Catechol-O-methyltransferase Val158Met polymorphism is associated with somatosensory amplification and nocebo responses

Nocebo expectations rather than placebo expectations affect topical pain relief: A randomized clinical trial

Patients' expectations and beliefs regarding the potential benefits and harms of medical interventions may induce placebo and nocebo effects, and affect the response to pain therapies. In a randomized clinical trial, we examined the effect of placebo and nocebo expectations on pain relief and adverse events (AEs) in association with a topical treatment among 65 cancer survivors experiencing chronic musculoskeletal pain. Participants received either a 1% camphor-based topical pain patch or a placebo treatment for 14 days. We measured pain severity with the worst pain item of the Brief Pain Inventory (BPI) at baseline and 14 days and treatment expectations at baseline with validated expectation questionnaires. We found that high vs. low nocebo expectations decreased pain severity improvements by 2.5 points (95% confidence interval [CI] -3.8 to -1.2; p<0.001) on a 0-10 numeric rating scale of the BPI and pain response rate by 42.7% (95% CI 0.2-0.6; p<0.001) at day 14, irrespective of placebo expectation status or treatment arms. Patients with high vs. low nocebo expectations in the true arm reported 22.4% more unwanted AEs. High nocebo expectations were associated with increased AEs by 39.5% (odds ratio: 12.0, 95% CI 1.2, 145.5; p=0.029) and decreased pain response in the true arm vs. placebo. Our study demonstrated that nocebo expectations, rather than placebo expectations, elevate the risk of AEs and compromise the effect of topical pain interventions. The findings raise the possibility that nocebo expectations may worsen somatic symptoms through heightening central pain amplification and should be further investigated.

Vague sensations. About the background and consequences of discordance between actual and perceived physiological changes

Empirical evidence consistently shows that discordance, also called dissociation or discrepancy, between actual physiological (mainly visceral) events and their perceived counterparts is substantial. On the one hand, we typically do not perceive actual visceral events occurring in our bodies; on the other hand, sometimes we do perceive bodily changes that do not really take place. This narrative review presents the available empirical findings on the discordance, and summarizes possible explanations that approach the phenomenon from the viewpoint of evolution, cognitive development, and predictive processing. Also, the role of top-down factors, such as expectations and experiences is discussed. Finally, practically relevant consequences of the discordance are presented using the examples of mind-body practices, the placebo and nocebo phenomenon, and medically unexplained symptoms. It is concluded that the discordance between actual and perceived body changes can have a negative impact on health, mainly through issues with adherence and other behavioral factors. The existence of actual-perceived discordance should be taught and demonstrated in the elementary and high school, as well as in many areas of higher education.

The Nocebo Effect

Adverse nocebo responses can cause harm to patients and interfere with treatment adherence and effects in both clinic practice and clinical trials. Nocebo responses refer to negative outcomes to active medical treatments in clinical trials or practice that cannot be explained by the treatment's pharmacologic effects. Negative expectancies and nocebo effects are less known than placebo responses. Nocebo effects can be triggered by verbal suggestions, prior negative experiences, observation of others experiencing negative outcomes, and other contextual and environmental factors. As research advances over the years, mechanistic knowledge is accumulating on the neurobiological mechanisms of nocebo effects. This review summarizes studies on different facets of nocebo effects and responses and discusses clinical implications, ethical considerations, and future directions.

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

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

The influence of psychological traits and prior experience on treatment expectations

BACKGROUND

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

METHODS

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

RESULTS

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

DISCUSSION

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

Expectations and Prior Experiences Associated With Adverse Effects of COVID-19 Vaccination

Importance

Uptake of vaccination against COVID-19 is strongly affected by concerns about adverse effects. Research on nocebo effects suggests that these concerns can amplify symptom burden.

Objective

To investigate whether positive and negative expectations prior to COVID-19 vaccination are associated with systemic adverse effects.

Design, Setting, and Participants

This prospective cohort study analyzed the association of expected benefits and risks of vaccination, adverse effects at first vaccination, and observed adverse effects in close contacts with severity of systemic adverse effects among adults receiving a second dose of messenger RNA (mRNA)-based vaccines between August 16 and 28, 2021. A total of 7771 individuals receiving the second dose at a state vaccination center in Hamburg, Germany, were invited to participate; of these, 5370 did not respond, 535 provided incomplete information, and 188 were excluded retrospectively. The mobile application m-Path was used for data collection.

Main Outcomes and Measures

Primary outcome was a composite severity index of systemic adverse effects in 12 symptom areas measured once daily with an electronic symptom diary over 7 consecutive days. Data were analyzed by mixed-effects multivariable ordered logistic regression adjusted for prevaccine symptom levels and observation times.

Results

A total of 10 447 observations from 1678 individuals receiving vaccinations (BNT162b2 [Pfizer BioNTech] in 1297 [77.3%] and mRNA-1273 [Moderna] in 381 [22.7%]) were collected. The participants' median age was 34 (IQR, 27-44) years, and 862 (51.4%) were women. The risk for more severe adverse effects was higher for persons expecting a lower benefit of vaccination (odds ratio [OR] for higher expectations, 0.72 [95% CI, 0.63-0.83]; P < .001), expecting higher adverse effects of vaccination (OR, 1.39 [95% CI, 1.23-1.58]; P < .001), having experienced higher symptom burden at the first vaccination (OR, 1.60 [95% CI, 1.42-1.82]; P < .001), scoring higher on the Somatosensory Amplification Scale (OR, 1.21 [95% CI, 1.06-1.38]; P = .004), and if the vaccine mRNA-1273 was given rather than BNT162b2 (OR, 2.45 [95% CI, 2.01-2.99]; P < .001). No associations were seen for observed experiences.

Conclusions and Relevance

In this cohort study, several nocebo effects occurred in the first week after COVID-19 vaccination. The severity of systemic adverse effects was associated not only with vaccine-specific reactogenicity but also more negative prior experiences with adverse effects from the first COVID-19 vaccination, more negative expectations regarding vaccination, and tendency to catastrophize instead of normalize benign bodily sensations. Clinician-patient interactions and public vaccine campaigns may both benefit from these insights by optimizing and contextualizing information provided about COVID-19 vaccines.

The beneficial effect of positive treatment expectations on pharmacological migraine prophylaxis

ABSTRACT

Migraine is one of the leading causes of years lived with disability and considered to be a major global health concern. Pharmacological preventive treatment often causes side effects that limit the adherence to longer-term treatment regimens. Both experimental and clinical evidence suggests that positive expectations can modulate pain and analgesic treatment effects. However, the role of expectations in migraine prophylactic treatment has not systematically been investigated. Here, we examined the influence of treatment expectation before commencing pharmacological preventive treatment on its efficacy and tolerability in N = 134 episodic (30%) and chronic migraine (70%) patients in a prospective, longitudinal observational study over the course of 6 months. The migraine prophylaxis reduced the number of headache and migraine days with acceptable tolerability. Positive treatment expectation was associated with a generally lower number of headache and migraine days and a stronger reduction in headache days over the course of the treatment in chronic but not in episodic migraine patients. Moreover, patients with prior treatment showed a stronger reduction in headache days with higher expectation as compared to patients without prior experience. Our results underscore the relevance of further exploring the role of treatment expectation and its systematic modulation in patients with migraine and other pain conditions.

[Perioperative Pain Management - Patient Information, Informed Consent and Discharge Management]

Many surgical procedures are followed by postoperative pain. Acute pain should be treated optimally for medical and ethical reasons. Different psychological, physical, interventional and pharmacological methods are employed in a procedure specific and institution specific matter. For optimum patient care, implementation of acute pain management concepts in recommendations on quality management in German hospitals and outpatient clinics was enacted in September 2020 by Gemeinsamer Bundessausschuss (G-BA). Implementation of discharge management had already been enacted in 2017 for structured prescription of medication after hospital discharge, among other things. On the other hand, new national and international developments require a new weighting of pharmacotherapy in particular. Examples include debates on the safe use of metamizol and the opioid crisis in the US. To address these issues adjustments in informed consent and patient information and education are necessary. This includes also the information and education of caregivers. This article describes the legal framework, technical solutions and the impact of placebo and nocebo effects on doctor-patient communication.

Impact of a 12-week open-label placebo treatment on headache days in episodic and chronic migraine: a study protocol for a parallel-group, multicentre, randomised controlled trial

INTRODUCTION

Migraine is the most common neurological disorder and one of the major causes of years lived with disability. Its treatment (especially of chronic forms) is often challenging and accompanied with adverse effects. Although new therapeutic approaches have recently emerged (eg, calcitonin gene-related peptide antibodies), these are linked to strict prescribing guidelines and therefore limited to only a minority of patients. Recently, randomised controlled trials have demonstrated that open-label placebo treatments can lead to significant and clinically relevant improvements of chronic pain conditions.

METHODS AND ANALYSIS

This multicentre, randomised controlled clinical trial following a parallel group between-subject design aims to systematically investigate the impact of a 12-week open-label placebo treatment on moderate to severe headache days (primary outcome) in patients with episodic and chronic migraine in addition to treatment as usual. Secondary outcomes comprise the number of migraine days, pain intensity, intake of acute medication, quality of life, disability, global impression of change, tolerability and a responder rate. To systematically address potential predictors of placebo responses in patients with migraine, this study assesses potential psychometric predictors, salivary cortisol and alpha-amylase awakening responses, catechol-o-methyltransferase Val158Met polymorphisms, as well as functional and structural brain connectivity (ie, resting state functional MRI, diffusion tensor imaging). The data analysis will be performed on basis of the general linear model considering repeated measures (mixed model).

ETHICS AND DISSEMINATION

This protocol and all corresponding documents were approved with regard to their content and compliance with ethical regulations by the Ethics Committee of the Medical Faculty of the University Duisburg-Essen, Germany and the Ethics Committee of the Landesärztekammer Hessen. The results from this study will be actively disseminated through manuscript publications and conference presentations.

TRIAL REGISTRATION NUMBER

German Clinical Trials Register (DRKS00021259).

What Physiotherapists Specialized in Orthopedic Manual Therapy Know About Nocebo-Related Effects and Contextual Factors: Findings From a National Survey

Objective

The aim of this study was to investigate the knowledge of orthopedic manual therapists (OMTs) regarding context factors (CFs) capable of triggering nocebo effects during the treatment and how this knowledge is related to their socio-demographic features.

Design

A cross-sectional online survey.

Setting

National.

Main Outcome Measures

A 20 items questionnaire composed by open-ended and closed single-choice questions was administered to explore: (a) socio-demographic variables (10 questions); (b) the relation between different CFs and nocebo-related effects (2 questions); and (c) the knowledge of participants about nocebo-related effects and how they managed them in the clinical practice (8 questions).

Participants

1288 OMTs were recruited from the database of the Master in Rehabilitation of Musculoskeletal Disorders (MRDM) of the University of Genova from March to May 2019. Inclusion criteria were: (a) to possess a valid email account; (b) to understand and use as a native language the Italian; (c) to be graduated as OMTs; and (d) to be employed as physiotherapists specialized-OMTs during the survey.

Results

791 responses were received (61.4%); 473 of them were male (59.8%), with an average age of 31.0 ± 7.1 years. OMTs defined nocebo-related effects as the psychosocial context effects around therapy and patient with specific biological bases (72.2%). OMTs know that their clinical practice is pervaded by nocebo-related effects (42.5%), triggered by CFs. Participants communicated nocebo-related effects balancing the positive features of the therapy with the negative ones (50.9%), during the decision of the therapeutic plan (42.7%). They reported associative learning as the main mechanism involved in nocebo-related effects (28.8%). OMTs taught and trained patient’s strategies to manage nocebo-related effects (39.6%) through an evaluation and correction of patient’s anxieties, doubts and expectations (37.7%). OMTs most frequently considered themselves to have a “medium” education about nocebo-related effects (48.2%) and that their management should be taught during bachelor (78.6%).

Conclusion

OMTs believed that nocebo-related effects were present in their clinical practice and that they can be triggered by CFs.

Nocebo and lessebo effects

The power of placebos is commonly associated with the placebo effect. In contrast, detrimental effects related to the use of a placebo are little studied and less well recognized. This chapter covers the nocebo and lessebo effects defined, respectively, as expectation of harm in the form of adverse events in a placebo arm and reduction of therapeutic benefit due to the uncertainty of being allocated to placebo. The lessebo effect is a more recent concept and has been described only in depression, schizophrenia and Parkinson's disease. The nocebo response was evaluated in many neurological diseases, including epilepsy, multiple sclerosis, Parkinson's disease, Alzheimer's disease, restless leg syndrome, among others. Meta-analyses of randomized controlled trials in these conditions reveal a significant variability of the magnitude of the nocebo response and that factors related to study design, study participants or neurological disease can be associated with a nocebo response, although with the opposing findings across conditions. The knowledge about neurobiological mechanisms of the nocebo effect is poor for neurological diseases, and most of the information has been generated in pain. Functional neuroimaging suggests the existence of a distinct network for the anticipation and the experience of a hyperalgesia nocebo response. Different types of neurotransmitters have been involved, including cholecystokinin, dopamine and opioids. Recognizing the potential impact of nocebo and lessebo effects, mitigating strategies are in development with application to clinical research and clinical practice, such as a contextualized informed consent process, alternative study designs and enhancement of patient-physician communication.

MTX intolerance in children and adolescents with juvenile idiopathic arthritis

MTX is the medication most commonly used for antirheumatic treatment in juvenile idiopathic arthritis. It has high efficacy, is usually well tolerated and has an excellent safety profile. However, frequently intolerance symptoms develop that manifest as nausea, feelings of disgust or abdominal complaints prior to or directly after administration of the medication. No obvious toxicity is causing these intolerance symptoms, but symptoms are strictly limited to MTX and not transferred to other medications. MTX intolerance causes a significant reduction of quality of life in affected patients, frequently puts the treating physician in difficult situations regarding treatment choice, and may lead to uncomfortable decisions whether or not to stop an otherwise effective drug. Conventional countermeasures such as antiemetics, change of route from subcutaneous to oral or vice versa, or taste masking usually have only a limited effect. In this review, we present the current knowledge on MTX intolerance, its clinical picture and commonly employed strategies. We also consider newer behavioural treatment strategies that may offer a more effective symptom control.

Placebo effects and the molecular biological components involved

Pharmacologically inactive substances have been used in medicine for more than 700 years and can trigger beneficial responses in the human body, which is referred to as the placebo effects or placebo responses. This effect is robust enough to influence psychosocial and physiological responses to the placebo and to active treatments in many settings, which has led to increased interest from researchers. In this article, we summarise the history of placebo, the characteristics of placebo effects and recent advancements reported from the studies on placebo effects and highlight placebome studies to identify various molecular biological components associated with placebo effects. Although placebos have a long history, the placebome concept is still in its infancy. Although behavioural, neurobiological and genetic studies have identified that molecules in the dopamine, opioid, serotonin and endocannabinoid systems might be targets of the placebo effect, placebome studies with a no-treatment control (NTC) are necessary to identify whole-genome genetic targets. Although bioinformatics analysis has identified the molecular placebome module, placebome studies with NTCs are also required to validate the related findings.

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

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

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

[MTX intolerance in children and adolescents with juvenile idiopathic arthritis]

Methotrexate (MTX) is the medication most commonly used for antirheumatic treatment in juvenile idiopathic arthritis. It has high efficacy, is usually well tolerated and has an excellent safety profile. However, intolerance symptoms frequently develop, which manifest as nausea, feelings of disgust, or abdominal complaints prior to or directly after application of the medication. A direct side effect can usually be easily excluded; however, the symptoms are limited to treatment with MTX. This MTX intolerance causes a significant reduction in the quality of life of affected patients, frequently puts the treating physician in an uncomfortable situation, and not uncommonly results in discontinuation of treatment. Conventional countermeasures such as antiemetics, change of route from subcutaneous to oral or vice versa, or, for example, taste masking, usually have only limited effect. Newer behavioral treatment strategies raise hopes of more effective symptom control.

Systems pharmacogenomics - gene, disease, drug and placebo interactions: a case study in COMT

Disease, drugs and the placebos used as comparators are inextricably linked in the methodology of the double-blind, randomized controlled trial. Nonetheless, pharmacogenomics, the study of how individuals respond to drugs based on genetic substrate, focuses primarily on the link between genes and drugs, while the link between genes and disease is often overlooked and the link between genes and placebos is largely ignored. Herein, we use the example of the enzyme catechol-O-methyltransferase to examine the hypothesis that genes can function as pharmacogenomic hubs across system-wide regulatory processes that, if perturbed in andomized controlled trials, can have primary and combinatorial effects on drug and placebo responses.

Psychobiological Mechanisms of Placebo and Nocebo Effects: Pathways to Improve Treatments and Reduce Side Effects

Placebo effects constitute a major part of treatment success in medical interventions. The nocebo effect also has a major impact, as it accounts for a significant proportion of the reported side effects for many treatments. Historically, clinical trials have aimed to reduce placebo effects; however, currently, there is interest in optimizing placebo effects to improve existing treatments and in examining ways to minimize nocebo effects to improve clinical outcome. To achieve these aims, a better understanding of the psychological and neurobiological mechanisms of the placebo and nocebo response is required. This review discusses the impact of the placebo and nocebo response in health care. We also examine the mechanisms involved in the placebo and nocebo effects, including the central mechanism of expectations. Finally, we examine ways to enhance placebo effects and reduce the impact of the nocebo response in clinical practice and suggest areas for future research.

Are Adverse Events Induced by the Acute Administration of Calcineurin Inhibitor Cyclosporine A Behaviorally Conditioned in Healthy Male Volunteers?

PURPOSE

The learned immunosuppressive placebo response has been demonstrated in experimental animals, healthy humans, and patients, and is suggested as a therapy for improving immunopharmacologic treatment. It remains unclear, however, whether potential adverse events induced by the drug are also behaviorally conditioned. Employing an established taste-immune learning paradigm in healthy humans using the calcineurin inhibitor and immunosuppressive drug cyclosporine A (CsA) as an unconditioned stimulus, we investigated whether and to what extent perceived adverse events induced by acute CsA administration are behaviorally conditioned.

METHODS

A total of 68 healthy male subjects were exposed to the established taste-immune learning paradigm, receiving either placebo or CsA (10 mg/kg) as an unconditioned stimulus, and a novel-tasting drink as a conditioned stimulus.

FINDINGS

Subjects repeatedly receiving CsA during acquisition reported significantly more adverse events than did placebo-receiving subjects. However, during reexposure to the conditioned stimulus, the reported adverse events did not differ from those in the placebo control condition.

IMPLICATIONS

These data indicate that acute adverse events are not behaviorally conditioned during the learned immunosuppressive response. Our results further strengthen the great potential clinical relevance of employing the learned immunosuppressive placebo response as a therapy to support immunopharmacologic regimens, ultimately aiming to reduce the medical dosages required, thereby minimizing adverse drug events while maximizing the therapeutic benefit in patients. German Clinical Trial Register (www.drks.de) identifier: DRKS00007693.

COMT Val158Met Polymorphism and Symptom Improvement Following a Cognitively Focused Intervention for Irritable Bowel Syndrome

BACKGROUND

Our nurse-delivered comprehensive self-management (CSM) program, a cognitive behavioral therapy intervention, is effective in reducing gastrointestinal and psychological distress symptoms in patients with irritable bowel syndrome (IBS). Findings from non-IBS studies indicate that the catechol-O-methyltransferase (COMT) Val158Met polymorphism may moderate the efficacy of cognitive behavioral therapy. It is unknown whether this COMT polymorphism is associated with symptom improvements in patients with IBS.

OBJECTIVE

We tested whether this COMT Val158Met polymorphism influences the efficacy of our 2-month CSM intervention.

METHODS

We analyzed data from two published randomized controlled trials of CSM. The combined European American sample included 149 women and 23 men with IBS (CSM, n = 111; usual care [UC], n = 61). The primary outcomes were daily reports of abdominal pain, depression, anxiety, and feeling stressed measured 3 and 6 months after randomization. Secondary outcomes were additional daily symptoms, retrospective psychological distress, IBS quality of life, and cognitive beliefs about IBS. The interaction between COMT Val158Met polymorphism and treatment group (CSM vs. UC) in a generalized estimating equation model tested the main objective.

RESULTS

At 3 months, participants with at least one Val allele benefited more from CSM than did those with the Met/Met genotype (p = .01 for anxiety and feeling stressed, and p < .16 for abdominal pain and depression). The moderating effect of genotype was weaker at 6 months.

DISCUSSION

Persons with at least one Val allele may benefit more from CSM than those homozygous for the Met allele. Future studies with larger and more racially diverse samples are needed to confirm these findings.

RCT REGISTRATION

Parent studies were registered at ClinicalTrials.gov (NCT00167635 and NCT00907790).

Nocebo and pain: An overview of the psychoneurobiological mechanisms

INTRODUCTION

Nocebo effects are defined as adverse events related to negative expectations and learning processes that are involved in the modulation of the descending pain pathways. Research over the last couple of decades has illustrated that behavioral, psychoneurobiological and functional changes occur during nocebo-induced pain processing.

OBJECTIVES

We aimed to review published human and non-human research on algesia and hyperalgesia resulting from negative expectations and nocebo effects.

METHODS

Herein, we searched and comprehensively reviewed scientific literature providing informative knowledge about the psychoneurobiological bases of the nocebo effect in the field of pain with an emphasis on how pain processes are shaped by both cognitive and non-cognitive factors.

RESULTS

Negative expectations are formed through verbal suggestions of heightened pain, prior nociceptive and painful experiences and observation of pain in others. Susceptibility to the nocebo effect can be also influenced by genetic variants, conscious and nonconscious learning processes, personality traits and psychological factors. Moreover, providers' behaviors, environmental cues and the appearance of medical devices can induce negative expectations that dramatically influence pain perception and processing in a variety of pain modalities and patient populations.

CONCLUSION

Importantly, we concluded that nocebo studies outline how individual expectations may lead to physiological changes underpinning the central integration and processing of magnified pain signaling. Further research is needed to develop strategies that can identify nocebo-vulnerable pain patients in order to optimize the psychosocial and therapeutic context in which the clinical encounter occurs, with the ultimate purpose of improving clinical outcomes.

Can Psychological Expectation Models Be Adapted for Placebo Research?

Placebo responses contribute substantially to the effect and clinical outcome of medical treatments. Patients' expectations have been identified as one of the major mechanisms contributing to placebo effects. However, to date a general theoretical framework to better understand how patient expectations interact with features of medical treatment has not been developed. In this paper we outline an expectation model that can be used as framework for experimental studies on both placebo and nocebo mechanisms. This model is based on psychological concepts of expectation development, expectation maintenance, and expectation change within the typical paradigms used in placebo research. This theoretical framework reflects the dynamic aspects of the interaction between expectations and medical treatment, and offers a platform to combine psychological and neurophysiological research activities. Moreover, this model can be used to identify important future research questions. For example, we argue that the dynamic processes of expectation maintenance vs. expectation changes are not sufficiently addressed in current research on placebo mechanisms. Therefore, the question about how to change and optimize patients' expectations prior to treatment should be a special focus of future clinical research.

Placebo, nocebo, and neuropathic pain

Over the last decade, the apparent increase in placebo responses in randomized controlled trials (RCTs) of neuropathic pain have complicated and potentially limited development and availability of new effective pain medication. Placebo analgesia and nocebo hyperalgesia effects are well described in nociceptive and idiopathic pain conditions, but less is known about the magnitude and mechanisms of placebo and nocebo effects in neuropathic pain. In neuropathic pain, placebo treatments have primarily been used as control conditions for active agents under investigation in RCTs and these placebo responses are typically not controlled for the natural history of pain and other confounding factors. Recently, mechanistic studies that control for the natural history of pain have investigated placebo and nocebo effects in neuropathic pain in their own right. Large placebo analgesia but no nocebo hyperalgesic effects have been found, and the underlying mechanisms are beginning to be elucidated. Here we review placebo and nocebo effects and the underlying mechanisms in neuropathic pain and compare them with those of nociceptive and idiopathic pain. This allows for a novel discussion on how knowledge of psychological, neurobiological, and genetic factors underlying well-controlled placebo effects may help improve the information that can be obtained from and potentially restore the utility of RCTs.

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.

Somatosensory Amplification Is a Predictor of Self-Reported Side Effects in the Treatment of Primary Hypertension: a Pilot Study

PURPOSE

Side effects consist of drug-specific and non-specific symptoms. Both components are based on bodily sensations that a person perceives after taking a drug and subsequently attributes to the drug. We suggest that somatosensory amplification (SSA) may explain a proportion of inter-individual differences in reports of side effects that cannot be accounted for by drug-specific safety profiles. This hypothesis was investigated in hypertensive patients starting a new pharmacotherapy.

METHOD

This longitudinal study included 50 patients (66 % women, aged 55 ± 14 years) with a diagnosis of primary hypertension. Patients completed the Somatosensory Amplification Scale (SSAS), started to take their new medication, and recorded side effects on a daily basis for 4 weeks.

RESULTS

After controlling for age, gender, number of pills taken, and previous personal and family experiences with medication side effects in the regression analyses, SSAS scores remained a significant predictor of reported side effects over the entire study period (weeks 1 and 2: β = .621, p < .001; weeks 3 and 4: β = .493, p = .003). In a subsample comprising patients taking the four most commonly used drug regimes, SSAS was a significant predictor of side effects, even when controlling for type of medication.

CONCLUSION

In this sample of patients undergoing anti-hypertensive pharmacotherapy, higher SSA scores predicted increased reports of medication side effects. To account for this tendency and to improve compliance with medication regimes, this group may require special education about the nocebo phenomenon.

The role of placebo in the diagnosis and treatment of functional neurologic disorders

Placebo therapy can produce meaningful, clinical relief for a variety of conditions. While placebos are not without their ethically fraught history, they continue to be used, largely covertly, even today. Because the prognosis for psychogenic disorders is often poor and recovery may be highly dependent on the patient's belief in the diagnosis and treatment regimen, some physicians find placebo therapy for psychogenic disorders compelling, but also particularly contentious. Yet placebos also have a long tradition of being used for provocative diagnosis (wherein placebo is used to elicit and/or terminate the symptoms as a way of diagnosing symptoms as "psychogenic"). In this chapter we discuss cases describing placebo as therapy for psychogenic disorders and the challenges related to embedded Cartesian beliefs in Western medicine. The legitimate ethical reservations against placebo therapy, in general, have been related to assumptions about their "inertness" and a requirement for deception, both which are being refuted by emerging data. In this chapter, we also re-evaluate the concerns associated with placebo therapy for psychogenic disorders by asking, "Are we harming patients by withholding placebo treatment?"

Is somatosensory amplification a risk factor for an increased report of side effects? Reference data from the German general population

OBJECTIVE

The study investigates the association between somatosensory amplification and the reporting of side effects. It establishes a German version of the Somatosensory Amplification Scale and examines its psychometric properties in a representative sample of the German population.

METHODS

Sample size was 2.469, with 51% taking any medication. Participants answered the Somatosensory Amplification Scale, Generic Assessment of Side Effects Scale, and indicated whether they were taking any medication and the type of medication. Correlational analysis and binary logistic regression were performed.

RESULTS

When examining a subsample reporting both medication intake and general bodily symptoms, participants higher in somatosensory amplification rated more of their general bodily symptoms as medication-attributed side effects. However, somatosensory amplification scores were not associated with the intake of any type of medication. In the overall sample, higher somatosensory amplification scores were associated with an increased report of bodily symptoms. Additionally, participants with higher somatosensory amplification reported intake of a greater number of different medications. The psychometric properties of the translated scale were good, and previously established associations of somatosensory amplification with demographic variables (age, sex) were replicated.

CONCLUSION

Results suggest a possible attributional bias concomitant to somatosensory amplification which in turn may increase the reporting of side effects after medication intake.

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.

The many faces of somatosensory amplification: The relative contribution of body awareness, symptom labeling, and anxiety

The questionnaire study aimed to evaluate the relative contribution of body awareness, subjective symptoms, and anxiety to the construct of somatosensory amplification in both healthy controls (n = 475) and patients visiting their general practitioner (n = 236). Regression analysis explained 52.0 percent of total variance of the somatosensory amplification scale scores. Body awareness was the most influential predictor (β = 0.489, p < 0.001) when considering all predictors simultaneously. The results suggest that dispositional interoceptive focus, as indicated by body awareness, may be an important aspect of somatosensory amplification, over and above dispositional anxiety or subjective symptom report.

Genetics and the placebo effect: the placebome

Placebos are indispensable controls in randomized clinical trials (RCTs), and placebo responses significantly contribute to routine clinical outcomes. Recent neurophysiological studies reveal neurotransmitter pathways that mediate placebo effects. Evidence that genetic variations in these pathways can modify placebo effects raises the possibility of using genetic screening to identify placebo responders and thereby increase RCT efficacy and improve therapeutic care. Furthermore, the possibility of interaction between placebo and drug molecular pathways warrants consideration in RCT design. The study of genomic effects on placebo response, 'the placebome', is in its infancy. Here, we review evidence from placebo studies and RCTs to identify putative genes in the placebome, examine evidence for placebo-drug interactions, and discuss implications for RCTs and clinical care.

Conscientiousness is modified by genetic variation in catechol-O-methyltransferase to reduce symptom complaints in IBS patients

BACKGROUND

Attention to and perception of physical sensations and somatic states can significantly influence reporting of complaints and symptoms in the context of clinical care and randomized trials. Although anxiety and high neuroticism are known to increase the frequency and severity of complaints, it is not known if other personality dimensions or genes associated with cognitive function or sympathetic tone can influence complaints. Genetic variation in catechol-O-methyltransferase (COMT) is associated with anxiety, personality, pain, and response to placebo treatment. We hypothesized that the association of complaint reporting with personality might be modified by variation in the COMT val158met genotype.

METHODS

We administered a standard 25-item complaint survey weekly over 3-weeks to a convenience sample of 187 irritable bowel syndrome patients enrolled in a placebo intervention trial and conducted a repeated measures analysis.

RESULTS

We found that complaint severity rating, our primary outcome, was negatively associated with the personality measures of conscientiousness (β = -0.31 SE 0.11, P = 0.003) and agreeableness (β = -0.38 SE 0.12, P = 0.002) and was positively associated with neuroticism (β = 0.24 SE 0.09, P = 0.005) and anxiety (β = 0.48 SE 0.09, P < 0.0001). We also found a significant interaction effect of COMT met alleles (β = -32.5 SE 14.1, P = 0.021). in patients genotyped for COMT val158met (N  = 87) specifically COMT × conscientiousness (β = 0.73 SE 0.26, P = 0.0042) and COMT × anxiety (β = -0.42 SE 0.16, P = 0.0078) interaction effects.

CONCLUSION

These findings potentially broaden our understanding of the factors underlying clinical complaints to include the personality dimension of conscientiousness and its modification by COMT.

Nocebo effect in randomized clinical trials of antidepressants in children and adolescents: systematic review and meta-analysis

OBJECTIVE

To compare the incidence of adverse events between active and placebo arms of randomized clinical trials in depressive children and adolescents (C&A) with antidepressant treatments, in order to look for similarities in both groups that allow to establish a possible nocebo effect.

METHODS

Systematic search strategy (January 1974-March 2013) in electronic databases, conference abstracts, and reference list of systematic reviews and included studies to identify parallel randomized placebo-controlled trials of antidepressants in C&A (<19 years) with major depressive disorder, and one or more interventions of any orally administered antidepressant. The pooled adverse events were calculated based on a fixed-effect model and statistical analysis involved the risk ratio (RR) of adverse events, with 95% confidence intervals (95% CI).

RESULTS

Sixteen studies were included in the review, of which seven studies with a sample of 1911 patients had data to include in the meta-analysis. There was similar risk for the incidence of adverse events between non-active and active group (global RR 1.04, 95% CI: 0.97-1.11).

CONCLUSION

Depressive C&A allocated to placebo or active group had similar risk to develop adverse events. These similarities in both groups are attributed to the nocebo effect. It is of note that defining "nocebo" effects is challenging in clinical populations because adverse effects may be attributed to the intervention or may be manifestation of the disease itself. The inclusion of a no-treatment arm may be warranted. Nocebo effects are likely when adverse events of placebo mimic the adverse events of active treatment, as was the case here.