Symptom perception, placebo effects, and the Bayesian brain

Efficacy of open-label placebos for premenstrual syndrome: a randomised controlled trial

OBJECTIVE

To investigate the efficacy and safety of open-label placebos (OLP) in premenstrual syndrome (PMS).

DESIGN

Randomised controlled trial.

SETTING

Switzerland, 2018-2020.

PARTICIPANTS

150 women (18-45 years of age) with PMS or premenstrual dysphoric disorder.

INTERVENTION

Random assignment (1:1:1) to treatment as usual (TAU), OLP without treatment rationale (OLP-), or OLP with treatment rationale (OLP+). OLP consisted of two placebo pills per day for 6 weeks.

MAIN OUTCOME MEASURES

Primary outcomes were PMS symptom intensity and interference between groups across three menstrual cycles (MC1-MC3); adverse events (ie, safety) were measured at weeks 3 and 6 after the start of the intervention. Secondary outcomes were psychological and somatic subscales of PMS symptom intensity, and adherence.

RESULTS

From 2 August 2018 to 3 December 2020, 150 women were randomly allocated to TAU (n=50), OLP- (n=50), and OLP+ (n=50), of whom 145 (96.7%) completed trial participation. Groups differed in symptom intensity (F(4)=4.419, p=0.002, r2=0.16) and interference (F(4)=3.159, p=0.014, r2=0.13) across three MCs. Mean symptom intensity at MC3 was lower for OLP+ compared to TAU (b=-9.97, SE=2.85, t(412)=3.50, p<0.001, d=0.90) and to OLP- (b=-6.10, SE=2.89, t(411)=2.11, p=0.036, d=0.55), but OLP- and TAU did not differ (b=-3.87, SE=2.87, t(411)=1.35, p=0.177, d=0.35). Mean interference at MC3 was lower for OLP+ compared to TAU (b=-1.23, SE=0.54, t(443)=2.30, p=0.022, d=0.55) and to OLP- (b=-1.10, SE=0.54, t(442)=2.02, p=0.044, d=0.48), but OLP- and TAU did not differ (b=-0.14, SE=0.54, t(442)=0.26, p=0.799, d=0.06). Four non-serious adverse events were reported in OLP- (n=1) and OLP+ (n=3). Improvement in psychological and somatic symptom intensity was comparable to primary outcomes. Adherence to the OLP intervention was high (93.18±18.95%), with no difference between groups.

CONCLUSIONS

The results of our clinical trial indicate that OLP provided with a treatment rationale is an effective, safe, and acceptable treatment for PMS.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03547661 (submitted 2 May 2018).

Thermosensory predictive coding underpins an illusion of pain

The human brain has a remarkable ability to learn and update its beliefs about the world. Here, we investigate how thermosensory learning shapes our subjective experience of temperature and the misperception of pain in response to harmless thermal stimuli. Through computational modeling, we demonstrate that the brain uses a probabilistic predictive coding scheme to update beliefs about temperature changes based on their uncertainty. We find that these expectations directly modulate the perception of pain in the thermal grill illusion. Quantitative microstructural brain imaging further revealed that individual variability in computational parameters related to uncertainty-driven learning and decision-making is reflected in the microstructure of brain regions such as the precuneus, posterior cingulate gyrus, cerebellum, as well as basal ganglia and brainstem. These findings provide a framework to understand how the brain infers pain from innocuous thermal inputs, with important implications for the etiology of thermosensory symptoms under chronic pain conditions.

Healthcare-seeking behaviors and barriers among medical students in Egypt: a national cross-sectional study

BACKGROUND

Medical students are particularly vulnerable to acquiring various health conditions due to the nature of their education but often hesitate to consult doctors and resort to self-managing their illnesses. This study aims to examine the healthcare-seeking behaviors and barriers among medical students in Egypt.

METHODS

This cross-sectional study involved a convenience sample of 1,535 medical students from 12 public universities across Egypt. Data on healthcare-seeking behaviors, barriers, and associated factors were collected using an online survey distributed through official university channels and social media platforms. Logistic regression analysis was used to identify factors associated with consulting a doctor when experiencing health problems.

RESULTS

Only 52.2% of participants reported consulting doctors when ill. Participants from rural backgrounds (COR = 0.69, CI: 0.51-0.93), those facing barriers to healthcare (COR = 0.80, CI: 0.66-0.98), with less than sufficient income (COR = 0.61, CI: 0.46-0.81), or a non-working mother (AOR = 0.76, CI: 0.58-0.99) were less likely to consult a doctor. In contrast, participants with more than sufficient income (COR = 1.35, CI: 1.02-1.78), a parent in healthcare (AOR = 13.18-17.31, CI: 6.87-36.35), or who exercised regularly (AOR = 1.48, CI: 1.09-2.01) were more likely to consult a doctor. A substantial proportion of students reported relying on past experiences with the illness (54.1%), using the Internet (46.8%), and self-diagnosing (36.2%). The most common reported barriers to seeking healthcare were lack of time (29.2%), long wait times (22.7%), and academic concerns (12%). A history of feeling uncomfortable or discriminated against when seeking healthcare was reported by 19.5% of participants.

CONCLUSION

Many medical students in Egypt engage in self-diagnosis and self-management rather than consulting doctors when ill. Addressing healthcare barriers is crucial for encouraging appropriate care-seeking behaviors within this population.

Beyond Needling: Integrating a Bayesian Brain Model into Acupuncture Treatment

Acupuncture is a medical tool in which a sterile needle is used to penetrate and stimulate a certain body area (acupoint), inducing a series of sensations such as numbness, dullness, or aching, often referred to as de-qi. But is that all? In this article, we adopt a Bayesian perspective to explore the cognitive and affective aspects of acupuncture beyond needling, specifically, how the body integrates bottom-up sensory signals with top-down predictions of acupuncture perception. We propose that the way in which we discern acupuncture treatment is the result of predictive coding, a probabilistic, inferential process of our brain. Active inference from both prior experience and expectations of acupuncture, when integrated with incoming sensory signals, creates a unique, individual internal generative model of our perception of acupuncture. A Bayesian framework and predictive coding may, therefore, aid in elucidating and quantifying the cognitive components of acupuncture and facilitate understanding of their differential interactions in determining individual expectations of treatment. Thus, a perception-based Bayesian model of acupuncture presented in this article may expand on how we perceive acupuncture treatment, from simply inserting needles into our body to one that encompasses a complex healing process supported by belief and hope of regaining health. By exploring how cognitive factors influence individual responsiveness to acupuncture treatment, this review sheds light on why acupuncture treatment is more effective in some individuals than in others.

The prediction of the analgesic placebo response is moderated by outward-focused attention: A sham, randomized clinical trial of chronic back pain patients

The within-subject variability (WSV) of pain-intensity reports has gained attention as a predictor of the placebo response but has demonstrated mixed results. We hypothesized that participants' inward- and outward-directed attention will moderate WSV's prediction of the analgesic placebo response. In this sham randomized clinical trial (protocol number NCT05994118); placebo response was induced in chronic back-pain patients (n=113) through a saline injection plus verbal suggestion. The WSV assessed by the focused analgesia selection test (FAST) served as a predictor. The revised Self-Consciousness Scale (SCS-R), evaluating a person's tendency to focus attention inward or outward was used to moderate the prediction. The placebo response prediction was significantly moderated by 2 SCS-R subscales: public self-consciousness (b = 46.36, SE = 23.08, t = 2.0, p = 0.047) and social anxiety (b = 44.01, SE = 18.02, t = 2.44, p = 0.016). The prediction was significant at low levels of both moderators (p < 0.01), but not at high levels of these traits. Prediction of the placebo response is of value and could promote personalized medical care. Better understanding of factors shaping the placebo response could further contribute to both clinical practice and clinical trials. PERSPECTIVE: The current study demonstrates that the prediction of the analgesic placebo response could be improved if relevant personal characteristics are included as moderators of the prediction. Better predictions of the placebo response could contribute to improve both clinical research and clinical care.

The complexity of caffeine's effects on regular coffee consumers

Why does coffee wake us up? Is it because it contains caffeine, or because we are used to it waking us up after drinking it? To answer this question, we recruited twenty habitual coffee drinkers who received either caffeinated or decaffeinated coffee (placebo) in a double-blind, randomized fashion. The two substances were identical except for the presence of caffeine. We measured cognitive performance, cardiovascular responses, and whole-head EEG during rest and during an auditory-oddball task. The same measurements were done before and after ingestion. We expected to find significant differences between caffeine and placebo groups across the outcome measures. However, except for the resting-state alpha power, changes due to ingestion in physiological responses and in cognitive functioning were not significantly different between the two groups. Actually, only one of the three cognitive measures was found to be significantly altered by the ingestion. These findings suggest that regular coffee consumers respond to coffee-like beverages independently of the presence of caffeine.

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

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

Listening to placebos: the contested lessons of antidepressants debates

The goal of this paper is to explore a set of epistemological and ontological issues regarding the historical and philosophical role of placebos in the contested history of antidepressants. Starting from an account of the dual nature of the placebo as both an epistemic and a therapeutic tool, and against the background of the heated debates on the efficacy of second-generation antidepressants, I propose two related arguments. First, I argue that placebos as controls played a crucial but paradoxical role in the rise of so-called evidence-based approaches to depression. Second, I discuss how current research on placebo effects puts into question some of the most crucial assumptions of psychiatric technoscience regarding the ontology of affective experiences. Ultimately, this paper aims to probe discussions around placebos, placebo effects, and the status of depression both as a diagnostic category and a lived experience.

A randomised, double-blind, placebo-controlled study to determine the analgesic efficacy, safety and tolerability of VPX638 administered topically to painful wounds

New analgesics are needed for painful wounds. Multiple reports suggest that topical sevoflurane may have analgesic effects. This placebo-controlled randomised trial evaluated the analgesic efficacy and safety of VPX638 (topical sevoflurane). Seventy-eight participants with painful wounds, were enrolled at eight Australian centres and randomly allocated to receive 2 × 5 mL of VPX638 (N = 39) or placebo (N = 40) during one wound dressing change. Numerical pain rating scores and use of opioids were recorded for 24 h. The primary endpoint was pain during wound cleaning, secondary endpoints evaluated pain for 24 h after drug application and opioids use. There was no significant difference in mean pain scores during wound cleaning between VPX638 and placebo (0.854; p = 0.23). The mean differences in summed pain intensity difference from baseline suggested VPX638 provided greater analgesia compared to placebo over 8 h (p < 0.02), 12 h (p < 0.01) and 24 h (p < 0.05) and significantly longer duration of analgesia, 24.3 h for VPX638 versus 7.1 h for placebo (p < 0.01). In the 24 h after drug administration, participants receiving VPX638 had a 50% decrease in opioid use over 24 h compared with placebo. VPX638 appeared safe and well-tolerated. In conclusion, this small placebo-controlled randomised trial suggested that VPX638 provides analgesia and is opioid-sparing for up to 24 h after wound cleaning. It supports the need for further evaluation of the benefit of VPX638 as a topical analgesic for painful wounds.

How the magnitude and precision of pain predictions shape pain experiences

BACKGROUND

In Bayesian models including predictive processing, the magnitude and precision of pain expectancies are key determinants of perception. However, relatively few studies have directly tested whether this holds for pain, and results so far have been inconclusive. Here, we investigated expectancy effects on pain experiences and associated affective responses.

METHODS

In two studies, healthy participants (n = 30 in each) received painful electrical stimuli preceded by explicit pain predictions. In study 1, the magnitude of pain predictions and administered pain intensities were varied. In study 2, the magnitude and precision of pain predictions were varied, while administered pain intensity was kept constant. Experienced pain intensity was the primary outcome in both studies.

RESULTS

Pain experiences assimilated towards both under- and overpredictions of pain. In study 1, however, effects were small, if present at all, for non-painful stimuli and effects were not necessarily larger with predictions of greater magnitude. In study 2, assimilation of pain experiences appeared regardless of precision level, while no significant effects on EMG eyeblink startle responses were observed. Moreover, under- and overpredictions caused disappointment and relief, respectively, with greater disappointment upon precise than imprecise predictions.

CONCLUSIONS

The influence of pain predictions on pain might be more complex than assumed in simple instantiations of current theoretical frameworks, with no systematically stronger assimilation of pain experiences to larger and more precise predictions. Since overpredictions are associated with relief, but underpredictions with disappointment, these findings underline the importance of providing correct predictions when preparing for upcoming painful procedures.

SIGNIFICANCE STATEMENT

Our work supports, challenges, and extends the application of Bayesian and predictive processing frameworks to the influence of pain predictions on pain. Under- and overpredictions of pain yielded assimilation of pain experiences, but assimilation was not systematically stronger with larger prediction errors or greater precision. Moreover, under- and overpredictions resulted in disappointment and relief, respectively. This research signifies the importance of establishing accurate predictions of pain in clinical practice.

Conceptualization of pain in Croatian adults: a cross-sectional and psychometric study

AIM

To ascertain whether Croatian respondents' knowledge on pain aligns with modern pain science, and determine the measurement properties of the Croatian version of the Concept of Pain Inventory for Adults (COPI-Adult).

METHODS

A cross-sectional, online survey was used to collect the respondents' sociodemographic, clinical, and COPI-Adult (CRO) data (n = 509). A Pearson correlation coefficient test was used to assess the correlations between sociodemographic, clinical, and COPI-Adult (CRO) data. Confirmatory factor analysis and Cronbach's coefficient, based on classical test theory, were used to determine the measurement properties of the questionnaire.

RESULTS

The average COPI-Adult (CRO) score was 35.91 ± 5.8 out of 52 and it was similar in respondents with (36.52±6.01) and without (35.36±5.57) formal medical/health care education. Respondents exhibited a reductionist understanding of pain as a result of structural damage. Higher COPI-Adult scores were very weakly correlated with formal medical/health care education, younger age, lower pain intensity, higher pain knowledge self-assessment, and higher education level. Formal medical education significantly moderately correlated with pain knowledge self-assessment (r=-0.425; P<0.001). One-factor COPI-Adult (CRO) model revealed significant factor loadings of each item (P<0.001) and good internal consistency (Cronbach α=0.803).

CONCLUSIONS

Croatian respondents' concept of pain aligns with their objective knowledge, but only partially with modern pain science. This indicates the need to bridge the gap between traditional and contemporary understandings of pain in the Croatian population. One-factor COPI-Adult (CRO) inventory serves as the first questionnaire for assessing the concept of pain among Croatian adults.

Integrated manual therapies: IASP taskforce viewpoint

Introduction

Manual therapy refers to a range of hands-on interventions used by various clinical professionals, such as osteopaths, osteopathic physicians, chiropractors, massage therapists, physiotherapists, and physical therapists, to treat patients experiencing pain.

Objectives

To present existing evidence of mechanisms and clinical effectiveness of manual therapy in pain.

Methods

This Clinical Update focuses on the 2023 International Association for the Study of Pain Global Year for Integrative Pain Care. Current models of manual therapy and examples of integrative manual therapy are discussed.

Results

The evolution of concepts in recent years are presented and current gaps in knowledge to guide future research highlighted. Mechanisms of manual therapy are discussed, including specific and contextual effects. Findings from research on animal and humans in manual therapy are presented including on inflammatory markers, fibrosis, and behaviours. There is low to moderate levels of evidence that the effect sizes for manual therapy range from small to large for pain and function in tension headache, cervicogenic headache, fibromyalgia, low back pain, neck pain, knee pain, and hip pain.

Conclusion

Manual therapies appear to be effective for a variety of conditions with minimal safety concerns. There are opportunities for manual therapies to integrate new evidence in its educational, clinical, and research models. Manual therapies are also well-suited to fostering a person-centred approach to care, requiring the clinician to relinquish some of their power to the person consulting. Integrated manual therapies have recently demonstrated a fascinating evolution illustrating their adaptability and capacity to address contemporary societal challenges.

Less Pain, but no changes in maximal inclination angles during an overhead reach task following local anesthetic in patients with ongoing shoulder pain

This multicenter observational study aimed to assess how pain reduction, induced by local anesthesia, affects the relative angular contributions of the shoulder girdle and trunk to the maximal angular performance during a semi-constrained overhead reach task in patients with ongoing shoulder pain. Twenty-nine individuals (age 59.0 SD 12.8 years;16-male) with symptomatic shoulders were administered corticosteroid and lidocaine injections by their attending orthopedic surgeon. Immediately before and after the injections, participants reached for a target on the ceiling ten times as high as possible while their pain levels, shoulder, and trunk movements were recorded. The analysis revealed that there was a significant reduction in pain following the injections. However, there were no significant differences in maximum shoulder and trunk inclination angles between the pre- and post-injection conditions. Notably, there were slight but statistically significant alterations in humeroscapular kinematics during the initial phase of arm elevation following the injections. In conclusion, acute pain relief following local anesthetics is not associated with immediate alterations in maximum shoulder girdle and trunk inclination angles during a semi-constrained overhead reach task in patients with ongoing shoulder pain. However, there are signs of small alterations in humeroscapular kinematics during the initial phase of arm elevation.

Climate change anxiety and its association with somatic symptom distress and idiopathic environmental intolerances: A cross-sectional study

CONTEXT

Individuals need greater climate change awareness in order to mitigate and adapt to climate changes but this awareness can lead to negative health outcomes including climate change anxiety.

OBJECTIVE

To explore the associations between climate change anxiety, idiopathic environmental intolerances and somatic symptom distress, after accounting for modern health worries, anxiety and depression.

METHODS

A non-representative sample of healthy volunteers completed a cross-sectional online survey that included the Climate Change Anxiety scale (CCA-13), single questions about idiopathic intolerance to five environmental agents, the Somatic Symptoms scale (SSS-8), the Modern Health Worries scale (MHW-12), and the Patient Health Questionnaire for symptoms of anxiety and depression (PHQ-4). Participants also reported their sex, age and subjective socioeconomic status. Bivariate analyses investigated associations between variables and path analyses explored potential mediating factors.

RESULTS

432 participants completed the questionnaire, 421 of whom were included in analyses (67 % women, mean age: 32.7 standard deviation: 12.4). Climate change anxiety, idiopathic environmental intolerances, somatic symptom distress, modern health worries, and symptoms of anxiety and depression were positively correlated in bivariate analyses (Pearson's ranging from 0.22 to 0.57, all p < 0.001). In path analyses, modern health worries (R2 = 9.9 %) partially mediated the relation between climate change anxiety (R2 = 20.3 %) and two correlated outcome variables, idiopathic environmental intolerances (R2 = 36.8 %) and somatic symptom distress (R2 = 32.4 %).

CONCLUSIONS

Climate change anxiety may negatively affect perceived physical health. Stakeholders should aim at promoting climate change awareness while addressing modern health worries to avoid negative health outcomes.

Placebo effects in neuropathic pain conditions

Management of neuropathic pain is exceptionally challenging and development of new drugs and ways to optimize treatment effects in clinical practice are needed. Over the last decade, some of the mechanisms underlying placebo effects have been elucidated and some of the insights have the potential to improve the treatment for neuropathic pain. Research suggests that the increasing placebo responses observed in randomized controlled trials (RCTs) for neuropathic pain pose challenges for the development and availability of new effective pain medications. In neuropathic pain, these placebo responses are typically not controlled for the natural history of pain and other confounding factors. Thus, our knowledge about the magnitude and mechanisms of placebo effects in neuropathic pain is sparse. A few mechanistic studies investigating placebo effects by controlling for natural history of pain have found large placebo analgesia effects in neuropathic pain. Psychological factors such as expectations and emotions play a substantial role in inducing the placebo effects. Here, we review placebo effects and the psychological and neurobiological mechanisms contributing to the placebo effects. The knowledge obtained from studies of placebo mechanisms can help improve the information that can be obtained from RCTs and potentially improve development of new pain medications and optimize treatment of neuropathic pain in clinical practice.

The Role of Attention in Placebo and Nocebo Effects

BACKGROUND

Although some existing models propose that attention may be crucially implicated in placebo/nocebo effects, empirical research on this aspect remains limited and scattered.

PURPOSE

This systematic review aims to provide an inclusive overview of studies that have either directly manipulated or assessed attention within the context of placebo and nocebo procedures so to gain a synthetized picture of the role of this variable in placebo/nocebo effects. Importantly, only studies in which attention represented a mechanism or mediator of the placebo/nocebo response, and not a primary outcome, were included.

METHODS

A systematic search was conducted across multiple databases, including PubMed, Scopus, PsycINFO, Web of Science, and Embase, to identify peer-reviewed studies. These studies were subjected to methodological evaluation and eligibility criteria for inclusion.

RESULTS

We identified and classified 12 studies into three categories based on their focus: (i) those that directly assessed attention, (ii) those that directly manipulated participants' attention, and (iii) those that combined both a direct manipulation and assessment of attention. In all selected studies attention acted as a mechanism or mediator of the placebo/nocebo response, and was not considered a primary outcome of the placebo/nocebo manipulation.

CONCLUSIONS

The synthesis of the included studies reveals that the role of attention in placebo and nocebo effects is still a topic of debate, marked by variations in how attention is conceptualized and measured. Results suggest that attention has significant clinical implications, particularly in optimizing therapeutic efficacy by directing patients' focus toward signs of healing and away from indicators of illness or distress. To advance our understanding, future research should explore these attentional mechanisms, in conjunction with neurophysiological correlates.

Exploring the role of therapeutic alliance and biobehavioural synchrony in musculoskeletal care: Insights from a qualitative study

BACKGROUND

Person-centred care underscores the therapeutic alliance (TA) as fundamental, fostering positive treatment outcomes through collaborative patient-clinician interactions. Biobehavioural synchrony within the TA, essential for effective care, reflects an adaptive process where organisms align responses during interactions. Enactivism and active inference provide profound insights into human perception, reshaping musculoskeletal care understanding. Touch and verbal communication, integral to the TA, foster synchrony and alignment of personal beliefs.

AIM

This study aimed to identify the tools used by manual therapists in musculoskeletal care to establish a TA with patients. Furthermore, it endeavours to evaluate the alignment of these strategies with current literature and their correlation with biobehavioural synchrony, enactivism, and the role of touch in active inference.

METHODS

The methodology followed rigorous qualitative research principles, particularly Grounded Theory and interpretative-constructivist principles, conducting eleven semi-structured interviews with open-ended questions.

RESULTS

The core category identified in the study is elucidated as follows: "Interwoven Connection: The Fabric of Therapeutic Synchrony." The interviews unveiled three main categories, each comprising sub-categories: (1) Creating a meaningful dialogue; (2) Promoting active patient participation; (3) Synchronisation.

CONCLUSION

Fostering meaningful dialogue, patient involvement, and therapeutic synchrony is crucial for a robust therapeutic alliance in musculoskeletal care. This underscores the importance of establishing a deep connection between clinicians and patients, central to effective person-centred care. Clinicians must prioritise two-way communication, empathy, and patient collaboration in defining personalised goals. Emphasizing touch and seeking patient feedback are also pivotal. Further research is needed to explore these elements and their impact.

Hacking the Predictive Mind

According to active inference, constantly running prediction engines in our brain play a large role in delivering all human experience. These predictions help deliver everything we see, hear, touch, and feel. In this paper, I pursue one apparent consequence of this increasingly well-supported view. Given the constant influence of hidden predictions on human experience, can we leverage the power of prediction in the service of human flourishing? Can we learn to hack our own predictive regimes in ways that better serve our needs and purposes? Asking this question rapidly reveals a landscape that is at once familiar and new. It is also challenging, suggesting important questions about scope and dangers while casting further doubt (as if any was needed) on old assumptions about a firm mind/body divide. I review a range of possible hacks, starting with the careful use of placebos, moving on to look at chronic pain and functional disorders, and ending with some speculations concerning the complex role of genetic influences on the predictive brain.

Low dose of morphine to relieve dyspnea in acute respiratory failure: the OpiDys double-blind randomized controlled trial

BACKGROUND

Morphine relieves dyspnea in various clinical circumstances. Whether or not this applies to patients admitted to intensive care units (ICUs) for acute respiratory failure (ARF) is unknown. We evaluated the efficacy and safety of low-dose morphine on dyspnea in patients admitted to the ICU for ARF.

METHODS

In this single-center, double-blind, phase 2, randomized, controlled trial, we assigned non-intubated adults admitted to the ICU for ARF with severe dyspnea, defined by a visual analog scale for dyspnea (dyspnea-VAS) from zero (no dyspnea) to 100 mm (worst imaginable dyspnea) ≥40 mm, to receive a low dose of Morphine Hydrochloride (intravenous titration followed by subcutaneous relay) or Placebo. All patients received standard therapy, including etiological treatment and non-invasive respiratory support.

RESULTS

Twenty-two patients were randomized, 11 in each group. The average dyspnea (median [interquartile range]) over 24 hours did not significantly differ between the two groups (40 [25 - 43] mm in the Morphine group vs. 40 [36 - 49] mm in the Placebo group, p=0.411). Dyspnea-VAS was lower in the Morphine group than in the Placebo group at the end of intravenous titration (30 [11 - 30] vs. 35 [30 - 44], p=0.044) and four hours later (18 [10 - 29] vs. 50 [30 - 60], p=0.043). The cumulative probability of intubation was higher in the Morphine group than in the Placebo group (p=0.046) CONCLUSION: In this phase 2 pilot trial, morphine did not improve 24-hour average dyspnea in adult patients with ARF, even though it had a statistically significant immediate effect. Of concern, Morphine use was associated with a higher intubation rate.

TRIAL REGISTRATION

The protocol was declared on the ClinicalTrial.gov database (no. NCT04358133) and was published in September 2022.

Preoperative Anxiolysis and Treatment Expectation (PATE Trial): open-label placebo treatment to reduce preoperative anxiety in female patients undergoing gynecological laparoscopic surgery - study protocol for a bicentric, prospective, randomized-controlled trial

One of the most common concerns of patients undergoing surgery is preoperative anxiety, with a prevalence of up to 48%. The effects of preoperative anxiety continue beyond the preoperative period and are associated with more severe postoperative pain and poorer treatment outcomes. Treatment options for preoperative anxiety are often limited as sedatives cause side effects and their efficacy remains controversial. Placebo research has shown that optimization of positive treatment expectations, as can be achieved through placebo administration and education, has clinically relevant effects on preoperative anxiety, pain and treatment outcomes. As the administration of masked placebos raises ethical questions, clinical studies have increasingly focused on the use of open, non-deceptive placebo administration (open-label placebo, OLP). The use of OLPs to reduce preoperative anxiety and modify clinically relevant postoperative outcomes has not yet been investigated. This bicentric, prospective, randomized-controlled clinical trial (PATE Trial; German Registry for Clinical Studies DRKS00033221), an associated project of the Collaborative Research Center (CRC) 289 "Treatment Expectation", aims to alleviate preoperative anxiety by optimizing positive treatment expectations facilitated by OLP. Furthermore, this study examines a potential enhancement of these effects through aspects of observational learning, operationalized by a positive expectation-enhancing video. In addition, patient's perspective on the self-efficacy and appropriateness of OLPs prior to surgery will be assessed. To achieve these objectives, female patients will be randomized into three groups before undergoing gynecological laparoscopic surgery. One group receives the OLP with a positive rationale conveyed by a study physician. A second group receives the same intervention, OLP administration and rationale provided by a physician, and additionally watches a video on OLP presenting a satisfied patient. A third group receives standard treatment as usual (TAU). Outcome measures will be effects on preoperative anxiety and postoperative experience, particularly visceral and somatic postoperative pain. As the non-deceptive administration of placebos; when indicated; may yield positive outcomes without side effects, and as current treatment of preoperative anxiety is limited, evidence from clinical placebo research has the potential to improve outcomes and patient experience in the surgical setting.

Risk factors associated with nocebo effects: A review of reviews

Objective

This meta-review aims to identify and categorize the risk factors that are associated with nocebo effects. The nocebo effect can exert a negative impact on treatment outcomes and have detrimental outcomes on health. Learning more about its potential predictors and risk factors is a crucial step to mitigating it.

Methods

Literature review studies about the risk factors for nocebo effects were searched through five databases (PubMed, Scopus, The Cochrane Library, PsycINFO, and Embase) and through grey literature. Methodological validity and risk of bias were assessed. We conducted a thematic analysis of the results of the forty-three included reviews.

Results

We identified nine categories of risk factors: prior expectations and learning; socio-demographic characteristics; personality and individual differences; neurodegenerative conditions; inflammatory conditions; communication of information and patient-physician relationship; drug characteristics; setting; and self-awareness. We also highlighted the main biochemical and neurophysiological mechanisms underlying nocebo effects.

Conclusions

Nocebo effects arise from expectations of adverse symptoms, particularly when triggered by previous negative experiences. A trusting relationship with the treating physician and clear, tailored treatment instructions can act as protective factors against a nocebo effect. Clinical implications are discussed.

Epistemological Flexibility in Person-Centered Care: The Cynefin Framework for (Re)Integrating Indigenous Body Representations in Manual Therapy

BACKGROUND

Chiropractic, osteopathy, and physiotherapy (COP) professionals regulated outside the United States traditionally incorporate hands-on procedures aligned with their historical principles to guide patient care. However, some authors in COP research advocate a pan-professional, evidence-informed, patient-centered approach to musculoskeletal care, emphasizing hands-off management of patients through education and exercise therapy. The extent to which non-Western sociocultural beliefs about body representations in health and disease, including Indigenous beliefs, could influence the patient-practitioner dyad and affect the interpretation of pillars of evidence-informed practice, such as patient-centered care and patient expectations, remains unknown.

METHODS

our perspective paper combines the best available evidence with expert insights and unique viewpoints to address gaps in the scientific literature and inform an interdisciplinary readership.

RESULTS

A COP pan-professional approach tends to marginalize approaches, such as prevention-oriented clinical scenarios traditionally advocated by osteopathic practitioners for patients with non-Western sociocultural health assumptions. The Cynefin framework was introduced as a decision-making tool to aid clinicians in managing complex clinical scenarios and promoting evidence-informed, patient-centered, and culturally sensitive care.

CONCLUSION

Epistemological flexibility is historically rooted in osteopathic care, due to his Indigenous roots. It is imperative to reintroduce conceptual and operative clinical frameworks that better address contemporary health needs, promote inclusion and equality in healthcare, and enhance the quality of manual therapy services beyond COP's Western-centered perspective.

Pain perception as hierarchical Bayesian inference: A test case for the theory of constructed emotion

An intriguing perspective about human emotion, the theory of constructed emotion considers emotions as generative models according to the Bayesian brain hypothesis. This theory brings fresh insight to existing findings, but its complexity renders it challenging to test experimentally. We argue that laboratory studies of pain could support the theory because although some may not consider pain to be a genuine emotion, the theory must at minimum be able to explain pain perception and its dysfunction in pathology. We review emerging evidence that bear on this question. We cover behavioral and neural laboratory findings, computational models, placebo hyperalgesia, and chronic pain. We conclude that there is substantial evidence for a predictive processing account of painful experience, paving the way for a better understanding of neuronal and computational mechanisms of other emotions.

A Fictionalist Account of Open-Label Placebo

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

Translating knowledge on placebo and nocebo effects into clinical practice

Introduction

Positive and negative treatment expectations are powerful modulators of health and treatment outcomes. A substantial part of treatment success is due to contextual factors modulating patient's expectations towards a treatment. Consequently, treatment expectations should be a target of therapeutic interventions themselves.

Objectives

This article highlights the neurobiological underpinnings of treatment expectations as well as strategies to modulate contextual factors to optimize treatment outcomes in daily clinical settings.

Methods

This clinical update aligns with the 2022 IASP Global Year Translating Pain Knowledge into Practice and selectively reviews the best available evidence and practice.

Results

The effects of treatment expectations, also known as placebo and nocebo effects, are observed in various clinical conditions and physiological systems. However, most of our knowledge comes from the field of pain, where expectation effects substantially contribute to overall analgesic treatment outcomes. Experimental placebo analgesia paradigms provide the best illustration of how analgesic effects can be attributed not only to a pharmacological or specific treatment, but instead are the result of the expectation towards the treatment. The impact of expectations on treatment outcome is highly variable between individuals, and the identification of factors predicting an individual's response has proven to be challenging. Further research is required to provide personalized treatment strategies for the daily clinical practice.

Conclusion

Patient's previous experiences and expectations are powerful modulators of treatment efficacy, tolerability, and adherence. By providing a comprehensive overview of recent advances in this field, this review offers valuable insights for clinicians and researchers seeking to improve patient-clinician interaction.

Application of a Clinical Approach to Diagnosing Primary Pain: Prevalence and Correlates of Primary Back and Neck Pain in a Community Physiatry Clinic

Chronic back or neck pain (CBNP) can be primary (nociplastic or neuroplastic; without clear peripheral etiology) or secondary (to nociceptive or neuropathic causes). Expanding on available models of nociplastic pain, we developed a clinic-ready approach to diagnose primary/nociplastic pain: first, a standard physical exam and review of imaging to rule out secondary pain; and second, a detailed history of symptom presentation to rule in primary pain. We trained a physician who evaluated 222 patients (73.9% female, age M = 59.6) with CBNP; patients separately completed pain and psychosocial questionnaires. We estimated the prevalence of primary CBNP and explored biomedical, imaging, and psychological correlates of primary CBNP. Although almost all patients (97.7%) had at least 1 spinal anomaly on imaging, the diagnostic approach estimated that 88.3% of patients had primary pain, 5.0% had secondary pain, and 6.8% had mixed pain. Patients with primary pain were more likely than the other 2 groups of patients (combined as "non-primary pain") to report certain functional conditions, central sensitization, and features such as sensitivity to light touch, spreading pain, and pain worsening with stress; however, no difference was detected in depression, anxiety, and pain catastrophizing between those with primary and nonprimary pain. These findings are consistent with prior estimates that 85 to 90% of CBNP is "nonspecific." Further research is needed to validate and perhaps refine this diagnostic approach, which holds the potential for better outcomes if patients are offered treatments targeted to primary pain, such as pain neuroscience education and several emerging psychological therapies. PERSPECTIVE: We developed an approach to diagnose chronic primary pain, which was applied in a physiatry clinic to 222 patients with CBNP. Most patients (88.3%) had primary pain, despite almost universal anomalies on spinal imaging. This diagnostic approach can guide educational and psychological treatments tailored for primary pain.

Landau model for illustrating the learning and unlearning process of nociplastic pain

Recent advancements in understanding the consolidation of nociplastic pain point to a complex, non-conscious learned process of threat perception. Neurobiological pain education is emerging as a promising approach to unlearn nociplastic pain, supported by biopsychosocial tools such as exposure to movement, mindfulness, and group sharing formats. However, this approach is still not well-known among clinicians and the society at large, creating a communication problem that unfortunately perpetuates the suffering of patients. Herein, we propose a Landau model to describe the learning and unlearning process of nociplastic pain, aiming to clarify this complex situation and facilitate communication across different sectors of the society. Nociplastic pain corresponds to a first-order transition, with attention more likely in the alert-protection state than in the trust-explore state. Two appealing results of the model are that the perception of the critical context depends on personal history regarding the symptom and that biopsychosocial loops are formed when there is alarming learned historical information about the symptom, along with confused and contradictory expert information, as seen in nocebo messages. Learning and unlearning in the model correspond to a chang in control parametrs that can weigh more on the alert-protection state, trust-explore state, uncertain state or neutral state. This description clarifies why neurobiological education is the foundational therapy from which others must be built to embody the accessible, clear, and trustworthy information.

Soreness Reminds Me of Grief: Patients With Chronic Pain Show Less Differentiated Representations of Emotional Feelings and Bodily States

People experience similarities between emotional feelings and bodily states on a daily basis, but both the magnitude and pervasiveness of this experiential similarity vary across individuals. Inspired by previous findings that chronic pain (CP) is characterized by strengthened pain-affect coupling and reduced interoceptive accuracy, we conducted 2 cross-sectional studies to examine whether patients with CP would exhibit less differentiated perception and mental representation of emotional feelings and bodily states. In study 1 (N = 500), patients with CP and healthy controls (HCs) completed a self-report questionnaire that asked explicitly about the perceived similarity between 5 basic emotion categories and a series of bodily states. In study 2 (N = 73), a specially designed false memory test was administered to examine whether patients with CP would have reduced differentiation of concepts of negative emotion and somatic distress. We found that patients with CP perceived greater and more pervasive similarities between emotional feelings and bodily states, as indicated by higher questionnaire scores and denser, less specialized bipartite emotion-body networks, both associated with lower subjective interoceptive accuracy. Furthermore, patients with CP formed false memories of negative emotion words (eg, grief) more readily than HCs after memorizing somatic distress words (eg, soreness), as if they represented negative emotion and somatic distress as a single, enmeshed semantic category. Our findings extend previous literature by demonstrating reduced discrimination between emotional and bodily experiences in CP that is not restricted to pain-related emotional and sensory experiences and may be related to a fundamentally less differentiated interoception. PERSPECTIVES: This study shows that patients with chronic pain have a profoundly less differentiated perception and implicit conceptualization of emotional feelings and bodily states, which appears to be associated with altered interoception. These findings may provide new perspectives on why they often experience a stronger pain-affect coupling.

Episodic breathlessness in patients with cancer: definition, terminology, clinical features - integrative systematic review

PURPOSE

Breatlessness flares directly impair quality of life of patients with cancer. The aim of this review was to analyse and synthesise the available information related to its terminology, definition and clinical features in patients with cancer.

METHODS

Integrative systematic review according to Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. Literature search was conducted in MEDLINE PubMed, CINAHLPlus, Web of Science, Cochrane Central Register Controlled Trials CENTRAL, Scopus and OpenAire.

RESULTS

Data from 1065 patients with cancer included in 12 studies were analysed. The preferred term for breathlessness flares was episodic dyspnoea (ED). The reported frequency of ED was 20.4% (70.9% in patients reporting background dyspnoea (BD)). ED intensity was moderate to severe with short duration (<10 min) in >80% of patients. The most common trigger was exertion (>90%) followed by emotional or environmental factors. ED management consisted mainly of pharmacological and non-pharmacological measures.

CONCLUSIONS

This systematic review shows that ED is common in patients with cancer, especially in those with BD. Further studies are urgently needed to better understand this condition and to develop specific therapeutic management.

PROSPERO REGISTRATION NUMBER

CRD42019126708.

Not a general, symptom-unspecific, transdiagnostic marker for functional symptoms: sensorimotor processing of head control is intact in chronic pain

Introduction

Functional disorders are prevalent in all medical fields and pose a tremendous public health problem, with pain being one of the most common functional symptoms. Understanding the underlying, potentially unifying mechanism in functional (pain) disorders is instrumental in facilitating timely diagnosis, stigma reduction, and adequate treatment options. Neuroscientific models of perception suggest that functional symptoms arise due to dysregulated sensorimotor processing in the central nervous system, with brain-based predictions dominating the eventual percept. Experimental evidence for this transdiagnostic mechanism has been established in various functional symptoms. The goal of the current study was to investigate whether erroneous sensorimotor processing is an underlying transdiagnostic mechanism in chronic (functional) pain.

Method

A total of 13 patients with chronic (functional) pain [three patients with chronic (functional) pain disorder, F45.40, ICD-10; 10 patients with chronic pain disorder with somatic and psychological factors, F45.41, ICD-10]; and 15 healthy controls performed large combined eye-head gaze shifts toward visual targets, naturally and with increased head moment of inertia. We simultaneously measured participants' eye and head movements to assess head oscillations at the end of the gaze shift, which are an established indicator of (transdiagnostic) sensorimotor processing deficits of head control.

Results

Using a Bayesian analysis protocol, we found that patients with chronic (functional) pain and control participants stabilized their heads equally well (Bayes Factor 01 = 3.7, Bayes Factor exclusion = 5.23; corresponding to substantial evidence) during all sessions of the experiment.

Conclusion

Our results suggest that patients with chronic (functional) pain do not show measurable symptom-unspecific sensorimotor processing deficits. We discuss outcome parameter choice, organ system specificity, and selection of patient diagnoses as possible reasons for this result and recommend future avenues for research.

Factors perpetuating functional cognitive symptoms after mild traumatic brain injury

INTRODUCTION

Self-reported memory difficulties (forgetting familiar names, misplacing objects) often persist long after a mild traumatic brain injury (mTBI), despite normal neuropsychological test performance. This clinical presentation may be a manifestation of a functional cognitive disorder (FCD). Several mechanisms underlying FCD have been proposed, including metacognitive impairment, memory perfectionism, and misdirected attention, as well as depression or anxiety-related explanations. This study aims to explore these candidate perpetuating factors in mTBI, to advance our understanding of why memory symptoms frequently persist following mTBI.

METHODS

A cross-sectional study of 67 adults (n = 39 with mTBI mean = 25 months ago and n = 28 healthy controls). Participants completed standardized questionnaires (including the Functional Memory Disorder Inventory), a metacognitive task (to quantify discrepancies between their trial-by-trial accuracy and confidence), and a brief neuropsychological test battery. We assessed candidate mechanisms in two ways: (1) between-groups, comparing participants with mTBI to healthy controls, and (2) within-group, examining their associations with functional memory symptom severity (FMDI) in the mTBI group.

RESULTS

Participants with mTBI performed similarly to controls on objective measures of memory ability but reported experiencing much more frequent memory lapses in daily life. Contrary to expectations, metacognitive efficiency did not differentiate the mTBI and control groups and was not associated with functional memory symptoms. Memory perfectionism was strongly associated with greater functional memory symptoms among participants with mTBI but did not differ between groups when accounting for age. Depression and checking behaviors produced consistent results across between-groups and within-group analyses: these factors were greater in the mTBI group compared to the control group and were associated with greater functional memory symptoms within the mTBI group.

CONCLUSIONS

This study highlights promising (e.g., depression, checking behaviors) and unlikely (e.g., metacognitive impairment) mechanisms underlying functional memory symptoms after mTBI, to guide future research and treatment.

Mechanisms of education and graded sensorimotor retraining in people with chronic low back pain: a mediation analysis

ABSTRACT

An improved understanding of the biopsychosocial influences that contribute to and maintain pain has promoted the development of new efficacious treatments for chronic low back pain (CLBP). This study aimed to investigate the mechanisms of a new treatment-education and graded sensorimotor retraining-on pain and disability. We conducted a preplanned causal mediation analysis of a randomized clinical trial which allocated 276 participants with CLBP to 12 weekly clinical sessions of education and graded sensorimotor retraining (n = 138) or a sham and attention control (n = 138). Outcomes were pain intensity and disability, both assessed at 18 weeks. Hypothesized mediators included tactile acuity, motor coordination, back self-perception, beliefs about the consequences of back pain, kinesiophobia, pain self-efficacy, and pain catastrophizing, all assessed at the end of treatment (12 weeks). Four of 7 mechanisms (57%) mediated the intervention effect on pain; the largest mediated effects were for beliefs about back pain consequences (-0.96 [-1.47 to -0.64]), pain catastrophizing (-0.49 [-0.61 to -0.24]), and pain self-efficacy (-0.37 [-0.66 to -0.22]). Five of 7 mechanisms (71%) mediated the intervention effect on disability; the largest mediated effects were for beliefs about back pain consequences (-1.66 [-2.62 to -0.87]), pain catastrophizing (-1.06 [-1.79 to -0.53]), and pain self-efficacy (-0.84 [-1.89 to -0.45]). When all 7 mechanisms were considered simultaneously, the joint mediation effect explained most of the intervention effect for both pain and disability. Optimizing interventions to target beliefs about the consequences of back pain, pain catastrophizing, and pain self-efficacy is likely to lead to improved outcomes for people with CLBP.

Psychometric validation and refinement of the Chinese Interoceptive Accuracy Scale (IAS) in general population and patients with chronic pain

OBJECTIVE

Interoception plays an important role in psychological functioning and mental and physical health. Recent studies have highlighted the need to distinguish between different aspects of interoception in self-report measures, including subjective interoceptive accuracy and attention. However, there is currently no questionnaire available in Chinese to measure either of these aspects, especially in patients with chronic pain conditions. This paper presents a Chinese translation of the Interoceptive Accuracy Scale (IAS; Murphy et al., 2020).

METHODS

In three studies (N = 1166), we examined the factor structure and improved dimensionality of the Chinese IAS using factor analysis and item response theory models, compared its criterion validity in respondents with and without chronic pain, and examined its construct (convergent and discriminant) validity using network analysis approach.

RESULTS

We demonstrated that the Chinese IAS is essentially unidimensional and developed a refined short form (IAS-SF) with improved unidimensionality. Both the Chinese IAS and IAS-SF showed comparable criterion validity in respondents with and without chronic pain, and both showed acceptable construct validity.

CONCLUSION

Overall, the Chinese IAS and Chinese IAS-SF will be useful tools for researchers and clinicians interested in interoceptive processes in Chinese populations or cross-cultural settings, especially in pain research.

Placebo and nocebo effects and mechanisms associated with pharmacological interventions: an umbrella review

OBJECTIVES

This review aimed to summarise the existing knowledge about placebo and nocebo effects associated with pharmacological interventions and their mechanisms.

DESIGN

Umbrella review, adopting the Assessment of Multiple Systematic Reviews 2 tool for critical appraisal.

DATA SOURCES

MEDLINE/PubMed, Scopus, Web of Science, PsycINFO, Cochrane Central Register of Controlled Trial were searched in September 2022, without any time restriction, for systematic reviews, narrative reviews, original articles. Results were summarised through narrative synthesis, tables, 95% CI.

OUTCOME MEASURES

Mechanisms underlying placebo/nocebo effects and/or their effect sizes.

RESULTS

The databases search identified 372 studies, for a total of 158 312 participants, comprising 41 systematic reviews, 312 narrative reviews and 19 original articles. Seventy-three per cent of the examined systematic reviews were of high quality.Our findings revealed that mechanisms underlying placebo and/or nocebo effects have been characterised, at least in part, for: pain, non-noxious somatic sensation, Parkinson's disease, migraine, sleep disorders, intellectual disability, depression, anxiety, dementia, addiction, gynaecological disorders, attention-deficit hyperactivity disorder, immune and endocrine systems, cardiovascular and respiratory systems, gastrointestinal disorders, skin diseases, influenza and related vaccines, oncology, obesity, physical and cognitive performance. Their magnitude ranged from 0.08 to 2.01 (95% CI 0.37 to 0.89) for placebo effects and from 0.32 to 0.90 (95% CI 0.24 to 1.00) for nocebo effects.

CONCLUSIONS

This study provides a valuable tool for clinicians and researchers, identifying both results ready for clinical practice and gaps to address in the near future.

FUNDING

Università Cattolica del Sacro Cuore, Milan, Italy with the 'Finanziamento Ponte 2022' grant.

PROSPERO REGISTRATION NUMBER

CRD42023392281.

Evidencing general acceptability of open-label placebo use for tackling overtreatment in primary care: a mixed methods study

BACKGROUND

Overtreatment poses a challenge to healthcare systems due to harmful consequences of avoidable side-effects and costs. This study presents the first account for examining the feasibility of placebo use for reducing overtreatment in primary care, including whether public attitudes support the use of different placebo types in place of inappropriate prescriptions of antibiotics, antidepressants, or analgesics.

METHODS

We used a multi-study, mixed-methods design, including patient and public (PPI) consultations, focus groups (Study 1) and two pre-registered online experiments (Studies 2 and 3).

RESULTS

Study 1 (N = 16) explored everyday conceptions and practicalities of potential placebo use in the context of respiratory infections. Findings highlighted the importance of trusting doctor-patient relationships and safety-netting. Study 2 employed a randomised experiment with a representative UK sample (N = 980), investigating attitudes towards 5 different treatment options for respiratory infections: (1) blinded + pure placebo, (2) open-label + pure placebo, (3) open-label + impure placebo, (4) antibiotic treatment, and (5) no treatment. Study 2 also examined how attitudes varied based on wording and individual differences. Findings indicated general support (ηp2 = .149, large effect size) for replacing inappropriate antibiotics with open-label + impure placebos, although personal placebo acceptability was lower. Also, older people, individuals suffering from chronic illness or those showing higher levels of health anxiety appeared less amenable to placebo use. Study 3 (N = 1177) compared attitudes towards treatment options across three clinical scenarios: respiratory infection, depression and pain. Findings suggested significant differences in the acceptability of placebo options based on the clinical context. In the infection scenario, options for open-label + pure placebos, open-label + impure placebos and no treatment were rated significantly more acceptable (ηp2 = .116, medium effect size) compared to the depression and pain scenarios. Again, general support for placebos was higher than placebo acceptability for personal use.

CONCLUSIONS

Findings from PPI and three studies indicate general support for combatting overprescribing in primary care through clinical placebo use. This is an indicator for wider UK public support for a novel, behavioural strategy to target a long-standing healthcare challenge. General acceptability appears to be highest for the use of open-label + impure placebos in the context of antibiotic overprescribing.

Placebo and Nocebo Effects as Bayesian-Brain Phenomena: The Overlooked Role of Likelihood and Attention

The Bayesian-brain framework applied to placebo responses and other mind-body interactions suggests that the effects on the body result from the interaction between priors, such as expectations and learning, and likelihood, such as somatosensorial information. Significant research in this area focuses on the role of the priors, but the relevance of the likelihood has been surprisingly overlooked. One way of manipulating the relevance of the likelihood is by paying attention to sensorial information. We suggest that attention can influence both precision and position (i.e., the relative distance from the priors) of the likelihood by focusing on specific components of the somatosensorial information. Two forms of attention seem particularly relevant in this framework: mindful attention and selective attention. Attention has the potential to be considered a "major player" in placebo/nocebo research, together with expectations and learning. In terms of application, relying on attentional strategies as "amplifiers" or "silencers" of sensorial information could lead to an active involvement of individuals in shaping their care process and health. In this contribution, we discuss the theoretical implications of these intuitions with the aim to provide a comprehensive framework that includes Bayesian brain, placebo/nocebo effects, and the role of attention in mind-body interactions.

Future medicine: from molecular pathways to the collective intelligence of the body

The remarkable anatomical homeostasis exhibited by complex living organisms suggests that they are inherently reprogrammable information-processing systems that offer numerous interfaces to their physiological and anatomical problem-solving capacities. We briefly review data suggesting that the multiscale competency of living forms affords a new path for biomedicine that exploits the innate collective intelligence of tissues and organs. The concept of tissue-level allostatic goal-directedness is already bearing fruit in clinical practice. We sketch a roadmap towards 'somatic psychiatry' by using advances in bioelectricity and behavioral neuroscience to design methods that induce self-repair of structure and function. Relaxing the assumption that cellular control mechanisms are static, exploiting powerful concepts from cybernetics, behavioral science, and developmental biology may spark definitive solutions to current biomedical challenges.

Long COVID as a functional somatic symptom disorder caused by abnormally precise prior expectations during Bayesian perceptual processing: A new hypothesis and implications for pandemic response

This review proposes a model of Long-COVID where the constellation of symptoms are in fact genuinely experienced persistent physical symptoms that are usually functional in nature and therefore potentially reversible, that is, Long-COVID is a somatic symptom disorder. First, we describe what is currently known about Long-COVID in children and adults. Second, we examine reported "Long-Pandemic" effects that create a risk for similar somatic symptoms to develop in non-COVID-19 patients. Third, we describe what was known about somatization and somatic symptom disorder before the COVID-19 pandemic, and suggest that by analogy, Long-COVID may best be conceptualized as one of these disorders, with similar symptoms and predisposing, precipitating, and perpetuating factors. Fourth, we review the phenomenon of mass sociogenic (functional) illness, and the concept of nocebo effects, and suggest that by analogy, Long-COVID is compatible with these descriptions. Fifth, we describe the current theoretical model of the mechanism underlying functional disorders, the Bayesian predictive coding model for perception. This model accounts for moderators that can make symptom inferences functionally inaccurate and therefore can explain how to understand common predisposing, precipitating, and perpetuating factors. Finally, we discuss the implications of this framework for improved public health messaging during a pandemic, with recommendations for the management of Long-COVID symptoms in healthcare systems. We argue that the current public health approach has induced fear of Long-COVID in the population, including from constant messaging about disabling symptoms of Long-COVID and theorizing irreversible tissue damage as the cause of Long-COVID. This has created a self-fulfilling prophecy by inducing the very predisposing, precipitating, and perpetuating factors for the syndrome. Finally, we introduce the term "Pandemic-Response Syndrome" to describe what previously was labeled Long-COVID. This alternative perspective aims to stimulate research and serve as a lesson learned to avoid a repeat performance in the future.

Yoga and massage are associated with small experimental placebo effects in chronic orofacial pain

BACKGROUND

Complementary and Integrative Health Approaches (CIHA), including but not limited to, natural products and Mind and Body Practices (MBPs), are promising non-pharmacological adjuvants to the arsenal of pain management therapeutics. We aim to establish possible relationships between use of CIHA and the capacity of descending pain modulatory system in the form of occurrence and magnitude of placebo effects in a laboratory setting.

METHODS

This cross-sectional study investigated the relationship between self-reported use of CIHA, pain disability, and experimentally induced placebo hypoalgesia in chronic pain participants suffering from Temporomandibular Disorders (TMD). In the 361 enrolled TMD participants, placebo hypoalgesia was measured using a well-established paradigm with verbal suggestions and conditioning cues paired with distinct heat painful stimulations. Pain disability was measured with the Graded Chronic Pain Scale, and use of CIHA were recorded with a checklist as part of the medical history.

RESULTS

Use of physically oriented MBPs (e.g., yoga and massage) was associated with reduced placebo effects (F1,2110.44  = 23.15, p < 0.001, Cohen's d = 0.171). Further, linear regressions indicated that greater number of physically oriented MBPs predicted smaller placebo effects (β = -0.17, p = 0.002), and less likelihood of being a placebo responder (OR = 0.70, p = 0.004). Use of psychologically oriented MBPs and natural product were not associated with placebo effects magnitude and responsiveness.

CONCLUSIONS

Our findings suggest that use of physically oriented CIHA was associated with experimental placebo effects possibly through an optimized capability to recognize distinct somatosensorial stimulations. Future research is needed to understand the mechanisms underlying placebo-induced pain modulation in CIHA users.

SIGNIFICANCE

Chronic pain participants who use physically oriented mind-body practices, such as yoga and massage, demonstrated attenuated experimentally induced placebo hypoalgesia in comparison with those who do not use them. This finding disentangled the relationship between use of complementary and integrative approaches and placebo effects, providing the potential therapeutic perspective of endogenous pain modulation in chronic pain management.

How Instructions, Learning, and Expectations Shape Pain and Neurobiological Responses

Treatment outcomes are strongly influenced by expectations, as evidenced by the placebo effect. Meta-analyses of clinical trials reveal that placebo effects are strongest in pain, indicating that psychosocial factors directly influence pain. In this review, I focus on the neural and psychological mechanisms by which instructions, learning, and expectations shape subjective pain. I address new experimental designs that help researchers tease apart the impact of these distinct processes and evaluate the evidence regarding the neural mechanisms by which these cognitive factors shape subjective pain. Studies reveal that expectations modulate pain through parallel circuits that include both pain-specific and domain-general circuits such as those involved in affect and learning. I then review how expectations, learning, and verbal instructions impact clinical outcomes, including placebo analgesia and responses to pharmacological treatments, and discuss implications for future work.

The Biology of Placebo and Nocebo Effects on Experimental and Chronic Pain: State of the Art

(1) Background: In recent years, placebo and nocebo effects have been extensively documented in different medical conditions, including pain. The scientific literature has provided strong evidence of how the psychosocial context accompanying the treatment administration can influence the therapeutic outcome positively (placebo effects) or negatively (nocebo effects). (2) Methods: This state-of-the-art paper aims to provide an updated overview of placebo and nocebo effects on pain. (3) Results: The most common study designs, the psychological mechanisms, and neurobiological/genetic determinants of these phenomena are discussed, focusing on the differences between positive and negative context effects on pain in experimental settings on healthy volunteers and in clinical settings on chronic pain patients. Finally, the last section describes the implications for clinical and research practice to maximize the medical and scientific routine and correctly interpret the results of research studies on placebo and nocebo effects. (4) Conclusions: While studies on healthy participants seem consistent and provide a clear picture of how the brain reacts to the context, there are no unique results of the occurrence and magnitude of placebo and nocebo effects in chronic pain patients, mainly due to the heterogeneity of pain. This opens up the need for future studies on the topic.

Exploring the Experience of Breathlessness with the Common-Sense Model of Self-Regulation (CSM)

Chronic breathlessness is a multidimensional, unpleasant symptom common to many health conditions. The Common-Sense Model of Self-Regulation (CSM) was developed to help understand how individuals make sense of their illness. This model has been underused in the study of breathlessness, especially in considering how information sources are integrated within an individual's cognitive and emotional representations of breathlessness. This descriptive qualitative study explored breathlessness beliefs, expectations, and language preferences of people experiencing chronic breathlessness using the CSM. Twenty-one community-dwelling individuals living with varying levels of breathlessness-related impairment were purposively recruited. Semi-structured interviews were conducted with questions reflecting components of the CSM. Interview transcripts were synthesized using deductive and inductive content analysis. Nineteen analytical categories emerged describing a range of cognitive and emotional breathlessness representations. Representations were developed through participants' personal experience and information from external sources including health professionals and the internet. Specific words and phrases about breathlessness with helpful or nonhelpful connotations were identified as contributors to breathlessness representations. The CSM aligns with current multidimensional models of breathlessness and provides health professionals with a robust theoretical framework for exploring breathlessness beliefs and expectations.

Acute exercise as active inference in chronic musculoskeletal pain, effects on gait kinematics and muscular activity in patients and healthy participants: a study protocol for a randomised controlled laboratory trial

INTRODUCTION

Chronic musculoskeletal pain is a highly prevalent, complex and distressing condition that may negatively affect all domains of life. In view of an active inference framework, and resting on the concept of allostasis, human movement per se becomes a prerequisite for health and well-being while chronic pain becomes a sign of a system unable to attenuate an allostatic load. Previous studies on different subgroups of chronic pain conditions have demonstrated alterations in gait kinematics and muscle activity, indicating shared disturbances in the motor system from long-term allostatic load. We hypothesise that such alterations exist in heterogenous populations with chronic musculoskeletal pain, and that exposure to acute and controlled exercise may attenuate these alterations. Therefore, the main aim of this study is to investigate the acute effects of exercise on gait kinematics and activity of the back and neck muscles during diverse walking conditions in patients with chronic musculoskeletal pain compared with a reference sample consisting of healthy participants.

METHODS AND ANALYSIS

This two-sample two-armed parallel randomised controlled laboratory trial will include 40 participants with chronic musculoskeletal pain (>3 months) and 40 healthy participants. Participants will be randomly allocated to either 30 min of aerobic exercise or rest. Primary outcomes are gait kinematics (walking speed, step frequency, stride length, lumbar rotation, gait stability) and muscular activity (spatial and temporal) of the back and neck during diverse walking conditions. Secondary outcomes are variability of gait kinematics and muscle activity and subjective pain ratings assessed regularly during the trial.

ETHICS AND DISSEMINATION

The study has been approved by the Regional Ethics Review Board in Uppsala, Sweden (#2018/307). Findings will be disseminated via conference presentations, publications in peer-reviewed journals and engagement with patient support groups and clinicians.

TRIAL REGISTRATION NUMBER

NCT03882333.

Cognitive exertion affects the appraisal of one's own and other people's pain

Correctly evaluating others' pain is a crucial prosocial ability. In both clinical and private settings, caregivers assess their other people's pain, sometimes under the effect of poor sleep and high workload and fatigue. However, the effect played by such cognitive strain in the appraisal of others' pain remains unclear. Fifty participants underwent one of two demanding tasks, involving either working memory (Experiment 1: N-Back task) or cognitive interference (Experiment 2: Stroop task). After each task, participants were exposed to painful laser stimulations at three intensity levels (low, medium, high), or video-clips of patients experiencing three intensity levels of pain (low, medium, high). Participants rated the intensity of each pain event on a visual analogue scale. We found that the two tasks influenced rating of both one's own and others' pain, by decreasing the sensitivity to medium and high events. This was observed either when comparing the demanding condition to a control (Stroop), or when modelling linearly the difficulty/performance of each depleting task (N-Back). We provide converging evidence that cognitive exertion affects the subsequent appraisal of one's own and likewise others' pain.

The role of expectations, control and reward in the development of pain persistence based on a unified model

Chronic, or persistent pain affects more than 10% of adults in the general population. This makes it one of the major physical and mental health care problems. Although pain is an important acute warning signal that allows the organism to take action before tissue damage occurs, it can become persistent and its role as a warning signal thereby inadequate. Although per definition, pain can only be labeled as persistent after 3 months, the trajectory from acute to persistent pain is likely to be determined very early and might even start at the time of injury. The biopsychosocial model has revolutionized our understanding of chronic pain and paved the way for psychological treatments for persistent pain, which routinely outperform other forms of treatment. This suggests that psychological processes could also be important in shaping the very early trajectory from acute to persistent pain and that targeting these processes could prevent the development of persistent pain. In this review, we develop an integrative model and suggest novel interventions during early pain trajectories, based on predictions from this model.

From fear of falling to choking under pressure: A predictive processing perspective of disrupted motor control under anxiety

Under the Predictive Processing Framework, perception is guided by internal models that map the probabilistic relationship between sensory states and their causes. Predictive processing has contributed to a new understanding of both emotional states and motor control but is yet to be fully applied to their interaction during the breakdown of motor movements under heightened anxiety or threat. We bring together literature on anxiety and motor control to propose that predictive processing provides a unifying principle for understanding motor breakdowns as a disruption to the neuromodulatory control mechanisms that regulate the interactions of top-down predictions and bottom-up sensory signals. We illustrate this account using examples from disrupted balance and gait in populations who are anxious/fearful of falling, as well as 'choking' in elite sport. This approach can explain both rigid and inflexible movement strategies, as well as highly variable and imprecise action and conscious movement processing, and may also unite the apparently opposing self-focus and distraction approaches to choking. We generate predictions to guide future work and propose practical recommendations.

Comparative effects of hypnotic suggestion and imagery instruction on bodily awareness

Bodily awareness is informed by both sensory data and prior knowledge. Although misleading sensory signals have been repeatedly shown to affect bodily awareness, only scant attention has been given to the influence of cognitive variables. Hypnotic suggestion has recently been shown to impact visuospatial and sensorimotor representations of body-part size although the mechanisms subserving this effect are yet to be identified. Mental imagery might play a causal or facilitative role in this effect, as it has been shown to influence body awareness in previous studies. Nonetheless, current views ascribe only an epiphenomenal role to imagery in the implementation of hypnotic suggestions. This study compared the effects of hypnotic suggestion and imagery instruction for influencing the visuospatial and sensorimotor aspects of body-size representation. Both experimental manipulations produced significant increases (elongation) in both representations compared to baseline, although the effects were larger in the hypnotic suggestion condition. The effects of both manipulations were highly correlated across participants, suggesting overlapping mechanisms. Self-reports suggested that the use of voluntary imagery did not significantly contribute to the efficacy of either manipulation. Rather, top-down effects on body representations seem to be partly driven by response expectancies, spontaneous imagery, and hypnotic suggestibility in both conditions. These results are in line with current theories of suggestion and raise fundamental questions regarding the mechanisms driving the influence of cognition on body representations.

Agency affects pain inference through prior shift as opposed to likelihood precision modulation in a Bayesian pain model

Agency and expectations play a crucial role in pain perception and treatment. In the Bayesian pain model, somatosensation (likelihood) and expectations (prior) are weighted by their precision and integrated to form a pain percept (posterior). Combining pain treatment with stimulus-related expectations allows the mechanistic assessment of whether agency enters this model as a shift of the prior or a relaxation of the likelihood precision. In two experiments, heat pain was sham treated either externally or by the subject, while a predictive cue was utilized to create high or low treatment expectations. Both experiments revealed additive effects and greater pain relief under self-treatment and high treatment expectations. Formal model comparisons favored a prior shift rather than a modulation of likelihood precision. Electroencephalography revealed a theta-to-alpha effect, temporally associated with expectations, which was correlated with trial-by-trial pain ratings, further supporting a prior shift through which agency exerts its influence in the Bayesian pain model.

Pain, from perception to action: A computational perspective

Pain is driven by sensation and emotion, and in turn, it motivates decisions and actions. To fully appreciate the multidimensional nature of pain, we formulate the study of pain within a closed-loop framework of sensory-motor prediction. In this closed-loop cycle, prediction plays an important role, as the interaction between prediction and actual sensory experience shapes pain perception and subsequently, action. In this Perspective, we describe the roles of two prominent computational theories-Bayesian inference and reinforcement learning-in modeling adaptive pain behaviors. We show that prediction serves as a common theme between these two theories, and that each of these theories can explain unique aspects of the pain perception-action cycle. We discuss how these computational theories and models can improve our mechanistic understandings of pain-centered processes such as anticipation, attention, placebo hypoalgesia, and pain chronification.