Brain-to-brain mechanisms underlying pain empathy and social modulation of pain in the patient-clinician interaction.

Social interactions such as the patient-clinician encounter can influence pain, but the underlying dynamic interbrain processes are unclear. Here, we investigated the dynamic brain processes supporting social modulation of pain by assessing simultaneous brain activity (fMRI hyperscanning) from chronic pain patients and clinicians during video-based live interaction. Patients received painful and nonpainful pressure stimuli either with a supportive clinician present (Dyadic) or in isolation (Solo). In half of the dyads, clinicians performed a clinical consultation and intake with the patient prior to hyperscanning (Clinical Interaction), which increased self-reported therapeutic alliance. For the other half, patient-clinician hyperscanning was completed without prior clinical interaction (No Interaction). Patients reported lower pain intensity in the Dyadic, relative to the Solo, condition. In Clinical Interaction dyads relative to No Interaction, patients evaluated their clinicians as better able to understand their pain, and clinicians were more accurate when estimating patients' pain levels. In Clinical Interaction dyads, compared to No Interaction, patients showed stronger activation of the dorsolateral and ventrolateral prefrontal cortex (dlPFC and vlPFC) and primary (S1) and secondary (S2) somatosensory areas (Dyadic-Solo contrast), and clinicians showed increased dynamic dlPFC concordance with patients' S2 activity during pain. Furthermore, the strength of S2-dlPFC concordance was positively correlated with self-reported therapeutic alliance. These findings support that empathy and supportive care can reduce pain intensity and shed light on the brain processes underpinning social modulation of pain in patient-clinician interactions. Our findings further suggest that clinicians' dlPFC concordance with patients' somatosensory processing during pain can be boosted by increasing therapeutic alliance.

Conclusions Regarding the Role of Expectations in Placebo Analgesia Studies May Depend on How We Investigate It: A Meta-Analysis, Systematic Review, and Proposal for Methodological Discussions.

OBJECTIVE: Expectations are highlighted as a key component in placebo effects. However, there are different approaches to whether and how placebo studies should account for expectations, and the direct contribution has yet to be estimated in meta-analyses. Using different methodological approaches, this meta-analysis and systematic review examines the extent to which expectations contribute to pain in placebo studies. METHODS: The databases PubMed, PsycINFO, Embase, and Web of Science were searched for placebo analgesia mechanism studies with numerical measures of both expectations and pain. Thirty-one studies, comprising 34 independent study populations (1566 subjects: patients and healthy participants) were included. Two meta-analyses were conducted: meta-analysis 1, using study-level data, estimated the effect of expectation interventions without taking measures of expectations into account (expectations assumed); and meta-analysis 2, using individual-level data, estimated the direct impact of participants' expectations on pain (expectations assessed). Risk of bias was assessed using the Cochrane risk-of-bias tool. RESULTS: Meta-analysis 1 showed a moderate effect of expectation interventions over no expectation intervention on pain intensity (Hedges g = 0.45, I2 = 54.19). Based on 10 studies providing individual-level data, meta-analysis 2 showed that expectations predicted pain intensity in placebo and control groups ( b = 0.36, SE = 0.05), although inconsistently across study methodologies. CONCLUSIONS: Participants' expectations contributed moderately to pain in placebo analgesia studies. However, this may largely be influenced by how we measure expectations and how their contribution is conceptualized and analyzed-both within and across studies.

Are They Side Effects? Extraintestinal Symptoms Reported During Clinical Trials of Irritable Bowel Syndrome May Be More Severe at Baseline.

BACKGROUND & AIMS: Many of the reported adverse events in clinical trials of irritable bowel syndrome are extraintestinal symptoms, which typically are assessed by open-ended questions during the trial and not at baseline. This may lead to misattribution of some pre-existing symptoms as side effects to the treatment. METHODS: The current study analyzed data from a 6-week clinical trial of irritable bowel syndrome. Participants were randomized to receive double-blind peppermint oil, double-blind placebo, or treatment as usual. Extraintestinal symptoms were assessed at baseline and at the end of the study. RESULTS: This analysis included 173 participants (30 received double-blind peppermint oil, 72 received treatment as usual, and 71 received double-blind placebo). At baseline, each group reported approximately 5 extraintestinal symptoms per participant. The number of symptoms per participant decreased to an average of 3 by the end-of-study visit, and this change was statistically significant in all groups (P < .001 for each group). When evaluating individual extraintestinal symptoms, the majority of participants did not report new/worse symptoms. In fact, between the baseline assessment and the final assessment, the average symptom severity decreased significantly in all 3 groups (P < .001). CONCLUSIONS: Our study suggests that participants with irritable bowel syndrome often experience extraintestinal symptoms at baseline and that these symptoms generally improve in severity over the course of a clinical trial, regardless of the treatment arm. Systematic assessment of extraintestinal symptoms at the beginning of a clinical trial is necessary to determine more definitively whether these symptoms may be considered an adverse event attributable to a study medication.

Remotely Provided Open-Label Placebo Reduces Frequency of and Impairment by Allergic Symptoms.

OBJECTIVE: Placebos being prescribed with full honesty and disclosure (i.e., open-label placebo [OLP]) have been shown to reduce symptom burden in a variety of conditions. With regard to allergic rhinitis, previous research provided inconclusive evidence for the effects of OLP, possibly related to a separate focus on either symptom severity or symptom frequency. Overcoming this limitation of previous research, the present study aimed to examine the effects of OLP on both the severity and frequency of allergic symptoms. METHODS: In a randomized-controlled trial, patients with allergic rhinitis ( N = 74) were randomized to OLP or treatment as usual (TAU). Because of the COVID-19 pandemic, OLP was administered remotely in a virtual clinical encounter. Participants took placebo tablets for 14 days. The primary outcomes were the severity and frequency of allergic symptoms. The secondary end point was allergy-related impairment. RESULTS: OLP did not significantly improve symptom severity over TAU ( F (1,71) = 3.280, p = .074, η2 = 0.044) but did reduce symptom frequency ( F (1,71) = 7.272, p = .009, η2 = 0.093) and allergy-related impairment more than TAU ( F (1,71) = 6.445, p = .013, η2 = 0.083), reflecting medium to large effects. The use of other antiallergic medication did not influence the results. CONCLUSIONS: Although OLP was able to lower the frequency of allergic symptoms and allergy-related impairment substantially, its effects on symptom severity were weaker. The remote provision of OLP suggests that physical contact between patients and providers might not be necessary for OLP to work.

Psychological Predictors of Response to Open-Label Versus Double-Blind Placebo in a Randomized Controlled Trial in Irritable Bowel Syndrome.

OBJECTIVE: There is growing evidence that open-label placebo (OLP) may be an efficacious treatment of chronic and functional conditions. However, patient-level predictors of response to OLP have not been clearly identified. The aim of this study is to evaluate the psychological predictors of response to OLP and to compare this to double-blind placebo (DBP) and no-pill control (NPC). METHODS: This study is a secondary analysis of data collected in a 6-week randomized controlled trial evaluating placebo effects in irritable bowel syndrome (IBS). The primary outcome was change in IBS severity. Hierarchical linear regression identified predictors of placebo response in general and compared them between those randomized to OLP, DBP, and NPC. Predictor variables included personality traits, generalized anxiety, depression, visceral sensitivity (a measure of symptom-specific anxiety), and pain catastrophizing. RESULTS: A total of 210 participants (mean age = 42.3 years, 73.3% female) were included. Regression models revealed that visceral sensitivity was a predictor of response to OLP and NPC but not DBP. Interestingly, the effects were opposite, with high visceral sensitivity predicting less improvement in NPC and more improvement in OLP. Pain catastrophizing was a negative predictor of response to OLP (i.e., high pain catastrophizing was associated with less improvement in OLP). Neither visceral sensitivity nor pain catastrophizing played a significant role for response to DBP. CONCLUSIONS: IBS participants who score low on the Pain Catastrophizing Scale but high on the Visceral Sensitivity Index seem to benefit particularly from OLP. Our study suggests that different psychological mechanisms may be involved in DBP and OLP interventions.

What Should Clinicians Tell Patients about Placebo and Nocebo Effects? Practical Considerations Based on Expert Consensus.

INTRODUCTION: Clinical and laboratory studies demonstrate that placebo and nocebo effects influence various symptoms and conditions after the administration of both inert and active treatments. OBJECTIVE: There is an increasing need for up-to-date recommendations on how to inform patients about placebo and nocebo effects in clinical practice and train clinicians how to disclose this information. METHODS: Based on previous clinical recommendations concerning placebo and nocebo effects, a 3-step, invitation-only Delphi study was conducted among an interdisciplinary group of internationally recognized experts. The study consisted of open- and closed-ended survey questions followed by a final expert meeting. The surveys were subdivided into 3 parts: (1) informing patients about placebo effects, (2) informing patients about nocebo effects, and (3) training clinicians how to communicate this information to the patients. RESULTS: There was consensus that communicating general information about placebo and nocebo effects to patients (e.g., explaining their role in treatment) could be beneficial, but that such information needs to be adjusted to match the specific clinical context (e.g., condition and treatment). Experts also agreed that training clinicians to communicate about placebo and nocebo effects should be a regular and integrated part of medical education that makes use of multiple formats, including face-to-face and online modalities. CONCLUSIONS: The current 3-step Delphi study provides consensus-based recommendations and practical considerations for disclosures about placebo and nocebo effects in clinical practice. Future research is needed on how to optimally tailor information to specific clinical conditions and patients' needs, and on developing standardized disclosure training modules for clinicians.

European Headache Federation recommendations for placebo and nocebo terminology.

BACKGROUND AND AIM: Despite recent publications, practitioners remain unfamiliar with the current terminology related to the placebo and nocebo phenomena observed in clinical trials and practice, nor with the factors that modulate them. To cover the gap, the European Headache Federation appointed a panel of experts to clarify the terms associated with the use of placebo in clinical trials. METHODS: The working group identified relevant questions and agreed upon recommendations. Because no data were required to answer the questions, the GRADE approach was not applicable, and thus only expert opinion was provided according to an amended Delphi method. The initial 12 topics for discussion were revised in the opinion of the majority of the panelists, and after a total of 6 rounds of negotiations, the final agreement is presented. RESULTS/RECOMMENDATIONS: Two primary and mechanism-based recommendations are provided for the results of clinical trials: [1] to distinguish the placebo or nocebo response from the placebo or nocebo effect; and [2] for any favorable outcome observed after placebo administration, the term "placebo response" should be used, and for any unfavorable outcome recorded after placebo administration, the term "nocebo response" should be used (12 out of 17 panelists agreed, 70.6% agreement). The placebo or nocebo responses are attributed to a set of factors including those that are related to the medical condition (e.g. natural history, random comorbidities, etc.), along with idiosyncratic ones, in which the placebo or nocebo effects are attributed to idiosyncratic, or nonspecific mechanisms, exclusively (e.g. expectation, conditioning, observational learning etc.). To help investigators and practitioners, the panel summarized a list of environmental factors and idiosyncratic dynamics modulating placebo and nocebo effects. Some of them are modifiable, and investigators or physicians need to know about them in order to modify these factors appropriately to improve treatment. One secondary recommendation addresses the use of the terms "placebo" and "nocebo" ("placebos" and "nocebos" in plural), which refer to the triggers of the placebo/nocebo effects or responses, respectively, and which are inert agents or interventions that should not be confused with the placebo/nocebo responses or effects themselves (all panelists agreed, 100% agreement). CONCLUSION: The working group recommends distinguishing the term response from effect to describe health changes from before to after placebo application and to distinguish the terms placebo(s) or nocebo(s) from the health consequences that they cause (placebo/nocebo responses or effects).

Implications of Placebo and Nocebo Effects for Clinical Practice: Expert Consensus.

BACKGROUND: Placebo and nocebo effects occur in clinical or laboratory medical contexts after administration of an inert treatment or as part of active treatments and are due to psychobiological mechanisms such as expectancies of the patient. Placebo and nocebo studies have evolved from predominantly methodological research into a far-reaching interdisciplinary field that is unravelling the neurobiological, behavioural and clinical underpinnings of these phenomena in a broad variety of medical conditions. As a consequence, there is an increasing demand from health professionals to develop expert recommendations about evidence-based and ethical use of placebo and nocebo effects for clinical practice. METHODS: A survey and interdisciplinary expert meeting by invitation was organized as part of the 1st Society for Interdisciplinary Placebo Studies (SIPS) conference in 2017. Twenty-nine internationally recognized placebo researchers participated. RESULTS: There was consensus that maximizing placebo effects and minimizing nocebo effects should lead to better treatment outcomes with fewer side effects. Experts particularly agreed on the importance of informing patients about placebo and nocebo effects and training health professionals in patient-clinician communication to maximize placebo and minimize nocebo effects. CONCLUSIONS: The current paper forms a first step towards developing evidence-based and ethical recommendations about the implications of placebo and nocebo research for medical practice, based on the current state of evidence and the consensus of experts. Future research might focus on how to implement these recommendations, including how to optimize conditions for educating patients about placebo and nocebo effects and providing training for the implementation in clinical practice.

Classical conditioning of analgesic and hyperalgesic pain responses without conscious awareness.

Pain reduction and enhancement can be produced by means of conditioning procedures, yet the role of awareness during the acquisition stage of classical conditioning is unknown. We used psychophysical measures to establish whether conditioned analgesic and hyperalgesic responses could be acquired by unseen (subliminally presented) stimuli. A 2 × 2 factorial design, including subliminal/supraliminal exposures of conditioning stimuli (CS) during acquisition/extinction, was used. Results showed significant analgesic and hyperalgesic responses (P < 0.001), and responses were independent of CS awareness, as subliminal/supraliminal cues during acquisition/extinction led to comparable outcomes. The effect was significantly larger for hyperalgesic than analgesic responses (P < 0.001). Results demonstrate that conscious awareness of the CS is not required during either acquisition or extinction of conditioned analgesia or hyperalgesia. Our results support the notion that nonconscious stimuli have a pervasive effect on human brain function and behavior and may affect learning of complex cognitive processes such as psychologically mediated analgesic and hyperalgesic responses.

Parental Attitudes About Placebo Use in Children.

OBJECTIVE: To assess parental attitudes regarding placebo use in pediatric randomized controlled trials and clinical care. STUDY DESIGN: Parents with children under age 18 years living in the US completed and submitted an online survey between September and November 2014. RESULTS: Among all 1300 participants, 1000 (76.9%; 538 mothers and 462 fathers) met the study inclusion criteria. The majority of surveyed parents considered the use of placebos acceptable in some pediatric care situations (86%) and some pediatric trials (91.5%), whereas only 5.7% of parents found the use of placebos in children always unacceptable. The clinical use of placebo was considered acceptable by a majority of parents for only 7 (mostly psychological) of the 17 conditions presented. Respondents' judgment about acceptability was influenced by the doctors' opinions about the therapeutic benefits of placebo treatment, the conditions for pediatric placebo use, transparency, safety, and purity of placebos. CONCLUSION: Most surveyed parents accepted the idea of using placebos in pediatric trials and within the clinic for some conditions without the practice of deception and with the creation of guidelines for ethical and safe use. This study suggests a need to reconsider pediatric trial design and clinical therapy in the light of generally positive parental support of appropriate placebo use.