Revelation of a personal placebo response: its effects on mood, attitudes and future placebo responding

Working with patients' treatment expectations - what we can learn from homeopathy

The usual homeopathic remedy, "globules," does not contain any pharmacologically active ingredient. However, many patients and practitioners report beneficial effects of homeopathic treatment on various health outcomes. Experimental and clinical research of the last two decades analyzing the underlying mechanisms of the placebo effect could explain this phenomenon, with patients' treatment expectations as the predominant mechanism. Treatment expectations can be optimized through various factors, such as prior information, communication, and treatment context. This narrative review analyses how homeopathy successfully utilizes these factors. Subsequently, it is discussed what evidence-based medicine could learn from homeopathic practice to optimize treatment expectations (e.g., using an empathic, patient-centered communication style, deliberately selecting objects in practice rooms, or using clear treatment rituals and salient contextual stimuli) and thereby treatment effectiveness. Homeopathic remedy does not work beyond the placebo effect but is recommended or prescribed as an active treatment by those who believe in it. Thus, practitioners need to understand the manner in which homeopathy (as an example of inert treatment) works and are advised to reintegrate its underlying effective placebo mechanisms into evidence-based medicine. This promises to increase treatment efficacy, tolerability, satisfaction, and compliance with evidence-based treatments, and addresses the desires patients are trying to satisfy in homeopathy in an ethical, fully informed way that is grounded in evidence-based medicine.

Task-dependent functional connectivity of pain is associated with the magnitude of placebo analgesia in pain-free individuals

BACKGROUND

Task-based functional connectivity (FC) of pain-related regions resulting from expectancy-based placebo induction has yet to be examined, limiting our understanding of regions and networks associated with placebo analgesia.

METHODS

Fifty-five healthy pain-free adults over 18 (M = 22.8 years, SD = 7.75) were recruited (65.5% women; 63.6% non-Hispanic/Latino/a/x; 58.2% White). Participants completed a baseline followed by a placebo session involving the topical application of an inactive cream in the context of an expectancy-enhancing instruction set. Noxious heat stimuli were applied to the thenar eminence of the right palm using an fMRI-safe thermode. Stimulus intensity was individually calibrated to produce pain ratings of approximately 40 on a 100-point visual analogue scale.

RESULTS

A total of 67.3% of the participants showed a reduction in pain intensity in the placebo condition with an average reduction in pain across the whole sample of 12.7%. Expected pain intensity was associated with reported pain intensity in the placebo session (b = 0.32, p = 0.004, R2  = 0.15). Voxel-wise analyses indicated seven clusters with significant activation during noxious heat stimulation at baseline (pFDR  < 0.05). Generalized psychophysiological interaction analysis suggested that placebo-related FC changes between middle frontal gyrus-superior parietal lobule during noxious stimulation were significantly associated with the magnitude of pain reduction (pFDR  < 0.05).

CONCLUSIONS

Results suggest that stronger expectancy-based placebo responses might be underpinned by greater FC among attentional and somatosensory regions.

SIGNIFICANCE

This article provides support and insight for task-dependent functional connectivity differences related to the magnitude of placebo analgesia. Our findings provide key support that the magnitude of expectation-based placebo response depends on the coupling of regions associated with somatosensory and attentional processing.

The impact of pharmaceutical form and simulated side effects in an open-label-placebo RCT for improving psychological distress in highly stressed students

Open-label placebo (OLP) may be utilized to reduce psychological distress. Yet, potential contextual effects have not been explored. We investigated the impact of pharmaceutical form and the simulation of side effects in a parallel group RCT (DRKS00030987). A sample of 177 highly stressed university students at risk of depression were randomly assigned by computer generated tables to a 1-week intervention with active or passive OLP nasal spray or passive OLP capsule or a no-treatment control group. After the intervention, groups differed significantly in depressive symptoms but not regarding other outcomes of psychological distress (stress, anxiety, sleep quality, somatization), well-being or treatment expectation. OLP groups benefitted significantly more compared to the no-treatment control group (d = .40), OLP nasal spray groups significantly more than the OLP capsule group (d = .40) and the active OLP group significantly more than the passive OLP groups (d = .42). Interestingly, before intervention, most participants, regardless of group assignment, believed that the OLP capsule would be most beneficial. The effectiveness of OLP treatments seems to be highly influenced by the symptom focus conveyed by the OLP rationale. Moreover, pharmaceutical form and simulation of side effects may modulate efficacy, while explicit treatment expectation seems to play a minor role.

Can insights from placebo and nocebo mechanisms studies improve the randomized controlled trial?

Background and aims The randomized controlled trial (RCT) is currently facing several challenges, one of these being that the placebo response appears to be increasing in RCTs, thereby making it difficult to demonstrate an effect of potentially new treatments over placebo. This problem has primarily been approached by predicting the magnitude of the placebo response via stable factors, such as demographic variables, and/or by developing complex designs aimed at reducing the placebo response in the hope that it will improve the test of the active treatment. Yet, the success of this approach has so far been limited. Methods A new approach toward improving the RCT is put forward based on placebo and nocebo mechanism studies, i.e. studies that investigate the mechanisms underlying placebo analgesia and nocebo hyperalgesia. In a series of meta-analyses the magnitude of placebo and nocebo effects were determined. Experimental studies across nociplastic and neuropathic pain conditions and across pharmacological and acupuncture treatments investigated psychological and neurobiological mechanisms underlying these effects. The obtained results were used to make approximations of expectations to see if that could predict the placebo response in RCTs and function as a new way of tapping into the placebo component of treatment effects. Results The magnitude of placebo and nocebo effects is large and highly variable. Placebo effects exist across chronic pain conditions with varying degrees of known etiology as well as across pharmacological and non-pharmacological treatments. Patients' perception of the treatment, the verbal suggestions given for pain relief, and the patients' expectations toward pain relief contribute to the magnitude of the placebo effect and to pain relief following placebo interventions. Also, unintentional unblinding and patients' perception of a treatment markedly influence the treatment outcome. By making approximations of expectations toward treatment effects it was possible to predict the magnitude of the placebo response in RCTs. Conclusions and implications The new approach of tapping into or directly asking patients about their perception and expectations toward a treatment, along with the account of the natural history of pain, has the potential to improve the information that can be obtained from RCTs. Thus, by interfacing insights from placebo and nocebo mechanism studies, it may be possible to enhance the information that can be obtained from RCTs and to account for a large part of the variability in the placebo component of the overall treatment effect. This approach has the potential to improve the scientific evaluation of treatments, as well as to illustrate how the effect of treatments can be optimized in clinical practice, which is the crux of evidence-based medicine.

Non-specific effects of acupuncture and sham acupuncture in clinical trials from the patient's perspective: a systematic review of qualitative evidence

BACKGROUND

Previous clinical trials have demonstrated that both acupuncture and sham acupuncture exert significant, non-specific effects on treatment outcomes when compared to no-treatment controls. A recently developed framework (mechanisms in orthodox and complementary and alternative medicine-MOCAM) suggests that the non-specific effects of acupuncture originate from multiple domains (e.g. patient characteristics, acupuncturist skill/technique, the patient-acupuncturist relationship, and the acupuncture environment). However, it remains to be determined precisely how these domains influence the non-specific effects of treatment among patients receiving acupuncture and sham acupuncture in clinical trials. Therefore, we conducted a systematic review to synthesize existing qualitative evidence on how trial participants randomized to acupuncture and sham acupuncture groups experience non-specific effects, regardless of the types of medical condition investigated.

METHODS

This systematic review included primary qualitative studies embedded in randomized controlled trials designed to investigate acupuncture or sham acupuncture interventions. Eligible studies published in English were derived from a search of five international databases. The methodological quality of included studies was evaluated using the Critical Appraisal Skills Programme (CASP) tool. Using a framework synthesis approach, the identified MOCAM framework was adapted based on the synthesis of the available qualitative evidence.

RESULTS

A total of 20 studies of high methodological quality were included. Our proposed model indicated that the effects of acupuncture may be increased by maintaining a professional status, applying a holistic treatment approach, practicing empathy, and providing patients with an appropriate explanation of the theory behind acupuncture and sham acupuncture. From the patient's perspective, the efficacy of treatment can be increased by following the lifestyle modification advice provided by acupuncturists, maintaining a positive attitude toward treatment efficacy, actively engaging with acupuncturists during consultation, and making behavioral changes based on experience gained during the trial.

CONCLUSION

The results of this study may provide a basis for improving and standardizing key components of non-specific effects in acupuncture treatment, and for improving the isolation of specific effects in future clinical trials involving acupuncture and sham acupuncture.

Investigating Knowledge, Attitude, and Beliefs Regarding Placebo Interventions in Clinical Practice: A Comparative Study of Nursing and Medical University Students

BACKGROUND

Placebo interventions are commonly used in medical practice for alleviating symptoms of illnesses. Placebo is considered a pseudo-medication and its use is debatable ethically, professionally, and legally. Despite that there is also a lack of evidence on understanding of placebo interventions among health profession students. Further, no previous studies have been conducted to investigate whether future nurses and physicians differ in their knowledge, attitudes, and beliefs regarding placebo intervention.

MATERIALS AND METHODS

A comparative cross-sectional study was carried out for exploring knowledge, attitude, and beliefs about placebo interventions among a convenient sample of 187 medical and nursing students at King Saud bin Abdulaziz University for Health Sciences. Data were collected using a sociodemographic data sheet and a 32-item placebo knowledge, beliefs, and attitude scale, which was developed from the evidence-based literature. Validity and reliability were ensured through utilizing a panel of experts and internal consistency analysis.

RESULTS

Overall mean participants' knowledge score was 7.68±2.07 (out of 15). Nursing students showed significantly higher knowledge than medical students (P=0.028). More nursing than medical students believed in the effectiveness of placebo (P˂0.001). Medical students had a stronger belief that the placebo effect is mental, while nursing students reported that it is both mental and physiologic (P˂0.006). Concerning placebo attitude, medical students significantly pointed out that it should generally be prohibited and should not be permitted unless research supports its use (P˂0.001). Both groups agreed that impure placebo intervention involves deception.

CONCLUSION

Participants' overall placebo knowledge was low. Inconsistencies in attitude and beliefs were shown among students. Current study findings offered a unique opportunity to better study misunderstandings for placebo, which might open the gate for misuse and place patients at risk of deception. Additionally, study findings were imperative as a relevant evidence-based recommendation for nursing and medical educators could be achieved.

"Placebo by Proxy" and "Nocebo by Proxy" in Children: A Review of Parents' Role in Treatment Outcomes

The "placebo (effect) by proxy" (PbP) concept, introduced by Grelotti and Kaptchuk (1), describes a positive effect of a patient's treatment on persons in their surrounding such as family members or healthcare providers, who feel better because the patient is being treated. The PbP effect is a complex dynamic phenomenon which attempts to explain a change in treatment outcome arising from an interaction between a patient and an effect from proxies such as parents, caregivers, physicians or even the media. By extension the effect of the proxy can also have a negative or adverse effect whereby a proxy feels worse when a patient is treated, giving rise to the possibility of a "nocebo (effect) by proxy" (NbP), and by extension can influence a patient's treatment response. While this has yet to be systematically investigated, such an effect could occur when a proxy observes that a treatment is ineffective or is perceived as causing adverse effects leading the patient to experience side effects. In this narrative review, we take these definitions one step further to include the impact of PbP/NbP as they transform to affect the treatment outcome for the patient or child being treated, not just the people surrounding the individual being treated. Following a systematic search of literature on the subject using the Journal of Interdisciplinary Placebo Studies (JIPS) database (https://jips.online) and PubMed (NCBI) resulted in very few relevant studies, especially in children. The effect of PbP per se has been studied in parents and their children for temper tantrums, acupuncture for postoperative symptoms, as well as for neuroprotection in very preterm-born infants. This paper will review the PbP/NbP concepts, show evidence for its presence in children's treatment outcome and introduce clinical implications. We will also offer suggestions for future research to further our understanding of the role of the proxy in promoting or distracting from treatment benefit in children. Increasing an appreciation of the PbP and NbP phenomena and the role of the proxy in children's treatment should improve research study design and ultimately harness them to improve clinical child healthcare.

Rewarded placebo analgesia: A new mechanism of placebo effects based on operant conditioning

BACKGROUND

Placebo analgesia is explained by two learning processes: classical conditioning and observational learning. A third learning process, operant conditioning, has not previously been investigated as a mechanism of placebo effects. We aimed to induce placebo analgesia by operant conditioning.

METHODS

Three groups of participants received electrocutaneous pain stimuli of the same intensity, preceded by either an orange or blue stimulus. In the conditioning phase of the study, participants from the experimental group were rewarded for low pain responses following one of the colour stimuli (placebo) and for high pain responses following the other colour stimuli (non-placebo). Moreover, they were punished when their pain responses were high following placebo stimuli and low following non-placebo stimuli. To investigate the role of contingency, that is dependent relation between rewards/punishers and pain responses, the random-control group received rewards and punishers in a non-contingent manner. The colour-control group did not receive any rewards or punishers to control for nonassociative learning. Pain intensity ratings were used as an outcome measure, and verbal feedback on pain ratings was used as rewards/punishers.

RESULTS

When rewarding and punishment were stopped, only participants from the experimental group experienced less pain following the placebo than following the non-placebo stimuli; that is, placebo analgesia was found in this group. This effect was not extinguished during the study.

CONCLUSIONS

Placebo analgesia can be induced by operant conditioning, which should be considered a third mechanism for producing placebo effects. Moreover, the contingency between pain responses and rewards/punishers is crucial to induce placebo analgesia through operant conditioning.

SIGNIFICANCE

According to the current placebo literature, placebo analgesia can be explained by two learning processes: classical conditioning and observational learning. A third learning process, operant conditioning, has not previously been investigated as a mechanism of placebo effects. Our study reveals that patients can learn placebo analgesia as a result of operant conditioning, suggesting that randomized controlled trials could be improved by controlling the reinforcement that might occur spontaneously when patients interact with, for example, medical personnel.

The Influence of Expectation on Nondeceptive Placebo and Nocebo Effects

Nondeceptive placebo has demonstrated its efficiency in clinical practice. Although the underlying mechanisms are still unclear, nondeceptive placebo effect and nondeceptive nocebo effect may be mediated by expectation. To examine the extent to which expectation influences these effects, the present study compared nondeceptive placebo and nocebo effects with different expectation levels. Seventy-two healthy female participants underwent a standard conditioning procedure to establish placebo and nocebo effects. Sequentially, participants were randomized to one of the four experimental groups—baseline (BL), no expectation intervention (NoEI), expectation increasing (EI), and expectation decreasing (ED) groups, to receive either no intervention or interventions through different verbal suggestions that modulated their expectation. Placebo and nocebo effects were established in all four groups after the conditioning phase. However, after disclosing the placebo and nocebo, the analgesic and the hyperalgesic effects only persisted in the EI group, when compared with the BL group. Our results provide evidence highlighting the critical role of increased expectation in nondeceptive placebo and nocebo effects. The finding suggests that open-label placebo or nocebo per se might be insufficient to induce strong analgesic or hyperalgesic response and sheds insights into administrating open-label placebo and avoiding open-label nocebo in clinical practice.

Placebo disclosure does not result in negative changes in mood or attitudes towards health care or the provider

Objectives: The purposes of this study were to (1) determine whether disclosure of having received a placebo treatment following participation in a randomized manual therapy trial resulted in changes in negative mood or attitudes towards health care and the provider and (2) examine the association between changes in mood or attitude and changes in clinical outcomes over the two-week study period. Methods: Participants with low back pain (N = 110) were randomly assigned to receive a spinal manipulative therapy (SMT), a standard placebo SMT in which participants were aware of a chance of receiving a placebo, an enhanced placebo SMT in which participants were instructed 'the manual therapy technique you will receive has been shown to significantly reduce low back pain in some people,' or no treatment. Outcomes included pain (Numeric Rating Scale), disability (Oswestry Disability Index), and negative mood and attitudes towards health care and the provider (visual analog scales). Pain and disability were obtained at baseline and two weeks. Mood and attitude measures were assessed at baseline, at the start of the final session, and upon completion of the final session following disclosure of group assignment. Results: Disclosure of having received a placebo treatment was not associated with worsening of mood or attitudes towards health care or the provider (p > 0.05). A small, but significant (p < 0.05) association was observed between two-week changes in disability and immediate changes in mood (r = 0.31-0.36) upon disclosure of having received a placebo. This analysis indicates an association between larger improvements in disability and more positive changes in mood. Discussion: Placebo treatment use in clinical practice is common yet controversial due to the deceptive nature. Our findings suggest disclosure of having received a placebo treatment is not associated with adverse changes in negative mood or attitudes towards health care or the provider.

A Comparison of Deceptive and Non-Deceptive Placebo Analgesia: Efficacy and Ethical Consequences

BACKGROUND

Research has demonstrated the efficacy of analgesic placebos. The manner in which they are usually delivered deceptively raises questions about their impact on recipients. However, there has been little empirical investigation into the potential harms of analgesic placebo. Moreover, the role of deception in determining the magnitude of analgesic placebo response remains poorly understood.

PURPOSE

This study aimed to investigate the consequences of deceptive placebo analgesia in terms of ethical/psychological effects and efficacy.

METHODS

Healthy adults (N = 75) were randomized to a control group, deceptive placebo manipulation, or non-deceptive placebo manipulation. All participants underwent repeated pain testing using a thermal stimulus. Placebo manipulation groups underwent placebo conditioning involving a cream that was described as being either analgesic or inert. State-specific negative mood and attitudes toward research and pain treatment were assessed before and after placebo conditioning.

RESULTS

Deceptive and non-deceptive placebo manipulations yielded pain ratings that did not differ significantly from one another but did differ from those of the control group, which experienced a pain sensitization response across trials. Results thus indicated that both deceptive and non-deceptive placebo manipulations prevented pain sensitization. Across groups, the participants reported improved depression, anxiety, frustration, and fear. The use of placebo did not negatively impact participants' attitudes and beliefs about research or pain treatments. The participants tended to rate several parameters related to research participation more positively after participating in our study.

CONCLUSIONS

Our results indicate that the placebo manipulation groups experienced an anti-sensitization effect. The use of analgesic placebo did not result in any detrimental ethical or psychological effects.

There Is Something in the Air: Testing the Efficacy of a new Olfactory Stress Relief Method (AromaStick®)

In recent years, aromatherapy has become increasingly popular for clinical treatment and therapeutic management of both acute and chronic stress. It targets distinct and unique neurobiological characteristics of the olfactory system, which is tightly linked to emotions and information processing as well as the autonomous nervous system. Yet, depending on the mode of application, aromatherapeutic interventions show varying degrees of therapeutic effectiveness. In a series of five experiments, the effects of a new mode of aromatherapeutic application (inhaler) was investigated, which is specifically designed to directly stimulate the olfactory system and to reduce the activity of the sympathetic nervous system. Overall, the application of the inhaler showed consistent and large psychological and physiological effects. It also clearly outperformed other stress management techniques, like progressive muscle relaxation, Bach flowers or passive resting periods (natural control). The effects occurred shortly after very few inhalations, drastically reduced stress related biomarkers (i.e. blood pressure, heart rate and cortisol) and considerably enhanced well-being. Copyright © 2015 John Wiley & Sons, Ltd.

Placebo Use in Pain Management: A Mechanism-Based Educational Intervention Enhances Placebo Treatment Acceptability

Health care providers use treatments whose effectiveness derives partially or completely from 'nonspecific' factors, frequently referred to as placebo effects. Although the ethics of interventional placebo use continues to be debated, evidence suggests that placebos can produce clinically meaningful analgesic effects. Burgeoning evidence suggest that patients with chronic pain might be open to placebo treatments in certain contexts despite limited knowledge of their well-established psychoneurobiological underpinnings. In this investigation we sought to examine the effects of a brief, mechanism-based placebo analgesia educational intervention on aspects placebo knowledge and acceptability. Participants with chronic musculoskeletal pain completed a web-based survey in which they rated their knowledge of placebo analgesia, assessed placebo acceptability across different medical contexts, and evaluated 6 unique patient-provider treatment scenarios to assess the role of treatment effectiveness and deception on patient-provider attributions. Using a pre-post design, participants were randomized to receive either a placebo educational intervention or an active control education. Results showed that the educational intervention greatly improved perceptions of placebo knowledge, effectiveness, and acceptability, even in deceptive treatment contexts. This was the first study of its kind to show the value of an educational intervention in increasing openness to and knowledge of placebo analgesic interventions among patients with chronic musculoskeletal pain.

PERSPECTIVE

In this we article highlight how patients with chronic pain might be open to placebo interventions, particularly adjunct and/or complementary treatments, when provided education on the neurobiological and psychological mechanisms that underlie placebo effects. Study findings highlight ethically acceptable ways to potentially use placebo factors to enhance existing pain treatments and improve patient health outcomes.

Placebo analgesia enhances descending pain-related effective connectivity: a dynamic causal modeling study of endogenous pain modulation

The use of placebo to reduce pain is well documented; however, knowledge of the neural mechanisms underlying placebo analgesia remains incomplete. This study used functional magnetic resonance imaging data from 30 healthy individuals and dynamic causal modeling to investigate changes in effective connectivity associated with the placebo analgesic response. Before scanning, participants were conditioned to expect less thermal pain at 2 of 4 sites on their feet. Visual analog scale pain ratings revealed a significant but small difference between the baseline and placebo sites (mean difference = 6.63, t(29) = 3.91, P ≤ .001, d = .97), confirming an analgesic effect. However, no significant differences in the magnitude of brain activation between conditions were observed via traditional random effects general linear modeling. Dynamic causal modeling was then used to investigate changes in effective connectivity during placebo analgesia. The results indicate that during placebo analgesia but not baseline condition, couplings between brain regions, including those involved in cognitive processes (eg, attention, expectation, evaluation), were significantly enhanced. Specifically, a significantly consistent decrease in the dorsolateral prefrontal cortex → periaqueductal gray coupling was found. These findings highlight the differences between pain processing and modulation at the network level. Moreover, our results suggest that small placebo effects may be better characterized via changes in the temporal dynamics among pain modulatory regions than only via changes in the magnitude of blood oxygenation level dependent activation. Further application of nuanced analytical approaches that are sensitive to temporal dynamics of pain-related processes such as dynamic causal modeling are necessary to better understand the neural mechanisms underlying pain processing in patient populations.

PERSPECTIVE

Changes in effective connectivity among pain-related brain regions may be more sensitive detectors of the neural representation of small placebo effects than are changes in the magnitude of brain activation. Knowledge of these mechanisms highlights the importance of integrated neural networks in the understanding of pain modulation.

Conditioned placebo analgesia persists when subjects know they are receiving a placebo

Belief in the effectiveness of a placebo treatment is widely thought to be critical for placebo analgesia. Many types of placebo responses--even those that depend on conditioning--appear to be mediated by expectations that are strengthened as treatment cues are reinforced with positive outcomes. However, placebo effects may occur even when participants are aware they are receiving a placebo. To address the question of whether conditioned placebo analgesia can persist in the absence of expectations, we studied the effects of long (4 days) versus short (1 day) conditioning to a placebo treatment. After an initial placebo test, a "reveal" manipulation convincingly demonstrated to participants that they had never received an active drug. Placebo analgesia persisted after the reveal in the long conditioning group only. These findings suggest that reinforcing treatment cues with positive outcomes can create placebo effects that are independent of reported expectations for pain relief.

PERSPECTIVE

This article demonstrates a form of placebo analgesia that relies on prior conditioning rather than current expected pain relief. This highlights the importance of prior experience on pain relief and offers insight into the variability of placebo effects across individuals.

Should placebo be used routinely for chronic pain in older people?

As research expands our understanding of underlying placebo mechanisms, interest turns to the clinical application of placebos. Whether placebos are appropriate and effective in the management of chronic pain in older people deserves considerable attention. The evidence suggests that adults of any age are responsive to placebos, and that placebo treatments can be effective for many conditions prevalent in older people. Though placebos in general already seem to be used with some regularity in medical practice, the use of placebos alone for chronic pain is probably unjustified unless other treatments are inadvisable or have been exhausted. However maximising the mechanisms that underpin placebo analgesia such as expectancy or the psychosocial context should be encouraged and would be considered a feature of good clinical practice. It would also be anticipated that older people may see an additional benefit with placebo treatments when such treatments reduce existing or planned medication regimes, as older people typically experience more comorbidities, increased susceptibility to adverse drug reactions, and altered pharmacological responses to drugs. Further research is still needed in placebo-related treatment paradigms for the management of chronic pain in older people.

Placebo use in pain management: The role of medical context, treatment efficacy, and deception in determining placebo acceptability

Placebo effects can act as powerful pain relievers. Although the ethics of therapeutic placebo use are highly controversial, recent evidence suggests that medical providers frequently utilize placebo treatments and patients may be open to these interventions in certain contexts. This investigation used a patient-centered approach to answer essential questions about placebo treatment acceptability. People with chronic musculoskeletal pain completed a placebo survey in which they rated their knowledge of placebo and its efficacy for alleviating pain, evaluated the acceptability of placebo analgesic interventions across several unique medical contexts, and responded to 6 different patient-physician treatment scenarios to assess the role of deception and placebo effectiveness on mood and provider trust. Results showed that participants had limited knowledge of placebo and its efficacy for alleviating pain. Placebo acceptability was highly dependent on the context of the intervention, as placebo treatments were considered acceptable when used as complementary/adjunct treatments and when no other established treatments were available. Also, an analgesic placebo response mitigated the negative consequences of deception by improving provider trust and decreasing negative mood. These findings suggest that, contrary to popular belief, patients may be rather pragmatic in their appraisals of placebo treatment acceptability, and may consider a variety of treatments/contexts as ethically permissible for managing their pain. This is the first study of its kind to quantify perceptions of placebo analgesia knowledge and efficacy among individuals with chronic pain, and to assess the role of different medical contexts in treatment acceptability.

Research on placebo analgesia is relevant to clinical practice

Over the decades, research into placebo responses has shed light onto several endogenous (i.e. produced from within) mechanisms underlying modulation of pain perception initiated after the administration of inert substances (i.e. placebos). Chiropractors and manual therapists should embrace analgesic-placebo-research in an attempt to maximize clinical benefit. Historical views that placebo responses are fake, passive, undesirable, and require deception and therefore should be minimized and avoided in clinical practice are outdated. Further, statements that contend the placebo response represents a single mechanism are overly simplistic. This commentary will discuss research that shows that there are several active biological processes underlying modulation of pain perception involved in placebo analgesia and its counterpart nocebo hyperalgesia. We contend that it is highly likely that, to some extent, all of these biological processes are engaged, in varying degrees, following all interventions and represent endogenous pain modulating processes. Failure, of chiropractors and manual therapists, to embrace a more contemporary view of analgesic-placebo-research serves as a barrier to transferring knowledge into clinical practice and represents a missed opportunity to improve the delivery of current treatments.

Placebo, nocebo, and learning mechanisms

Recent substantial laboratory and theoretical research hints for different learning mechanisms regulating the formation of placebo and nocebo responses. Moreover, psychological and biological variants may play a role as modulators of learning mechanisms underlying placebo and nocebo responses. In this chapter, we present pioneering and recent human and nonhuman research that has impressively increased our knowledge of learning mechanisms in the context of placebo and nocebo effects across different physiological processes and pathological conditions.

The potential benefit of the placebo effect in sham-controlled trials: implications for risk-benefit assessments and informed consent

There has been considerable debate surrounding the ethics of sham-controlled trials of procedures and interventions. Critics argue that these trials are unethical because participants assigned to the control group have no prospect of benefit from the trial, yet they are exposed to all the risks of the sham intervention. However, the placebo effect associated with sham procedures can often be substantial and has been well documented in the scientific literature. We argue that, in light of the scientific evidence supporting the benefits of sham interventions for pain and Parkinson's disease that stem from the placebo effect, these sham-controlled trials should be considered as offering potential direct benefit to participants. If scientific evidence demonstrates the positive effect of placebo from sham interventions on other conditions, sham-controlled trials of interventions for the treatment of these conditions should be considered to have prospects of benefit as well. This potential benefit should be taken into account by research ethics committees in risk-benefit analyses, and be included in informed consent documents.

Placebo response to manual therapy: something out of nothing?

The mechanisms through which manual therapy inhibits musculoskeletal pain are likely multifaceted and related to the interaction between the intervention, the patient, the practitioner, and the environment. Placebo is traditionally considered an inert intervention; however, the pain research literature suggests that placebo is an active hypoalgesic agent. Placebo response likely plays a role in all interventions for pain and we suggest that the same is true for the treatment effects associated with manual therapy. The magnitude of a placebo response may be influenced by negative mood, expectation, and conditioning. We suggest that manual therapists conceptualize placebo not only as a comparative intervention, but also as a potential active mechanism to partially account for treatment effects associated with manual therapy. We are not suggesting manual therapists include known sham or ineffective interventions in their clinical practice, but take steps to maximize placebo responses to reduce pain.

Analgesic placebo treatment perceptions: acceptability, efficacy, and knowledge

Current evidence supports the efficacy of placebo analgesia and illustrates that patients may be open to placebo use despite uncertainty regarding its mechanisms. Debate persists, however, concerning the ethics of placebo treatments. The purpose of the present web-based study was to expand upon the empirical literature on placebo analgesia ethics and acceptability. Participants (n = 100) provided their definition of a placebo and responded to 24 questions addressing placebo analgesia perceived knowledge, acceptability, effectiveness, and likelihood of placebo use among different health care providers. Results support previous research on the effects of placebo on negative mood and health care provider attributions, with findings illustrating that negative consequences of administration were largely mitigated by a beneficial treatment outcome. Results showed that participants conceptualized placebo as predominately inert and were mixed regarding interpretations of placebo effectiveness. Though acceptability ratings were dependent on the context of placebo administration, participants endorsing even moderate placebo acceptability were more open to placebo interventions and reported overall more positive treatment outcomes. Participants believed that placebos were used differentially among health care providers. Additional studies are needed to determine if placebo education can beneficially impact perceptions of placebo analgesia knowledge, acceptability, and treatment effectiveness.

PERSPECTIVE

This study presents an examination of analgesic placebo treatment perceived acceptability, efficacy, and knowledge among lay individuals. Our findings highlight the importance of assessing placebo conceptualizations and treatment perceptions in evaluating placebo ethics-a highly relevant finding that informs the clinical use of placebo components in managing pain.

Participants' experiences of being debriefed to placebo allocation in a clinical trial

Participants in placebo-controlled clinical trials give informed consent to be randomized to verum or placebo. However, researchers rarely tell participants which treatment they actually received. We interviewed 4 participants in a trial of acupuncture for irritable bowel syndrome before, during, and after they received a course of placebo treatments over 6 weeks. During the final interview, we informed participants that they had received a course of placebo treatments. We used an idiographic phenomenological approach based on the Sheffield School to describe each participant's experiences of being blinded to and then debriefed to placebo allocation. The participants' experiences of blinding and debriefing were embodied, related to their goals in undertaking the study, and social (e.g., embedded in trusting and valued relationships with acupuncturists). We suggest ways in which debriefing to placebo allocation can be managed sensitively to facilitate positive outcomes for participants.

Factors affecting placebo acceptability: deception, outcome, and disease severity

A burgeoning body of evidence supports the efficacy and elucidates the mechanisms of placebo analgesia. Debate persists, however, concerning their ethical use, with many of the present arguments being philosophically based. The present web-based study empirically investigated the acceptability of an analgesic placebo treatment. Participants (103) responded to vignettes depicting patients receiving a placebo analgesic. We experimentally manipulated: 1) placebo treatment instructions (level of deception); 2) treatment outcome; and 3) patients' pain severity. Participants rated vignettes on outcome measures of deception, physician-patient relationship, and patient mood. Participants then characterized a range of placebo acceptability through ratings of deceptiveness, effectiveness, and negative consequences. Results showed that placebos described as "medication shown to be a powerful analgesic in some people" were equally deceptive as those described as "standard drug treatment." Ratings of patient mood and physician approval were determined as much by treatment instruction as by treatment outcome and an analgesic response mitigated the negative consequences of deceptive administration. Participants tolerated moderate effectiveness and considerable negative consequences in an acceptable placebo, although results suggest lay individuals may not have a sophisticated conceptualization of placebo effectiveness. Studies altering individuals' understanding of placebo effectiveness and mechanisms are needed to identify additional factors determining placebo acceptability.

PERSPECTIVE

This study represents an empirical examination of analgesic placebo acceptability among lay individuals. This article is the first to systematically manipulate deception, treatment outcome, and disease severity to determine how these factors interact to differentially determine placebo acceptability-a highly relevant finding that informs the clinical use of placebo.

Practice, practitioner, or placebo? A multifactorial, mixed-methods randomized controlled trial of acupuncture

The nonspecific effects of acupuncture are well documented; we wished to quantify these factors in osteoarthritic (OA) pain, examining needling, the consultation, and the practitioner. In a prospective randomised, single-blind, placebo-controlled, multifactorial, mixed-methods trial, 221 patients with OA awaiting joint replacement surgery were recruited. Interventions were acupuncture, Streitberger placebo acupuncture, and mock electrical stimulation, each with empathic or nonempathic consultations. Interventions involved eight 30-minute treatments over 4 weeks. The primary outcome was pain (VAS) at 1 week posttreatment. Face-to-face qualitative interviews were conducted (purposive sample, 27 participants). Improvements occurred from baseline for all interventions with no significant differences between real and placebo acupuncture (mean difference -2.7 mm, 95% confidence intervals -9.0 to 3.6; P=.40) or mock stimulation (-3.9, -10.4 to 2.7; P=.25). Empathic consultations did not affect pain (3.0mm, -2.2 to 8.2; P=.26) but practitioner 3 achieved greater analgesia than practitioner 2 (10.9, 3.9 to 18.0; P=.002). Qualitative analysis indicated that patients' beliefs about treatment veracity and confidence in outcomes were reciprocally linked. The supportive nature of the trial attenuated differences between the different consultation styles. Improvements occurred from baseline, but acupuncture has no specific efficacy over either placebo. The individual practitioner and the patient's belief had a significant effect on outcome. The 2 placebos were equally as effective and credible as acupuncture. Needle and nonneedle placebos are equivalent. An unknown characteristic of the treating practitioner predicts outcome, as does the patient's belief (independently). Beliefs about treatment veracity shape how patients self-report outcome, complicating and confounding study interpretation.

Dynamic nature of the placebo response

Traditionally, placebo has been associated with using an inert substance, in part so the subsequent response could be attributed to the target treatment, controlling for the confound of a “placebo effect.” ^,, Placebo’s link with inert substances is so strong that “sham treatment” is a common synonym, and widespread placebo use is discouraged—even when there is supporting evidence for its effectiveness.^,, Recent research has helped to redefine placebo, and this editorial will highlight key information supporting a contemporary view of placebo.

Inclusion of authorized deception in the informed consent process does not affect the magnitude of the placebo effect for experimentally induced pain

The ethics of placebo research have been of paramount concern since the discovery of the phenomenon. To address these ethical concerns, Miller and colleagues (PLoS Med 2005 Sep;2(9):e262, 0853-0859) propose an alternate approach to placebo research, called "authorized deception", in which participants are alerted of the use of deception in the research prior to study enrollment and thus knowingly permit its use if they decide to participate. The present study sought to investigate the authorized deception methodology in experimentally induced placebo analgesia. The participants were randomly assigned to an authorized deception or non-authorized deception group. A commonly used protocol was employed wherein heat pain stimulation was surreptitiously lowered following the application of a placebo cream during a series of conditioning trials and the magnitude of the placebo effect was subsequently assessed in test trials for which the stimulus intensity was the same for both the placebo and control creams. Authorized deception did not have any negative impact on the magnitude of the placebo effect, recruitment and retention of participants, nor did it result in any significant psychological harm. The majority of participants who received this form of consent preferred it to the traditional approach in which the participants are not alerted to the presence of deception. These findings suggest that the use of authorized deception is a viable and ethically preferable alternative consent process for laboratory-based studies on placebo analgesia. Further studies are needed to examine the effect of authorized deception in clinical trials and other placebo research within a clinical setting.

New insights into the placebo and nocebo responses

In modern medicine, the placebo response or placebo effect has often been regarded as a nuisance in basic research and particularly in clinical research. The latest scientific evidence has demonstrated, however, that the placebo effect and the nocebo effect, the negative effects of placebo, stem from highly active processes in the brain that are mediated by psychological mechanisms such as expectation and conditioning. These processes have been described in some detail for many diseases and treatments, and we now know that they can represent both strength and vulnerability in the course of a disease as well as in the response to a therapy. However, recent research and current knowledge raise several issues that we shall address in this review. We will discuss current neurobiological models like expectation-induced activation of the brain reward circuitry, Pavlovian conditioning, and anxiety mechanisms of the nocebo response. We will further explore the nature of the placebo responses in clinical trials and address major questions for future research such as the relationship between expectations and conditioning in placebo effects, the existence of a consistent brain network for all placebo effects, the role of gender in placebo effects, and the impact of getting drug-like effects without drugs.

Neurophysiology and psychobiology of the placebo response

PURPOSE OF REVIEW

The placebo literature has substantially increased in 2006 and 2007, and more and more medical and psychological subspecialties have added empirical data to our knowledge.

RECENT FINDINGS

The theoretical framework of our understanding of the placebo response needs extension to account for findings that cannot be attributed to (Pavlovian) conditioning or suggestions alone. In addition, imaging studies need to address individual responses rather than group means, and to expand beyond experimental pain research. Gender aspects have been demonstrated for the placebo response but still widely ignored, especially in neurophysiological studies. It has been shown that nocebo research needs a methodological and ethical framework that allows its exploration. Finally, analyses of clinical trial data, either as metaanalyses or as reanalyses of trial raw data, may allow us to identify factors that subsequently can be used in experimental work.

SUMMARY

Novel findings will allow better planning of clinical drug trials, better handling of clinical trial data in the future, and finally, may eventually result in improved patient management.