Expectation and the placebo effect in Parkinson's disease patients with subthalamic nucleus deep brain stimulation

How Information Affects Patients with Parkinson's Disease: A Scoping Review of the Literature

Background

Patients with Parkinson's disease (PD) need to receive adequate information to manage their disease. However, little is known about how information provision affects patients.

Objective

To conduct a scoping review of the literature on the relationship between content, timing, manner of delivery, and source of PD-specific information on the one hand, and patient outcomes on the other.

Methods

All literature reporting about original data and published until April 2024 in peer-reviewed journals was searched in MEDLINE (Ovid), Embase (Ovid) and PsychInfo (Ovid). Subsequently, data were extracted and synthesized.

Results

40 publications describing the effects of information provision or patients' evaluation thereof were retrieved. Four categories of patient outcomes were described, namely 1) evaluation and experience of information provision; 2) physical functioning; 3) psychosocial well-being; and 4) quality of life. In intervention studies, patients generally valued the provided information. Findings from cross-sectional and qualitative studies showed the importance of tailoring information to individuals' needs and capabilities. Due to variation in study designs and outcomes, no unambiguous conclusions could be drawn regarding the relationship between information and outcomes.

Conclusions

This scoping review identified how PD patients acquire information and revealed a lack of systematic research into the effect of information on patient outcomes. Future studies should assess 1) what information is currently provided by clinicians; 2) what additional information might be beneficial to provide; and 3) how information can be effectively aligned to benefit patients. This will eventually yield insight into how information might optimally empower PD patients.

Effects of deep brain stimulation and verbal suggestions on pain in Parkinson's disease

BACKGROUND AND OBJECTIVES

In Parkinson's disease (PD) patients, verbal suggestions have been shown to modulate motor and clinical outcomes in treatment with subthalamic deep brain stimulation (DBS). Furthermore, DBS may alleviate pain in PD. However, it is unknown if verbal suggestions influence DBS' effects on pain.

METHODS

Twenty-four people with PD and DBS had stimulation downregulated (80-60 to 20%) and upregulated (from 20-60 to 80%) in a blinded manner on randomized test days: (1) with negative and positive suggestions of pain for down- and upregulation, respectively, and (2) with no suggestions to effect (control). Effects of DBS and verbal suggestions were assessed on ongoing and evoked pain (hypertonic saline injections) via 0-10 numerical rating scales along with motor symptoms, expectations, and blinding.

RESULTS

Stimulation did not influence ongoing and evoked pain but influenced motor symptoms in the expected direction. Baseline and experimental pain measures showed no patterns in degree of pain. There was a trend toward negative suggestions increasing pain and positive suggestions decreasing pain. Results show significant differences in identical stimulation with negative vs positive suggestions (60% conditions AUC 38.75 vs 23.32, t(13) = 3.10, p < 0.001). Expectations to pain had small to moderate effects on evoked pain. Patients estimated stimulation level correctly within 10 points.

CONCLUSION

Stimulation does not seem to influence ongoing and evoked pain, but verbal suggestions may influence pain levels. Patients appear to be unblinded to stimulation level which is an important consideration for future studies testing DBS in an attempted blind fashion.

Role of expectations in clinical outcomes after deep brain stimulation in patients with Parkinson's disease: a systematic review

Deep brain stimulation (DBS) is a well-established treatment that significantly improves the motor symptoms of patients with Parkinson's disease (PD); however, patients may experience post-operative psychological distress and social maladjustments. This phenomenon has been shown to be related to patients' pre-operative cognitive representations, such as expectations. In this systematic review, we discuss the findings on the role of the expectations of patients with PD regarding the clinical outcomes of DBS to identify areas of intervention to improve pre-operative patient education and promote successful post-operative psychosocial adjustment. PubMed was searched for relevant articles published up to 16 January 2023. Of the 84 identified records, 10 articles focusing on the treatment expectations of patients with PD undergoing DBS were included in this review. The selected studies were conducted among cohorts of patients with different DBS targets, among which the most common was the bilateral subthalamic nucleus. Overall, the data showed that patients' expectations contribute to treatment efficacy. Experiments investigating the placebo effect itself have shown clinical improvement after the induction of positive therapeutic expectations; conversely, unrealistic treatment expectations can affect patient satisfaction after surgery, clinical outcomes, and subjective well-being. This review highlights the need for routine clinical practice to better investigate and manage patients' pre-operative expectations, as well as multidisciplinary education to improve patient satisfaction and psychosocial adjustment after DBS.

Development and psychometric validation of the hospitalized patients' expectations for treatment scalepatient version

Objectives

A general expectation measurement of inpatients across wards is needed in the patient safety management systems of general hospitals. This study developed and psychometrically validated a new scale fulfilling the requirements above: the Hospitalized Patients' Expectations for Treatment Scale-Patient version (HOPE-P).

Methods

A total of 35 experts and ten inpatients were interviewed during the formulation of the HOPE-P scale, which was initially designed with three dimensions: doctor-patient communication expectations, treatment outcome expectations, and disease management expectancy. We recruited 210 inpatients from a general hospital in China and explored the reliability, validity, and psychometric characteristics of the questionnaire. Item analysis, construct validity, internal consistency and 7-day test-retest reliability analysis were applied.

Results

Exploratory and confirmatory analyses supported a 2-dimension (doctor-patient communication expectation and treatment outcome expectation) structure with satisfactory model fit parameters (root mean square residual (RMR) = 0.035, a root-mean-square-error of approximation (RMSEA) = 0.072, comparative fit index (CFI) = 0.984, Tucker-Lewis index (TLI) = 0.970). Item analysis revealed an appropriate item design (r = 0.573-0.820). The scale exhibited good internal consistency, with Cronbach's α of 0.893, 0.761, and 0.919 for the overall scale, the doctor-patient communication expectation subscale, and the treatment outcome expectation subscale, respectively. The 7-day test-retest reliability was 0.782 (p < .001).

Conclusion

Our results indicated that the HOPE-P is a reliable and valid assessment tool to measure the expectations of general hospital inpatients, with a strong capacity to recognize patients' expectations regarding doctor-patient communication and treatment outcomes.

Effects of Generic Exchange of Levodopa Medication in Patients With Parkinson Disease

OBJECTIVES

Generic exchange is common practice in most healthcare systems. This study investigated how patients with Parkinson disease (PD) perceived a switch of their levodopa medication and the resulting effects on their PD symptoms.

METHODS

A questionnaire was developed, piloted, and finally distributed to 13,857 members of the national PD patient support group. It was designed to be completed by patients and their pharmacies. χ 2 tests for independence statistics with or without Monte Carlo simulation were performed. Cramér φ and Cramér V were calculated. McNemar test was used to investigate whether a generic switch of a levodopa-containing medication had an impact on PD symptoms.

RESULTS

Analyses were done with 410 finalized respondents of 13,857 distributed questionnaires. More than half of the responders were 75 years or older and rated themselves Hoehn and Yahr stages 3 to 5. Most patients were confused by a change of their medication. A total of 54.7% of the switchers (n = 148) reported swallowing difficulties with medication, which was significantly more frequent than with nonswitchers (37.3% of 204, P = 0.001). Adverse effects related to the switch were reported by 26.6% of all switchers (switchback rate, 20.5%). The patients at higher Hoehn and Yahr stages were affected to a greater extend.

CONCLUSIONS

Patients, who experienced any brand switch of their levodopa medication, frequently expressed distrust and confusion. Swallowing difficulties and negative effects on their symptoms were problems, which were more pronounced in advanced disease stages. It remains unclear whether the detrimental impact on therapy was caused by the brand switch or by a nocebo effect.

Expectancy in placebo-controlled trials of psychedelics: if so, so what?

Modern psychedelic research remains in an early phase, and the eventual introduction of psychedelics into clinical practice remains in doubt. In this piece, we discuss the role of blinding and expectancy in psychedelic trials, and place this in a broader historical and contemporary context of blinding in trials across the rest of healthcare. We suggest that premature and uncritical promotion ('hype') of psychedelics as medicines is not only misleading, but also directly influences participant expectancy in ongoing psychedelic trials. We argue that although psychedelic trials are likely to significantly overestimate treatment effects by design due to unblinding and expectancy effects, this is not a unique situation. Placebo-controlled RCTs are not a perfect fit for all therapeutics, and problems in blinding should not automatically disqualify medications from licencing decisions. We suggest that simple practical measures may be (and indeed already are) taken in psychedelic trials to partially mitigate the effects of expectancy and unblinding, such as independent raters and active placebos. We briefly suggest other alternative trial methodologies which could be used to bolster RCT results, such as naturalistic studies. We conclude that the results of contemporary placebo-controlled RCTs of psychedelics should neither be dismissed due to imperfections in design, nor should early data be taken as firm evidence of effectiveness.

Parkinson's Disease Symptoms Associated with Developing On-State Axial Symptoms Early after Subthalamic Deep Brain Stimulation

Background: The relationship between axial symptoms in Parkinson’s disease (PD) and subthalamic deep brain stimulation (STN-DBS) is still unclear. Purpose: We searched for particular clinical characteristics before STN-DBS linked to on-state axial problems after surgery. Methods: We retrospectively analyzed baseline motor, emotional and cognitive features from PD patients with early axial symptoms (within 4 years after STN-DBS) and late axial symptoms (after 4 years). We also considered a group of PD patients without axial symptoms for at least 4 years after surgery. Results: At baseline, early-axial PD patients (n = 28) had a higher on-state Unified Parkinson’s Disease Rating Scale III (15.0 ± 5.6 to 11.6 ± 6.2, p = 0.020), higher axial score (2.4 ± 1.8 to 0.7 ± 1.0, p < 0.001) and worse dopaminergic response (0.62 ± 0.12 to 0.70 ± 0.11, p = 0.005), than non-axial PD patients (n = 51). Early-axial PD patients had short-term recall impairment, not seen in non-axial PD (36.3 ± 7.6 to 40.3 ± 9.3, p = 0.041). These variables were similar between late-axial PD (n = 18) and non-axial PD, but late-axial PD showed worse frontal dysfunction. Conclusions: PD patients with early axial symptoms after DBS may have a significantly worse presurgical motor phenotype, poorer dopaminergic response and memory impairment. This may correspond to a more severe form of PD.

Methodological Considerations for Setting Up Deep Brain Stimulation Studies for New Indications

Deep brain stimulation (DBS) is a neurosurgical treatment with a growing range of indications. The number of clinical studies is expanding because of DBS for new indications and efforts to improve DBS for existing indications. To date, various methods have been used to perform DBS studies. Designing a clinical intervention study with active implantable medical devices has specific challenges while expanding patient treatment. This paper provides an overview of the key aspects that are essential for setting up a DBS study.

The subthalamic nucleus and the placebo effect in Parkinson's disease

The study of the placebo effect, or response, is related to the investigation of the psychologic component of different therapeutic rituals. The high rate of placebo responses in Parkinson's disease clinical trials provided the impetus for investigating the underlying mechanisms. Ruling out spontaneous remission and regression to the mean through the appropriate experimental designs, genuine psychologic placebo effects have been identified, in which both patients' expectations of therapeutic benefit and learning processes are involved. Specifically, placebo effects are associated with dopamine release in the striatum and changes in neuronal activity in the subthalamic nucleus, substantia nigra pars reticulata, and motor thalamus in Parkinson's disease, as assessed through positron emission tomography and single-neuron recording during deep brain stimulation, respectively. Conversely, verbal suggestions of clinical worsening or drug dose reduction induce nocebo responses in Parkinson's disease, which have been detected at both behavioral and electrophysiologic level. Important implications and applications emerge from this new knowledge. These include better clinical trial designs, whereby patients' expectations should always be assessed, as well as better drug dosage in order to reduce drug intake.

A Deep Brain Stimulation Trial Period for Treating Chronic Pain

Early studies of deep brain stimulation (DBS) for various neurological disorders involved a temporary trial period where implanted electrodes were externalized, in which the electrical contacts exiting the patient's brain are connected to external stimulation equipment, so that stimulation efficacy could be determined before permanent implant. As the optimal brain target sites for various diseases (i.e., Parkinson's disease, essential tremor) became better established, such trial periods have fallen out of favor. However, deep brain stimulation trial periods are experiencing a modern resurgence for at least two reasons: (1) studies of newer indications such as depression or chronic pain aim to identify new targets and (2) a growing interest in adaptive DBS tools necessitates neurophysiological recordings, which are often done in the peri-surgical period. In this review, we consider the possible approaches, benefits, and risks of such inpatient trial periods with a specific focus on developing new DBS therapies for chronic pain.

Deep Brain Stimulation for Major Depression and Obsessive-Compulsive Disorder—Discontinuation of Ongoing Stimulation

Deep brain stimulation (DBS) is currently under research for the treatment of psychiatric disorders, e.g., obsessive-compulsive disorder (OCD) and treatment-resistant depression (TRD). Since the application of DBS in psychiatry has been in use for about 20 years, it is necessary to evaluate its long-term use now. A main issue in the long-term treatment of DBS concerns the effects of a discontinuation of stimulation due to intended as well as unintended reasons. In this contribution, the literature describing discontinuation effects following DBS in OCD and TRD is reviewed. Furthermore, a patient is reported in depth who experienced an unintended discontinuation of supero-lateral medial forebrain bundle (slMFB) DBS for TRD. In this case, the battery was fully depleted without the patient noticing. DBS had led to a sustained response for seven years before discontinuation of stimulation for just several weeks caused a progressive worsening of depression. Altogether, the rapid occurrence of symptom worsening, the absence of a notification about the stimulation status and the difficulties to recapture antidepressant response represent important safety aspects. For a further understanding of the described effects, time courses until worsening of depression as well as biological mechanisms need to be investigated in double-blind controlled trials.

Maximizing placebo response in neurological clinical practice

The placebo effect is a widely recognized phenomenon in clinical research, with a negative perception that it could hide the "true" drug effect. In clinical care its positive potential to increase known drug effects has been neglected for too long. The placebo and nocebo responses have been described in many neurologic disorders such as Parkinson's, Huntington's and Alzheimer's diseases, restless leg syndrome, tics, essential tremor, dystonia, functional movement disorders, neuropathic pain, headaches, migraine, amyotrophic lateral sclerosis, myasthenia gravis, chronic inflammatory demyelinating polyneuropathy, multiple sclerosis and epilepsy. Knowledge regarding placebo mechanisms and their consequences on clinical outcome have greatly improved over the last two decades. This evolution has led to reconsiderations of the importance of placebo response in the clinic and has given several clues on how to improve it in daily practice. In this chapter, we first illustrate "why," e.g. the reasons (relevance to clinical practice, help in differential diagnosis/treatment of psychogenic movements, clinical impact, proven neurobiological grounds, health economic potential), and "how," e.g. the means (increase patients' knowledge, increase learning, improve patient-doctor relationship, increase Hawthorne effect, increase positive/decrease negative expectations (the Rosenthal effect), personalize placebo response), the placebo should be maximized (and nocebo avoided) in neurological clinical practice. Future studies regarding more specific neurobiological mechanisms will allow a finer tuning of placebo response in clinical practice. The use of placebo in clinical practice raises ethical issues, and a recent expert consensus regarding placebo use in the clinic is a first step to future guidelines necessary to this field.

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.

Placebo effects in pain

Placebo effects influence symptom perceptions and treatment outcomes. Placebo effects can be explored in laboratory settings controlling for natural history and expectations. Such a mechanistic approach to neurological disorders has been implemented in the domain of chronic clinical pain and other neurological disorders. This article therefore focuses on definitions and historical notes related to placebo effects and mechanisms of placebo effects in chronic pain. Knowledge on mechanisms of placebo effects could inform current clinical practice for the treatment of neurological disorders by focusing on patients (and providers) expectations for outcome optimization.

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

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

The effects of deep-brain non-stimulation in severe obsessive-compulsive disorder: an individual patient data meta-analysis

Non-intervention-related effects have long been recognized in an array of medical interventions, to which surgical procedures like deep-brain stimulation are no exception. While the existence of placebo and micro-lesion effects has been convincingly demonstrated in DBS for major depression and Parkinson's disease, systematic investigations for obsessive-compulsive disorder (OCD) are currently lacking. We therefore undertook an individual patient data meta-analysis with the aim of quantifying the effect of DBS for severe, treatment-resistant OCD that is not due to the electrical stimulation of brain tissue. The MEDLINE/PubMed database was searched for double-blind, sham-controlled randomized clinical trials published in English between 1998 and 2018. Individual patient data was obtained from the original authors and combined in a meta-analysis. We assessed differences from baseline in obsessive-compulsive symptoms following sham treatment, as measured by the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS). Four studies met the inclusion criteria, randomizing 49 patients to two periods of active or sham stimulation. To preclude confounding by period effects, our estimate was based only on data from those patients who underwent sham stimulation first (n = 24). We found that sham stimulation induced a significant change in the Y-BOCS score (t = -3.15, P < 0.005), lowering it by 4.9 ± 1.6 points [95% CI = (-8.0, -1.8)]. We conclude that non-stimulation-related effects of DBS exist also in OCD. The identification of the factors determining the magnitude and occurrence of these effects will help to design strategies that will ultimately lead to a betterment of future randomized clinical trials.

Verbal communication about drug dosage balances drug reduction in Parkinson's disease: Behavioral and electrophysiological evidences

INTRODUCTION

Changing drug dosage is common in clinical practice. Recent evidence showed that psychological factors may affect the therapeutic outcome. The aim of this study is to test whether verbal communication about drug dosage changes motor performance and fatigue in Parkinson's Disease (PD) patients.

METHODS

We performed clinical (Unified PD Rating Scale), motor (number of finger flexions and perceived fatigue), and electrophysiological measurements (readiness potential, RP) in PD patients during medication-off and medication-on conditions in three groups. The first group got a full dose of l-dopa and was told it was a full dose. The second group got half dose and was told it was half dose. The third group got half dose, but it was told it was a full standard dose.

RESULTS

We found that overt half dose was less effective than the full dose for clinical improvement, motor performance, and readiness potential. However, if half dose was given along with verbal instructions that it was a full dose, clinical improvement, motor performance and readiness potential were not significantly different from the full dose.

CONCLUSIONS

Our findings indicate that verbal communication about dose reduction is as effective as the 50% dose reduction itself, demonstrating that deceptive information about the dose may have an important impact on the therapeutic outcome. Moreover, the supplementary motor area, source of the RP, seems to be involved in this psychological effect.

Placebo analgesia effects across central nervous system diseases: what do we know and where do we need to go?

Placebo effects are well established in healthy participants experiencing experimental or acute pain. Yet, little is known about the mechanisms of placebo analgesia effects in patients with chronic pain and even less is known in patients suffering from central nervous system (CNS) diseases where pain is prevalent, difficult to manage, and often undertreated. This article briefly reviews the current knowledge of placebo analgesia effects in healthy participants with the aim of discussing how the mechanisms in placebo analgesia differ between healthy participants and patients. The focus will be on placebo analgesia effects in chronic pain conditions as well as in 2 CNS diseases: Alzheimer disease and Parkinson disease. Finally, strengths and weaknesses of the current knowledge will be discussed and it will be demonstrated how insights from the placebo literature may point to new ways of improving treatments among patients experiencing pain in relation to CNS diseases.

Rapid overview of systematic reviews of nocebo effects reported by patients taking placebos in clinical trials

Background

Trial participants in placebo groups report experiencing adverse events (AEs). Existing systematic reviews have not been synthesized, leaving questions about why these events occur as well as their prevalence across different conditions unanswered.

Objectives

To synthesize the evidence of prevalence of AEs in trial placebo groups across different conditions.

To compare AEs in trial placebo groups with AEs reported in untreated groups within a subset of randomized trials.

Search methods

We searched PubMed for records with the word “nocebo” in the title and “systematic” in any field. We also contacted experts and hand-searched references of included studies.

Study eligibility

We included any systematic review of randomized trials where nocebo effects were reported. We excluded systematic reviews of non-randomized studies.

Participants and interventions

We included studies in any disease area.

Study appraisal and synthesis methods

We appraised the quality of the studies using a shortened version of the Assessment of Multiple Systematic Reviews tool (AMSTAR) tool. We reported medians and interquartile ranges (IQRs) of AEs. Among the trials within the review that included untreated groups, we compared the prevalence of AEs in untreated groups with the prevalence of AEs in placebo groups.

Results

We identified 20 systematic reviews. These included 1271 randomized trials and 250,726 placebo-treated patients. The median prevalence of AEs in trial placebo groups was 49.1% (IQR 25.7–64.4%). The median rate of dropouts due to AEs was 5% (IQR 2.28–8.4%). Within the 15 of trials that reported AEs in untreated groups, we found that the AE rate in placebo groups (6.51%) was higher than that reported in untreated groups (4.25%).

Limitations

This study was limited by the quality of included reviews and the small number of trials that included untreated groups.

Conclusions and implications of key findings

AEs in trial placebo groups are common and cannot be attributed entirely to natural history. Trial methodologies that reduce AEs in placebo groups while satisfying the requirement of informed consent should be developed and implemented.

Electronic supplementary material

The online version of this article (10.1186/s13063-018-3042-4) contains supplementary material, which is available to authorized users.

Functional Movement Disorders and Placebo: A Brief Review of the Placebo Effect in Movement Disorders and Ethical Considerations for Placebo Therapy

Background

Functional movement disorders are common and disabling neurologic conditions. Patients with functional neurologic disorders represent a large proportion of neurology clinic referrals, and limited availability of subspecialty care creates a considerable burden for the healthcare system. These conditions are currently treated with a combination of physical therapy and cognitive behavioral therapy, with variable success.

Methods

We searched the Medline database for studies on the epidemiology and physiology of functional movement disorders, as well as those on the placebo effect in movement disorders. We reviewed and summarized the literature on these topics and explored ethical issues concerning the administration of placebos to patients with functional movement disorders.

Results

Studies of placebos, particularly in patients with movement disorders, have shown that these "inert" agents can provide demonstrable neurophysiologic benefits, even in open-label studies. Physician surveys have shown that many administer placebos for diagnostic and therapeutic purposes, although there are ethical concerns about this practice. We used a principle-based approach and reviewed ethical arguments for (justice and beneficence) and against (non-maleficence and autonomy) the use of placebos in functional movement disorders. In this context, we argue for the importance of the therapeutic alliance in preserving patient autonomy while exploring the potential benefits of placebo therapy.

Conclusions

An ethical argument is presented in support of nondeceptive clinical placebo use for the treatment of functional movement disorders. Patient and clinician attitudes regarding the use of placebos should be investigated before placebo-therapy trials are conducted.

The Placebo Effect in Pain Therapies

Pharmacological strategies for pain management have primarily focused on dampening ascending neurotransmission and on opioid receptor-mediated therapies. Little is known about the contribution of endogenous descending modulatory systems to clinical pain outcomes and why some patients are mildly affected while others suffer debilitating pain-induced dysfunctions. Placebo effects that arise from patients' positive expectancies and the underlying endogenous modulatory mechanisms may in part account for the variability in pain experience and severity, adherence to treatment, distinct coping strategies, and chronicity. Expectancy-induced analgesia and placebo effects in general have emerged as useful models to assess individual endogenous pain modulatory systems. Different systems and mechanisms trigger placebo effects that highly impact pain processing, clinical outcomes, and sense of well-being. This review illustrates critical elements of placebo mechanisms that inform the methodology of clinical trials, the discovery of new therapeutic targets, and the advancement of personalized pain management.

Harnessing the power of placebos in movement disorders: Insights from Parkinson's disease in clinical research and practice

The placebo effect alongside the detrimental nocebo and lessebo effects associated with the use of placebos are well-recognized phenomena. Research conducted in the last two decades has demonstrated that the placebo effect is a measurable health benefit with well-known neurobiological correlates. In this review, we describe the current knowledge about how to best make use of the placebo effect to improve clinical research and optimize clinical care. We will cover four key topics: (1) setting the stage: historical perspectives on the use of placebos; (2) optimizing the use of placebos in clinical trials; (3) use of placebos in clinical practice; and (4) how can we minimize the ethical risks of using placebos? The adoption of the placebo-controlled trial as a standard in the therapeutic development reduced the placebo effect to background noise in a therapeutic signal. Strategies to minimize the placebo effect in clinical trials have been used to obtain positive efficacy results. In more recent years, new study paradigms encouraged a change in the views on placebos and the placebo effect. Alternative study designs and the development of biomarkers for a placebo response permit a better understanding of the contribution of the placebo effect to the results of interventional studies, without minimizing it. In clinical practice, optimizing the placebo effect (and reducing nocebo effects) has the potential to improve care for our patients, but raises ethical challenges. An enhanced patient-physician relationship would be central to any evidence-based intervention used in clinical care to heighten the placebo effect. © 2018 International Parkinson and Movement Disorder Society.

Modulation of the Motor System by Placebo and Nocebo Effects

There is strong behavioral evidence that placebo and nocebo effects can influence aspects of motor performance like speed, force, and resistance to fatigue in athletes and non-athletes alike. These behavioral studies were essential for extending experimental investigation of the placebo and nocebo effects from the pain to the motor domain and to reveal how verbal suggestions and experiential learning are involved in shaping modulatory systems and related behavioral responses. However, the neural underpinnings of these effects in the motor domain are still largely unknown. Studies in healthy subjects demonstrated that the placebo-induced enhancement of force is associated with increased activity in the corticospinal system and that the placebo-induced reduction of fatigue can be disclosed by recording the readiness potential, an electrophysiological sign of movement preparation. Further evidence derives from studies in patients with Parkinson's disease that have directly demonstrated that placebo-induced improvements in motor symptoms are related to changes in subcortical neural firing activity and dopamine release. Future investigations are needed to better clarify the complex neural architecture underpinning the placebo and nocebo effects in the motor domain.

A mechanistic review on GNAO1-associated movement disorder

Mutations in the GNAO1 gene cause a complex constellation of neurological disorders including epilepsy, developmental delay, and movement disorders. GNAO1 encodes Gα_o, the α subunit of G_o, a member of the G_i/o family of heterotrimeric G protein signal transducers. G_o is the most abundant membrane protein in the mammalian central nervous system and plays major roles in synaptic neurotransmission and neurodevelopment. GNAO1 mutations were first reported in early infantile epileptic encephalopathy 17 (EIEE17) but are also associated with a more common syndrome termed neurodevelopmental disorder with involuntary movements (NEDIM). Here we review a mechanistic model in which loss-of-function (LOF) GNAO1 alleles cause epilepsy and gain-of-function (GOF) alleles are primarily associated with movement disorders. We also develop a signaling framework related to cyclic AMP (cAMP), synaptic vesicle release, and neural development and discuss gene mutations perturbing those mechanisms in a range of genetic movement disorders. Finally, we analyze clinical reports of patients carrying GNAO1 mutations with respect to their symptom onset and discuss pharmacological/surgical treatments in the context of our mechanistic model.

Can knowledge of Placebo and Nocebo Mechanisms Help Improve Randomized Clinical Trials?

Over the last decade, there has been a substantial increase in negative results from randomized controlled trials (RCTs), which may be due to an increasing placebo response among other factors. Currently, identification and exclusion of placebo responders from trials are attempted to overcome this problem, but so far the success of these approaches has been limited. At the same time, the placebo-mechanism literature has highlighted how contextual factors, such as patients' expectations, interfere with the effect of drug administration, leading to a certain degree of uncertainty in RCTs. In this chapter, we review the current challenges of RCTs including the uncertainties of the active arm, the placebo arm, the additivity assumption, and the double-blind procedure. We use the placebo-mechanism literature to debate the strengths and weaknesses of attempts to identify and exclude placebo responders from trials. Finally, we illustrate how insights from the placebo-mechanism literature may point to new ways of improving RCTs.

The placebo effect on resting tremor in Parkinson's disease: an electrophysiological study

INTRODUCTION

The aim of our study was to investigate the effect of apomorphine and placebo on resting tremor in tremor-dominant Parkinson's disease (tPD) patients.

METHODS

Fifteen tPD patients were enrolled. Each patient underwent two treatments on two consecutive days: on day one the patients received a subcutaneous injection of placebo, while on day two they received apomorphine. On each day, the patients underwent three electrophysiological recording sessions: T0, T1, and T2: before, 30 min, and 60 min after the treatment respectively. Electrophysiological changes in tremor amplitude were evaluated using a triaxial accelerometer.

RESULTS

Placebo was effective in improving resting tremor in all tPD patients (p = 0.009) at T1, but not at T2. Eight out of 15 tPD patients (53.3%) responded to placebo with an at least 70% reduction in tremor amplitude compared to the basal condition (responders). By contrast, seven out of 15 tPD patients (46.7%) did not show any variation in tremor amplitude after placebo administration (non-responders). Apomorphine induced a marked reduction in tremor amplitude at 30 min and 60 min in all investigated tPD patients. Of note, the decrease in tremor amplitude in placebo responders was similar to that achieved with dopaminergic stimulation induced by apomorphine.

CONCLUSIONS

Our study demonstrates that placebo was very effective in reducing resting tremor in about half of patients with tPD. The decrease in tremor amplitude in placebo responders was similar to that induced by apomorphine. The cerebral mechanisms underlying the placebo effect on resting tremor need further investigations.

Does non-invasive brain stimulation modify hand dexterity? Protocol for a systematic review and meta-analysis

INTRODUCTION

Dexterity is described as coordinated hand and finger movement for precision tasks. It is essential for day-to-day activities like computer use, writing or buttoning a shirt. Integrity of brain motor networks is crucial to properly execute these fine hand tasks. When these networks are damaged, interventions to enhance recovery are frequently accompanied by unwanted side effects or limited in their effect. Non-invasive brain stimulation (NIBS) are postulated to target affected motor areas and improve hand motor function with few side effects. However, the results across studies vary, and the current literature does not allow us to draw clear conclusions on the use of NIBS to promote hand function recovery. Therefore, we developed a protocol for a systematic review and meta-analysis on the effects of different NIBS technologies on dexterity in diverse populations. This study will potentially help future evidence-based research and guidelines that use these NIBS technologies for recovering hand dexterity.

METHODS AND ANALYSIS

This protocol will compare the effects of active versus sham NIBS on precise hand activity. Records will be obtained by searching relevant databases. Included articles will be randomised clinical trials in adults, testing the therapeutic effects of NIBS on continuous dexterity data. Records will be studied for risk of bias. Narrative and quantitative synthesis will be done.

ETHICS AND DISSEMINATION

No private health information is included; the study is not interventional. Ethical approval is not required. The results will be reported in a peer-review journal.

REGISTRATION DETAILS

PROSPERO International prospective register of systematic reviews registration number: CRD42016043809.

Dopamine Transporter Imaging has no Impact on Functional Outcomes in de Novo Probable Parkinson's Disease

BACKGROUND

Parkinson's disease (PD) is among the most prevalent neurodegenerative conditions. While motor and non-motor aspects of this disease have been well characterized, no objective biomarker exists to support an accurate clinical diagnosis. However, newer imaging techniques, including [123I]-FP-CIT (DaTSCAN), have demonstrated utility in differentiating between PD and non-neurodegenerative tremor disorders.

OBJECTIVE

DaTSCAN has been primarily investigated in situations where diagnostic confusion exists, and in these instances has been shown to significantly impact clinical management. The goal of this pilot study was to evaluate the impact of DaTSCAN on the clinical management of patients with early probable PD, where no diagnostic uncertainty exists.

METHODS

This was a prospective, 54-week, comparative pilot study, in which twenty subjects with de novo PD were randomly assigned to DaTSCAN either immediately upon diagnosis (and again at 6 and 12 months) or delayed to 6 months (and again at 12 months). The primary outcome measure was the frequency of deviation from the initial treatment plan from baseline to 54 weeks between the two groups. Secondary outcomes included motor and non-motor assessments.

RESULTS

There was no significant difference in the number of treatment changes over the course of the study between the two groups: initial imaging group = 4.2 (SD:2.74) vs. delayed imaging group = 2.3 (SD:2.0, p = 0.11). In addition, there were no group differences in medication requirements, motor performance, or patient expectations of disease.

CONCLUSIONS

In patients with early, probable PD, DaTSCAN contributes no additional impact on clinical management or functional outcomes when added to the diagnostic algorithm.

Factors influencing the outcome of deep brain stimulation: Placebo, nocebo, lessebo, and lesion effects

Deep brain stimulation (DBS) is a well-established treatment option for movement disorders, especially for Parkinson's disease (PD). There is a need to determine the role of expectation of benefit and the use of placebo to better understand the effects of electrode placement including the (micro)lesion effect. These factors must be understood to better interpret and attribute the therapeutic value of DBS. In this review, we critically present currently available data on the placebo, nocebo, lessebo, and lesion effects in the context of DBS. We provide a discussion of strategies that have the potential for controlling these effects in the setting of future DBS trials. We conclude that there is a need to standardize definitions for nocebo and (micro)lesion effects and that there are intrinsic limitations in defining the effect of expectation of benefit in DBS. These issues will be challenging to overcome especially with current technology and available study designs. New stimulation paradigms, better study designs, and the use of adaptive closed-loop DBS devices may facilitate a more accurate assessment of the placebo, nocebo, and lessebo effects in future DBS trials.

Diffusion Tensor Imaging-Based Thalamic Segmentation in Deep Brain Stimulation for Chronic Pain Conditions

BACKGROUND/AIMS

Thalamic deep brain stimulation (DBS) for the treatment of medically refractory pain has largely been abandoned on account of its inconsistent and oftentimes poor efficacy. Our aim here was to use diffusion tensor imaging (DTI)-based segmentation to assess the internal thalamic nuclei of patients who have undergone thalamic DBS for intractable pain and retrospectively correlate lead position with clinical outcome.

METHODS

DTI-based segmentation was performed on 5 patients who underwent sensory thalamus DBS for chronic pain. Postoperative computed tomography images obtained for electrode placement were fused with preoperative magnetic resonance images that had undergone DTI-based thalamic segmentation. Sensory thalamus maps of 4 patients were analyzed for lead positioning and interpatient variability.

RESULTS

Four patients who experienced significant pain relief following DBS demonstrated contact positions within the DTI-determined sensory thalamus or in its vicinity, whereas 1 patient who did not respond to stimulation did not. Only 4 voxels (2%) within the sensory thalamus were mutually shared among patients; 108 voxels (58%) were uniquely represented.

CONCLUSIONS

DTI-based segmentation of the thalamus can be used to confirm thalamic lead placement relative to the sensory thalamus and may serve as a useful tool to guide thalamic DBS electrode implantation in the future.

Placebo Response is Driven by UCS Revaluation: Evidence, Neurophysiological Consequences and a Quantitative Model

Despite growing scientific interest in the placebo effect and increasing understanding of neurobiological mechanisms, theoretical modeling of the placebo response remains poorly developed. The most extensively accepted theories are expectation and conditioning, involving both conscious and unconscious information processing. However, it is not completely understood how these mechanisms can shape the placebo response. We focus here on neural processes which can account for key properties of the response to substance intake. It is shown that placebo response can be conceptualized as a reaction of a distributed neural system within the central nervous system. Such a reaction represents an integrated component of the response to open substance administration (or to substance intake) and is updated through “unconditioned stimulus (UCS) revaluation learning”. The analysis leads to a theorem, which proves the existence of two distinct quantities coded within the brain, these are the expected or prediction outcome and the reactive response. We show that the reactive response is updated automatically by implicit revaluation learning, while the expected outcome can also be modulated through conscious information processing. Conceptualizing the response to substance intake in terms of UCS revaluation learning leads to the theoretical formulation of a potential neuropharmacological treatment for increasing unlimitedly the effectiveness of a given drug.

Teaching neurons to respond to placebos

KEY POINTS

We analysed the placebo response at the single-neuron level in the thalamus of Parkinson patients to see the differences between first-time administration of placebo and administration after pharmacological pre-conditioning. When the placebo was given for the first time, it induced neither clinical improvement, as assessed through muscle rigidity reduction at the wrist, nor neuronal changes in thalamic neurons. However, if placebo was given after two, three or four prior administrations of an anti-Parkinson drug, apomorphine, it produced both clinical and neuronal responses. Both the magnitude and the duration of these placebo responses depended on the number of prior exposures to apomorphine, according to the rule: the greater the number of previous apomorphine administrations, the larger the magnitude and the longer the duration of the clinical and neuronal placebo responses. These findings show that learning plays a crucial role in the placebo response and suggest that placebo non-responders can be turned into placebo responders, with important clinical implications.

ABSTRACT

Placebos have been found to affect the patient's brain in several conditions, such as pain and motor disorders. For example, in Parkinson's disease, a placebo treatment induces a release of dopamine in the striatum and changes the activity of neurons in both thalamic and subthalamic nuclei. The present study shows that placebo administration for the first time induces neither clinical nor neuronal improvement in Parkinson patients who undergo implantation of electrodes for deep brain stimulation. However, this lack of placebo responsiveness can be turned into substantial placebo responses following previous exposure to repeated administrations of the anti-Parkinson agent apomorphine. As the number of apomorphine administrations increased from one to four, both the clinical response and the neuronal activity in the ventral anterior and anterior ventrolateral thalamus increased. In fact, after four apomorphine exposures, placebo administration induced clinical responses that were as large as those to apomorphine, along with long-lasting neuronal changes. These clinical placebo responses following four apomorphine administrations were again elicited after a re-exposure to a placebo 24 h after surgery, but not after 48 h. These data indicate that learning plays a crucial role in placebo responsiveness and suggest that placebo non-responders can be turned into responders, with important implications in the clinical setting.

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?"

A randomized double-blind crossover trial of deep brain stimulation of the subcallosal cingulate gyrus in patients with treatment-resistant depression: a pilot study of relapse prevention

BACKGROUND

To date, antidepressant drugs show limited efficacy, leaving a large number of patients experiencing severe and persistent symptoms of major depression. Previous open-label clinical trials have reported significant sustained improvements with deep brain stimulation (DBS) of the subcallosal cingulate gyrus (SCG) in patients with severe, chronic treatment-resistant depression (TRD). This study aimed to confirm the efficacy and measure the impact of discontinuation of the electrical stimulation.

METHODS

We conducted a 6-month double-blind, randomized, sham-controlled crossover study in implanted patients with previous severe TRD who experienced full remission after chronic stimulation. After more than 3 months of stable remission, patients were randomly assigned to 2 treatment arms: the ON-OFF arm, which involved active electrode stimulation for 3 months followed by sham stimulation for 3 months, and the OFF-ON arm, which involved sham stimulation for 3 months followed by active stimulation for 3 months. The primary outcome measure was the difference in the 17-item Hamilton Rating Scale for Depression (HAMD-17) total score between sham and active stimulation.

RESULTS

We enrolled 5 patients in our trial. A Friedman repeated-measures analysis of variance revealed a significant effect of treatment (χ(2)1 = 5.0, p = 0.025) in patients with higher depression scores during sham stimulation. At the end of active stimulation, depression was remitted in 4 of 5 patients and none of them had experienced a relapse, whereas at the end of sham stimulation, 2 patients remained in remission, 2 relapsed and 1 showed a progressive worsening without reaching relapse criteria.

LIMITATIONS

The small sample size limited the statistical power and external validity.

CONCLUSION

These preliminary findings indicate that DBS of the SCG is an effective and safe treatment for severe forms of TRD and that continuous electrical stimulation is required to maintain therapeutic effects.

TRIAL REGISTRATION

NCT01268137 (ClinicalTrials.gov).

Deep brain stimulation for movement disorders: update on recent discoveries and outlook on future developments

Modern deep brain stimulation (DBS) has become a routine therapy for patients with movement disorders such as Parkinson's disease, generalized or segmental dystonia and for multiple forms of tremor. Growing numbers of publications also report beneficial effects in other movement disorders such as Tourette's syndrome, various forms of chorea and DBS is even being studied for Parkinson's-related dementia. While exerting remarkable effects on many motor symptoms, DBS does not restore normal neurophysiology and therefore may also have undesirable side effects including speech and gait deterioration. Furthermore, its efficacy might be compromised in the long term, due to progression of the underlying disease. Various programming strategies have been studied to try and address these issues, e.g., the use of low-frequency rather than high-frequency stimulation or the targeting of alternative brain structures such as the pedunculopontine nucleus. In addition, further technical developments will soon provide clinicians with an expanded choice of hardware such as segmented electrodes allowing for a steering of the current to optimize beneficial effects and reduce side effects as well as the possibility of adaptive stimulation systems based on closed-loop concepts with or without accompanying advances in programming and imaging software. In the present article, we will provide an update on the most recent achievements and discoveries relevant to the application of DBS in the treatment of movement disorder patients and give an outlook on future clinical and technical developments.

Occipital nerve stimulation for chronic migraine--a systematic review and meta-analysis

BACKGROUND

Chronic migraine is a debilitating headache disorder that has significant impact on quality of life. Stimulation of peripheral nerves is increasingly being used to treat chronic refractory pain including headache disorders. This systematic review examines the effectiveness and adverse effects of occipital nerve stimulation (ONS) for chronic migraine.

METHODS

Databases, including the Cochrane Library, MEDLINE, EMBASE, CINAHL and clinical trial registers were searched to September 2014. Randomized controlled trials (RCTs), other controlled and uncontrolled observational studies and case series (n≥ 10) were eligible. RCTs were assessed using the Cochrane risk of bias tool. Meta-analysis was carried out using a random-effects model. Findings are presented in summary tables and forest plots.

RESULTS

Five RCTs (total n=402) and seven case series (total n=115) met the inclusion criteria. Pooled results from three multicenter RCTs show that ONS was associated with a mean reduction of 2.59 days (95% CI 0.91 to 4.27, I2=0%) of prolonged, moderate to severe headache per month at 3 months compared with a sham control. Results for other outcomes generally favour ONS over sham controls but quantitative analysis was hampered by incomplete publication and reporting of trial data. Lead migration and infections are common and often require revision surgery. Open-label follow-up of RCTs and case series suggest long-term effectiveness can be maintained in some patients but evidence is limited.

CONCLUSIONS

While the effectiveness of ONS compared to sham control has been shown in multiple RCTs, the average effect size is modest and may be exaggerated by bias as achieving effective blinding remains a methodological challenge. Further measures to reduce the risk of adverse events and revision surgery are needed.

SYSTEMATIC REVIEW REGISTRATION

this systematic review is an update and expanded work of part of a broader review registered with PROSPERO. Registration No. CRD42012002633.