body ignorance, effects of positive and negative VSs were stronger. Moreover, moderated mediation was observed in the open-label groups of Studies 2 and 3: The expectation-mediated effects of VSs on itch were stronger when BAS drive was lower. Conclusion: Overall, the effects of VSs on itch were mediated by expectations in the open-label, but not the closed-label context. Moreover, the current work suggests that placebo and nocebo effects may be moderated by ignorance of bodily signals and the BAS. There was limited evidence that other interindividual differences modulated placebo and nocebo responding in itch.

What Should Clinicians Tell Patients about Placebo and Nocebo Effects? Practical Considerations Based on Expert Consensus

INTRODUCTION

Clinical and laboratory studies demonstrate that placebo and nocebo effects influence various symptoms and conditions after the administration of both inert and active treatments.

OBJECTIVE

There is an increasing need for up-to-date recommendations on how to inform patients about placebo and nocebo effects in clinical practice and train clinicians how to disclose this information.

METHODS

Based on previous clinical recommendations concerning placebo and nocebo effects, a 3-step, invitation-only Delphi study was conducted among an interdisciplinary group of internationally recognized experts. The study consisted of open- and closed-ended survey questions followed by a final expert meeting. The surveys were subdivided into 3 parts: (1) informing patients about placebo effects, (2) informing patients about nocebo effects, and (3) training clinicians how to communicate this information to the patients.

RESULTS

There was consensus that communicating general information about placebo and nocebo effects to patients (e.g., explaining their role in treatment) could be beneficial, but that such information needs to be adjusted to match the specific clinical context (e.g., condition and treatment). Experts also agreed that training clinicians to communicate about placebo and nocebo effects should be a regular and integrated part of medical education that makes use of multiple formats, including face-to-face and online modalities.

CONCLUSIONS

The current 3-step Delphi study provides consensus-based recommendations and practical considerations for disclosures about placebo and nocebo effects in clinical practice. Future research is needed on how to optimally tailor information to specific clinical conditions and patients' needs, and on developing standardized disclosure training modules for clinicians.

Descriptions of Hearing Aids Influence the Experience of Listening to Hearing Aids

OBJECTIVES

Experiences can be strongly influenced by expectations. In hearing healthcare, previous studies have shown that descriptions of hearing aids or contextual factors during the hearing aid fitting process can change subjective and even objective outcomes with hearing aids via the placebo effect. Personality factors have also been shown to affect susceptibility to placebo effects. The purposes of the present study were to (a) investigate the effects of communicating narratives designed to foster positive, negative, or neutral expectations about hearing aids on short-term patient outcomes, and (b) to determine if the degree to which the narratives affected end-user outcomes could be predicted by personality factors.

DESIGN

Nineteen adults between the ages of 54 and 81 (mean age = 68.5, SD = 8.9) had 3 separate research appointments, each exposing them to a different narrative condition: positive, negative, or neutral. the appointment was designed to look and feel like a "traditional" hearing aid fitting appointment, during which the experimenter introduced (i.e., the narrative condition) and fit a pair of hearing aids, the participant was asked to provide their initial feedback about the hearing aids, and the participant performed speech-in-noise testing. Unbeknownst to the research participant, the hearing aids fitted at all three appointments were the same, and the only difference between the three appointments was the way the hearing aids were described to the participants.

RESULTS

The results of this study showed that communication of a positive narrative about hearing aids before a hearing aid fitting led to better speech-in-noise performance on the QuickSIN as compared with performance following the negative or neutral narrative conditions. Also, the positive narrative led to the perception that acclimatization to the hearing aids would occur faster than the negative or neutral narrative conditions. Notably, the effect of communication of a positive narrative was stronger for individuals who scored higher on agreeableness, and susceptibility to positive and negative messaging was stronger for individuals low in neuroticism.

CONCLUSIONS

The study suggests that short-term evaluations of hearing aids can be strongly influenced by narratives as provided by the hearing healthcare provider at the time of a hearing aid fitting.

Conditioned open-label placebo for opioid reduction after spine surgery: a randomized controlled trial

ABSTRACT

Placebo effects have traditionally involved concealment or deception. However, recent evidence suggests that placebo effects can also be elicited when prescribed transparently as "open-label placebos" (OLPs), and that the pairing of an unconditioned stimulus (eg, opioid analgesic) with a conditioned stimulus (eg, placebo pill) can lead to the conditioned stimulus alone reducing pain. In this randomized control trial, we investigated whether combining conditioning with an OLP (COLP) in the immediate postoperative period could reduce daily opioid use and postsurgical pain among patients recovering from spine surgery. Patients were randomized to COLP or treatment as usual, with both groups receiving unrestricted access to a typical opioid-based postoperative analgesic regimen. The generalized estimating equations method was used to assess the treatment effect of COLP on daily opioid consumption and pain during postoperative period from postoperative day (POD) 1 to POD 17. Patients in the COLP group consumed approximately 30% less daily morphine milligram equivalents compared with patients in the treatment as usual group during POD 1 to 17 (-14.5 daily morphine milligram equivalents; 95% CI: [-26.8, -2.2]). Daily worst pain scores were also lower in the COLP group (-1.0 point on the 10-point scale; 95% CI: [-2.0, -0.1]), although a significant difference was not detected in average daily pain between the groups (-0.8 point; 95% CI: [-1.7, 0.2]). These findings suggest that COLP may serve as a potential adjuvant analgesic therapy to decrease opioid consumption in the early postoperative period, without increasing pain.

Effectiveness of placebo interventions for patients with nonspecific low back pain: a systematic review and meta-analysis

ABSTRACT

Little is known about the effectiveness of placebo interventions in patients with nonspecific low back pain (LBP). This systematic review assessed the magnitude of the effects of placebo interventions as compared to no intervention in randomized controlled trials (RCTs) including patients with LBP. Embase, MEDLINE (Ovid), and Cochrane CENTRAL databases were searched from inception to December 5, 2019. Randomized controlled trials comparing placebo intervention vs no intervention in adult patients with nonspecific LBP were included. Pain intensity, physical functioning, and health-related quality of life measured at short-term, medium-term, and long-term follow-up were the outcomes of this review. Twenty-one randomized controlled trials were included; one concerning acute LBP and one subacute LBP, whereas 19 studies reported on chronic LBP. In chronic LBP, placebo interventions were more effective than no intervention at short-term follow-up for pain intensity (standardized mean difference = -0.37, 95% confidence interval [CI] = -0.55 to -0.18, moderate-quality evidence), physical functioning (standardized mean difference -0.19, 95% CI = -0.39-0.01, moderate-quality evidence), and physical quality of life (mean difference = -2.71, 95% CI = -4.71-0.71, high-quality evidence), respectively. These effects were not significant at medium-term follow-up, and no data were available at long-term follow-up. These results show placebo interventions are more effective than no intervention at short-term follow-up in patients with chronic LBP. However, the magnitude of the effects is probably not clinically relevant (approximately 8 points on a 0-100 pain scale). Future research should identify effect modifiers and causal mechanisms explaining the short-term effects of placebo interventions in patients with chronic LBP.

Information About the Optimism of a Placebo/Nocebo Provider and Placebo/Nocebo Side Effects

Background

Research has demonstrated that personality characteristics, such as optimism are associated with placebo/nocebo responding. The present study investigated whether written information about the optimism of a placebo/nocebo provider can influence the occurrence of reported placebo/nocebo side effects.

Method

We analyzed data from 201 females (mean age = 26 years) who participated in a “clinical study on a new massage oil with stone clover extract.” The oil (sunflower oil) was introduced as either eliciting a negative side effect (unpleasant itching; “nocebo oil”) or a positive side effect (pleasant tingling; “placebo oil”). The administration of the oil was combined with written information about the maker of the product. The oil maker was either portrayed as a very optimistic person or no personal information was provided (only the company name). The participants had no personal contact with the experimenter and received all materials and instructions per post.

Results

The participants reported more frequent and intense itching when they received a nocebo suggestion compared to a placebo suggestion. Positive tingling sensations were reported more frequently than itching but did not differ between the placebo/nocebo conditions. Information about the optimism of the oil maker was associated with a lower frequency of reported side effects (adverse and beneficial).

Conclusion

This study demonstrated that it is sufficient to provide participants with written information about an inert substance to elicit the suggested side effect. Information about the provider’s optimistic personality did not specifically influence reported side effects. Future studies should focus on how to adapt written information about a drug/product to minimize adverse side effects and to maximize positive side effects.

Nocebo-Prone Behaviour in Patients with Autoimmune Rheumatic Diseases during the COVID-19 Pandemic

BACKGROUND

The COVID-19 pandemic is associated with emotional distress and significant disruptions in health-care services. These are key players in the development of nocebo phenomena. We aimed to investigate nocebo-prone behaviour in patients with autoimmune rheumatic diseases (ARD) amid the COVID-19 pandemic-associated lockdown.

METHODS

Consecutive patients were telephone-interviewed during the COVID-19 pandemic in Greece. Clinical and socioeconomic characteristics (eg, level of education) were recorded. For nocebo behaviour, a four-item validated questionnaire (Q-No, cut-off score>15), was used. Results were compared with pre-COVID-19 Q-No scores collected from patients followed-up in our department.

RESULTS

Nocebo behaviour was detected in 51/500 (10.2%) individuals. In patients with nocebo behaviour, use of anti-hypertensives was less common (17.6% vs 31.8%, p=0.04), but a higher level of education was more common (58.8% vs 35.9%, p=0.002), compared with patients with Q-No score ≤15; the latter retained statistical significance in multivariate regression analysis (p=0.009, OR [95%CI]: 2.29, [1.23-4.25]). Total Q-No scores were higher in the COVID-19-period compared to the pre-COVID-19 era [median (range); 12 (4-20) vs 11 (4-20), p=0.02]. Among 78 patients with available Q-No questionnaires in the pre-COVID-19 era, 11 (14.1%) displayed nocebo behaviour, which increased to 16 (20.5%) amid the COVID-19 pandemic. Interim development of nocebo behaviour was also associated with higher educational level (p=0.049, OR: 3.65, 95%CI: 1.005-13.268).

CONCLUSION

A considerable proportion of ARD patients manifested nocebo-prone behaviour during the COVID-19 pandemic, which was more common among those with high educational level.

Context matters: the psychoneurobiological determinants of placebo, nocebo and context-related effects in physiotherapy

Background

Placebo and nocebo effects embody psychoneurobiological phenomena where behavioural, neurophysiological, perceptive and cognitive changes occur during the therapeutic encounter in the healthcare context. Placebo effects are produced by a positive healthcare context; while nocebo effects are consequences of negative healthcare context. Historically, placebo, nocebo and context-related effects were considered as confounding elements for clinicians and researchers. In the last two decades this attitude started to change, and the understanding of the value of these effects has increased. Despite the growing interest, the knowledge and the awareness of using the healthcare context to trigger placebo and nocebo effects is currently limited and heterogeneous among physiotherapists, reducing their translational value in the physiotherapy field.

Objectives

To introduce the placebo, nocebo and context-related effects by: (1) presenting their psychological models; (2) describing their neurophysiological mechanisms; (3) underlining their impact for the physiotherapy profession; and (4) tracing lines for future researches.

Conclusion

Several psychological mechanisms are involved in placebo, nocebo and context-related effects; including expectation, learning processes (classical conditioning and observational learning), reinforced expectations, mindset and personality traits. The neurophysiological mechanisms mainly include the endogenous opioid, the endocannabinoid and the dopaminergic systems. Neuroimaging studies have identified different brain regions involved such as the dorsolateral prefrontal cortex, the rostral anterior cingulate cortex, the periaqueductal gray and the dorsal horn of spine. From a clinical perspective, the manipulation of the healthcare context with the best evidence-based therapy represents an opportunity to trigger placebo effects and to avoid nocebo effects respecting the ethical code of conduct. From a managerial perspective, stakeholders, organizations and governments should encourage the assessment of the healthcare context aimed to improve the quality of physiotherapy services. From an educational perspective, placebo and nocebo effects are professional topics that should be integrated in the university program of health and medical professions. From a research perspective, the control of placebo, nocebo and context-related effects offers to the scientific community the chance to better measure the impact of physiotherapy on different outcomes and in different conditions through primary studies.

Maximizing placebo response in neurological clinical practice

The placebo effect is a widely recognized phenomenon in clinical research, with a negative perception that it could hide the "true" drug effect. In clinical care its positive potential to increase known drug effects has been neglected for too long. The placebo and nocebo responses have been described in many neurologic disorders such as Parkinson's, Huntington's and Alzheimer's diseases, restless leg syndrome, tics, essential tremor, dystonia, functional movement disorders, neuropathic pain, headaches, migraine, amyotrophic lateral sclerosis, myasthenia gravis, chronic inflammatory demyelinating polyneuropathy, multiple sclerosis and epilepsy. Knowledge regarding placebo mechanisms and their consequences on clinical outcome have greatly improved over the last two decades. This evolution has led to reconsiderations of the importance of placebo response in the clinic and has given several clues on how to improve it in daily practice. In this chapter, we first illustrate "why," e.g. the reasons (relevance to clinical practice, help in differential diagnosis/treatment of psychogenic movements, clinical impact, proven neurobiological grounds, health economic potential), and "how," e.g. the means (increase patients' knowledge, increase learning, improve patient-doctor relationship, increase Hawthorne effect, increase positive/decrease negative expectations (the Rosenthal effect), personalize placebo response), the placebo should be maximized (and nocebo avoided) in neurological clinical practice. Future studies regarding more specific neurobiological mechanisms will allow a finer tuning of placebo response in clinical practice. The use of placebo in clinical practice raises ethical issues, and a recent expert consensus regarding placebo use in the clinic is a first step to future guidelines necessary to this field.

Determinants of placebo effects

Determinants of placebo effects and placebo response can be considered from multiple intrinsic and extrinsic perspectives. Intrinsic factors may influence the patient and the clinician/researcher. Patient expectations and previous experiences are considered two of the major intrinsic determinants of placebo response. Other patient determinants include the neural systems under treatment/study, situational factors and reactions to the environment, and personality traits. Clinician/researcher determinants of placebo response include personality factors such as empathy, perceived expertise, the clinical relationship with the patient, and the clinician's belief in the efficacy of the treatment. Extrinsic determinants include the type of study design, influence of advertising or branding, and forces expressed by the cultural milieu. These determinants do not act in isolation, but rather form a complex interaction that ultimately impacts the promotion or deterrence of the placebo effect in clinical and research settings.

Understanding placebo and nocebo effects in the context of sport: A psychological perspective

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.

The influence of personality traits on the placebo/nocebo response: A systematic review

OBJECTIVE

Some people might be more prone to placebo and nocebo responses than others depending on their personality traits. We aimed to provide a systematic review on the influence of personality traits on placebo and nocebo responses in controlled and uncontrolled studies.

METHODS

We conducted a systematic literature search in the databases CINAHL, AMED, PsycINFO and EMBASE for relevant publications published between January 1997 and March 2018. For all included papers, we conducted an additional forward search.

RESULTS

After screening 407 references, we identified 24 studies. The Big Five (i.e., neuroticism, extraversion, openness to experience, agreeableness and conscientiousness) and optimism were the most frequently investigated personality traits. Several studies found a positive association between optimism and the placebo response. Furthermore, we found that higher anxiety was associated with increased nocebo responses.

CONCLUSION

Evidence points to a possible association between optimism and the placebo response. Therefore, further emphasising the investigation of the influence of optimism on the placebo/nocebo response seems warranted. For clinical practice, the impact of anxiety on the nocebo response might be important to identify patients who might be more prone to experiencing side effects of medical treatments.

The Clinical Implications of Nocebo Effects for Biosimilar Therapy

Nocebo effects encompass negative responses to inert interventions in the research setting and negative outcomes with active treatments in the clinical research or practice settings, including new or worsening symptoms and adverse events, stemming from patients' negative expectations and not the pharmacologic action of the treatment itself. Numerous personality, psychosocial, neurobiological, and contextual/environmental factors contribute to the development of nocebo effects, which can impair quality of life and reduce adherence to treatment. Biologics are effective agents widely used in autoimmune disease, but their high cost may limit access for patients. Biosimilar products have gained regulatory approval based on quality, safety, and efficacy comparable to that of originator biologics in rigorous study programs. In this review, we identified gaps in patients' and healthcare professionals' awareness, understanding, and perceptions of biosimilars that may result in negative expectations and nocebo effects, and may diminish their acceptance and clinical benefits. We also examined features of nocebo effects with biosimilar treatment that inform research and clinical practices. Namely, when biosimilars are introduced to patients as possible treatment options, we recommend adoption of nocebo-reducing strategies to avoid negative expectations, including delivery of balanced information on risk-benefit profiles, framing information to focus on positive attributes, and promoting shared decision-making processes along with patient empowerment. Healthcare professionals confident in their knowledge of biosimilars and aware of bias-inducing factors may help reduce the risk of nocebo effects and improve patients' adherence in proposing biosimilars as treatment for autoimmune diseases such as rheumatoid arthritis and inflammatory bowel disease.

Meta-Analysis of Placebo Response in Adult Antidepressant Trials

BACKGROUND

Roughly 80% of the symptom improvement experienced on antidepressants in clinical trials is also observed in the placebo comparison group. Understanding the correlates of placebo improvement and response is important to designing efficient and successful trials of future antidepressants.

OBJECTIVE

The objective of this meta-analysis was to investigate the magnitude of placebo symptom improvement and placebo response rates in second-generation antidepressant trials of depression, anxiety, and obsessive-compulsive disorder.

METHODS

We searched PubMed on 10 June, 2016, with no date or language limits, to identify randomized placebo-controlled trials of second-generation antidepressants in adults with depression, anxiety, or obsessive-compulsive disorder. We used a random-effects meta-analysis to examine the magnitude of placebo symptom improvement using standardized mean difference and placebo response rate. Stratified subgroup analysis and meta-regression were utilized to examine the effect of diagnostic indication and correlates of placebo symptom improvement.

RESULTS

The meta-analysis included 164 trials involving 19,591 participants. Magnitude of placebo improvement and placebo response rates varied significantly between diagnostic indications. The magnitude of placebo improvement was much lower in obsessive-compulsive disorder (standardized mean difference = 0.58, 95% confidence interval 0.36-0.79) than in depression (standardized mean difference = 1.22, 95% confidence interval 1.12-1.32) or anxiety (standardized mean difference = 1.01, 95% confidence interval 0.90-1.12) trials. There was a large amount of heterogeneity in placebo improvement between studies (Q = 899, df = 110, p < 0.001, I² = 88%). A greater number of study sites and a later publication year were associated with a greater magnitude of placebo improvement and response rate. Presence of a placebo lead-in and absence of non-US sites were associated with a reduced magnitude of placebo improvement. Trial duration was positively associated with the magnitude of placebo improvement in depression trials but negatively associated with the magnitude of placebo improvement in anxiety and obsessive-compulsive disorder trials.

CONCLUSIONS

Magnitude of placebo symptom improvement differed significantly based on diagnostic indication with improvement being significantly less in obsessive-compulsive disorder than anxiety and depression. Some trial characteristics were associated with a greater magnitude of placebo improvement in trials across disorders but others were disorder specific.

Boundary effects of expectation in human pain perception

Perception of sensory stimulation is influenced by numerous psychological variables. One example is placebo analgesia, where expecting low pain causes a painful stimulus to feel less painful. Yet, because pain evolved to signal threats to survival, it should be maladaptive for highly-erroneous expectations to yield unrealistic pain experiences. Therefore, we hypothesised that a cue followed by a highly discrepant stimulus intensity, which generates a large prediction error, will have a weaker influence on the perception of that stimulus. To test this hypothesis we collected two independent pain-cueing datasets. The second dataset and the analysis plan were preregistered ( https://osf.io/5r6z7/ ). Regression modelling revealed that reported pain intensities were best explained by a quartic polynomial model of the prediction error. The results indicated that the influence of cues on perceived pain decreased when stimulus intensity was very different from expectations, suggesting that prediction error size has an immediate functional role in pain perception.

It is not just the drugs that matter: the nocebo effect

The role of psychological mechanisms in the treatment process cannot be underestimated, the well-known placebo effect unquestionably being a factor in treatment. However, there is also a dark side to the impact of mental processes on health/illness as exemplified by the nocebo effect. This phenomenon includes the emergence or exacerbation of negative symptoms associated with the therapy, but arising as a result of the patient's expectations, rather than being an actual complication of treatment. The exact biological mechanisms of this process are not known, but cholecystokinergic and dopaminergic systems, changes in the HPA axis, and the endogenous secretion of opioids are thought to be involved. The nocebo effect can affect a significant proportion of people undergoing treatment, including cancer patients, leading in some cases to the cessation of potentially effective therapy, because of adverse effects that are not actually part of the biological effect of treatment. In extreme cases, as a result of suggestions and expectations, a paradoxical effect, biologically opposite to the mechanism of the action of the drug, may occur. In addition, the nocebo effect may significantly interfere with the results of clinical trials, being the cause of a significant proportion of complications reported. Knowledge of the phenomenon is thus necessary in order to facilitate its minimalization and thus improve the quality of life of patients and the effectiveness of treatment.

How to prevent, minimize, or extinguish nocebo effects in pain: a narrative review on mechanisms, predictors, and interventions

Possible factors that contribute to nocebo effects on pain are explored. Strategies that can prevent, minimize, or extinguish nocebo effects in clinical settings are suggested.

Nocebo effects, such as side effects due to negative expectations regarding the pain treatment, are a concern for health care providers and come with significant costs. This narrative review focuses on underlying mechanisms and possible factors that contribute to the susceptibility to the nocebo effect on pain and related outcomes and suggests strategies that can prevent, minimize, or extinguish nocebo effects in clinical settings. Nocebo effects are the result of psychological (eg, conditioning, verbal suggestions, and observational learning) and neurobiological (eg, cholecystokinin and dopamine regulation) mechanisms. Evidence from clinical and experimental studies lead to various recommendations and strategies to alter the nocebo effect in order to optimize pain treatments, such as providing patients with enhanced information, optimizing patient–physician communication and relationships, and offering psychoeducation on coping skills in order to manage patient expectations. The current literature from both clinical and experimental studies provides a better understanding of the nocebo effect and possible factors that modulate its strength on treatment outcomes. This allows for the development of evidence-based strategies aimed at the prevention, minimization, and treatment of the nocebo effect in pain conditions and possible other somatic disorders.

The Influence of Expectancy Level and Personal Characteristics on Placebo Effects: Psychological Underpinnings

Placebo effects benefit a wide range of clinical practice, which can be profoundly influenced by expectancy level and personal characteristics. However, research on the issue of whether these factors independently or interdependently affect the placebo effects is still in its infancy. Here, we adopted a 3-day between-subject placebo analgesia paradigm (2-day conditioning and 1-day test) to investigate the influence of expectancy levels (i.e., No, Low, and High) and personal characteristics (i.e., gender, dispositional optimism, and anxiety state) on placebo effects in 120 healthy participants (60 females). Our results showed that the reduction of pain intensity in the test phase was influenced by the interaction between expectancy and gender, as mainly reflected by greater reductions of pain intensity in females at Low expectancy level than females at No/High expectancy levels, and greater reductions of pain intensity in males than in females at High expectancy level. Additionally, the reduction of pain unpleasantness was not only modulated by the interaction between expectancy and gender, but also by the interaction between expectancy and dispositional optimism, as well as the interaction between expectancy and anxiety state. Specifically, participants who were more optimistic in Low expectancy group, or those who were less anxious in High expectancy group showed greater reductions of pain unpleasantness. To sum up, we emphasized on regulating the expectancy level individually based on the assessment of personal characteristics to maximize placebo effects in clinical conditions.

Open-label placebo response - Does optimism matter? A secondary-analysis of a randomized controlled trial

OBJECTIVE

Open-label placebos (OLPs) have been found to elicit significant and clinical meaningful effects, but in comparison to deceptive placebo administration there is a lack of research regarding possible predictors. This study sets out to examine the effects of optimism and other personality-related variables on OLP responses.

METHODS

We conducted a secondary-analysis of an OLP trial in healthy participants (N = 160), who were randomized to no treatment (NT), OLP without rationale (OPR^-), OLP with rationale (OPR⁺), and deceptive placebo (DP) in an experimental heat pain paradigm.

RESULTS

The association between objective posttreatment pain tolerance and optimism did not differ among groups. However, for subjective heat pain ratings at posttreatment, regression analyses showed a significant interaction between group and optimism scores in subjective intensity (F[3, 142] = 3.81, P = 0.012) and unpleasantness ratings (F[3, 142] = 2.95, P = 0.035), indicating that the association between optimism and subjective ratings differed among groups, in particular between OPR⁺ and NT (intensity: P = 0.012; unpleasantness: P = 0.037), and OPR⁺ and DP (intensity: P = 0.016). Thus, higher optimism scores were negatively associated with subjective ratings in the NT and DP groups but not in the OPR⁺ group. Additional exploratory analyses revealed no significant interactions between group and further personality-related variables on heat pain analgesia.

CONCLUSION

Taken together, OLPs are effective, the underlying personality-related variables seem, however, to differ significantly from the deceptive placebo response. Therefore, the concept of "placebo responders" might depend on the route of placebo administration.

An Analysis of the Basic Processes of Formation and Change of Placebo Expectations

Placebo effects are the measurable psychological, biological, and behavioral changes that can result from expecting a treatment to be effective. Here we argue that not all expectations are created equally and there is much to learn by clarifying the psychological processes that underlie the expectations that cause placebo effects. It is proposed that the formation and change of placebo expectations can be understood from the standpoint of a general psychological model describing the basic processes of mental change. Specifically, we use the Elaboration Likelihood Model to explain how placebo-relevant variables (e.g., doctor’s lab coat, drug price, number and color of pills, patient’s mood) can work to affect expectations. Clarifying the antecedent processes responsible for placebo expectations leads to new insights regarding placebo effects, including their durability, directionality, and ability to alter subsequent behaviors (e.g., treatment adherence). A key point from our approach is that expectations causing placebo effects can be formed under high or low thought. High-thought expectations should be more likely to resist change, last over time, predict placebo effects better than low-thought expectations, and have a greater likelihood to alter subsequent behaviors. We conclude by describing a variety of theoretical innovations that this new conceptualization raises and suggest novel paths for research and application.

Placebo hypoalgesia: above and beyond expectancy and conditioning

Placebo hypoalgesia provides pain relief for individuals via the expectation of a beneficial or therapeutic outcome, while nocebo hyperalgesia results in increased pain in response to anxious anticipation of harmful outcomes. These forms of placebo pain modulation can be induced through repeated associations, verbal cues, and social interactions. Understanding these methods of pain modulation can provide greater insight into the psychosocial contexts of pain modulation, as well as develop novel approaches to pain management.

Psychologic Factors Do Not Affect Placebo Responses After Upper Extremity Injections: A Randomized Trial

BACKGROUND

Studies on how psychologic factors influence the placebo effect have shown conflicting results in an experimental setting. Pessimists are more likely to experience a nocebo effect (feel worse after an inert intervention), whereas other studies suggest that patients with more symptoms of depression or anxiety or greater neuroticism have a greater response to a placebo. This is important because treatment benefits are potentiated by placebo effects, and optimal utilization of this phenomenon may improve clinical outcomes.

QUESTIONS/PURPOSES

(1) What psychologic factors are associated with a decrease in magnitude of limitations (Disabilities of the Arm, Shoulder and Hand [DASH] score) and pain intensity (visual analog scale [VAS] for pain) after placebo injections for the treatment of painful nontraumatic upper extremity conditions? (2) What psychologic factors are associated with achieving a minimum clinically important difference (MCID) in disability and pain intensity?

METHODS

We performed a secondary analysis of data acquired in two prospective, double-blind, randomized controlled trials of patients with lateral elbow pain, trapeziometacarpal arthrosis, and de Quervain tendinopathy who received a single injection of dexamethasone and lidocaine or lidocaine alone (placebo). One hundred six patients were included between June 2003 and February 2008. Sixty-three patients (59%) received dexamethasone and lidocaine, and we analyzed the subset of 43 patients (41%) who received lidocaine alone. The primary outcomes of interest were the DASH questionnaire and the VAS for pain measured three times: when they received the injection, between 1 and 3 months after the injection, and between 5 and 8 months after the injection. Seven patients missed the first followup visit and 14 patients missed the second visit. Based on previous research, we chose a MCID threshold of 10 for the DASH and a threshold of 1.0 for the VAS score. In bivariate analysis, we accounted for sex, race, marital status, degree, education, work status, pretreatment pain, diagnosis, symptoms of depression (Center of Epidemiologic Studies-Depression Scale), coping strategies in response to nociception (Pain Catastrophizing Scale), and personality traits (measured with the Multidimensional Health Locus of Control scale and the Eysenck Personality Questionnaire-Revised score). Variables with p values < 0.10 in bivariate analysis were included in the multivariable regression models. An a priori power analysis showed that a sample of 43 participants provides 80% statistical power, with α set at 0.05, for a regression with five predictors if the depression score would account for 15% or more of the variability in pain score. We used multiple imputations (imputations = 50) for a total of 66 (8.5%) missing or incomplete questionnaires.

RESULTS

In the final multivariable models, no psychologic factors were associated with a change in DASH score between injection and followup, and no factors were associated with greater decrease in pain intensity. After injection, no psychologic factors were independently associated with achieving a MCID in the DASH and VAS.

CONCLUSIONS

Our study confirms that patient factors are less important mediators of the placebo effect than clinician factors. In other words, clinician warmth and competence can help diminish symptoms and limitations of people in various states of mind, even when using inert or ineffective treatments.

LEVEL OF EVIDENCE

Level II, therapeutic study.

Brain and psychological determinants of placebo pill response in chronic pain patients

The placebo response is universally observed in clinical trials of pain treatments, yet the individual characteristics rendering a patient a ‘placebo responder’ remain unclear. Here, in chronic back pain patients, we demonstrate using MRI and fMRI that the response to placebo ‘analgesic’ pills depends on brain structure and function. Subcortical limbic volume asymmetry, sensorimotor cortical thickness, and functional coupling of prefrontal regions, anterior cingulate, and periaqueductal gray were predictive of response. These neural traits were present before exposure to the pill and most remained stable across treatment and washout periods. Further, psychological traits, including interoceptive awareness and openness, were also predictive of the magnitude of response. These results shed light on psychological, neuroanatomical, and neurophysiological principles determining placebo response in RCTs in chronic pain patients, and they suggest that the long-term beneficial effects of placebo, as observed in clinical settings, are partially predictable.

People vary in the extent to which they feel better after taking an inert, placebo, treatment, but the basis for individual placebo response is unclear. Here, the authors show how brain structural and functional variables, as well as personality traits, predict placebo response in those with chronic back pain.

The nocebo effect: a clinical challenge in the era of biosimilars

INTRODUCTION

The nocebo effect is defined as a negative effect of a pharmacological or non-pharmacological medical treatment that is induced by patients' expectations, and that is unrelated to the physiological action of the treatment. The nocebo effect is an important clinical challenge in the current era of biosimilars. Areas covered: This review aims to answer five key questions about the nocebo effect, namely to reveal its definition, pathophysiology, clinical relevance, contributing factors, and management. Expert commentary: The nocebo effect lowers patients' quality of life and negatively affects treatment adherence rates in biosimilar-treated patients. It may negatively impact on the cost-savings of biosimilars. Health-care providers in charge of biosimilar-treated patients need to be aware of the nocebo effect and adopt strategies to minimize it. They have to be well-informed and confident about the existing evidence about biosimilars. A good patient-physician relationship will improve patients' acceptance of biosimilars, and limits the risk of inappropriate negative bias and the nocebo effect.

Is the rationale more important than deception? A randomized controlled trial of open-label placebo analgesia

Research on open-label placebos questions whether deception is a necessary characteristic of placebo effects. Yet, comparisons between open-label and deceptive placebos (DPs) are lacking. We therefore assessed effects of open-label placebos and DPs in comparison with no treatment (NT) with a standardized experimental heat pain paradigm in a randomized controlled trial in healthy participants. Participants (N = 160) were randomly assigned to NT, open-label placebo without rationale (OPR-), open-label placebo with rationale (OPR), and DP. We conducted baseline and posttreatment measurements of heat pain threshold and tolerance. Apart from the NT, all groups received an application of a placebo cream. Primary outcomes were planned comparisons of heat pain tolerance and the corresponding intensity and unpleasantness ratings. Objective posttreatment pain tolerance did not differ among groups. However, for subjective heat pain ratings at the posttreatment tolerance level, groups with a rationale (OPR and DP) reported diminished heat pain intensity (t(146) = -2.15, P = 0.033, d = 0.43) and unpleasantness ratings (t(146) = -2.43, P = 0.016, d = 0.49) compared with the OPR-group. Interestingly, the OPR and the DP groups did not significantly differ in heat pain intensity (t(146) = -1.10, P = 0.272) or unpleasantness ratings (t(146) = -0.05, P = 0.961) at the posttreatment tolerance level. Our findings reveal that placebos with a plausible rationale are more effective than without a rationale. Even more, open-label placebos did not significantly differ in their effects from DPs. Therefore, we question the ubiquitously assumed necessity of concealment in placebo administration.

What's in a word? How instructions, suggestions, and social information change pain and emotion

Instructions, suggestions, and other types of social information can have powerful effects on pain and emotion. Prominent examples include observational learning, social influence, placebo, and hypnosis. These different phenomena and their underlying brain mechanisms have been studied in partially separate literatures, which we discuss, compare, and integrate in this review. Converging findings from these literatures suggest that (1) instructions and social information affect brain systems associated with the generation of pain and emotion, and with reinforcement learning, and that (2) these changes are mediated by alterations in prefrontal systems responsible for top-down control and the generation of affective meaning. We argue that changes in expectation and appraisal, a process of assessing personal meaning and implications for wellbeing, are two potential key mediators of the effects of instructions and social information on affective experience. Finally, we propose a tentative model of how prefrontal regions, especially dorsolateral and ventromedial prefrontal cortex may regulate affective processing based on instructions and socially transmitted expectations more broadly.

What Is the Role of the Placebo Effect for Pain Relief in Neurorehabilitation? Clinical Implications From the Italian Consensus Conference on Pain in Neurorehabilitation

Background

It is increasingly acknowledged that the outcomes of medical treatments are influenced by the context of the clinical encounter through the mechanisms of the placebo effect. The phenomenon of placebo analgesia might be exploited to maximize the efficacy of neurorehabilitation treatments. Since its intensity varies across neurological disorders, the Italian Consensus Conference on Pain in Neurorehabilitation (ICCP) summarized the studies on this field to provide guidance on its use.

Methods

A review of the existing reviews and meta-analyses was performed to assess the magnitude of the placebo effect in disorders that may undergo neurorehabilitation treatment. The search was performed on Pubmed using placebo, pain, and the names of neurological disorders as keywords. Methodological quality was assessed using a pre-existing checklist. Data about the magnitude of the placebo effect were extracted from the included reviews and were commented in a narrative form.

Results

11 articles were included in this review. Placebo treatments showed weak effects in central neuropathic pain (pain reduction from 0.44 to 0.66 on a 0-10 scale) and moderate effects in postherpetic neuralgia (1.16), in diabetic peripheral neuropathy (1.45), and in pain associated to HIV (1.82). Moderate effects were also found on pain due to fibromyalgia and migraine; only weak short-term effects were found in complex regional pain syndrome. Confounding variables might have influenced these results.

Clinical implications

These estimates should be interpreted with caution, but underscore that the placebo effect can be exploited in neurorehabilitation programs. It is not necessary to conceal its use from the patient. Knowledge of placebo mechanisms can be used to shape the doctor-patient relationship, to reduce the use of analgesic drugs and to train the patient to become an active agent of the therapy.

Medicine-related beliefs predict attribution of symptoms to a sham medicine: A prospective study

OBJECTIVES

To investigate a range of possible predictors of nocebo responses to medicines.

DESIGN

Prospective cohort study.

METHODS

In total, 203 healthy adult volunteers completed measures concerning demographics, psychological factors, medicine-related beliefs, baseline symptoms, and symptom expectations before taking a sham pill, described as 'a well-known tablet available without prescription' that was known to be associated with several side effects. Associations between these measures and subsequent attribution of symptoms to the tablet were assessed using a hurdle model consisting of a joint logistic and truncated negative binomial regression.

RESULTS

Men had an increased odds of attributing symptoms to the tablet OR = 1.52, and older participants had decreased odds, OR = 0.97. Medicine-related beliefs were important, with modern health worries, belief that medicines cause harm and perceived sensitivity to medicines associated with increased odds of symptom attribution, OR = 1.02, 1.10, 1.09, respectively. Trust in medicines and pharmaceutical companies decreased the odds of symptom attribution, OR = 0.91, 0.88, respectively. The number of symptoms at baseline and the expected likelihood of symptoms were associated with an increased odds of attributing symptoms to the tablet, OR = 1.07, 1.06, respectively. Anxiety, previous symptom experience, symptom expectations, and modern health worries were also important in predicting the number of symptoms participants attributed to the tablet.

CONCLUSION

It is hard to predict who is at risk of developing nocebo responses to medicines from demographic or personality characteristics. Context-specific factors such as beliefs about and trust in medicines, current symptoms and symptom expectations are more useful as predictors. More work is needed to investigate this in a patient sample. Statement of contribution What is already known on this subject? Many patients report non-specific side effects to their medication which may arise through a nocebo effect. Whether some people are particularly predisposed to experience nocebo effects remains unclear. What does this study add? Demographic and personality characteristics are poor predictors of symptom attribution to a sham medicine. Instead, context-specific factors that concern people's beliefs surrounding medicines, their current symptoms, and symptom expectations are more useful as predictors of symptom attribution.

Can knowledge of Placebo and Nocebo Mechanisms Help Improve Randomized Clinical Trials?

Over the last decade, there has been a substantial increase in negative results from randomized controlled trials (RCTs), which may be due to an increasing placebo response among other factors. Currently, identification and exclusion of placebo responders from trials are attempted to overcome this problem, but so far the success of these approaches has been limited. At the same time, the placebo-mechanism literature has highlighted how contextual factors, such as patients' expectations, interfere with the effect of drug administration, leading to a certain degree of uncertainty in RCTs. In this chapter, we review the current challenges of RCTs including the uncertainties of the active arm, the placebo arm, the additivity assumption, and the double-blind procedure. We use the placebo-mechanism literature to debate the strengths and weaknesses of attempts to identify and exclude placebo responders from trials. Finally, we illustrate how insights from the placebo-mechanism literature may point to new ways of improving RCTs.

People's Understanding of Verbal Risk Descriptors in Patient Information Leaflets: A Cross-Sectional National Survey of 18- to 65-Year-Olds in England

Introduction

Evidence suggests the current verbal risk descriptors used to communicate side effect risk in patient information leaflets (PILs) are overestimated.

Objectives

The aim was to establish how people understand the verbal risk descriptors recommended for use in PILs by the European Commission (EC), and alternative verbal risk descriptors, in the context of mild and severe side effects.

Methods

A cross-sectional online survey was carried out by a market research company recruiting participants aged between 18 and 65 years living in England. Data were collected between 18 March and 1 April 2016. Participants were given a hypothetical scenario regarding the risk of mild or severe medication side effects and asked to estimate how many out of 10,000 people would be affected for each of the verbal risk descriptors being tested.

Results

A total of 1003 participants were included in the final sample. The risks conveyed by the EC recommended verbal risk descriptors were greatly overestimated by participants. Two distinct distributions were apparent for participant estimates of side effect risks: those for ‘high risk’ verbal descriptors (e.g. ‘common’, ‘likely’, ‘high chance’) and those for ‘low risk’ verbal descriptors (e.g. ‘uncommon’, ‘unlikely’, ‘low chance’). Within these two groups, the distributions were near to identical regardless of what adverb (e.g. very, high, fair) or adjective (e.g. common, likely, chance) was used. The EC recommended verbal risk descriptors were more likely to be understood in accordance with their intended meanings when describing severe side effects. Very few demographic or psychological factors were consistently associated with how well participants understood the EC recommended verbal risk descriptors.

Discussion

The current verbal risk descriptors used in PILs are ineffective at best and misleading at worst. Discontinuing the use of verbal risk descriptors would limit the likelihood of people overestimating the risk of side effects.

Electronic supplementary material

The online version of this article (doi:10.1007/s40264-017-0542-1) contains supplementary material, which is available to authorized users.

Something out of nothing: the placebo effect

The history of the concept of the placebo effect and research into its quantification and mechanisms are reviewed, particularly in relation to psychiatry. Research has demonstrated a notable placebo effect in depression: a large proportion of the clinical effect of antidepressant medication is attributable to the effect. Various mechanisms have been hypothesised: anxiety relief, expectation, transference, ‘meaning effects' and conditioning. Recent research from neuroimaging has unveiled that the effect is associated with biological correlates in the brain. Despite the renewal of research into the placebo effect, many questions remain unanswered. This partly reflects philosophical obstacles such as the mind/body dichotomy, which are inherent in conceptualising the effect. However, it also demonstrates the vast scope for further research into this area. Ultimately, an understanding of the processes that underlie the placebo effect should allow a rationalised therapeutic approach to be developed to maximise the clinical benefit of the therapeutic encounter.

Five Interpersonal Factors Are Predictive of the Response to Treatment of Major Depression With Antidepressants in Primary Care

Introduction: Factors relating to the interpersonal relationship between the patient and their physician and social environment are important components, which contribute to their response to treatment for major depressive disorder. This study aimed to assess the influence of optimism, perfectionism, therapeutic alliance, empathy, social support, and adherence to medication regimen in the response to antidepressant treatments in the context of normal primary care clinical practice. Method: We conducted a prospective study in which 24 primary care physicians administered sertraline or escitalopram to 89 patients diagnosed with major depressive disorder. The response to treatment and remission of the episode was assessed at 4 and 12 weeks by Cox regression. The effect of adherence to the medication regimen was assessed by multiple regression statistical techniques. Results: Adherence to medication (HR = 0.262, 95% CI = 0.125-0.553, p < 0.001) and patient perfectionism (HR = 0.259, 95% CI = 0.017-0.624, p < 0.01) negatively predicted the initial response to treatment, whereas patient optimism (HR = 1.221, 95% CI = 1.080-1.380, p < 0.05) positively predicted it. Patient optimism (HR = 1.247, 95% CI = 1.1-1.4, p < 0.05), empathy perceived by the patient (HR = 1.01, 95% CI = 1001-1002, p < 0.05), and therapeutic alliance (HR = 1.02, 95% CI = 1001-1.04, p < 0.05) positively predicted episode remission, while patient perfectionism (HR = 0.219, 95% CI = 0.093-0.515, p < 0.001) and low adherence to the treatment regimen (HR = 0.293, 95% CI = 0.145-0.595, p < 0.001) negatively predicted it. Finally, social support (p < 0.01) and therapeutic alliance (p < 0.05) predicted adherence to the medication regimen. Conclusions: In addition to taking the antidepressant drug, other factors including the personal interactions between the patient with their primary care physician and with their social environment significantly influenced the patients' initial response and the final rate of episode remission.

How does the side-effect information in patient information leaflets influence peoples' side-effect expectations? A cross-sectional national survey of 18- to 65-year-olds in England

OBJECTIVES

To establish how the terms recommended by the European Commission to describe side-effect risk in patient information leaflets (PILs) influences expectations of side-effects and to identify factors associated with these side-effect expectations.

DESIGN

A cross-sectional online survey was carried out by a market research company.

SETTING

Data were collected in England between 18th March and 1st April 2016.

PARTICIPANTS

A total of 1003 adults aged between 18 and 65.

MAIN OUTCOME MEASURES

Self-reported expectation that the described side-effects would affect participants if they took the medicine, measured on a likelihood scale from 1 (very unlikely) to 5 (very likely).

RESULTS

Participants formed high expectations of side-effects for "very common" and "common" side-effects, with 51.9% and 45.0% of participants rating these as "very likely" or "likely" to happen to them, respectively. This fell to 8.1% for "uncommon," 5.8% for "rare" and 4.1% for "very rare." For each descriptor, higher expectations of side-effects were more associated with women or being from an ethnic minority, or having less education, a household illness, high perceived sensitivity to medicines or negative beliefs about medicines.

DISCUSSION

The current use of verbal descriptors to communicate side-effect risk in PILs leads to high side-effect expectations. These expectations could contribute to nocebo-induced medication side-effects experienced by patients. Additional work is required to identify ways to improve the way risk information is conveyed in PILs.