The sweetest pill to swallow: How patient neurobiology can be harnessed to maximise placebo effects

Therapeutic and Structural Dimensions in Psychiatric Prescribing: Bridging Psychedelics and Antidepressants

ABSTRACT

As practitioners seek more personalized approaches, exploring how patients' environments, relationship templates, and mindsets factor into symptom burden can help broaden understanding of how psychotropic medications facilitate recovery. Despite increasing focus on medications to provide relief, there is an important and undeniable influence the therapeutic environment has on shaping outcomes, particularly for the patient-clinician alliance. While environmental dimensions are relevant for informing possible placebo or nocebo responses, they also build upon the pharmacodynamic and neurobiological effects of medications. By heightening neuroplasticity, some antidepressants may amplify the effects of nonmedication factors in patients' lives, including the patient-prescriber therapeutic relationship. There are important parallels between antidepressants and psychedelics in emerging literature. For instance, the preparatory and integrative work with a provider can be crucial in determining outcomes. This paper will draw from the extant literature to discuss the therapeutic relationship in psychiatric practice, including in acute care settings and instances in which psychotropic prescribing is a key aspect of treatment.

Premovement activity in the corticospinal tract is amplified by the placebo effect: an active inference account

The aim of this study is to investigate whether expectancy, induced through a placebo procedure, favors the activation of the corticospinal tract before movement initiation. By adopting the premovement facilitation paradigm, we applied transcranial magnetic stimulation over the left or right primary motor cortex at rest and 100 ms or 50 ms before movement onset while healthy volunteers performed a reaction time (RT) motor task consisting of abductions of the right or left thumb after a go signal. Participants in the placebo group received an inert electrical device applied on the right forearm along with information on its speed-enhancing properties. A control group received the same device with overt information about its inert nature, while another control group underwent no intervention. Along with RT, we measured the amplitude of the motor evoked potential (MEP) before and after the procedure. Compared to the control groups, the placebo group had faster RT and greater MEP amplitude before movement initiation. This study demonstrates that the placebo effect can boost the activity of the corticospinal tract before movement onset, and this modulation positively impacts motor performance. These results give experimental support to the active inference account.

Placebo effect on gait: a way to reduce the dual-task cost in older adults

The ability to perform two tasks simultaneously is essential for daily activities. In older adults, this ability is markedly reduced, as evidenced by the dual-task cost on gait. Preliminary evidences indicate that the dual-task cost can be influenced by different types of manipulations. Here, we explored the effectiveness of a new approach to reduce the dual-task cost, based on the placebo effect, a psychobiological phenomenon whereby a positive outcome follows the administration of an inert device thought to be effective. Thirty-five healthy older adults were asked to walk on a sensorized carpet (single-task condition) and to walk while counting backward (dual-task condition) in two sessions (pre-test and post-test). A placebo group, randomly selected, underwent sham transcranial direct current stimulation over the supraorbital areas between sessions, along with information about its positive effects on concentration and attention. A control group did not receive any intervention between sessions. The dual-task cost was significantly reduced in the placebo group at the post-test session compared to the pre-test for several gait parameters (Cohen's d > 1.43). At the post-test session, the dual-task cost was also lower in the placebo group than in the control group (d > 0.73). Cognitive (number of subtractions and number of errors) and subjective (perceived mental fatigability) variables remained stable across sessions. The reduced dual-task cost in the placebo group could indicate the ability to re-establish the allocation of attentional resources between tasks. These findings could contribute to the development of cognitive strategies that leverage positive expectations to boost motor control in older adults.

The placebo effect shortens movement time in goal-directed movements

The placebo effect is a powerful psychobiological phenomenon whereby a positive outcome follows the administration of an inert treatment thought to be effective. Growing evidence shows that the placebo effect extends beyond the healing context, affecting also motor performance. Here we explored the placebo effect on the control of goal-directed movement, a fundamental function in many daily activities. Twenty-four healthy volunteers performed upper-limb movements toward a target at different indexes of difficulty in two conditions: in the placebo condition, an electrical device (inert) was applied to the right forearm together with verbal information about its positive effects in improving movement precision; in the control condition, the same device was applied along with verbal information about its neutral effects on performance. Interestingly, we found shorter movement time in the placebo compared to the control condition. Moreover, subjective perception of fatigability was reduced in the placebo compared to the control condition. These findings indicate that the placebo effect can improve the execution of goal-directed movements, thus adding new evidence to the placebo effect in the motor domain. This study could inspire future applications to improve upper-limb movements or in clinical settings for patients with motor deficits.

Consideration in Randomized Placebo-Controlled Trial on Neck Pain to Avoid the Placebo Effect in Analgesic Action

Background: In neck pain treatment, many therapies are focused on etiology, while it is well-known that placebo analgesia is also present in these therapies. The specific efficacy for etiology may be underestimated by ignoring their actual placebo effect. In this study, a logistic regression analysis is used to explore the risk factors causing different placebo responses in patients with neck pain among two RCTs. The probability of the placebo effect is predicted based on these risk factors.

Methods: Trial A and Trial B were similarly designed, randomized, double-/single-blind, placebo-controlled trials in patients treating neck pain with Qishe pill or Shi-style manipulation. Both studies set a placebo pill twice a day or traction for every other day as control. For further analyses on the placebo effect in neck pain management, logistic regression was used to assess subgroup-placebo interactions. The odds ratio assessed a significant influence on the placebo effect.

Results: In this pooled analysis, the total number of patients recruited for these two studies was 284, of which 162 patients received placebo treatment (placebo drug or traction for every other day). No statistically significant differences are found at baseline between the participants with placebo effect and non-placebo effect in the gender, age, and disease duration except in VAS and NDI at the initial time. There are numerically more patients with placebo effect in the shorter disease duration subgroup (< 4 months [76%]), higher initial VAS subgroup (>60 mm [90%]), and worse initial NDI subgroup (>24 [72%]) compared with the gender and age subgroup. An ROC curve is established to assess the model-data fit, which shows an area under the curve of 0.755 and a 95% confidence interval of 0.677–0.830. Participants who show placebo effect after 2 weeks have significantly lower VAS scores after 4 weeks, while there is no significant difference in NDI improvement between the two groups after 4 weeks.

Conclusion: Neck pain patients with shorter disease duration are more likely to overscore their pain severity, because of their less experience in pain perception, tolerance, and analgesia expectation.

The Role of Expectation and Beliefs on the Effects of Non-Invasive Brain Stimulation

Non-invasive brain stimulation (NIBS) techniques are used in clinical and cognitive neuroscience to induce a mild magnetic or electric field in the brain to modulate behavior and cortical activation. Despite the great body of literature demonstrating promising results, unexpected or even paradoxical outcomes are sometimes observed. This might be due either to technical and methodological issues (e.g., stimulation parameters, stimulated brain area), or to participants’ expectations and beliefs before and during the stimulation sessions. In this narrative review, we present some studies showing that placebo and nocebo effects, associated with positive and negative expectations, respectively, could be present in NIBS trials, both in experimental and in clinical settings. The lack of systematic evaluation of subjective expectations and beliefs before and after stimulation could represent a caveat that overshadows the potential contribution of placebo and nocebo effects in the outcome of NIBS trials.

The ethical dilemma of placebo use in clinical practice

The clinical use of placebo that involves some ethical issues has led to much controversy. From the standpoint of both supporters and opponents, this article discusses this topic from three ethical principles such as beneficence, justice, and autonomy and also gives the recommendations. Finally, the moral dilemma caused by the different views between nurses and doctors in clinical practice is discussed.

The role of the dorsolateral prefrontal cortex in the motor placebo effect

The neural correlates of the placebo effect in the motor domain are still unknown. The aim of this study was to tackle the role of a frontal cortical region, the dorsolateral prefrontal cortex (dlPFC). To this end, we stimulated the cortical site corresponding to the left dlPFC with transcranial direct current stimulation (tDCS) during a placebo procedure and measured any change in the motor placebo effect in all the participants and more specifically in placebo-responders. Three different experiments were conducted in which healthy volunteers performed a force motor task with the index finger. The placebo treatment consisted of transcutaneous electrical nerve stimulation (TENS). In Experiment 1 (expectation alone), participants were only verbally suggested about the positive effects of TENS. In Experiment 2 (expectation and conditioning), participants were verbally suggested about TENS and conditioned with a surreptitious increase in a visual feedback of force. In Experiment 3 (control procedure), participants were told that TENS was inefficient. Each participant was tested in three different days with anodal, cathodal and sham tDCS over the dlPFC. Results showed that in Experiment 1 and 2 force increased after the procedure, independently of tDCS. By focusing on placebo-responders, we found that in Experiment 1 force remained stable after active tDCS, whereas it increased after inactive tDCS. These findings bring new evidence on the neural underpinnings of the motor placebo effect, by showing that independently of the polarity, active tDCS over the left dlPFC may undermine the expectation-induced enhancement of force in placebo-responders.

Neurobiology of placebo effect in Parkinson's disease: What we have learned and where we are going

The placebo effect is a phenomenon produced when an inert substance administered like a regular treatment improves the clinical outcome. Parkinson's disease (PD) is one of the main clinical disorders for which the placebo response rates are high. The first evidence of the neurobiological mechanisms underlying the placebo effect in PD stems from 2001, when de la Fuente-Fernandez and colleagues demonstrated that a placebo injection led to the release of dopamine in the striatal nuclei of PD measured with positron emission tomography technology. Since then, several studies have been conducted to investigate the neurobiological underpinnings of placebo responses. This article presents a systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. Of an initial yield of 143 papers, 19 were included. The lessons learned from these studies are threefold: (i) motor improvement is dependent on the activation of the entire nigrostriatal pathway induced by dopamine release in the dorsal striatum; (ii) the magnitude of placebo-induced effects is modulated by an expectancy of improvement, which is in turn related to the release of dopamine within the ventral striatum; (iii) the functioning of the neural pathways underlying the placebo response can be tuned by prior exposure and learning strategies. In conclusion, although the neural network underlying the placebo effect in PD has been largely confirmed and accepted, what remains to be established is how, when, and where the expectation of reward (mediated by the ventral striatum) interacts with the primary motor system (mediated by the dorsal striatum) to induce clinical improvement in motor symptoms. © 2018 International Parkinson and Movement Disorder Society.

Altered striatal reward processing in abstinent dependent cannabis users: Social context matters

Public perception of cannabis as relatively harmless, alongside claimed medical benefits, have led to moves towards its legalization. Yet, long-term consequences of cannabis dependence, and whether they differ qualitatively from other drugs, are still poorly understood. A key feature of addictive drugs is that chronic use leads to adaptations in striatal reward processing, blunting responsivity to the substance itself and natural (non-drug) rewards. Against this background, the present study investigated whether cannabis dependence is associated with lasting alterations in behavioral and neural responses to social reward in 23 abstinent cannabis-dependent men and 24 matched non-using controls. In an interpersonal pleasant touch fMRI paradigm, participants were led to believe they were in physical closeness of or touched (CLOSE, TOUCH) by either a male or female experimenter (MALE, FEMALE), allowing contextual modulation of the perceived pleasantness and associated neural responses. Upon female compared to male touch, dependent cannabis users displayed a significantly attenuated increase of pleasantness experience compared to healthy controls. Controls responded to female as compared to male interaction with increased striatal activation whereas cannabis users displayed the opposite activation pattern, with stronger alterations being associated with a higher lifetime exposure to cannabis. Neural processing of pleasant touch in dependent cannabis users was found to be intact. These findings demonstrate that cannabis dependence is linked to blunted striatal processing of non-drug rewards and suggest that these alterations may contribute to social processing deficits.

The Effect of a Pilot Dietary Intervention on Pain Outcomes in Patients Attending a Tertiary Pain Service

The aim of this study was to examine the effect of a six-week 2 × 2 design on pain scores, quality of life, and dietary intake in patients attending an Australian tertiary pain clinic. The two intervention components were (1) personalized dietary consultations or waitlist control, and (2) active or placebo dietary supplement (fruit juice). Sixty participants were randomized into one of four groups at baseline (68% female, mean age 49 ± 15 years) with 42 completing the study (70% retention). All groups had statistically significant improvements in three of five pain outcomes. The personalized dietary consultation groups had clinically important improvements in three of five pain outcomes compared to the waitlist control groups. All groups had a statistically significant improvement in six of eight quality-of-life categories post intervention. All groups increased percentage energy from nutrient-dense foods (+5.2 ± 1.4%, p < 0.001) with a significant group-by-time effect for percentage energy from total fat (p = 0.024), with the personalized dietary consultations plus placebo fruit juice reporting the largest reduction (−5.7 ± 2.3%). This study indicates that dietitian-delivered dietary intervention can improve pain scores, quality of life, and dietary intake of people experiencing chronic pain. Future research should evaluate efficacy in a full-powered randomized control trial.

The Use of Expectancy and Empathy When Communicating With Patients With Advanced Breast Cancer; an Observational Study of Clinician-Patient Consultations

Background: Information provision about prognosis, treatments, and side-effects is important in advanced cancer, yet also associated with impaired patient well-being. To counter potential detrimental effects, communication strategies based on placebo and nocebo effect mechanisms might be promising to apply in daily practice. This study aimed to provide more insight into how often and how oncologists use expectancy and empathy expressions in consultations with patients with advanced breast cancer. Methods: Forty-five consultations between oncologists and patients were audiotaped. To determine how often expectancy and empathy expressions were used, a coding scheme was created. Most consultations (n = 33) were coded and discussed by two coders, and the remaining 13 were coded by one coder. To determine how expectancy and empathy expressions were used, principles of inductive content analysis were followed. Results: Discussed evaluation (i.e., scan) results were good (n = 26,58%) or uncertain (n = 12,27%) and less often bad (n = 7,15%). Uncertain expectations about prognosis, treatment outcomes, and side effects occurred in 13, 38, and 27 consultations (29%, 85%, and 56%), followed by negative expectations in 8, 26, and 28 consultations (18%, 58%, and 62%) and positive expectations in 6, 34, and 17 consultations (13%, 76%, and 38%). When oncologists provided expectancy expressions, they tapped into three different dimensions: relational, personal, and explicit. Positive expectations emphasized the doctor-patient relationship, while negative expectations focused on the severity of the illness, and uncertainty was characterized by a balance between (potential) negative outcomes and hope. Observed generic or specific empathy expressions were regularly provided, most frequently understanding (n = 29,64% of consultations), respecting (n = 17,38%), supporting (n = 16,36%), and exploring (n = 16,36%). A lack of empathy occurred less often and contained, among others, not responding to patients' emotional concerns (n = 13,27% of consultations), interrupting (n = 7,16%), and an absence of understanding (n = 4,9%). Conclusion: In consultations with mainly positive or uncertain medical outcomes, oncologists predominantly made use of uncertain expectations (hope for the best, prepare for the worst) and used several empathic behaviors. Replication studies, e.g., in these and other medical situations, are needed. Follow-up studies should test the effect of specific communication strategies on patient outcomes, to counter potential negative effects of information provision. Studies should focus on uncertain situations. Ultimately, specific placebo and nocebo effect-inspired communication strategies can be harnessed in clinical care to improve patient outcomes.

Evaluating the importance of sham-controlled trials in the investigation of medical devices in interventional cardiology

Cardiovascular medicine is one of the specialties that has relied most heavily on evidence from randomised clinical trials in determining best practice for the management of common disease conditions. When comparing treatment approaches, trials incorporating random allocation are the most appropriate method for protecting against treatment allocation bias. In order to protect against performance and ascertainment bias, trial designs including placebo control are preferable where feasible. In contrast to testing of medicines, treatments based on procedures or use of medical devices are more challenging to assess, as sham procedures are necessary to facilitate blinding of participants. However, in many cases, ethical concerns exist, as individual patients allocated to sham procedure are exposed only to risk without potential for benefit. Accordingly, the potential benefits to the general patient population must be carefully weighed against the risks of the exposed individuals. For this reason, trial design and study conduct are critically important to ensure that the investigation has the best chance of answering the study question at hand. In the current manuscript, we aim to review issues relating to the conduct of sham-controlled trials and discuss a number of recent examples in the field of interventional cardiology.

Examining the effects of enhanced provider-patient communication on postoperative tonsillectomy pain: protocol of a randomised controlled trial performed by nurses in daily clinical care

INTRODUCTION

Placebo effects (true biopsychological effects not attributable to the active ingredients of medical technical interventions) can be attributed to several mechanisms, such as expectancy manipulation and empathy manipulation elicited by a provider's communication. So far, effects have primarily been shown in laboratory settings. The aim of this study is to determine the separate and combined effects of expectancy manipulation and empathy manipulation during preoperative and postoperative tonsillectomy analgesia care on clinical adult patients' outcomes.

METHODS AND ANALYSIS

Using a two-by-two randomised controlled trial, 128 adult tonsillectomy patients will be randomly assigned to one out of four conditions differing in the level of expectancy manipulation (standard vs enhanced) and empathy manipulation (standard vs enhanced). Day care ward nurses are trained to deliver the intervention, while patients are treated via the standard analgesia protocol and hospital routines. The primary outcome, perceived pain, is measured via hospital routine by a Numeric Rating Scale, and additional prehospitalisation, perihospitalisation and posthospitalisation questionnaires are completed (until day 3, ie, 2 days after the operation). The manipulation is checked using audio recordings of nurse-patient interactions.

ETHICS AND DISSEMINATION

Although communication is manipulated, the manipulations do not cross norms or values of acceptable behaviour. Standard medical care is provided. The ethical committee of the UMC Utrecht and the local OLVG hospital committee approved the study. Results will be published via (inter)national peer-reviewed journals and a lay publication.

TRIAL REGISTRATION NUMBER

NTR5994; Pre-results.

What techniques might be used to harness placebo effects in non-malignant pain? A literature review and survey to develop a taxonomy

OBJECTIVES

Placebo effects can be clinically meaningful but are seldom fully exploited in clinical practice. This review aimed to facilitate translational research by producing a taxonomy of techniques that could augment placebo analgesia in clinical practice.

DESIGN

Literature review and survey.

METHODS

We systematically analysed methods which could plausibly be used to elicit placebo effects in 169 clinical and laboratory-based studies involving non-malignant pain, drawn from seven systematic reviews. In a validation exercise, we surveyed 33 leading placebo researchers (mean 12 years’ research experience, SD 9.8), who were asked to comment on and add to the draft taxonomy derived from the literature.

RESULTS

The final taxonomy defines 30 procedures that may contribute to placebo effects in clinical and experimental research, proposes 60 possible clinical applications and classifies procedures into five domains: the patient’s characteristics and belief (5 procedures and 11 clinical applications), the practitioner’s characteristics and beliefs (2 procedures and 4 clinical applications), the healthcare setting (8 procedures and 13 clinical applications), treatment characteristics (8 procedures and 14 clinical applications) and the patientâ€"practitioner interaction (7 procedures and 18 clinical applications).

CONCLUSION

The taxonomy provides a preliminary and novel tool with potential to guide translational research aiming to harness placebo effects for patient benefit in practice.

Symptoms and the body: Taking the inferential leap

The relationship between the conscious experience of physical symptoms and indicators of objective physiological dysfunction is highly variable and depends on characteristics of the person, the context and their interaction. This relationship often breaks down entirely in the case of "medically unexplained" or functional somatic symptoms, violating the basic assumption in medicine that physical symptoms have physiological causes. In this paper, we describe the prevailing theoretical approach to this problem and review the evidence pertaining to it. We then use the framework of predictive coding to propose a new and more comprehensive model of the body-symptom relationship that integrates existing concepts within a unifying framework that addresses many of the shortcomings of current theory. We describe the conditions under which a close correspondence between the experience of symptoms and objective physiology might be expected, and when they are likely to diverge. We conclude by exploring some theoretical and clinical implications of this new account.

The Insula: A "Hub of Activity" in Migraine

The insula, a "cortical hub" buried within the lateral sulcus, is involved in a number of processes including goal-directed cognition, conscious awareness, autonomic regulation, interoception, and somatosensation. While some of these processes are well known in the clinical presentation of migraine (i.e., autonomic and somatosensory alterations), other more complex behaviors in migraine, such as conscious awareness and error detection, are less well described. Since the insula processes and relays afferent inputs from brain areas involved in these functions to areas involved in higher cortical function such as frontal, temporal, and parietal regions, it may be implicated as a brain region that translates the signals of altered internal milieu in migraine, along with other chronic pain conditions, through the insula into complex behaviors. Here we review how the insula function and structure is altered in migraine. As a brain region of a number of brain functions, it may serve as a model to study new potential clinical perspectives for migraine treatment.

Unanticipated Insights into Biomedicine from the Study of Acupuncture

Research into acupuncture has had ripple effects beyond the field of acupuncture. This paper identifies five exemplars to illustrate that there is tangible evidence of the way insights gleaned from acupuncture research have informed biomedical research, practice, or policy. The first exemplar documents how early research into acupuncture analgesia has expanded into neuroimaging research, broadening physiologic understanding and treatment of chronic pain. The second describes how the acupuncture needle has become a tool to enhance biomedical knowledge of connective tissue. The third exemplar, which illustrates use of a modified acupuncture needle as a sham device, focuses on emergent understanding of placebo effects and, in turn, on insights into therapeutic encounters in treatments unrelated to acupuncture. The fourth exemplar documents that two medical devices now in widespread use were inspired by acupuncture: transcutaneous electrical nerve stimulators for pain control and antinausea wrist bands. The final exemplar describes how pragmatic clinical trial designs applied in acupuncture research have informed current general interest in comparative effectiveness research. In conclusion, these exemplars of unanticipated outcomes of acupuncture research comprise an additional rationale for continued support of basic and clinical research evaluating acupuncture and other under-researched therapies.

The effect of patient-practitioner communication on pain: a systematic review

BACKGROUND AND OBJECTIVE

Communication between patients and health care practitioners is expected to benefit health outcomes. The objective of this review was to assess the effects of experimentally varied communication on clinical patients' pain.

DATABASES AND DATA TREATMENT

We searched in July 2012, 11 databases supplemented with forward and backward searches for (quasi-) randomized controlled trials in which face-to-face communication was manipulated. We updated in June 2015 using the four most relevant databases (CINAHL, Cochrane Central, Psychinfo, PubMed).

RESULTS

Fifty-one studies covering 5079 patients were included. The interventions were separated into three categories: cognitive care, emotional care, procedural preparation. In all but five studies the outcome concerned acute pain. We found that, in general, communication has a small effect on (acute) pain. The 19 cognitive care studies showed that a positive suggestion may reduce pain, whereas a negative suggestion may increase pain, but effects are small. The 14 emotional care studies showed no evidence of a direct effect on pain, although four studies showed a tendency for emotional care lowering patients' pain. Some of the 23 procedural preparation interventions showed a weak to moderate effect on lowering pain.

CONCLUSIONS

Different types of communication have a significant but small effect on (acute) pain. Positive suggestions and informational preparation seem to lower patients' pain. Communication interventions show a large variety in quality, complexity and methodological rigour; they often used multiple components and it remains unclear what the effective elements of communication are. Future research is warranted to identify the effective components.

Neuro-Bio-Behavioral Mechanisms of Placebo and Nocebo Responses: Implications for Clinical Trials and Clinical Practice

The placebo effect has often been considered a nuisance in basic and particularly clinical research. This view has gradually changed in recent years due to deeper insight into the neuro-bio-behavioral mechanisms steering both the placebo and nocebo responses, the evil twin of placebo. For the neuroscientist, placebo and nocebo responses have evolved as indispensable tools to understand brain mechanisms that link cognitive and emotional factors with symptom perception as well as peripheral physiologic systems and end organ functioning. For the clinical investigator, better understanding of the mechanisms driving placebo and nocebo responses allow the control of these responses and thereby help to more precisely define the efficacy of a specific pharmacological intervention. Finally, in the clinical context, the systematic exploitation of these mechanisms will help to maximize placebo responses and minimize nocebo responses for the patient's benefit. In this review, we summarize and critically examine the neuro-bio-behavioral mechanisms underlying placebo and nocebo responses that are currently known in terms of different diseases and physiologic systems. We subsequently elaborate on the consequences of this knowledge for pharmacological treatments of patients and the implications for pharmacological research, the training of healthcare professionals, and for the health care system and future research strategies on placebo and nocebo responses.

From Randomized Controlled Trials of Antidepressant Drugs to the Meta-Analytic Synthesis of Evidence: Methodological Aspects Lead to Discrepant Findings

During the last decade, several meta-analytic studies employing different methodological approaches have had inconsistent conclusions regarding antidepressant efficacy. Herein, we aim to comment on methodological aspects that may have contributed to disparate findings. We initially discuss methodological inconsistencies and limitations related to the conduct of individual antidepressant randomized controlled trials (RCTs), including differences in allocated samples, limitations of psychometric scales, possible explanations for the heightened placebo response rates in antidepressant RCTs across the past two decades as well as the reporting of conflicts of interest. In the second part of this article, we briefly describe the various meta-analyses techniques (e.g., simple random effects meta-analysis and network meta-analysis) and the application of these methods to synthesize evidence related to antidepressant efficacy. Recently published antidepressant metaanalyses often provide discrepant results and similar results often lead to different interpretations. Finally, we propose strategies to improve methodology considering real-world clinical scenarios.

Understanding and translating the knowledge about placebo effects: the contribution of psychology

PURPOSE OF REVIEW

Recent articles have summarized the literature on the neurobiological mechanisms involved in placebo effects. In this article, we review and evaluate the status of the psychological mechanisms in theory and research regarding placebo effects.

RECENT FINDINGS

Currently, the placebo effect literature concentrates more on neurobiological mechanisms than on psychological mechanisms. Both theoretical and empirical coverage of the psychological mechanisms are typically limited to two variables: conditioning and verbally induced expectations. Because psychological processes take center stage in mediating the link between the therapeutic context and placebo responding, greater effort is needed to build empirically derived and theoretically complex psychological process models. Such models would include a broader array of psychological constructs and mechanisms.

SUMMARY

Research and theory on placebo effects has illuminated much regarding the neurobiological mechanisms. The psychological mechanisms, however, have received much less attention. Expanding our knowledge regarding the psychological processes involved in placebo responding would open up opportunities for developing nondeceptive intervention techniques that encourage placebo responses. Ultimately, a concerted empirical effort to clarify the psychological model underlying placebo effects could merge with the evolving neurobiological model to fulfill the promise that placebo effects have for improving patient outcomes.

The placebo-nocebo response: controversies and challenges from clinical and research perspective

Placebo and nocebo responses fascinate, confuse, mystify and challenge. They are genuine social, cultural and psychobiological phenomena which can significantly modify the overall treatment outcome. The placebo-nocebo phenomenon represents a very good model for our better understanding the role of treatment context and how the words, indices, symbols and icons act on our brains. Placebo response is associated with reward expectancy and relief of anticipatory anxiety, while nocebo response is related to lack of reward/positive expectancy and to increase of anticipatory anxiety. Placebo-nocebo responses are mediated through changes in various cortico-subcortical networks and psychophysiological systems. In spite of many existing complementary theories and still growing research on placebo and nocebo response, the implementation of our current knowledge to benefit basic research, clinical trials and routine clinical practice is still so scarce.