The placebo effect: dissolving the expectancy versus conditioning debate

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.

Manual Therapy in Primary Dysmenorrhea: A Systematic Review and Meta-Analysis

Objective

This research aimed to assess the effectiveness of manual therapy in alleviating pain among women undergoing primary dysmenorrhea (PD).

Methods

All randomized controlled trials (RCTs) regarding manual therapy for PD were searched from online databases, spanning from their inception to July 2023. The identified literature underwent a thorough screening process, and the data were meticulously extracted and analyzed using RevMan 5.3. Subsequently, the included studies underwent Cochrane's quality assessment and meta-analysis. The evidence obtained was then assessed using the grading of recommendations, assessment, development, and evaluation (GRADE) approach.

Results

32 RCTs, involving 2566 women were finally included for analysis. The overall quality of the concluding evidence was generally rated as low or very low. Performance bias and blind bias were found to be the main risk of bias of the included studies. In comparison to no treatment, manual therapy demonstrated a significant increase in pain relief in short-term (n=191, MD=1.30, 95% CI: 0.24~2.37). The differences in the effects of manual therapy and the placebo on pain intensity may not be statistically significant (n=255, MD=0.10, 95% CI: -0.37~0.58). In contrast to NSAIDs, manual therapy exhibited superior pain alleviation (n=507, MD=3.01, 95% CI: 1.08~4.94) and a higher effective rate (n=1029, OR=4.87, 95% CI: 3.29~7.20). Importantly, no severe adverse events were reported across all studies, indicating a relatively safe profile for manual therapy.

Conclusion

Manual therapy presented promise in effectively relieving menstrual pain with minimal adverse events in short term, outperforming both no treatment and NSAIDs. However, this conclusion is tempered by the low quality of the included RCTs, highlighting the necessity for more robust trials to validate it.

Practitioner warmth and empathy attenuates the nocebo effect and enhances the placebo effect

Augmented patient-practitioner interactions that enhance therapeutic alliance can increase the placebo effect to sham treatment. Little is known, however, about the effect of these interactions on maladaptive health outcomes (i.e., the nocebo effect). Healthy participants (N = 84) were randomised to a 3-day course of Oxytocin nasal drops (actually, sham treatment) in conjunction with a high-warmth interaction (Oxy-HW: N = 28), a low-warmth interaction (Oxy-LW: N = 28) or to a no treatment control group (NT: N = 28). All participants were informed that the Oxytocin treatment could increase psychological well-being but was associated with several potential side effects. Treatment-related side effects, unwarned symptoms, and psychological well-being were measured at baseline and all post-treatment days. Side effect reporting was increased in the Oxy-LW condition compared to the other groups across all days. Conversely, increased psychological well-being was observed in the Oxy-HW condition, relative to the other conditions, but only on Day 1. Among those receiving treatment, positive and negative expectations, and treatment-related worry, did not vary by interaction-style, while psychological well-being and side effect reporting were inversely associated at the level of the individual. Results have important implications for practice, suggesting poorer quality interactions may not only reduce beneficial health outcomes but also exacerbate those that are maladaptive.

Creating Placebo Nonresponders in the Lab

Conditioning and expectation are known to be the main mechanisms of placebo analgesia. They may operate together, so that expectations may be enhanced by a conditioning procedure. Although most of the studies have tried to potentiate expectations through conditioning in order to generate good placebo responders, a few studies have tried to mismatch conditioning and expectations in order to investigate the subsequent administration of a placebo. In this study, we want to further investigate this mismatch. We generated incongruent associations during a conditioning procedure in which the study participants did not get what they expected. In fact, although the participants received verbal instructions of pain decrease following the administration of a placebo, we surreptitiously increased the painful electric stimulation. Two pairings of these incongruent associations (mismatch between what was expected and what was experienced) disrupted expectations of analgesia as well as the placebo effect, as assessed by measuring electric pain thresholds on the hand. The effects of mismatch conditioning on the hand extended to the contralateral arm and to a different type of pain (tourniquet), which suggests that local mismatch conditioning may affect the whole body. In all cases, expectations predicted placebo analgesia. These findings indicate that placebo nonresponders can be created in the laboratory by acting on expectations and that local effects can be generalized to other parts of the body. They also stress the importance of expectations in the therapeutic outcome, with important implications for clinical trials. PERSPECTIVE: By using mismatch conditioning, in which study participants did not get what they expected, we reduced expectations of analgesia, and this reduction abolished placebo analgesia. This effect extended to other parts of the body and other types of pain, which indicates that placebo nonresponders can be created in the laboratory.

Can Pharmacological Conditioning as an Add-On Treatment Optimize Standard Pharmacological Treatment in Patients with Recent-Onset Rheumatoid Arthritis? A Proof-of-Principle Randomized Clinical Trial

Medication regimens using conditioning via variable reinforcement have shown similar or improved therapeutic effects as full pharmacological treatment, but evidence in patient populations is scarce. This proof-of-principle double-blind randomized clinical trial examined whether treatment effects in recent-onset rheumatoid arthritis (RA) can be optimized through pharmacological conditioning. After four months of standardized treatment (n = 46), patients in clinical remission (n = 19) were randomized to the Control group (C), continuing standardized treatment (n = 8), or the Pharmacological Conditioning (PC) group, receiving variable treatment according to conditioning principles (n = 11). After eight months, treatment was tapered and discontinued linearly (C) or variably (PC). Standard treatment led to large improvements in disease activity and HRQoL in both groups. The groups did not differ in the percentage of drug-free clinical remission obtained after conditioning or continued standard treatment. The PC group did show a larger decrease in self-reported disease activity (Cohen's d = 0.9) and a smaller increase in TNF-α levels (Cohen's d = 0.7) than the C group. During all phases, more differences between groups were found for the patients who followed protocol than for the intention-to-treat sample. Although the results are not conclusive, pharmacological conditioning may have some advantages in terms of disease progression and stability, especially during the conditioning phase, compared with standard clinical treatment. The effects may be particularly beneficial for patients who show a good initial response to increased medication dosages.

Does Active Inference Provide a Comprehensive Theory of Placebo Analgesia?

Placebo interventions generate mismatches between expected pain and sensory signals from which pain states are inferred. Because we lack direct access to bodily states, we can only infer whether nociceptive activity indicates tissue damage or results from noise in sensory channels. Predictive processing models propose to make optimal inferences using prior knowledge given noisy sensory data. However, these models do not provide a satisfactory explanation of how pain relief expectations are translated into physiological manifestations of placebo responses. Furthermore, they do not account for individual differences in the ability to endogenously regulate nociceptive activity in predicting placebo analgesia. The brain not only passively integrates prior pain expectations with nociceptive activity to infer pain states (perceptual inference) but also initiates various types of actions to ensure that sensory data are consistent with prior pain expectations (active inference). We argue that depending on whether the brain interprets conflicting sensory data (prediction errors) as a signal to learn from or noise to be attenuated, the brain initiates opposing types of action to facilitate learning from sensory data or, conversely, to enhance the biasing influence of prior pain expectations on pain perception. Furthermore, we discuss the role of stress, anxiety, and unpredictability of pain in influencing the weighting of prior pain expectations and sensory data and how they relate to the individual ability to regulate nociceptive activity (endogenous pain modulation). Finally, we provide suggestions for future studies to test the implications of the active inference model of placebo analgesia.

A synthesis of meta-analyses of mindfulness-based interventions in pain

ABSTRACT

Mindfulness interventions have become popular in recent decades, with many trials, systematic reviews, and meta-analyses of the impact of mindfulness-based interventions (MBIs) on pain. Although many meta-analyses provide support for MBIs, the results are more mixed than they at first appear. The aim of this umbrella review was to determine the strength of evidence for MBIs by synthesizing available meta-analyses in pain. We conducted a systematic search in 5 databases and extracted data from published meta-analyses as the unit of analysis. For each outcome, we reported the range of effect sizes observed across studies and identified the largest meta-analysis as the "representative" study. We separately analysed effect sizes for different pain conditions, different types of MBIs, different control groups, and different outcomes. We identified 21 meta-analyses that included 127 unique studies. According to Assessment of Multiple Systematic Review ratings, the meta-analyses ranged from very strong to weak. Overall, there was an impact of MBIs on pain severity, anxiety, and depression but not pain interference or disability. When conditions were considered in isolation, only fibromyalgia and headache benefited significantly from MBIs. Mindfulness-based interventions were more efficacious for pain severity than passive control conditions but not active control conditions. Only pain severity and anxiety were affected by MBIs at follow-up. Overall, our results suggest that individual meta-analyses of MBIs may have overestimated the efficacy of MBIs in a range of conditions. Mindfulness-based interventions likely have a role in pain management but should not be considered a panacea.

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.

The influence of psychological traits and prior experience on treatment expectations

BACKGROUND

Placebo and nocebo responses are modulated by the treatment expectations of participants and patients. However, interindividual differences predicting treatment expectations and placebo responses are unclear. In this large-scale pooled analysis, we aim to investigate the influence of psychological traits and prior experiences on treatment expectations.

METHODS

This paper analyses data from six different placebo studies (total n = 748). In all studies, participants' sociodemographic information, treatment expectations and prior treatment experiences and traits relating to stress, somatization, depression and anxiety, the Big Five and behavioral inhibition and approach tendencies were assessed using the same established questionnaires. Correlation coefficients and structural equation models were calculated to investigate the relationship between trait variables and expectations.

RESULTS

We found small positive correlations between side effect expectations and improvement expectations (r = 0.187), perceived stress (r = 0.154), somatization (r = 0.115), agitation (r = 0.108), anhedonia (r = 0.118), and dysthymia (r = 0.118). In the structural equation model previous experiences emerged as the strongest predictors of improvement (β = 0.32, p = .005), worsening (β = -0.24, p = .005) and side effect expectations (β = 0.47, p = .005). Traits related to positive affect (β = - 0.09; p = .007) and negative affect (β = 0.04; p = .014) were associated with side effect expectations.

DISCUSSION

This study is the first large analysis to investigate the relationship between traits, prior experiences and treatment expectations. Exploratory analyses indicate that experiences of symptom improvement are associated with improvement and worsening expectations, while previous negative experiences are only related to side effect expectations. Additionally, a proneness to experience negative affect may be a predictor for side effect expectation and thus mediate the occurrence of nocebo responses.

Effects of one single-dose methylphenidate compared to one single-dose placebo on QbTest performance in adults with untreated ADHD: a randomized controlled trial

BACKGROUND

Treatment of adults with attention-deficit/hyperactivity disorder (ADHD) primary involves methylphenidate (MPH). Earlier studies have identified placebo responders to increase toward the end of the treatment periods. However, little is known about the immediate effects of placebo on the core symptoms of ADHD in adults. The present study aimed to examine the effects of one single-dose MPH compared to one single-dose placebo during clinical assessments with continuous performance tests (CPT).

METHODS

In a randomized study with cross-over design, 40 adults between 19 and 64 years (72.5% women) with untreated ADHD were consecutively enrolled. The study comprised two trial days with four days in between. The QbTest was performed twice on the same day, before and 80 min after intake of one single-dose 20 mg immediate release methylphenidate (IR-MPH) and with one single-dose placebo, in randomized order.

RESULTS

Performance improved in QbInattention, F (3, 117) = 38.25, p < 0.001, after given IR-MPH (mean diff = 1.14) and after placebo (mean diff = 0.60) with the effect sizes 1.17 and 0.63 respectively. IR-MPH improved performance in QbActivity (mean diff = 0.81, p < 0.001) and QbImpulsivity (mean diff = 0.46, p < 0.04). The proportion of improvements (a decrease by ≥ 0.5 Qb-score) in the parameters QbInattention, QbActivity and QbImpulsivity were 90%, 60% and 52.5%, respectively. After given placebo, corresponding proportions were 60%, 30% and 35%, respectively.

CONCLUSIONS

There seems to be an immediate placebo response in the core symptom inattention. The effect of placebo cannot be ruled out and must be taken in consideration during drug trials with continuous performance tests (CPTs).

TRIAL REGISTRATION

ClinicalTrials.gov; Identifier: NCT02473185.

The Role of Subjective Expectations for Exhaustion and Recovery: The Sample Case of Work and Leisure

We propose a new model of exhaustion and recovery that posits that people evaluate an activity as exhausting or recovering on the basis of the subjective expectation about how exhausting or recovering activities related to a certain life domain are. To exemplify the model, we focus as a first step on the widely shared expectations that work is exhausting and leisure is recovering. We assume that the association of an activity related to a life domain associated with exhaustion (e.g., work) leads people to monitor their experiences and selectively attend to signs of exhaustion; in contrast, while pursuing an activity related to a life domain associated with recovery (e.g., leisure), people preferentially process signs of recovery. We further posit that the preferential processing of signs of exhaustion (vs. recovery) leads to experiencing more exhaustion when pursuing activities expected to be exhausting (e.g., work activities) and more recovery when pursuing activities expected to be recovering (e.g., leisure activities). This motivational process model of exhaustion and recovery provides new testable hypotheses that differ from predictions derived from limited-resource models.

A novel lotion formulation of 20% oxybutynin hydrochloride for the treatment of primary palmar hyperhidrosis: A randomized, placebo-controlled, double-blind, phase III study

BACKGROUND

No previous controlled studies have been specifically designed or adequately powered to show the efficacy of topical oxybutynin for palmar hyperhidrosis by using quantitative measures.

OBJECTIVE

To evaluate efficacy of 20% oxybutynin hydrochloride lotion (20% OL) in reducing palmar sweat volume in patients with primary palmar hyperhidrosis (PPHH).

METHODS

In a randomized controlled trial, Japanese patients with PPHH aged 12 years and older received either 20% OL (n = 144) or placebo (n = 140) on both palms once daily for 4 weeks. Palmar sweat volume was measured by the ventilated capsule method. For the primary outcome, response was defined as a reduction of sweat volume of at least 50% from baseline.

RESULTS

At week 4, the responder rate for sweat volume was significantly higher in the 20% OL arm than in the placebo arm (52.8% vs 24.3%, respectively; treatment difference, 28.5% [95% CI, 17.7% to 39.3%]; P < .001). No serious adverse events occurred, and no adverse events led to treatment discontinuation.

LIMITATIONS

The treatment period was only 4 weeks.

CONCLUSIONS

In patients with PPHH, 20% OL is superior to placebo in reducing palmar sweat volume.

Treatment Invasiveness and Illness Perceptions Are Strongly Associated With Outcome Expectations in Patients Treated for Hand or Wrist Conditions: A Cross-sectional Study

BACKGROUND

Multiple studies have shown that more-positive outcome expectations are associated with better treatment outcomes. Although this has not been shown to represent a causal relationship, there nonetheless is an interest in positively modifying outcome expectations to improve treatment outcomes. However, little is known about what is independently associated with outcome expectations in clinical practice. For example, it is unknown to what extent expectations are associated with treatment or patient characteristics such as sociodemographics or with patient-reported outcome measures (PROMs) on patient perceptions of physical or mental health or illness. Studying factors associated with outcome expectations may provide relevant information for clinicians and researchers aiming to improve outcome expectations. Improving expectations might, in turn, improve treatment outcomes.

QUESTION/PURPOSE

Which factors (that is, sociodemographics, PROMs, illness perceptions, treatment, surgeon, and location) are independently associated with outcome expectations in patients with hand or wrist conditions?

METHODS

This was a cross-sectional study. Between July 2018 and December 2021, we screened 21,327 patients with a diagnosed hand or wrist condition with complete baseline sociodemographic data such as age and workload. Sixty percent (12,765 of 21,327) of patients completed all relevant PROMs. We excluded patients receiving rare treatments, leaving 58% (12,345 of 21,327) for inclusion in the final sample. Those who participated were more often scheduled for surgical treatment and had higher expectations. We performed a multilevel analysis involving two steps. First, we evaluated whether patients receiving the same treatment, being counseled by the same surgeon, or being treated at the same location have more similar outcome expectations. We found that only patients receiving the same treatment had more similar outcome expectations. Therefore, we used a multilevel regression model to account for this correlation within treatments, and added treatment characteristics (such as nonsurgical versus minor or major surgery) to potential explanatory factors. Second, in the multilevel hierarchical regression analysis, we added sociodemographics (Model 1), PROMs for physical and mental health (Model 2), illness perceptions (Model 3), and treatment characteristics (most-definitive model) to assess the explained variance in outcome expectations per step and the relative association with outcome expectations.

RESULTS

Sociodemographic factors such as age and workload explained 1% of the variance in outcome expectations. An additional 2% was explained by baseline PROMs for physical and mental health, 9% by illness perceptions, and 18% by treatment characteristics, resulting in an explained variance of 29% of the most-definitive model. A large number of patient and treatment characteristics were associated with outcome expectations. We used standardized betas to compare the magnitude of the effect of the different continuous and categorical variables. Among the associated variables, minor surgery (standardized beta [β] = 0.56 [95% confidence interval 0.44 to 0.68]; p < 0.001) and major surgery (β = 0.61 [95% CI 0.49 to 0.73]; p < 0.001) had the strongest positive association with outcome expectations (receiving surgery is associated with higher outcome expectations than nonsurgical treatment). A longer illness duration expected by the patient (-0.23 [95% CI -0.24 to -0.21]; p < 0.001) and being treated for the same condition as before (-0.08 [95% CI -0.14 to -0.03]; p = 0.003) had the strongest negative association with outcome expectations.

CONCLUSION

Outcome expectations are mainly associated with the invasiveness of the treatment and by patients' illness perceptions; patients before surgical treatment have more positive expectations of the treatment outcome than patients before nonsurgical treatment, even after accounting for differences in clinical and psychosocial profiles. In addition, patients with a more-positive perception of their illness had more-positive expectations of their treatment. Our findings suggest expectation management should be tailored to the specific treatment (such as surgical versus nonsurgical) and the specific patient (including their perception of their illness). It may be more beneficial to test and implement expectation management strategies for nonsurgical treatments such as physical therapy than for surgical treatments, given that our findings indicate a greater need to do so. An additional advantage of such a strategy is that successful interventions may prevent converting to surgical interventions, which is a goal of the stepped-care principles of standard care. Future studies might investigate the causality of the association between pretreatment expectations and outcomes by performing an experimental study such as a randomized controlled trial, in which boosting expectations is compared with usual care in nonsurgical and surgical groups.

LEVEL OF EVIDENCE

Level III, prognostic study.

Predicting placebo analgesia in patients with chronic pain using natural language processing: a preliminary validation study

ABSTRACT

Patients with chronic pain show large placebo effects in clinical trials, and inert pills can lead to clinically meaningful analgesia that can last from days to weeks. Whether the placebo response can be predicted reliably, and how to best predict it, is still unknown. We have shown previously that placebo responders can be identified through the language content of patients because they speak about their life, and their pain, after a placebo treatment. In this study, we examine whether these language properties are present before placebo treatment and are thus predictive of placebo response and whether a placebo prediction model can also dissociate between placebo and drug responders. We report the fine-tuning of a language model built based on a longitudinal treatment study where patients with chronic back pain received a placebo (study 1) and its validation on an independent study where patients received a placebo or drug (study 2). A model built on language features from an exit interview from study 1 was able to predict, a priori, the placebo response of patients in study 2 (area under the curve = 0.71). Furthermore, the model predicted as placebo responders exhibited an average of 30% pain relief from an inert pill, compared with 3% for those predicted as nonresponders. The model was not able to predict who responded to naproxen nor spontaneous recovery in a no-treatment arm, suggesting specificity of the prediction to placebo. Taken together, our initial findings suggest that placebo response is predictable using ecological and quick measures such as language use.

Teenagers' and parental attitudes towards the use of placebo pills

The placebo response a significant therapeutic improvement after a placebo intervention - can be high in children. The question arises of how optimal advantages of placebo treatment in pediatric clinical care be achieved. In this era of shared-decision making, it is important to be aware of patients' and parental attitudes. Therefore, the aim of the current study was to assess teenagers' and parental views on the use of placebo pills in pediatric clinical care. All patients (aged 12-18 years) and parents of children (aged 0-18 years), visiting the pediatric outpatient clinic between March 2020 through December 2020, were invited to participate in this study multicenter survey study. Of 1644 distributed questionnaires: 200/478 (47%) teenagers and 456/1166 (45%) parents filled out the complete survey. More parents were positive towards prescribing placebo medication than teenagers (80% vs. 71%, p = .019), especially when the clinician disclosed the use of a placebo to parents and teenagers, respectively (76% vs. 55%, p = .019). Increasing age of teenagers was positively associated with the willingness for placebo interventions (OR 0.803, 95%CI 0.659-0.979), as was a higher level of parental education (OR 0.706, 95%CI 0.526-0.949).  Conclusion: This study emphasizes the willingness of teenagers and parents to receive placebo medication. Placebo medication becoming more acceptable and integrated into daily care may contribute to a decrease in medication use. What is Known: • A placebo is a treatment without inherent power to produce any therapeutic effect, but can result in significant therapeutic improvement, the so-called placebo response. • Treatment response rates after placebo interventions in children can be high, ranging from 41 to 46% in pediatric trials. What is New: • Most teenagers (71%) and parents (80%) find it appropriate for healthcare professionals to prescribe placebo medication. • Compared to adult care, pediatrics has a unique feature to disclose placebo treatment to parents while concealing it for the young patient: the majority of teenagers (85%) and parents (91%) agree to disclose placebo treatment to parents exclusively.

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."

Contrasting expectancy effects with objective measures in adults with untreated ADHD during QbTest

Expectancy has been associated with neuropsychological assessments and cognitive performance. However, little is known about the effects of expectations in clinical assessments during drug trials with continuous performance tests (CPTs). In a randomized, double-blind study with cross-over design, we examined if the participants' self-reported expectations changed after one-single dose immediate release methylphenidate (MPH) and after one-single dose placebo during the QbTest. Forty adults between 19 and 64 years (72.5% women) with un treated ADHD were consecutively enrolled in the study and their assessments of expected performance, mental effort, perceived performance and help from the pill were analyzed. The study comprised two trial days with four days in between. The QbTest was performed twice on the same day, before and 80 minutes after a pill. Our study demonstrates that there were expectancy effects during CPTs. Participants reported lower mental effort and improved their performance in the coronary parameter QbInattention both after MPH and after placebo. No significant differences in expected performance were reported. The participants seemed to show some uncertainty when assessing their expected performance, however, they could evaluate their performance afterwards. In clinical practice, the focus should be on reinforcing patients' expectations in order to increase treatment effects.

Systematic Review and Meta-analysis: Psychosocial Treatments for Disruptive Behavior Symptoms and Disorders in Adolescence

OBJECTIVE

Disruptive behavior disorders (DBDs) represent a common motive for referral among youths. This meta-analysis aimed at estimating the efficacy of psychosocial interventions for adolescents with DBDs.

METHOD

A Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)-compliant systematic review of MEDLINE/PubMED/PsycINFO/Cochrane Central Register of Controlled Trials was conducted. Eligible studies were randomized controlled trials (RCTs) administering psychosocial interventions to adolescents with DBD, published before April 5, 2020. From the initial set of 6,006 records, 17 RCTs involving 18 cohorts (16 publications) were subjected to a random-effect meta-analysis (involving sensitivity, subgroup, and meta-regression analyses). Primary and secondary outcomes were externalizing symptoms at RCT endpoint (ie, standardized mean difference [SMD]) and acceptability (drop-out odds ratio [OR]), respectively. Risk of bias was assessed using the Risk of Bias 2 tool.

RESULTS

A total of 17 RCTs, involving 1,954 adolescents, were included. The mean age was 14.09 (SD 1.33) years; 61% were male. The mean RCT duration was 12 weeks, with a mean follow-up of 8 (SD 3.98) months. Concern over risk of bias emerged in 12 studies, with high concern in 6. Psychosocial interventions had a large effect size at RCT endpoint (SMD = 0.98, 95% CI = -0.55 to -1.38, k = 18) and were acceptable (drop-out OR = 1.29, 95% CI = 0.62-2.70, k = 13). However, this beneficial effect did not persist at follow-up (SMD = -0.36, 95% CI = 0.06 to -0.78, k = 10). Family format was the most effective variable. No other clinically significant moderator was found.

CONCLUSION

Psychosocial interventions involving the families of DBD adolescents are effective and acceptable in the short term. Future studies should focus on strategies to achieve their long-term efficacy.

The influence of video-based social modelling on the nocebo effect

OBJECTIVE

Seeing someone else experience side effects (i.e., social modelling) can increase negative expectations and subsequent nocebo effects. In face-to-face contexts, this effect appears stronger in female participants. Less is known about the influence of gender on negative expectations and nocebo effects generated via video-based social modelling.

METHODS

One hundred and seven undergraduate participants recruited from a participant pool at an Australian university took part in a study ostensibly investigating the influence of beta-blocker medications (actually a sham treatment) on physiological and psychological aspects of anxiety. Participants were randomly assigned to either a no-treatment control group, a standard treatment group, or a video modelling group, in which participants viewed video-recorded confederates (one male, one female) report experiencing four side effects (two each) after taking the study treatment. Symptoms were assessed 15-min following pill ingestion, and at follow-up 24 h later.

RESULTS

Video modelling of side effects, compared to standard treatment, interacted with gender and was associated with increased reporting of modelled symptoms in female compared to male participants, p = .01, η_p²=0.06. Video modelling also increased negative expectations in female compared to male participants, p = .03, η_p²=0.07, and expectations mediated the influence of modelling on modelled symptoms in female participants.

CONCLUSIONS

Social modelling of side effects via video increased negative expectations, and nocebo symptoms, to a greater extent in female participants. These findings suggest that males and females are differentially impacted by video-based side effect modelling. Results have implications for social modelling of side effects via social media and patient-support websites.

Development of an Instrument to Assess Expectations for the Use of Online Gaming, Social Networking Sites, and Online Pornography: the Marburg Internet Use Expectations (MINUS-X) Questionnaire

User’s expectations contribute to the maintenance of problematic use of online gaming (OG), social networking (SN), and online pornography (OP). Since an instrument to assess use expectations across applications is lacking, this study aimed at developing and testing such a questionnaire. It consists of a general module (GM), which includes expectations relevant to all three applications, and three application-specific modules. A pilot and a validation study were conducted with 2880 German adults. We conducted item analyses, exploratory factor analyses (EFA), exploratory structural equation modelling, and correlation analyses. The EFA revealed six factors for the GM and two factors for each specific module. The GM demonstrated measurement invariance between applications. The instrument showed excellent psychometric properties, indicating its suitability for assessing expectations concerning the use of OG, SN, and OG reliably and validly. It could be helpful for treating patients with problematic use of the applications and investigating the role of the relevant expectations.

Normal saline injection produces a therapeutic effect in patients with plantar fasciitis: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Injectable therapies have been increasingly investigated to treat plantar fasciitis in randomized controlled trials (RCT) where normal saline injections are frequently used as placebo. The purpose was to quantify the effect of saline injections and compared against available minimal clinically important difference (MCID) criteria specific for plantar fasciitis to assess if changes were clinically meaningful.

METHODS

RCT including a placebo group (normal saline) and reporting changes in pain and functional outcomes in plantar fasciitis were identified through a search in MEDLINE, Embase, Web of Science, and Scopus to February 2022. PRISMA guidelines and a registered protocol (PROSPERO: CRD42020214035) were followed to conduct the study.

RESULTS

Pooled analysis of 13 RCT (379 subjects) included for analysis revealed a significant improvement on pain (P < .00001) and functional scores (P < .00001) after normal saline injections. These changes exceeded the established MCID criteria.

CONCLUSIONS

Normal saline injections in plantar fasciitis showed a therapeutic effect with statistically and clinically meaningful improvement when administered in the setting of an RCT for up to 12 months. The control of potential confounders influencing the effect of saline injections is required for future research.

Manual Therapy Effect in Placebo-Controlled Trials: A Systematic Review and Meta-Analysis

PURPOSE

Background: Evaluate whether the design of placebo control groups could produce different interpretations of the efficacy of manual therapy techniques.

METHODS

Nine databases were searched (EMBASE, CINAHL, PsycINFO, MEDLINE, PubMed, SCOPUS, WEB of SCIENCE, COCHRANE, and PEDro). Randomized placebo-controlled clinical trials that used manual therapy as a sham treatment on subjects suffering from pain were included. Data were summarized qualitatively, and meta-analyses were conducted with R.

RESULTS

53 articles were included in the qualitative analysis and 48 were included in the quantitative analyses. Manipulation techniques did not show higher effectiveness when compared with all types of sham groups that were analyzed (SMD 0.28; 95%CI [-0.24; 0.80]) (SMD 0.28; 95%CI [-0.08; 0.64]) (SMD 0.42; 95%CI [0.16; 0.67]) (SMD 0.82; 95%CI [-0.57; 2.21]), raising doubts on their therapeutic effect. Factors such as expectations of treatment were not consistently evaluated, and analysis could help clarify the effect of different sham groups. As for soft tissue techniques, the results are stronger in favor of these techniques when compared to sham control groups (SMD 0.40; 95%CI [0.19, 0.61]). Regarding mobilization techniques and neural gliding techniques, not enough studies were found for conclusions to be made.

CONCLUSIONS

The literature presents a lack of a unified placebo control group design for each technique and an absence of assessment of expectations. These two issues might account for the unclear results obtained in the analysis.

Prosocial correlates of transformative experiences at secular multi-day mass gatherings

Humans have long sought experiences that transcend or change their sense of self. By weakening boundaries between the self and others, such transformative experiences may lead to enduring changes in moral orientation. Here we investigated the psychological nature and prosocial correlates of transformative experiences by studying participants before (n = 600), during (n = 1217), 0-4 weeks after (n = 1866), and 6 months after (n = 710) they attended a variety of secular, multi-day mass gatherings in the US and UK. Observations at 6 field studies and 22 online followup studies spanning 5 years showed that self-reported transformative experiences at mass gatherings were common, increased over time, and were characterized by feelings of universal connectedness and new perceptions of others. Participants' circle of moral regard expanded with every passing day onsite-an effect partially mediated by transformative experience and feelings of universal connectedness. Generosity was remarkably high across sites but did not change over time. Immediately and 6 months following event attendance, self-reported transformative experience persisted and predicted both generosity (directly) and moral expansion (indirectly). These findings highlight the prosocial qualities of transformative experiences at secular mass gatherings and suggest such experiences may be associated with lasting changes in moral orientation.

Perceived Consumption of a High-Dose Caffeine Drink Delays Neuromuscular Fatigue

ABSTRACT

Elhaj, HM, Imam, O, Page, BW, Vitale, JM, and Malek, MH. Perceived consumption of a high-dose caffeine drink delays neuromuscular fatigue. J Strength Cond Res 36(5): 1185-1190, 2022-The placebo effect is a concept in which a desired outcome arises, mainly from the belief that the treatment (i.e., supplement or drug) was beneficial although no active ingredient was given. The results of studies related to the placebo effect primarily examine functional performance. What remains unanswered, however, is whether these changes in performance are associated with neuromuscular alterations in the exercised muscles. The purpose of the study, therefore, was to determine the influence of the placebo effect on the physical working capacity fatigue threshold (PWCFT) for a continuous exercise paradigm. To achieve this aim, subjects were told that they were participating in a study to determine the dosage response (low or high) of caffeine on neuromuscular fatigue when in fact no caffeine was given during the experiment. We hypothesized that the perceived consumption of the high-dose caffeine drink would result in a higher PWCFT than the perceived consumption of the low-dose caffeine drink and placebo. Secondarily, we hypothesized that the perceived consumption of the high-dose caffeine drink would result in a higher power output than the perceived consumption of the placebo. Nine healthy college-aged men (mean ± SEM: age, 25.7 ± 1.3 years; body mass, 84.4 ± 3.1 kg; and height: 1.82 ± 0.02 m) volunteered to be in the study. For each of the visits, subjects were given an 8 oz. bottle of water with dissolved crystal light. After the drink was consumed, subjects rested in the laboratory for 1 hour before performing the incremental single-leg knee-extensor ergometry. Immediately after the termination of the incremental single-leg knee-extensor ergometry, the subject was asked which caffeine dose (placebo, low, or high) they believed they consumed for that visit. There were no significant mean differences for maximal power output for the 3 perceived conditions (placebo: 62 ± 3, low-dose caffeine: 62 ± 4, and high-dose caffeine: 65 ± 3 W). When the subjects perceived consuming the high-dose caffeine drink, there were significant mean differences (all p-values < 0.01), for PWCFT, between the other conditions (mean ± SEM: placebo: 23 ± 3 W, low-dose caffeine: 26 ± 2 W, and high-dose caffeine: 42 ± 3 W). This corresponded to a significant mean difference (all p-values < 0.01) when the PWCFT was presented as a percentage of the maximal power output (mean ± SEM: placebo: 37 ± 5%, low-dose caffeine: 42 ± 3%, and high-dose caffeine: 64 ± 3%). The application of our results may indicate that the subject's expectancy, to caffeine consumption, plays a critical role in delaying the onset of neuromuscular fatigue despite not receiving any caffeine in their drinks.

Validating a biosignature-predicting placebo pill response in chronic pain in the settings of a randomized controlled trial

ABSTRACT

The objective of this study is to validate a placebo pill response predictive model-a biosignature-that classifies chronic pain patients into placebo responders (predicted-PTxResp) and nonresponders (predicted-PTxNonR) and test whether it can dissociate placebo and active treatment responses. The model, based on psychological and brain functional connectivity, was derived in our previous study and blindly applied to current trial participants. Ninety-four chronic low back pain (CLBP) patients were classified into predicted-PTxResp or predicted-PTxNonR and randomized into no treatment, placebo treatment, or naproxen treatment. To monitor analgesia, back pain intensity was collected twice a day: 3 weeks baseline, 6 weeks of treatment, and 3 weeks of washout. Eighty-nine CLBP patients were included in the intent-to-treat analyses and 77 CLBP patients in the per-protocol analyses. Both analyses showed similar results. At the group level, the predictive model performed remarkably well, dissociating the separate effect sizes of pure placebo response and pure active treatment response and demonstrating that these effects interacted additively. Pain relief was about 15% stronger in the predicted-PTxResp compared with the predicted-PTxNonR receiving either placebo or naproxen, and the predicted-PTxNonR successfully isolated the active drug effect. At a single subject level, the biosignature better predicted placebo nonresponders, with poor accuracy. One component of the biosignature (dorsolateral prefrontal cortex-precentral gyrus functional connectivity) could be generalized across 3 placebo studies and in 2 different cohorts-CLBP and osteoarthritis pain patients. This study shows that a biosignature can predict placebo response at a group level in the setting of a randomized controlled trial.

Experience with opioids does not modify the brain network involved in expectations of placebo analgesia

Placebo analgesia (PA) is defined as a psychobiological phenomenon triggered by the information surrounding an analgesic drug instead of its inherent pharmacological properties. PA is hypothesized to be formed through either verbal suggestions or conditioning. The present study aims at disentangling the neural correlates of expectations effects with or without conditioning through prior experience using the model of PA.

We addressed this question by recruiting two groups of individuals holding comparable verbally‐induced expectations regarding morphine analgesia but either (i) with or (ii) without prior experience with opioids. We then contrasted the two groups' neurocognitive response to acute heat‐pain induction following the injection of sham morphine using electroencephalography (EEG). Topographic ERP analyses of the N2 and P2 pain evoked potential components allowed to test the hypothesis that PA involves distinct neural networks when induced by expectations with or without prior experience.

First, we confirmed that the two groups showed corresponding expectations of morphine analgesia (Hedges' g_s < .4 positive control criteria, g_s = .37 observed difference), and that our intervention induced a medium‐sized PA (Hedges' g_av ≥ .5 positive control, g_av = .6 observed PA). We then tested our hypothesis on the recruitment of different PA‐associated brain networks in individuals with versus without prior experience with opioids and found no evidence for a topographic N2 and P2 ERP components difference between the two groups. Our results thus suggest that in the presence of verbally‐induced expectations, modifications in the PA‐associated brain activity by conditioning are either absent or very small.

Temporal expectancy induced by the mere possession of a placebo analgesic affects placebo analgesia: preliminary findings from a randomized controlled trial

Research on placebo analgesia usually shows that people experienced a reduction in pain after using a placebo analgesic. An emerging line of research argues that, under some circumstances, merely possessing (but not using) a placebo analgesic could induce placebo analgesia. The current study investigates how temporary expectation of pain reduction associated with different forms of possessing a placebo analgesic affects pain outcomes. Healthy participants (n = 90) were presented with a vial of olive oil (placebo), described as a blended essential oil that blocks pain sensations upon nasal inhalation, and were asked to anticipate the benefits of such analgesic oil to the self (such as anticipating the analgesic oil to reduce their pain). Participants were randomized into one of three different possession conditions: physical-possession condition (participants possessed a tangible placebo analgesic oil, inducing an expectation to acquire analgesic benefit early upon the experience of pain), psychological-possession condition (participants possessed a coupon, which can be redeemed for a placebo analgesic oil, inducing an expectation to acquire analgesic benefit later upon the experience of pain), or no-possession condition. Participants did a cold pressor test (CPT) to experience experimentally-induced pain on their non-dominant hand. Their objective physical pain responses (pain-threshold and pain-tolerance), and subjective psychological pain perception (pain intensity, severity, quality, and unpleasantness) were measured. Results revealed that participants in the physical-possession condition reported greater pain-threshold, F(2, 85) = 6.65, p = 0.002, and longer pain-tolerance, F(2, 85) = 7.19, p = 0.001 than participants in the psychological-possession and no-possession conditions. No significant group difference was found in subjective pain perception. The results of this study can advance knowledge about pain mechanisms and novel pain management.

Home-Based Transcranial Direct Current Stimulation for the Treatment of Symptoms of Depression and Anxiety in Temporal Lobe Epilepsy: A Randomized, Double-Blind, Sham-Controlled Clinical Trial

We conducted a double-blind randomized clinical trial in order to examine the effects and the safety of home-based transcranial direct current stimulation (tDCS) on depressive and anxious symptoms of patients with temporal lobe epilepsy (TLE). We evaluated 26 adults with TLE and depressive symptoms randomized into two different groups: active tDCS (tDCSa) and Sham (tDCSs). The patients were first submitted to 20 sessions of tDCS for 20 min daily, 5 days a week for 4 weeks and then received a maintenance tDCS application in the research laboratory once a week for 3 weeks. The intensity of the current was 2 mA, applied bilaterally over the dorsolateral prefrontal cortex, with the anode positioned on the left side and the cathode on the right side. Participants were evaluated on days 1, 15, 30, and 60 of the study using the Beck Depression Inventory II (BDI). A follow-up evaluation was performed 1 year after the end of treatment. They were also evaluated for quality of life and for anxious symptoms as secondary outcomes. The groups did not differ in clinical, socioeconomic or psychometric characteristics at the initial assessment. There was no statistically significant difference between groups regarding reported adverse effects, seizure frequency or dropouts. On average, between the 1st and 60th day, the BDI score decreased by 43.93% in the active group and by 44.67% in the Sham group (ΔBDIfinal – initial = −12.54 vs. −12.20, p = 0.68). The similar improvement in depressive symptoms observed in both groups was attributed to placebo effect and interaction between participants and research group and not to tDCS intervention per se. In our study, tDCS was safe and well tolerated, but it was not effective in reducing depressive or anxiety symptoms in patients with temporal lobe epilepsy.

Clinical Trial Registration: [ClinicalTrials.gov], identifier [NCT03871842].

Does a 7-day restriction on the use of social media improve cognitive functioning and emotional well-being? Results from a randomized controlled trial

Introduction

Screen time apps that allow smartphone users to manage their screen time are assumed to combat negative effects of smartphone use. This study explores whether a social media restriction, implemented via screen time apps, has a positive effect on emotional well-being and sustained attention performance.

Methods

A randomized controlled trial (N = 76) was performed, exploring whether a week-long 50% reduction in time spent on mobile Facebook, Instagram, Snapchat and YouTube is beneficial to attentional performance and well-being as compared to a 10% reduction.

Results

Unexpectedly, several participants in the control group pro-actively reduced their screen time significantly beyond the intended 10%, dismantling our intended screen time manipulation. Hence, we analyzed both the effect of the original manipulation (i.e. treatment-as-intended), and the effect of participants' relative reduction in screen time irrespective of their condition (i.e. treatment-as-is). Neither analyses revealed an effect on the outcome measures. We also found no support for a moderating role of self-control, impulsivity or Fear of Missing Out. Interestingly, across all participants behavioral performance on sustained attention tasks remained stable over time, while perceived attentional performance improved. Participants also self-reported a decrease in negative emotions, but no increase in positive emotions.

Conclusion

We discuss the implications of our findings in light of recent debates about the impact of screen time and formulate suggestions for future research based on important limitations of the current study, revolving among others around appropriate control groups as well as the combined use of both subjective and objective (i.e., behavioral) measures.

The placebo and nocebo effects in functional urology

A placebo is an inert substance normally used in clinical trials for comparison with an active substance. However, a placebo has been shown to have an effect on its own; commonly known as the placebo effect. A placebo is an essential component in the design of conclusive clinical trials but has itself become the focus of intense research. The placebo effect is partly the result of positive expectations of the recipient on the state of health. Conversely, a nocebo effect is when negative expectations from a substance lead to poor treatment outcomes and/or adverse events. Randomized controlled trials in functional urology have demonstrated the importance of the placebo and nocebo effects across different diseases such as overactive bladder, urinary incontinence, lower urinary tract symptoms and interstitial cystitis/painful bladder syndrome, as well as male and female sexual dysfunction. Understanding the true nature of the placebo-nocebo complex and the scope of its effect in functional urology could help urologists to maximize the positive effects of this phenomenon while minimizing its potentially negative effects.

The Mindset of Intelligence Is Not a Contributor of Placebo Effects in Working Memory Training

Whether working memory training is effective in enhancing fluid intelligence remains in dispute. Several researchers, who doubt the training benefits, consider that placebo effects may be the reason for positive training gains. One of the vital variables that may induce the placebo effect is the mindset of intelligence. In this article, we provide a test of whether the mindset of intelligence leads to placebo effects in working memory training. Participants were overtly recruited and allocated to the growth mindset group or the fixed mindset group by Theories of Intelligence Scale scores. A single, 1 h session working memory training is the cue to introduce the placebo effects. During pre/post-testing, all participants completed tasks measuring working memory capacity (near transfer) and fluid intelligence (far transfer). Our findings show no significant difference between the two groups in both tasks. Therefore, these results suggest that the placebo effect does not exist in this study, which means individuals' mindset of intelligence may not be a contributor to the placebo effect in 1 h working memory training. This research will further help to clarify the mechanism of the placebo effect in working memory training.

μ Opioid Antagonist Naltrexone Partially Abolishes the Antidepressant Placebo Effect and Reduces Orbitofrontal Cortex Encoding of Reinforcement

BACKGROUND

Like placebo analgesia, the antidepressant placebo effect appears to involve cortical and subcortical endogenous opioid signaling, yet the mechanism through which opioid release affects mood remains unclear. The orbitofrontal cortex (OFC)-which integrates various attributes of a stimulus to predict associated outcomes-has been implicated in placebo effects and is rich in μ opioid receptors. We hypothesized that naltrexone blockade of μ opioid receptors would blunt OFC-dependent antidepressant placebo effects.

METHODS

Twenty psychotropic-free patients with major depressive disorder completed a randomized, double-blind, placebo-controlled crossover study of 1 oral dose of 50 mg of naltrexone or matching placebo immediately before completing 2 sessions of the antidepressant placebo functional magnetic resonance imaging task. This task manipulates placebo-associated expectancies and their reinforcement while assessing expected and actual mood improvement.

RESULTS

Behaviorally, manipulations of antidepressant placebo expectancies and their reinforcement had positive, interactive effects on participants' expectancy and mood ratings. The high-expectancy condition recruited the dorsolateral and ventrolateral prefrontal cortex, as well as dorsal attention stream regions. Interestingly, increased dorsolateral and ventrolateral prefrontal cortex brain responses appeared to attenuate the antidepressant placebo effect. The administration of 1 oral dose of naltrexone, compared with placebo, partially abolished the interaction of the expectancy and reinforcement manipulation on mood and blocked reinforcement-induced responses in the right central OFC.

CONCLUSIONS

Our results show preliminary evidence for the role of μ opioid central OFC modulation in antidepressant placebo effects by positively biasing the value of placebo based on reinforcement and enhancing subsequent hedonic experiences.

The role of expectations and future-oriented cognitions in quality of life of people with multiple sclerosis: A systematic review

PURPOSE

Multiple Sclerosis (MS) is a highly variable condition characterised by uncertainty of disease course which can make formation of expectations about the future difficult. This systematic review aimed to examine associations between expectations, or Future Oriented Cognitions (FOCs), and Quality of Life (QOL) in people with MS (PwMS).

METHODS

Following PRISMA guidelines, literature up to October 2019 was searched using Medline, EMBASE, PsycINFO and Web of Science. Quantitative studies that investigated relationships between FOCs and QOL in PwMS (assessed using a standardised QOL assessment) were considered for inclusion. After data extraction, results were analysed using narrative synthesis, focusing on the valence of FOCs (positive, negative, unvalenced). Quality appraisal was conducted using the Mixed Methods Appraisal Tool (MMAT). All stages of the review were patient-led by a person with MS.

RESULTS

A total of 13 studies met the review inclusion criteria, with a combined sample size of 4,179. Of these studies, 11 involved measures of positive FOCs, most commonly self-efficacy, one measured a negative FOC, with one FOC unclassified. Nine studies found significant associations between QOL and self-efficacy. Although other positively valenced constructs were less frequently reported, significant associations with higher QOL were also evidenced.

CONCLUSIONS

Identifying ways to foster positive FOCs, particularly self-efficacy, may have beneficial effects on QOL. More research is needed to understand the impacts of negative FOCs on QOL to determine whether these processes could be meaningfully targeted in interventions.

The influence of nocebo information on fatigue and urge to stop: An experimental investigation

BACKGROUND AND OBJECTIVES

Fatigue is an adaptive state after prolonged effort and often goes hand in hand with changes in behavior and motivation, such as the urge to stop exerting further effort. However, fatigue may become chronic in nature, as seen in multiple psychiatric disorders and chronic diseases, thereby losing its adaptive function. The etiology of fatigue symptoms remains poorly understood. We aimed to investigate whether nocebo information about the fatigue inducing nature of a cognitive task may contribute to the experience of fatigue and the motivational urge to stop.

METHODS

Participants (N = 46) repeatedly rated currently experienced fatigue while engaging in cognitive effort (working memory task). Crucially, half of participants received nocebo instructions prior to this task, whereas the other half only received neutral information.

RESULTS

Over the entire sample, results showed an increase in fatigue and urge to stop as the task progressed. Crucially, participants in the nocebo condition reported a higher urge to stop throughout the task relative to participants in the neutral condition. No significant effects were found for fatigue. Interestingly however, after controlling for baseline differences between conditions in negative affect, there was a significant Condition*Task block interaction effect on fatigue.

LIMITATIONS

Limitations include the relatively short experimental protocol and the underrepresentation of male relative to female participants.

CONCLUSIONS

These findings suggest that heightened awareness among clinicians and therapists about potential nocebo effects in their communication is warranted.

Placebo comparator group selection and use in surgical trials: the ASPIRE project including expert workshop

BACKGROUND

The use of placebo comparisons for randomised trials assessing the efficacy of surgical interventions is increasingly being considered. However, a placebo control is a complex type of comparison group in the surgical setting and, although powerful, presents many challenges.

OBJECTIVES

To provide a summary of knowledge on placebo controls in surgical trials and to summarise any recommendations for designers, evaluators and funders of placebo-controlled surgical trials.

DESIGN

To carry out a state-of-the-art workshop and produce a corresponding report involving key stakeholders throughout.

SETTING

A workshop to discuss and summarise the existing knowledge and to develop the new guidelines.

RESULTS

To assess what a placebo control entails and to assess the understanding of this tool in the context of surgery is considered, along with when placebo controls in surgery are acceptable (and when they are desirable). We have considered ethics arguments and regulatory requirements, how a placebo control should be designed, how to identify and mitigate risk for participants in these trials, and how such trials should be carried out and interpreted. The use of placebo controls is justified in randomised controlled trials of surgical interventions provided that there is a strong scientific and ethics rationale. Surgical placebos might be most appropriate when there is poor evidence for the efficacy of the procedure and a justified concern that results of a trial would be associated with a high risk of bias, particularly because of the placebo effect.

CONCLUSIONS

The use of placebo controls is justified in randomised controlled trials of surgical interventions provided that there is a strong scientific and ethics rationale. Feasibility work is recommended to optimise the design and implementation of randomised controlled trials. An outline for best practice was produced in the form of the Applying Surgical Placebo in Randomised Evaluations (ASPIRE) guidelines for those considering the use of a placebo control in a surgical randomised controlled trial.

LIMITATIONS

Although the workshop participants involved international members, the majority of participants were from the UK. Therefore, although every attempt was made to make the recommendations applicable to all health systems, the guidelines may, unconsciously, be particularly applicable to clinical practice in the UK NHS.

FUTURE WORK

Future work should evaluate the use of the ASPIRE guidelines in making decisions about the use of a placebo-controlled surgical trial. In addition, further work is required on the appropriate nomenclature to adopt in this space.

FUNDING

Funded by the Medical Research Council UK and the National Institute for Health Research as part of the Medical Research Council-National Institute for Health Research Methodology Research programme.

Expectation predicts performance in the mental heartbeat tracking task

The mental heartbeat tracking task by Schandry is sensitive to non-interoceptive (top-down) influences, e.g., estimation of heart rate and expectation. The two studies reported here investigated the impact of these factors on the outcome of the task. In Study 1, performance-related expectation was assessed between the training interval and the real trials. Performance was strongly related (β = .595, p < .001) to expectation even after controlling for sex, body fat, resting heart rate and estimation of heart rate. In Study 2, expectation was assessed before and after the training interval for Group 1 and 2, respectively. The strong association (r = 0.78, p < .001) between performance and expectation was replicated for Group 2; however, a moderate association (r = 0.39, p < .01) was also found in Group 1. People with high expectation may be prone to categorize and count vague sensations, such as attention evoked sensations, as heartbeats; this can lead to an inflated Schandry-score.

The Use of Conditioning Open-Label Placebo in Opioid Dose Reduction: A Case Report and Literature Review

Introduction: Adequate pain management for inpatients in rehabilitation units is essential for achieving therapeutic goals. Opioid treatments are commonly prescribed, but these are associated with numerous adverse effects, including the risk of addiction and decreased quality of life. Conditioning an open-label placebo is a promising approach to extend the analgesic effect of the opioid while reducing its overall dosage. Objectives: To describe a patient's experience in using conditioning open-label placebo (COLP) as a pharmaco-behavioral intervention to decrease opioid intake and its side effects after inpatient rehabilitation discharge, and to perform a literature review about the use of open-label placebo in pain. Methods: This case study has been extracted from a clinical trial initiated in 2018. A 61-year-old male was recruited at a tertiary rehabilitation hospital after suffering a traumatic sport-related injury and orthopedic surgery. Pain management included prescription of non-steroidal anti-inflammatory drugs (NSAIDs) and short-acting oxycodone. After trial participation, the patient requested off-label COLP treatment to help him decrease outpatient opioid utilization. Results: After COLP treatment, the patient could discontinue oxycodone intake (a reduction from 15 morphine equivalents/day) after rehabilitation discharge. Moreover, opioid side effects decreased from 46 to 9 points on the numerical opioid side-effects scale. A literature review identified five clinical trials using "honest" open-label placebo (OLP) or COLP as an experimental intervention for pain control. From these studies, two were in the area of chronic lower back pain, one in post spine surgery, one in irritable bowel syndrome, and another in spinal cord injury and polytrauma. Four studies reported positive outcomes related to pain control, while one study showed no significant differences in pain management between treatment-as-usual and the COLP group. Conclusion: The case report illustrates how a pharmaco-behavioral intervention can facilitate downward opioid titration safely after inpatient rehabilitation. It initiates a discussion about new approaches for opioid management using conditioning and the patient's expectation of pain relief.

Slowed Processing Speed Disrupts Patient Expectancy in Late Life Depression

OBJECTIVE

Slowed processing speed and executive dysfunction are associated with poor outcomes in Late Life Depression (LLD), though it is unclear why. We investigated whether these variables interfere with the development of positive treatment expectancies in an antidepressant trial.

METHODS

Depressed older subjects were randomized to Open (intended to increase patient expectancy) or Placebo-controlled (termed 'Hidden,' intended to decrease expectancy) administration of antidepressant medication for 8 weeks. Analysis of covariance analyzed the between-group difference on expectancy (Credibility and Expectancy Scale [CES]) and depression (Hamilton Rating Scale for Depression [HRSD], Clinical Global Impressions [CGI] Severity). Moderator analyses examined whether these Open versus Hidden differences varied based on higher versus lower processing speed and executive function.

RESULTS

Among the 108 participants, a significant between-group difference was observed on expectancy (effect size [ES, Cohen's d] = 0.51 on CES Item 2; ES = 0.64 on Item 4), indicating the manipulation was effective. Processing speed as measured by the Stroop Color-Word Test (number color-words named in congruent condition) was a significant moderator of the Open versus Hidden effect on expectancy. Depressive symptom improvement was greater on average for Open versus Hidden participants who received active drug (CGI-severity ES = 1.25, HRSD ES = 0.41), but no neurocognitive moderators of the between-group difference reached statistical significance.

CONCLUSIONS

Slowed processing speed impairs the development of expectancies in antidepressant trials for LLD, which may help explain lower antidepressant response among older adults. Future studies may address whether interventions to optimize treatment expectancies are capable of improving treatment outcomes.

Nocebo effects on motor performance: A systematic literature review

Directionally opposite to placebo effects are the nocebo effects that negatively impact people's thoughts, feelings, and actions. An important but scarcely studied aspect of everyday functioning is motor performance, in which nocebo effects might impair athletic skills and the much-needed purposeful daily movements and motor actions. The aim of this literature review is to unveil the nocebo effects on motor performance. Searched databases were PubMed, PsycINFO, and SPORTDiscus. Twenty-one articles, reporting 23 studies, met the eligibility criteria for inclusion in the current review. All reports exhibited "some" risk of bias. Of the 23 studies, 14 found a nocebo effect on motor performance, equivocal results emerged from two studies, and negative findings were reported in seven studies. Most (10/12) studies using a between-subjects design have reported a nocebo effect. The mean effect size was 0.60, suggesting a medium-to-large effect of nocebo intervention on motor performance. Based on this review, we conclude that nocebo effects do influence motor performance and can be evoked with negative verbal information. This effect may be more robust than the placebo effect but also depends on the type of motor performance, on the examined sample, and on the nocebo agent. Hence, nocebo effects should be recognized and controlled in empirical research on motor performance, and they should be prevented or extinguished in practical and therapeutic settings. More extensive examination of the nocebo effect on motor performance is warranted, especially using between-subjects research design and a "no agent" control condition.

Meaning and Affect in the Placebo Effect

This article presents and defends an integrated view of the placebo effect, termed "affective-meaning-making" model, which draws from theoretical reflection, clinical outcomes, and neurophysiological findings. We consider the theoretical limitations of those proposals associated with the "meaning view" on the placebo effect which (a) leave the general aspects of meaning unspecified, (b) fail to analyze fully the role of emotions and affect, and (c) establish no clear connection between the theoretical, physiological, and psychological aspects of the effect. We point out that a promising way to overcome these limitations is given by grounding the placebo effect on Peirce's theory of meaning, in which the role of the meaning constitution and change is placed in logical and objective structures. We also show the connection between our theoretical proposal and the appraisal theory and integrate it with emotion regulation.

Placebo From an Enactive Perspective

Due to their complexity and variability, placebo effects remain controversial. We suggest this is also due to a set of problematic assumptions (dualism, reductionism, individualism, passivity). We critically assess current explanations and empirical evidence and propose an alternative theoretical framework—the enactive approach to life and mind—based on recent developments in embodied cognitive science. We review core enactive concepts such as autonomy, agency, and sense-making. Following these ideas, we propose a move from binary distinctions (e.g., conscious vs. non-conscious) to the more workable categories of reflective and pre-reflective activity. We introduce an ontology of individuation, following the work of Gilbert Simondon, that allow us to see placebo interventions not as originating causal chains, but as modulators and triggers in the regulation of tensions between ongoing embodied and interpersonal processes. We describe these interrelated processes involving looping effects through three intertwined dimensions of embodiment: organic, sensorimotor, and intersubjective. Finally, we defend the need to investigate therapeutic interactions in terms of participatory sense-making, going beyond the identification of individual social traits (e.g., empathy, trust) that contribute to placebo effects. We discuss resonances and differences between the enactive proposal, popular explanations such as expectations and conditioning, and other approaches based on meaning responses and phenomenological/ecological ideas.

The placebo effect: To explore or to exploit?

How people choose between options with differing outcomes (explore-exploit) is a central question to understanding human behaviour. However, the standard explore-exploit paradigm relies on gamified tasks with low-stake outcomes. Consequently, little is known about decision making for biologically-relevant stimuli. Here, we combined placebo and explore-exploit paradigms to examine detection and selection of the most effective treatment in a pain model. During conditioning, where 'optimal' and 'suboptimal' sham-treatments were paired with a reduction in electrical pain stimulation, participants learnt which treatment most successfully reduced pain. Modelling participant responses revealed three important findings. First, participants' choices reflected both directed and random exploration. Second, expectancy modulated pain - indicative of recursive placebo effects. Third, individual differences in terms of expectancy during conditioning predicted placebo effects during a subsequent test phase. These findings reveal directed and random exploration when the outcome is biologically-relevant. Moreover, this research shows how placebo and explore-exploit literatures can be unified.

Treatment expectations as a possible prognostic factor for DMARD response in rheumatoid arthritis: a prospective cohort study

Background:

The prediction of the individual’s response to disease modifying antirheumatic drugs (DMARDs) in rheumatoid arthritis (RA) is challenging and often limited. Here we evaluated the influence of patients’ expectations towards a change in treatment with DMARD on clinical outcome in RA.

Methods:

One hundred patients (74 female) with RA (2010 ACR/EULAR classification criteria) and an upcoming change in DMARD treatment due to non-response or adverse effects were included. Patients’ treatment beliefs, health-related quality of life and treatment expectations were measured using the Beliefs about Medicines Questionnaire (BMQ), the Short Form 36, and self-designed questions about expectations before treatment initiation (T0), and DAS28-CRP was calculated at T0 and after 4 months (T4). Associations between patients’ beliefs and expectations and changes in DAS28-CRP (T0 to T4, ΔDAS28-CRP) were explored by regression analyses after multiple imputation.

Results:

A total of 99 patients were included, of whom 84 completed all questionnaires. Thirty-six percent of all variability in treatment response (ΔDAS28-CRP) was explained by expectations assessed with the questionnaires and the C-reactive protein (CRP)-value at T0. Among these, the expected improvement rate, with 10.5%, as well as the CRP-value at T0, with 10.6%, had the greatest positive effect whereas the fear of adverse effects, with 11.4%, and the BMQ.concern scale, with 9.0%, had the greatest negative impact on ΔDAS28.

Conclusion:

Patients’ expectations towards newly induced DMARD therapies influence clinical response and may serve as possible explanatory factors for treatment response affecting subjective and objective outcome parameters.

Clinical trial registration number:

DRKS00017005

Generalization of placebo pain relief

ABSTRACT

Efficacy of treatment is heavily dependent on experience and expectations. Moreover, humans can generalize from one experience to a perceptually similar but novel situation. We investigated whether and how this applies to pain relief, using ecologically valid tonic pain stimuli treated by surreptitiously lowering the applied temperature. Using different face cues, participants experienced better treatment from one physician than another. Participants were then tested on 6 additional face cues perceptually lying between both faces. Our data from 2 independent samples (N = 18 and N = 39) show a treatment experience effect, ie, for physically identical treatments, the initially superior physician was reported to deliver stronger pain relief. More importantly, the other faces on the perceptual continuum showed a graded effect of pain relief, indicating placebo generalization. Introducing a paradigm feasible to induce placebo pain relief, we show that the generic learning principle of generalization can explain carryover effects between learned and novel treatment situations.

Evidence for the additive effects of dispositional negative mood regulation expectancies and placebo-induced expectancies on mood recovery

OBJECTIVE

Low negative mood regulation expectancies (NMRE) are associated with greater anticipated and experienced negative mood states, as well as with coping strategies that prolong these states. Individuals with low NMRE may be especially responsive to placebos because confidence in an external source of mood improvement can provide the positive mood expectancies and motivation for active coping that they typically lack. This study investigated how NMRE and placebo-induced expectancies contribute to mood recovery.

METHOD

Participants (N = 125) completed personality scales, including NMRE, online. During a subsequent in-person session, participants were randomly assigned to one of three conditions: (1) placebo treatment-participants learned of a mood-enhancing treatment and received it; (2) treatment deprivation-participants learned of the same treatment, but did not receive it; (3) control-treatment was never mentioned. Participants also completed measures of mood, active coping, and expectations.

RESULTS

NMRE was a stronger predictor of mood recovery than placebo-induced expectancies regardless of group assignment. Additionally, pessimistic expectations arose when participants believed treatment was being deprived, and these participants exhibited the least active coping.

CONCLUSION

Our results confirm the reliability of NMRE in predicting affective outcomes and suggest that personality and placebo-induced expectations have additive effects on mood recovery.

Placebo effect in children: the role of expectation and learning

Classical conditioning and expectations are well-known underlying mechanisms of placebo hypoalgesia. Only little is known about their differential effect in adults, however, and even less in children. Previous studies in children evoked placebo hypoalgesia either with expectations alone or in combination with classical conditioning and revealed conflicting results. Furthermore, these studies investigated children of different ages making it even more difficult to draw conclusions. This study tried to disentangle classical conditioning and expectations by investigating them separately. To examine age effects, n = 172 children (6-9, 10-13, and 14-17 years) as well as n = 32 adults (> = 18 years) were tested using a heat pain paradigm investigating the effectiveness of creams some of which were bogusly introduced as analgesic. In addition to subjective pain intensity ratings, peripheral physiological measures were recorded. Results showed a successful induction of placebo hypoalgesia by both mechanisms for pain ratings and heart rate acceleration. Placebo hypoalgesia was particularly pronounced in children younger than 14 years. Furthermore, placebo hypoalgesia was more marked in children whose mothers raised the expectations. It was also stronger in participants who noticed a strong pain reduction during learning trials. These results encourage the use of placebo effect in clinical practice, particularly for younger children. They underline the relevance of an initial pain reduction and encourage the inclusion of parents in treatment.