Effects of suggestion and conditioning on the action of chemical agents in human subjects; the pharmacology of placebos

A Fictionalist Account of Open-Label Placebo

The placebo effect is now generally defined widely as an individual's response to the psychosocial context of a clinical treatment, as distinct from the treatment's characteristic physiological effects. Some researchers, however, argue that such a wide definition leads to confusion and misleading implications. In response, they propose a narrow definition restricted to the therapeutic effects of deliberate placebo treatments. Within the framework of modern medicine, such a scope currently leaves one viable placebo treatment paradigm: the non-deceptive and non-concealed administration of "placebo pills" or open-label placebo (OLP) treatment. In this paper, I consider how the placebo effect occurs in OLP. I argue that a traditional, belief-based account of OLP is paradoxical. Instead, I propose an account based on the non-doxastic attitude of pretence, understood within a fictionalist framework.

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

OBJECTIVE

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

DATA SOURCES

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

STUDY SELECTION

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

DATA EXTRACTION

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

RESULTS

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

CONCLUSION

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

SYSTEMATIC REVIEW REGISTRATION NUMBER

PROSPERO, CRD42019125979.

HOW DO THEY ADD UP? THE INTERACTION BETWEEN THE PLACEBO AND TREATMENT EFFECT: A SYSTEMATIC REVIEW

Aim

The placebo effect and the specific effect are often thought to add up (additive model). Whether additivity holds can dramatically influence the external validity of a trial. This assumption of additivity was tested by Kleijnen et al in 1994 but the data produced since then have not been synthetized. In this review, we aimed to systematically review the literature to determine whether additivity held.

Methods

We searched Medline and PsychInfo up to 10 January 2019. Studies using the balanced placebo design (BPD), testing two different strengths of placebos, were included. The presence of interaction was evaluated by comparing each group in the BPD with analysis of variance or covariance.

Results

Thirty studies were included and the overall risk of bias was high: four found evidence of additivity and 16 studies found evidence of interaction (seven had evidence of positive additivity).

Conclusion

Evidence of additivity between placebo and specific features of treatments was rare in included studies. We suggest interventions for placebo‐sensitive ailments should be tested in trials designed to take interactions seriously once an exploratory RCTs has proven their efficacy with sufficient internal validity.

Rethinking Clinical Trials and Personalized Medicine with Placebogenomics and Placebo Dose

Pharmacogenomics, nutrigenomics, vaccinomics, and the nascent field of plant omics are examples of variability science. They are embedded within an overarching framework of personalized medicine. Across these public health specialties, the significance and biology of the placebo response have been historically neglected. A placebo is any substance such as a sugar pill administered in the guise of medication, but one that does not have pharmacological activity. Placebos do have clinical effects, however, that can be substantive in magnitude and vary markedly from person-to-person depending, for example, on the type of disease, symptoms, or clinical trial design. Research over the past several decades attests to a genuine neurobiological basis for placebo effects. All drugs have placebo components that contribute to their overall treatment effect. Placebos are used in clinical trials as control groups to ascertain the net pharmacological effect of a drug candidate. Not only less well known but also relevant to rational therapeutics and personalized medicine is the nocebo. A nocebo effect occurs when an inert substance is administered in a context that induces negative expectations, worsening patients' symptoms. With the COVID-19 pandemic, there are high public expectations for new vaccines and medicines to end the contagion, while at the same time antiscience, post-truth, and antivaccine movements are worrisomely on the rise. These social movements, changes in public health cultures, and conditioned behavioral responses can trigger both placebo and nocebo effects. Hence, in clinical trials, forecasting and explaining placebo and nocebo variability are more important than ever for robust science and personalized health care. Against this overarching context, this article provides (1) a brief history of placebo and (2) a discussion on biology, mechanisms, and variability of placebo effects, and (3) discusses three emerging new concepts: placebogenomics, nocebogenomics, and augmented placebo, that is, the notion of a "placebo dose." We conclude with a roadmap for placebogenomics, its synergies with the nascent field of social pharmacology, and the ways in which a new taxonomy of drug and placebo variability can be anticipated in the next decade.

[The learned placebo response in the immune system]

The learned placebo response of the immune system is based on the mutual interaction between the brain and the immune system; both systems continually exchange information via humoral and neural communication pathways. This communication network enables the modification, i.e. suppression or stimulation, of peripheral immune functions by classical or Pavlov's conditioning. The present article provides an overview of the results of recent experimental animal studies, which also document the potential clinical relevance of learned immune responses. Learned immunological responses mediated by classical conditioning have also been demonstrated in humans. The knowledge gained from experimental data and clinical observations paves the way for a potential implementation of learned immune responses as supportive measures to standard immunopharmacological treatment strategies to reduce drug dosage as well as adverse side effects while simultaneously maximizing the therapeutic effect.

Better than nothing: A historical account of placebos and placebo effects from modern to contemporary medicine

Throughout the history of medicine, multiple conceptions of "placebo" and "placebo effect" have often co-existed across different domains, and today the meaning of these concepts is still disputed. Against this background, this chapter provides a succinct account of the key events in the history of the concepts of "placebo," "placebo control," and "placebo effect." The first section reconstructs the etymology of the term "placebo" and its first introduction in medicine. The next sections provide an account of how placebos have been employed in both medical practice and scientific research in modern medicine. Later sections trace the emergence of the concepts of "placebo control" and "placebo effect" in the first half of the 20th century, from the first empirical studies investigating the effects of placebos up to the publication of Beecher's landmark article "The Powerful Placebo." Finally, the last two sections review the varieties of randomized, placebo-controlled trials (RCTs) in the second half of the 20th century, and the subsequent wave of empirical studies that, starting from the 1970s, have investigated the psychological, pharmacological and neurobiological mechanisms of placebo effects.

Subjunctive medicine: A manifesto

Despite the manifest advantages of modern medicine, many aspects of the experience of illness and healing are not reducible to bodily dysfunction and its restoration. Clinicians and researchers now largely understand that medical practice needs to accommodate a dual aspectivity of the physical body and the lived body. This is increasingly operationalised through the framework of person-centred care, focussed on initiating, integrating, and safeguarding the partnership between the patient-as-person and the clinician-as-person, informed by a narrative perspective on selfhood. In this manifesto, we develop the narrative focus of person-centred care into an alternative framework for medical practice - subjunctive medicine - grounded in ritual efficacy and an explicit appeal to the imagination. We argue that the healing effects of a clinical encounter are reliant on the subjunctive co-construction of a temporary shared social world for a particular purpose. More explicit awareness of the subjunctive nature of the clinical encounter may expand clinicians' opportunities for healing, whilst fostering resilience. We further suggest that, to be fully actualised, subjunctive medicine requires a shift towards conscious appreciation of the nature of subjunctivity at the social level; a social reawakening to the power of the imagination in modern medicine.

Case report of instantaneous resolution of juvenile macular degeneration blindness after proximal intercessory prayer

An 18-year-old female lost the majority of her central vision over the course of three months in 1959. Medical records from 1960 indicate visual acuities (VA) of less than 20/400 for both eyes corresponding to legal blindness. On fundus examination of the eye there were dense yellowish-white areas of atrophy in each fovea and the individual was diagnosed with juvenile macular degeneration (JMD). In 1971, another examination recorded her uncorrected VA as finger counting on the right and hand motion on the left. She was diagnosed with macular degeneration (MD) and declared legally blind. In 1972, having been blind for over 12 years, the individual reportedly regained her vision instantaneously after receiving proximal-intercessory-prayer (PIP). Subsequent medical records document repeated substantial improvement; including uncorrected VA of 20/100 in each eye in 1974 and corrected VAs of 20/30 to 20/40 were recorded from 2001 to 2017. To date, her eyesight has remained intact for forty-seven years.

Pavlovian Conditioning of Immunological and Neuroendocrine Functions

The phenomenon of behaviorally conditioned immunological and neuroendocrine functions has been investigated for the past 100 yr. The observation that associative learning processes can modify peripheral immune functions was first reported and investigated by Ivan Petrovic Pavlov and his co-workers. Their work later fell into oblivion, also because so little was known about the immune system’s function and even less about the underlying mechanisms of how learning, a central nervous system activity, could affect peripheral immune responses. With the employment of a taste-avoidance paradigm in rats, this phenomenon was rediscovered 45 yr ago as one of the most fascinating examples of the reciprocal functional interaction between behavior, the brain, and peripheral immune functions, and it established psychoneuroimmunology as a new research field. Relying on growing knowledge about efferent and afferent communication pathways between the brain, neuroendocrine system, primary and secondary immune organs, and immunocompetent cells, experimental animal studies demonstrate that cellular and humoral immune and neuroendocrine functions can be modulated via associative learning protocols. These (from the classical perspective) learned immune responses are clinically relevant, since they affect the development and progression of immune-related diseases and, more importantly, are also inducible in humans. The increased knowledge about the neuropsychological machinery steering learning and memory processes together with recent insight into the mechanisms mediating placebo responses provide fascinating perspectives to exploit these learned immune and neuroendocrine responses as supportive therapies, the aim being to reduce the amount of medication required, diminishing unwanted drug side effects while maximizing the therapeutic effect for the patient’s benefit.

[Use of placebo in French hospitals: data from polyvalent medicine units]

A placebo drug is defined as a treatment without any specific pharmacological efficacy, that works when the patient thinks to receive an active treatment, through a psychological and physiological mechanism. This study aimed to evaluate the use of placebo in French hospitals, in Polyvalent Medicine units. A questionnaire comprising 15 items was sent to 372 units. The analysis of 153 responses was conducted from dynamic crosstabs in Excel and using the R software available online. The survey confirmed that the use of placebos in hospital is frequent, with nearly 2/3 of professionals answering the questionnaire declared to use it. The oral capsule is the most commonly used form. Placebo is mainly administered at night, in case of pain, insomnia or anxiety, to so-called "difficult" patients. Placebo is not always given after medical prescription. In most cases, patients are not informed that they receive a placebo. The majority of professionals believed in the placebo effect but considered to be insufficiently informed and trained in the use of placebo in current practice. Although the placebo effect is now demonstrated, ethical and legal considerations recommend placebo treatment only on medical prescription, with the prior information of the patient. The placebo could be used as complementary therapy to conventional treatment in the cases of this therapeutic effectiveness has been demonstrated. Professionals should be trained in the use of placebo in order to avoid nocebo effect and potentiate beneficial effects of placebo.

Placebo Effects in Psychotherapy: A Framework

The issue of placebo response and the extent of its effect on psychotherapy is complex for two specific reasons: i) Current standards for drug trials, e.g., true placebo interventions, double-blinding, cannot be applied to most psychotherapy techniques, and ii) some of the "nonspecific effects" in drug therapy have very specific effects in psychotherapy, such as the frequency and intensity of patient-therapist interaction. In addition, different psychotherapy approaches share many such specific effects (the "dodo bird verdict") and lack specificity with respect to therapy outcome. Here, we discuss the placebo effect in psychotherapy under four aspects: a) nonspecific factors shared with drug therapy (context factors); b) nonspecific factors shared among all psychotherapy traditions (common factors); c) specific placebo-controlled options with different psychotherapy modalities; and d) nonspecific control options for the specific placebo effect in psychotherapy. The resulting framework proposes that the exploration and enumeration of context factors, common factors, and specific factors contributes to the placebo effects in psychotherapy.

Response to Drugs and Psychiatry

Fashion is more deep-rooted than contemporary custom will allow, and the current enthusiasm for drug treatment in psychiatry is no evanescent fad. The Greeks made good use of the pharmacopœia, prescribing borage, buglosse, marigold, polypodie and epithyme for melancholy, more specifically recommending wormwood, centaury and pennyroll for the hypochondriac malady. Burton (a) discussing black hellebor, relates that its virtues were extolled by Galen, Pliny and Coelius Aurelianus, the mentally afflicted being sent to the Anticyrae, or to Phocis in Achaia to be purged, the plant growing there in abundance. Burton (b) describes how the Melangoga, or melancholy purging medicines, were classified as simple or compound, purging upwards or downwards. Asarum, brassivola, laurel, scilla, white hellebor, and antimony purged upwards, whereas polypodie, epithyme, black hellebor, lapis lazuli and aloes purged downwards. Sceptics throve then, no doubt, as they do now. Meryon (1861) mentions Asclepiades—dismissed by Pliny as an impudent quack, who contended that drugs injured the stomach and induced complaints more dangerous than those which they were intended to cure.

A Comparative Controlled Trial of Methotrimeprazine (“Veractil”) in Chronic Schizophrenia

Despite the good results reported in recent years in many cases of chronic schizophrenia following the use of tranquillizing drugs, there remains in mental hospitals a group of chronic and often deteriorated patients who have shown a strong resistance to all forms of treatment. In many such cases disturbances of behaviour are modified and sometimes controlled by such drugs as chlorpromazine and reserpine. Nevertheless, the overall situation is far from satisfactory and the search for more effective drugs continues.

Antipsychotic combinations in schizophrenia

In the treatment of resistant schizophrenia, a number of meta-analyses attempted to quantify the efficacy and tolerability of antipsychotic (AP) polypharmacy v. monotherapy with contradictory results. Recently, a systematic review and meta-analysis of randomised controlled trials investigated the efficacy and tolerability of AP combination v. monotherapy in schizophrenia. It included 31 studies: 21 double-blind (considered high-quality studies) and 10 open-label (considered low-quality studies). The meta-analysis showed that, overall, the combination of two APs was more effective than monotherapy in terms of symptom reduction (standardised mean difference (SMD) = -0.53, 95% confidence interval (CI) -0.87 to -0.19); however, this result was confirmed only in the subgroup of low-quality studies. Negative symptoms improved when combining a D2 antagonist with a D2 partial agonist (SMD = -0.41, 95% CI -0.79 to -0.03) both in double-blind and open-label studies. In the present commentary, the results of this systematic review are critically discussed in terms of their clinical and research implications.

The effect of blinding on estimates of mortality in randomised clinical trials of intensive care interventions: protocol for a systematic review and meta-analysis

INTRODUCTION

Evidence exists that unblinded randomised clinical trials (RCTs) overestimate intervention effects compared with blinded RCTs. It has been suggested that this is less pronounced for objective (ie, not subject to interpretation) outcome measures, including mortality. This may not apply in the intensive care unit (ICU), as most deaths are preceded by decisions to withhold or withdraw treatments. Lack of blinding of physicians in RCTs of ICU interventions may potentially influence the decision towards a higher threshold for discontinuing treatment in patients who receive the investigational treatment and/or a lower threshold for discontinuing treatment in patients who receive the comparator (control). This may have important implications for patients, caregivers, researchers and society. Accordingly, we aim to assess whether lack of blinding affects mortality effect estimates in RCTs of ICU interventions.

METHODS AND ANALYSIS

We will conduct a systematic review with meta-analyses and assess the effect of blinding versus no blinding on mortality effect estimates in RCTs of interventions used in adult ICU patients.We will systematically search the Cochrane Library for systematic reviews reporting mortality effect estimates of any intervention used in adult ICU patients which includes at least one RCT with 'low risk of bias' in the bias domains 'blinding of participants and personnel' and/or 'blinding of outcome assessment' and one RCT with 'unclear' or 'high risk of bias' in the same bias domain(s). For each intervention, we will compare summary mortality effect estimates in blinded versus unblinded trials.

ETHICS AND DISSEMINATION

This research does not require ethical approval as we will use summary data from trials already approved by relevant ethical institutions. We will report the results in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) statement and submit the final paper to an international peer-reviewed journal.

TRIAL REGISTRATION NUMBER

PROSPERO, registration number: CRD42017056212.

Different Disclosed Probabilities to Receive an Antiemetic Equally Decrease Subjective Symptoms in an Experimental Placebo Study: To Be or Not to Be Sure

PURPOSE

The purpose of this study was to examine whether the disclosed probability of receiving an antiemetic affects nausea.

METHODS

Forty-eight healthy participants (mean [SD] age, 26.8 [5.4] years; 50% female) were exposed to 5 × 2 minutes of nauseogenic body rotations on 2 days. On day 2, participants were randomized to 3 experimental groups that were given different instructions concerning the probability of receiving an antiemetic remedy (100%, 50%, or 0% probability), whereas all received an inert substance. Subjective symptoms, behavioral (rotation tolerance) measures, and physiologic (electrogastrogram) measures of nausea were assessed and mediator and moderator analyses performed for effects of expectations and psychological characteristics on outcomes.

FINDINGS

Disclosed probabilities of both 100% and 50% significantly reduced subjective symptoms of nausea in an equal manner compared with the 0% probability group from day 1 to day 2. This effect was found for neither rotation tolerance nor myoelectric gastric activity. Expectations and psychological characteristics did not affect the results found. Post hoc analyses revealed that women only seem to be susceptible to this placebo effect.

IMPLICATIONS

Nausea is susceptible to placebo effects independent of the disclosed probability of receiving a drug and of explicit expectations. In line with placebo research, this effect is probably attributable to central mechanisms, and it is speculated that it could be related to the reward circuitry and social interactions.

Rational-Emotive Therapy: Research Data That Supports The Clinical and Personality Hypotheses of RET and Other Modes of Cognitive-Behavior Therapy

This article examines 32 important clinical and personality hypotheses of rational-emotive therapy (RET) and other modes of cognitive-behavior therapy and lists a large number of research studies that provide empirical confirmation of these hypotheses. It concludes that (1) a vast amount of research data exists, most of which tends to confirm the major clinical and personality hypotheses of RET; (2) this data keeps increasing by leaps and bounds; (3) RET hypotheses nicely lend themselves to experimental investigation and therefore encourage a considerable amount of research; (4) researchers have not yet tested some of the major RET formulations and could do so with profit to the field of psychotherapy and personality theory.

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.

The placebo effect: From concepts to genes

Despite its initial treatment as a nuisance variable, the placebo effect is now recognized as a powerful determinant of health across many different diseases and encounters. This is in light of some remarkable findings ranging from demonstrations that the placebo effect significantly modulates the response to active treatments in conditions such as pain, anxiety, Parkinson's disease, and some surgical procedures. Here, we review pioneering studies and recent advances in behavioral, neurobiological, and genetic influences on the placebo effect. Consistent with recent conceptualizations, the placebo effect is presented as the product of a general expectancy learning mechanism in which verbal, conditioned, and social cues are centrally integrated to change behaviors and outcomes. Examples of the integration of verbal and conditioned cues, such as instructed reversal of placebo effects are also incorporated into this model. We discuss neuroimaging studies that have identified key brain regions and modulatory mechanisms underlying placebo effects using well-established behavioral paradigms. Finally, we present a synthesis of recent genetics studies on the placebo effect, highlighting a promising link between genetic variants in the dopamine, opioid, serotonin, and endocannabinoid pathways and placebo responsiveness. Greater understanding of the behavioral, neurobiological, and genetic influences on the placebo effect is critical for evaluating medical interventions and may allow health professionals to tailor and personalize interventions in order to maximize treatment outcomes in clinical settings.

Placebo effects and their determinants in gastrointestinal disorders

Placebo effects in clinical trials have sparked an interest in the placebo phenomenon, both in randomized controlled trials (RCTs) and in experimental gastroenterology. RCTs have demonstrated similar short-term and long-term placebo response rates in gastrointestinal compared to other medical diagnoses. Most mediators and moderators of placebo effects in gastrointestinal diseases are also of similar type and size to other medical diagnoses and not specific for gastrointestinal diagnoses. Other characteristics such as an increase in the placebo response over time and the placebo-enhancing effects of unbalanced randomization were not seen, at least in IBS. Experimental placebo and nocebo studies underscore the 'power' of expectancies and conditioning processes in shaping gastrointestinal symptoms not only at the level of self-reports, but also within the brain and along the brain-gut axis. Brain imaging studies have redressed earlier criticism that placebo effects might merely reflect a response bias. These findings raise hope that sophisticated trials and experiments designed to boost positive expectations and minimize negative expectations could pave the way for a practical and ethically sound use of placebo knowledge in daily practice. Rather than focusing on a 'personalized' choice of drugs based on biomarkers or genes, it might be the doctor-patient communication that needs to be tailored.

Characteristics of women with nausea and vomiting of pregnancy who chose to continue compassionate use of placebo after a randomised trial

The placebo effect has not been characterised in pregnant women suffering from nausea and vomiting of pregnancy (NVP). Our aim was to characterise determinants of the placebo effect in women treated with placebo for NVP. We analysed data from a multicentre, double blind randomised controlled trial of Diclectin (delayed release doxylamine and pyridoxine) vs placebo for the treatment of NVP. A total of 127 women in the placebo arm and 130 in the active arm provided evaluable data for this analysis. Women who chose to continue placebo on a compassionate basis (n = 41) had significantly better improvement in symptoms of NVP and higher Wellbeing scores than those who did not ask to continue compassionate use. Results were similar in the active drug arm. The request to continue compassionate use of either placebo or active drug could be predicted by greater improvement in symptoms of NVP during the trial period.

Central nervous system influences in asthma

Asthma is a biomedical disorder whose presentation can be markedly influenced by neurological and psychological factors. This chapter describes several approaches that provide insight into the role of psychological factors and brain function in asthma. These include the study of placebo responses and recent explorations using functional neuroimaging during the onset of asthma symptoms. Although the specific mechanisms involved remain uncertain, we are gaining an appreciation for some of the neurocircuitry that is involved. The insula and ACC may modulate inflammatory processes by their influence on neuroendocrine responses to stress, including highly studied effects on the HPA axis and its physiologic responses. However much we have recently learned, it is clear that further study of this topic is critical to fully explicate the role of the brain in asthma.

Placebo responses on cardiovascular, gastrointestinal, and respiratory organ functions

It is widely acknowledged that placebo responses are accompanied by physiological changes in the central nervous system, but little is known about placebo responses on end organ functions. The present chapter aims to fill this gap by reviewing the literature on peripheral placebo responses. Overall, there is a wide range of placebo and nocebo responses on various organ functions of the cardiovascular, the gastrointestinal system, and the respiratory system. Most of these studies used expectation paradigms to elicit placebo and nocebo responses. Expectations can affect heart rate, blood pressure, coronary diameter, gastric motility, bowel motility, and lung function. Classical conditioning can induce placebo respiratory depression after prior exposure to opioid drugs, and habitual coffee drinkers show physiological arousal in response to coffee-associated stimuli. Similar to findings in placebo pain research, peripheral placebo responses can be target specific. The autonomic nervous system is a likely candidate to mediate peripheral placebo responses. Further studies are necessary to identify the brain mechanisms and pathways involved in peripheral placebo responses.

Antidepressant effects on serotonin 1A/1B receptors in the rat brain using a gene x environment model

A gene-environment (GxE) interaction is implicated in both the pathophysiology and treatment of major depressive disorder (MDD). This study modeled the effects of genetic vulnerability by using the Flinders sensitive line (FSL), a rat model of depression and its control counterpart-the Flinders resistant line (FRL). The effects of environmental vulnerability (e.g., early-life stress) were modeled by using maternal separation. Rats (n=105) were drawn from four groups reflecting experimental crossing of strain (FSL vs. FRL) and early-life stress (high vs. low) to assess the effects of two antidepressants (escitalopram or nortriptyline) compared to vehicle. Quantitative in vitro autoradiography was performed using [(125)I]MPPI (5-HT1A) and [(125)I]CYP (5-HT1B) in prefrontal cortex (PFC) and hippocampus. Stringent, Bonferroni-corrected statistical analyses showed significant strain-by-rearing-by-treatment (three-way) interactions in PFC 5-HT1A and hippocampal 5-HT1B receptors. Either vulnerability reduced serotonergic binding; no additive effects were associated with the two vulnerabilities. Both antidepressants increased hippocampal 5-HT1B receptor binding; however, only nortriptyline selectively increased PFC 5-HT1A receptor binding. Taken together, our findings demonstrate that antidepressant effects on the serotonergic system are shaped by a GxE interaction that depends on antidepressant class and brain region.

Placebos in 19th century medicine: a quantitative analysis of the BMJ

OBJECTIVE

To provide the first quantitative data on the use of the term "placebo" in the 19th century.

DESIGN

Computer search of BMJ's archival database from January 1840 (the first issue) through December 1899 for uses of the words "placebo(s)." Grounded theory was used to categorise the implications of uses of the term.

RESULTS

71 citations contained the term "placebo(s)." Of these, 22 (31%) used the term to mean "no effect" or as a general pejorative term, 18 (25%) portrayed placebo treatment as permitting the unfolding of the natural history (the normal waxing and waning of illness), 14 (20%) described placebo as important to satisfy patients, 7 (10%) described it as fulfilling a physician's performance role, 3 (4%) described its use to buy time, 3 (4%) described its use for financial gain, 2 (3%) used it in a manner similar to a placebo control, and only one implied that placebo could have a clinical effect. Only one citation mentioned telling the patient about his placebo treatment.

CONCLUSION

Nineteenth century physicians had diverse a priori assumptions about placebos. These findings remind us that contemporary medicine needs to use rigorous science to separate fact from its own beliefs concerning the "provision of care." As in previous generations, ethical issues concerning placebos continue to challenge medicine.

The placebo effect and the autonomic nervous system: evidence for an intimate relationship

For many subjectively experienced outcomes, such as pain and depression, rather large placebo effects have been reported. However, there is increasing evidence that placebo interventions also affect end-organ functions regulated by the autonomic nervous system (ANS). After discussing three psychological models for autonomic placebo effects, this article provides an anatomical framework of the autonomic system and then critically reviews the relevant placebo studies in the field, thereby focusing on gastrointestinal, cardiovascular and pulmonary functions. The findings indicate that several autonomic organ functions can indeed be altered by verbal suggestions delivered during placebo and nocebo interventions. In addition, three experimental studies provide evidence for organ-specific effects, in agreement with the current knowledge on the central control of the ANS. It is suggested that the placebo effects on autonomic organ functions are best explained by the model of 'implicit affordance', which assumes that placebo effects are dependent on 'lived experience' rather than on the conscious representation of expected outcomes. Nevertheless, more studies will be needed to further elucidate psychological and neurobiological pathways involved in autonomic placebo effects.

The placebo phenomenon and medical ethics: rethinking the relationship between informed consent and risk-benefit assessment

It has been presumed within bioethics that the benefits and risks of treatments can be assessed independently of information disclosure to patients as part of the informed consent process. Research on placebo and nocebo effects indicates that this is not true for symptomatic treatments. The benefits and risks that patients experience from symptomatic treatments can be shaped powerfully by information about these treatments provided by clinicians. In this paper we discuss the implications of placebo and nocebo research for risk-benefit assessment and informed consent.

Introduction to placebo effects in medicine: mechanisms and clinical implications

The field of placebo research has made considerable progress in the last years and it has become a major focus of interest. We know now that the placebo effect is a real neurobiological phenomenon and that the brain's 'inner pharmacy' is a critical determinant for the occurrence of psychobiological and behavioural changes relevant to healing processes and well-being. However, harnessing the advantages of placebo effects in healthcare is still a challenge. The first part of the theme issue summarizes and discusses the various kinds of placebo mechanisms across medical fields, thereby not only focusing on two main explanatory models-expectation and conditioning theory-but also taking into account empathy and social learning, emotion and motivation, spirituality and the healing ritual. The second part of the issue focuses on questions related to transferring knowledge from placebo research into clinical practice and discusses implications for the design and interpretation of clinical trials, for the therapeutic settings in daily patient care, and for future translational placebo research.

How placebo responses are formed: a learning perspective

Despite growing scientific interest in the placebo effect and increasing understanding of neurobiological mechanisms, theoretical conceptualization of the placebo effect remains poorly developed. Substantial mechanistic research on this phenomenon has proceeded with little guidance by any systematic theoretical paradigm. This review seeks to present a theoretical perspective on the formation of placebo responses. We focus on information processing, and argue that different kinds of learning along with individuals' genetic make-up evolved as the proximate cause for triggering behavioural and neural mechanisms that enable the formation of individual expectations and placebo responses. Conceptualizing the placebo effect in terms of learning offers the opportunity for facilitating scientific investigation with a significant impact on medical care.

[The placebo effect: general information and specificities in psychiatry (depression and schizophrenia)]

INTRODUCTION

Placebos, consequences of their use, the placebo effect and the associated negative effects, the nocebo effect, have been widely studied. However, the lack of any consensus definition makes the interpretation and analysis of such findings difficult.

LITERATURE FINDINGS

In this article, we will review existing definitions and factors affecting the placebo effect in medicine. We will then consider the possible mechanisms of action of the placebo effect, with a view to improving understanding of this issue. Finally, we will analyse data relating to placebos used in psychiatry and, more specifically, for schizophrenic patients. In an extensive review of the literature, we identified the various factors playing a role in the appearance of placebo effects in general medicine. As well as purely factual elements, such as the disorder, the sex of the subject and the treatment given, the placebo effect is strongly correlated with the quality of the relationship between the doctor and patient and with the capacity of the patient to communicate and establish a link. The attitude of the doctor, the temperament of the subject and the expectations and beliefs of each also contribute to the appearance and extent of a placebo effect. We then investigated placebo effects in psychiatry, particularly in depressed patients (the most widely studied condition) where studies have shown particular efficacy. We also addressed the use of placebos in schizophrenia: the placebo effect in patients with this disorder is essentially used as a tool for assessing new molecules to be released onto the market but the phenomenon itself has been little studied, if at all. Thus, it is of particular interest to consider in detail the use of placebos in schizophrenia, to try to gain a deeper understanding of the factors involved. This will allow potential specific effects associated with placebo use in this disorder to be established, improving the integration of placebos into therapy and to optimize the efficacy of treatment prescribed, taking into account mental state; indeed, the placebo effect is present in all treatments, whether involving a placebo or an active compound.

The "placebo" response in osteoarthritis and its implications for clinical practice

Many observations support a major biological effect from the way in which people interpret the meaning of each component of their medical experience and the context in which this occurs. A recent systematic review of randomised controlled trials in osteoarthritis has demonstrated that the effect size of "placebo" is substantial and is usually greater than that obtained from the specific effect of an individual treatment. In the context of a randomised controlled trial, such a large placebo or "meaning" response is considered a nuisance, but in the context of clinical practice the optimisation of such meaning and contextual responses, through enhanced "care", could greatly benefit people who suffer from osteoarthritis.

Acupressure bands are effective in reducing radiation therapy-related nausea

Previous studies have shown that acupressure bands can reduce chemotherapy-related nausea. Patients' expectations of efficacy account for part of this outcome. We conducted a three-arm randomized clinical trial to investigate the effectiveness of acupressure bands in controlling radiation therapy-induced nausea and to test whether an informational manipulation designed to increase expectation of efficacy would enhance the effectiveness of the acupressure bands. Patients who experienced nausea at prior treatments were randomized to either standard care (Arm 1, n=29) or standard care plus acupressure bands with either neutral (Arm 2, n=30) or positive (Arm 3, n=29) information regarding the efficacy of the bands. Patients reported nausea for two days prior to randomization (baseline) and for five days following using a seven-point semantic rating scale (1=not nauseated to 7=extremely nauseated). Patients in Arms 2 and 3 combined reported greater reduction in average nausea than patients in Arm 1 (P=0.01; mean(bands)=0.70, mean(no bands)=0.10). This equates to a 23.8% decrease in nausea in the band groups compared to a 4.8% decrease in the control group, a 19% difference. The informational manipulation failed to alter efficacy expectations and there was no statistically significant difference in nausea between patients in Arms 2 and 3. Acupressure bands are an effective, low-cost, nonintrusive, well-accepted, and safe adjunct to standard antiemetic medication. An attempt to boost the efficacy of the acupressure bands by providing positive information was not successful.

The placebo effect: illness and interpersonal healing

The placebo effect has been a source of fascination, irritation, and confusion within biomedicine over the past 60 years. Although scientific investigation has accelerated in the past decade, with particular attention to neurobiological mechanisms, there has been a dearth of attention to developing a general theory of the placebo effect. In this article, we attempt to address this gap. To set the stage, we review evidence relating to the reality and clinical significance of the placebo effect. Next we investigate the scope and limits of the placebo effect by examining the hypothesis that the placebo effect operates predominantly by modifying the experience and perceptions of illness symptoms, such as pain, anxiety, and fatigue, rather than by modifying the pathophysiology of disease. Based on this background, we characterize the placebo effect as a form of interpersonal healing, as distinct from spontaneous natural healing and from technological healing dependent on physiologically active pharmaceuticals or procedures. Finally, we argue that research on the placebo effect has the potential to revitalize the art of medicine.

Challenging received wisdom: antidepressants and the placebo effect

This article explores the reaction when an article challenging received wisdom is published and covered extensively by the media (1). The article in question was a meta-analysis of antidepressant clinical trials indicating that for most patients, difference between drug and placebo was not clinically significant. Reactions ranged from denial that the effects of antidepressants are so small to criticisms of the clinical trials that were analyzed. Each of these reactions is explored and countered.

Imaging the placebo response: a neurofunctional review

An emerging literature has started to document the neuronal changes associated with the placebo phenomenon. This has altered placebo from being considered a nuisance factor in clinical research to a target of scientific investigation per se. This paper reviews the neuroimaging literature on the placebo effect, and illustrates how imaging tools can improve current understanding of brain mechanisms underlying the placebo response. Imaging studies provide evidence of specific, predictable and replicable patterns of neural changes associated with placebo administration. In general, placebo responses seem mediated by "top-down" processes dependent on frontal cortical areas that generate and maintain cognitive expectancies. Dopaminergic reward pathways may underlie these expectancies. Placebo-induced clinical benefits also involve disorder-specific neuronal responses, yielding neurofunctional or neurochemical alterations similar to those produced by pharmacological treatments.

Expectations and associations that heal: Immunomodulatory placebo effects and its neurobiology

The use of placebo may have accompanied healing and medical practices since their origins (Plato; Charmides, 155-156). Recent experimental data indicate that we would be well advised to further consider placebo effects in future therapeutic strategies, with a better knowledge of their potency, psychological basis and underlying neurobiological mechanisms. Current research in the areas of pain, depression and Parkinson's disease has uncovered some of the potential neurobiological mechanisms of placebo effects. These data indicate that conscious expectation and unconscious behavioral conditioning processes appear to be the major neurobiological mechanisms capable of releasing endogenous neurotransmitters and/or neurohormones that mimic the expected or conditioned pharmacological effects. To date, research on placebo responses affecting immune-related diseases is scarce, but there are consistent indications that skin and mucosal inflammatory diseases, in particular, are strongly modulated by placebo treatments. However, the brain's capability to modulate peripheral immune reactivity has been impressively demonstrated by paradigms of behavioral conditioning in animal experiments and human studies. Thus, placebo effects can benefit end organ functioning and the overall health of the individual through positive expectations and behavioral conditioning processes.

The effects of manipulating expectations through placebo and nocebo administration on gastric tachyarrhythmia and motion-induced nausea

BACKGROUND

Interest in the role of expectation in the development of nausea and other adverse conditions has existed for decades. The purpose of this study was to examine the effects of manipulating expectations through the administration of placebos and nocebos on nausea and gastric tachyarrhythmia provoked by a rotating optokinetic drum.

METHOD

Seventy-five participants were assigned to one of three groups. Positive-expectancy group participants were given placebo pills that would allegedly protect them against the development of nausea and motion sickness. Negative-expectancy group participants were given the same pills as nocebos; they were led to believe there was a tendency for them to make nausea somewhat worse. Placebo-control group participants were told the pills were indeed placebos that would have no effect whatsoever.

RESULTS

Subjective symptoms of motion sickness were significantly lower among negative-expectancy group participants than positive-expectancy and placebo-control group participants (p<0.05). Gastric tachyarrhythmia, the abnormal stomach activity that frequently accompanies nausea, was also significantly lower among negative-expectancy group participants than positive-expectancy and Placebo-Control Group participants during drum rotation (p<.05) [corrected]

CONCLUSIONS

Inducing negative expectations through nocebo administration reduced nausea and gastric dysrhythmia during exposure to provocative motion, whereas positive placebos were ineffective for preventing symptom development. That manipulation of expectation affected gastric physiological responses as well as reports of symptoms, suggests an unspecified psychophysiological mechanism was responsible for the observed group differences. These results also suggest that patients preparing for difficult medical procedures may benefit most from being provided with detailed information about how unpleasant their condition may become.