Neuro-Bio-Behavioral Mechanisms of Placebo and Nocebo Responses: Implications for Clinical Trials and Clinical Practice

Allergy-like nocebo events reported with COVID-19 vaccines: a case control study

BACKGROUND

Allergy-like symptoms after COVID-19 vaccination are frequently reported, though true allergic reactions are rare. Clinical trials suggest many reported symptoms may reflect nocebo effects. This study aimed to characterize nocebo responses and identify associated factors.

RESEARCH DESIGN AND METHODS

A case-control study was conducted using pharmacovigilance records and a cross-sectional questionnaire. Cases were defined as patients reporting allergy-like symptoms without anaphylaxis; controls reported reactogenicity or localized reactions. Data on demographics, medical history, vaccinations, and psychological factors were analyzed using multivariate logistic regression to identify risk factors associated with nocebo effects.

RESULTS

Among 1038 participants, 320 were nocebo cases and 718 were controls. Cases frequently reported cutaneous (71.8%) and respiratory (38.8%) symptoms, with 43.4% occurring after the first dose. Nocebo responses were positively associated with a history of allergy (OR 1.78, 95% CI: 1.32-2.4) and COMIRNATY vaccine (OR 1.60, 95% CI: 1.20-2.14), and negatively correlated with perceived vaccine effectiveness (OR 0.93, 95% CI: 0.88-0.98).

CONCLUSIONS

The nocebo effect appears to differ by vaccine type and is more common in individuals with a history of allergy and lower perceived vaccine effectiveness. While further research is needed to validate these findings, this underscores the importance of clear, evidence-based communication to reduce nocebo responses.

Is It All in Your Head? Placebo Effects in Concussion Prevention

Sports-related concussions (SRCs) are a major health issue in athletes of varying ages, ability levels, and sports. Concerns over the short- and long-term consequences of SRCs have incentivized a wealth of products and policies aimed at reducing SRC risk. Research suggesting the effectiveness of such interventions at reducing SRCs has facilitated their adoption by sports organizations and, in some cases, product commercialization. However, the body of SRC mitigation research is almost entirely devoid of placebo or sham groups, which raises important questions about the true clinical effectiveness of these interventions. This Current Opinion explores the plausibility of placebo effects within the scope of SRC prevention, describes why the lack of placebo/sham groups in the current body of literature is problematic, and provides recommendations for including placebo/sham groups in future SRC research.

Effects of a preoperative psychological expectation-focused intervention in patients undergoing valvular surgery - the randomized controlled ValvEx (valve patients' expectations) study

BACKGROUND

Many patients experience a reduced quality of life for months after heart surgery. Besides medical factors, psychological factors such as preoperative expectations influence the recovery process. The ValvEx study investigated whether an expectation-focused preoperative intervention before heart valve surgery would (i) improve the postoperative recovery process by reducing illness-related disability and ii) impact secondary outcomes such as increased positive realistic expectations, and reduce preoperative anxiety.

METHODS

N = 89 patients undergoing heart valve surgery were randomized into 1 of 2 groups after a baseline assessment: Standard medical care (SOC) vs SOC plus psychological expectation-focused intervention (EXPECT) on the day of hospital admission. Further assessments were conducted on the evening before surgery, 4 to 6 days and 3 months after surgery. The primary outcome was illness-related disability. Constrained longitudinal data analyses were conducted to analyze the intervention effects, while the need for information was considered as a potential moderator.

RESULTS

No general effects were observed for the EXPECT intervention over time regarding the primary outcome illness-related disability (Pain Disability Index, PDI) and the secondary outcomes (P ≥ .167). The intervention effects were moderated by the individual need for information: Patients with a higher need for information who received the EXPECT intervention were less anxious on the evening before surgery (P = .020, d = 0.314) and less restricted in their quality of life 4 to 6 days after surgery compared to patients who received SOC (P = .005, d = 0.464).

CONCLUSIONS

The ValvEx study is the first multicentre study investigating the expectation-optimizing preoperative intervention in heart valve patients. The implementation of the EXPECT intervention seemed to optimize outcomes after heart valve surgery for certain patients, such as patients with a high need for information. It is possible that there were no direct effects of the EXPECT intervention because the intervention dose was too low. These preliminary findings need to be corroborated by larger multicenter trials. Trial registration The study was preregistered at ClinicalTrials (identifier: NCT04502121, https://clinicaltrials.gov/study/NCT04502121).

A biopsychological network approach to variables contributing to preoperative quality of life in patients undergoing cardiac surgery

Quality of life (QoL) in cardiac surgery patients is increasingly recognized as a critical outcome, influenced by biopsychosocial variables. This study aims to explore the associations between preoperative QoL and various psychological and biomedical variables in patients undergoing cardiac surgery. The study includes cross-sectional baseline data from 204 cardiac surgery patients in two distinct cardiac surgery samples: Data collection for the PSY-HEART I trial (coronary artery bypass grafting) was conducted from 2011 to 2015, while data for the ValvEx (valvular surgery) trial were collected between 2020 and 2022. We assessed psychological variables, such as illness beliefs and expectations, alongside biomedical variables, including body mass index, EuroSCORE II, and C-reactive protein levels. Data analysis involved partial correlation Gaussian Graphical Models (GGM) and Directed Acyclic Graphs (DAGs) to identify key nodes and pathways affecting QoL. The resulting GGM was estimated to be rather sparse (38 of 136 possible edges were present) and the case-drop bootstrap node stability estimates ranged from sufficient (CS-Coefficient Bridge Expected Influence = 0.28) to good (CS-Coefficient Expected Influence = 0.51). Our analyses revealed strong associations between psychological variables and preoperative QoL, with current and expected illness-related disability being central to the network. Medical variables showed weaker connections to QoL. The DAG indicated that expected disability influenced current disability and preoperative QoL, suggesting that preoperative expectations may be crucial for postoperative outcomes. This study underscores the importance of psychological variables, particularly illness perceptions and expectations, in determining QoL in cardiac surgery patients. Targeting these variables through preoperative interventions may enhance postoperative recovery and QoL, advocating for a biopsychosocial approach in cardiac surgery care.

Non-Pharmacological Interventions for Managing the Symptoms of Depression in Women with Breast Cancer: A Literature Review of Clinical Trials

Symptoms of depression represent a significant burden to patients with breast cancer, not only because of the psychological stress associated with their diagnosis, but also because of the adverse effects of its treatment. We reviewed the clinical trials examining the management of the symptoms of depression in breast cancer patients through different non-pharmacological interventions in different databases (PubMed, Embase, Scopus, and the American Psychological Association). Cognitive behavioural therapy, interpersonal psychotherapy or psychodynamic psychotherapy, as well as acceptance and commitment therapy have been effective in improving symptoms of depression in cancer patients with moderate to severe symptoms. Physical exercise, yoga, mindfulness, and support groups have been shown to benefit patients with mild depressive symptoms. These interventions not only showed positive results in interventions in women with breast cancer in terms of the symptoms of depression, but also highlighted their benefits for comorbid anxiety, stress, and poor sleep quality; moreover, it is suggested that these interventions should be leveraged to manage mental health issues in breast cancer patients. The molecular effects of these interventions, such as the reduction in inflammatory cytokines and cortisol levels, have seldom been reported and need further studies.

A scoping review of placebo and nocebo responses and effects: insights for clinical trials and practice

Placebo and nocebo responses and effects influence treatment outcomes across a variety of conditions. The current scoping review aims to synthesise evidence from systematic reviews and meta-analyses in both clinical and healthy populations, elucidating key determinants of placebo and nocebo responses and effects, including individual, clinical, psychological and contextual factors. Among the 306 publications identified, 83% were meta-analyses and 17% systematic reviews, with a predominance of research in medical specialties (81.7%) such as psychiatry and neurology. Placebo responses were significantly more studied than nocebo responses. Individual determinants (e.g., age), clinical determinants (e.g., baseline symptom severity) and psychological determinants (e.g., expectations) were found to influence placebo and nocebo outcomes. Contextual determinants, including trial design and the method of treatment administration, also played critical roles. Several key underinvestigated areas in the current body of systematic reviews and meta-analyses were also identified. This scoping review highlights valuable insights into the determinants of placebo and nocebo responses and effects on a group level, potentially offering practical implications for optimising clinical trial designs and enhancing patient care strategies in clinical practice. However, to fully leverage these benefits, it is crucial to address the underexplored topics through more rigorous investigations using a person-centred perspective.

Assessment of psychosocial aspects in adults in post-COVID-19 condition: the EURONET-SOMA recommendations on core outcome domains for clinical and research use

BACKGROUND

Harmonizing core outcome domains allows for pooling data, comparing interventions, and streamlining research evaluation. At the same time clinicians require concise and feasible measures for routine practice. Considering the heterogeneity of post-COVID-19 condition, a biopsychosocial approach requires sufficient coverage of the psychosocial dimension with assessments. Previous recommendations for core outcome sets have serious limitations regarding the psychosocial aspects of post-COVID-19 condition. This paper specifically focuses on psychosocial outcomes for adults with post-COVID-19 condition, providing both a comprehensive set of outcome domains for research and a streamlined clinical core set tailored for routine clinical use.

METHODS

In a structured Consensus Development Approach, the European Network to improve diagnostic, treatment, and healthcare for patients with persistent somatic symptoms (EURONET-SOMA) developed psychosocial core outcome domains and assessments regarding post-COVID-19 condition. The experts identified variables and instruments which should be considered in studies on adults suffering from post-COVID-19 condition, and which are feasible in the clinical setting and relevant for research.

RESULTS

We identified three higher-order dimensions with each encompassing several domains: The first higher-order dimension, "outcomes", encompasses (1) the classification/ diagnostics of post-COVID-19 condition, (2) somatic symptoms (including fatigue), (3) the psychopathological status and mental comorbidities, (4) the physical status and somatic comorbidities, (5) neurocognitive symptoms, and (6) illness consequences. The second higher-order domain "mechanisms" encompasses (7) cognitive components, (8) affective components, (9) behavioral components, (10) social components, and (11) psychobiological bridge markers (e.g., neuroimmunological and psychoneuroendocrinological variables). The third higher-order domain, "risk factors", includes factors such as (12) socioeconomic status and sociocultural factors, (13) pre-existing mental and somatic health issues, (14) personality factors (e.g., neuroticism), (15) adverse childhood experiences, (16) ongoing disability or pension claim, and (17) social media use. For each domain, specific instruments are suggested for research purposes and clinical use.

CONCLUSIONS

The recommended core domains help to increase consistency in a biopsychosocial approach to post-COVID-19 condition across investigations, improve synergies, and facilitate decision-making when comparing different interventional approaches. It allows to better identify relevant subgroups in heterogeneous post-COVID-19 condition populations offering practical tools for routine clinical practice through the clinical core set.

Evidence-informed language: interpretation and impact on intentions to treat - results of an online survey of medical students and specialists in German-speaking countries

OBJECTIVES

Currently, there is no generally accepted consensus on how to translate strength of evidence into language. Against this background, we here investigated how widely used verbal descriptors of evidence grades and clinical practice recommendations, respectively, are understood, interpreted and transferred into intentions to treat. We explored differences between medical specialists and undergraduate medical students.

DESIGN

Cross-sectional, anonymous online survey. Assessment was based on publicly available proposals for wording to characterise strength of evidence from randomised versus non-randomised trials and of clinical practice recommendations, respectively.

SETTING

The online survey was conducted between September 2021 and March 2022 and promoted by several professional organisations in German-speaking European countries (Germany, Austria and Switzerland).

PARTICIPANTS

Medical students, trainees and medical specialist (open to all medical specialties).

OUTCOME

The survey was composed of two sections: (1) Aim of the first survey section was to assess if the linguistic differentiation between results from randomised versus non-randomised studies is correctly understood as put forward by the proponents. To this end, participants were asked to grade the relative weight of the expression for the results of a randomised trial versus two proposals for how to express the results of non-randomised studies. (2) Next, strong positive, weak positive, weak negative and strong negative clinical recommendations were presented, and participants were asked to answer in a forced-choice format if they would treat all/no patients, selected patients or only consider treatment. Additionally, the number of eligible patients who would be treated was assessed.

RESULTS

N=1081 physicians and N=539 medical students completed the survey. (1) Less than half of the participants (48.5%) interpreted use of 'associated with' as linguistic differentiation between results from randomised versus non-randomised trials in a sense as put forward by the proponents. However, use of the subjunctive mood ('could') resulted in 87.3% correct differentiations. (2) Even with only four types of clinical practice recommendations (positive/negative and strong/weak), interpretation and translation into intention to treat, respectively, showed a heterogeneous picture: while the presentation of a strong clinical recommendation led to largely congruent responses, the interpretation of weak recommendations showed a high variability, with no clear response pattern for intentions to treat. Responses from physicians and medical students were largely comparable.

CONCLUSION

This study demonstrates limitations in the currently used linguistic expressions of strength of evidence and clinical practice recommendations and supports the need to prospectively test effects of language on intentions to treat prior to implementation of a certain wording. Study results cast doubt on that linguistic means alone will lead to optimally targeted intentions to treat.

Do patients with fibromyalgia syndrome and healthy people differ in their opinions on placebo effects in routine medical care?

OBJECTIVES

Placebo effects can relieve acute and chronic pain in both research and clinical treatments by learning mechanisms. However, the application of placebo-based treatment strategies in routine medical care is questioned. The current study investigated the opinions of patients with fibromyalgia and healthy controls regarding learning of placebo effects and their practical applications.

METHOD

An online survey asked 158 age- and sex-matched adult patients and controls (79 per group) to rate the perceived influence of various placebo learning mechanisms on pain relief, and the acceptability and perceived effectiveness of placebo-based strategies (open-label, closed-label, dose-extending, and treatment-enhancing strategies). Respondents' knowledge about placebo effects was obtained through a 7-item quiz.

RESULTS

The groups did not differ in the perceived influence of placebo learning mechanisms on pain relief (p = 0.217). Controls considered closed-label and treatment-enhancing strategies more acceptable than patients (p = 0.003 and p < 0.001), whereas controls perceived all strategies more effective. In both groups, closed-label strategies were significantly less acceptable than any other strategy (p-values < 0.001), and treatment-enhancing or dose-extending strategies were most acceptable. Higher acceptability was predicted by higher perceived effectiveness ratings (p < 0.001). Also, increased placebo knowledge was related to higher acceptability (p = 0.03) and perceived effectiveness (p < 0.001).

DISCUSSION

This survey suggests that both the medical history of patients and knowledge about placebo effects affect the acceptability and perceived effectiveness of placebo-based strategies. Furthermore, strategies that are transparent, assumed effective, or combined with existing medical treatments are deemed most acceptable. Keeping these factors in mind is essential for the clinical implementation of placebo-based strategies in routine medical care.

Shaping Treatment Expectation to Optimize Efficacy of Interleukin 17A Antagonist Secukinumab in Psoriasis Patients

Purpose

Patients' treatment expectations significantly influence the effectiveness of medical and pharmacological treatments. This clinical proof-of-concept study aimed to enhance treatment outcomes by targeting positive treatment expectations of psoriasis patients beginning systemic anti-psoriatic therapy with secukinumab, an interleukin (IL)-17A antagonist.

Patients and Methods

We randomly assigned patients to three groups: a treatment as usual (TAU) group receiving the standard 300mg dose of secukinumab, a dose-control (DC) group with 75% dose reduction and an experimental (EXP) group receiving the same reduced dose along with a "cover story" designed to positively influence treatment expectations. We evaluated skin symptoms using the Psoriasis Area and Severity Index (PASI), the Dermatology Life Quality Index (DLQI), perceived itch, mood and plasma IL-17A levels at baseline and at 1, 2, 3, 4, 8, 12, and 16 weeks post intervention.

Results

The study included N = 120 patients (average age = 45.78 years, 34% female). A high baseline expectation level (8.1 of 10 points) was observed across all groups which could not be further increased by the EXP-group's "cover story". The EXP and DC groups did not differ with regard to reaching 75% improvement in PASI scores (PASI75), a DLQI score of 0 or 1 or at least 4 points improvement in itch. Over time, the EXP-group showed a faster decline in PASI scores and anxiety symptoms compared to the DC-group, but less improvement in quality of life. IL-17A levels significantly increased throughout the treatment, with no significant differences between groups despite the 75% dose reduction.

Conclusion

This study demonstrates an attempt to modify patients' treatment expectations to enhance the effectiveness of pharmacological therapy with secukinumab in psoriasis patients. However, verbal suggestion alone did not significantly improve clinical outcomes, suggesting that future studies should explore alternative approaches to leverage placebo effects to the benefit of patients with psoriasis.

The influence of expectations on shame, rumination and cognitive flexibility: an experimental investigation on affect-regulatory characteristics of deceptive placebos

Background

Several studies identified affect-regulatory qualities of deceptive placebos within negative and positive affect. However, which specific characteristics of an affect-regulatory framing impacts the placebo effect has not yet been subject to empirical investigations. In particular, it is unclear whether placebo- induced expectations of direct emotion inhibition or emotion regulation after emotion induction elicit stronger effects in affect regulation.

Purpose

The aim of the study was to identify whether specifically framed expectations on the occurrence (antecedent-focused) vs. regulation capability (response-modulating) of affect, induced with an active placebo nasal-spray, have effects on affect-regulatory processes. Because personality traits have been suspected to influence placebo responses and affect regulation, an additional goal of the study was to examine modulating influences of shame proneness, level of depression, experiential avoidance, and emotional control.

Methods

Healthy volunteers (n = 121) were randomized to either a deceptive placebo condition (antecedent-focused vs. response-modulating instruction) or a no-treatment control group before shame was experimentally induced via autobiographical recall. Groups were compared on outcomes of state shame, rumination, and cognitive flexibility.

Results

Both antecedent-focused and response-modulating placebo framings influenced changes in state shame (b = 3.08, 95% CI = [0.80-5.92], p = 0.044), rumination (b = 4.80, 95% CI = [1.50-8.09], p ≤ 0.001) and cognitive flexibility outcomes (b = -3.63, 95% CI = [-6.75 - -0.51], p = 0.011) after shame-induction interventions. Only the antecedent-focused placebo response was modulated by personality traits. Experiential avoidance modulated shame experience (F(2,115) = 3.470, p = 0.031) whereas emotional control influenced the reports of state rumination (F(2,115) = 4.588, p = 0.012). No modulatory influences of levels of depression and shame proneness could be observed (ps > 0.05).

Conclusion

The results suggest that shame, rumination and cognitive flexibility can be positively influenced by placebo treatment in healthy subjects. Personality traits of emotional control and experiential avoidance influenced the placebo response of the antecedent-focused treatment rationale on outcomes individually.

Clinical trial registration

ClinicalTrials.gov, identifier NCT05372744.

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.

The jeong and haan of Vincent van Gogh: neuropeptides of bondedness and loss

We introduce two Korean-named yet transcultural feelings, jeong and haan, to fill gaps in neuroscientific understanding of mammalian bondedness, loss, and aggression. Jeong is a visceral sense of connectedness to a person, place, or thing that may arise after proximity, yet does not require intimacy. The brain opioid theory of social attachment (BOTSA) supports the idea that jeong involves increased activity of enkephalins and beta-endorphins. We propose that withdrawal of jeong-related neuropeptides leads to original haan, a sense of "missingness" that is too subtle to be grossly dysphoric. Through narrative, cognitive appraisals, or moral assignments, however, original haan may transform into the feeling of constructed haan-resentment, bitterness, grievance, sorrow, or suppressed anger. In males, the transformation may be driven by arginine vasopressin, an ancient fight-or-flight neurohormone. Constructed haan may also be driven by vasopressin in females, though data is more sparse, and in both sexes it may depend on situational or societal context. Endogenous opioids inhibit vasopressin, so that when jeong diminishes, vasopressin release may become disinhibited. This relationship implies a companion to the BOTSA, which we articulate as the brain opioid and vasopressin theory of original and constructed haan (BOVTOCH). To illustrate, we reflect on borderline personality disorder, and Vincent van Gogh's self-severing of his ear while living and working with Paul Gauguin, and fearing abandonment by him; yet to understand Van Gogh more completely we also present the brain opioid theory of stable euphoric creativity (BOTSEC), to model the subjective "highs" associated with creative flow states. Together these brain opioid theories may help to explain how feelings related to social bondedness can influence a range of phenomena. For example, opioid drug dependence may be, at least partly, a maladaptive response to feelings of isolation or disconnectedness; the health protective effects of social bonds could be related to tonic exposure to endogenous opioids and their anti-inflammatory properties; endogenous opioid-based social relational enhancement may contribute to placebo responding. Finally we conclude by pointing out the possibility of virtuous cycles of social connectedness and creativity, when feelings of bondedness and euphoric flow reinforce one another through endogenous opioid elevation.

Side-effect expectations are associated with disability, physical fitness, and somatic symptoms 3 months after post-COVID neurological inpatient rehabilitation

INTRODUCTION

The COVID-19 pandemic, caused by SARS-CoV-2, has led to long-term health issues known as post-COVID-19 condition, including fatigue and cognitive disruptions. Despite its recognition as a public health concern, the efficacy of therapeutic interventions, especially in neurological rehabilitation, remains unclear. This study examines how treatment expectations are associated with psychological and physical outcomes in post-COVID-19 condition neurological rehabilitation.

METHODS

In an observational cohort study 61 patients with confirmed post-COVID-19 condition were included. Baseline (T0) data on treatment and side effect expectations were collected, before participants underwent a 4-6 week multidisciplinary rehabilitation program. Primary outcome was illness-related disability (Pain Disability Index). Secondary outcomes included depressive symptoms (PHQ-9), anxiety levels (GAD-7), functional status (PCFS), fatigue (CFS), and physical fitness (6MWT). Regression models analyzed the associations of baseline expectations with outcomes at the end of rehabilitation (T1) and three months post-rehabilitation (T2).

RESULTS

After adjusting for multiple testing, higher baseline side-effect expectations were associated with greater illness-related disability (β = 0.42, p = 0.007), reduced physical fitness (β = - 0.24, p = 0.04), and more somatic symptoms (β = 0.33, p = 0.006) at follow-up (T2). Positive treatment expectations were associated with poorer functional status (β = 0.35, p = 0.011) at T2.

CONCLUSION

This study highlights the associations of side-effect expectations with post-COVID-19 condition rehabilitation outcomes. Higher side-effect expectations were associated to poorer outcomes, indicating a nocebo effect. Surprisingly, positive expectations were linked to worse outcomes, possibly due to unrealistic optimism. Managing patient expectations realistically and addressing side-effect concerns seems crucial for optimizing rehabilitation outcomes.

Effects of Progesterone on Vasomotor Symptoms in Postmenopausal Women (PROGEST) - a Prospective Multi-Center Randomized Double-Blind Placebo-Controlled Trial (RDPCT)

Introduction Monotherapy with progesterone for treatment of vasomotor symptoms (VMS) was more effective than placebo treatment of postmenopausal healthy women in a Canadian trial. The PROGEST-trial was initiated to fulfill FDA-approval criteria for the indication of treatment of postmenopausal VMS. Methods This prospective randomized, double-blind placebo-controlled clinical trial studied three doses of oral micronized progesterone (200 mg, 300 mg, 400 mg) and placebo for 12 weeks. Postmenopausal women with moderate to severe VMS (> 50 per week) were screened for one week for VMS frequency, then randomized to 200, 300 or 400 mg progesterone daily or placebo for a double-blinded trial of 12 weeks duration. Results 74 women were recruited in 12 study centers. 44 terminated the study as per protocol (PP). Moderate to severe hot flushes decreased by 7.4/d in the placebo arm, 7.7 VMS/d with 200 mg/d progesterone (P4), 8.3 VMS/d on 300 mg/d and 9.0 VMS/d on 400 mg/d P4, respectively by week 12. 32 treatment emergent adverse events were documented in 18 participants, mostly minor AEs. The only SAE was a syncope requiring hospitalization on the day after treatment initiation, leading to discontinuation of the drug. Discussion Baseline VMS frequency was much higher in the German than in the Canadian study and the course of the placebo group had a markedly stronger decrease in VMS-frequency during the PROGEST study (-7.4/d) than in the Canadian trial (-1.4/d). Trial populations differed by age, BMI, the number of women with natural menopause, and comorbidities, mainly hypertension. Conclusion Premature discontinuation of the trial due to insufficient subject accrual rate led to only 55 randomized participants for analysis, therefore the study results lack statistical power. Still, a slight dose-dependent improvement in VMS was seen for all doses, while AE frequency did not increase with progesterone dose.

Repeated saline injections reduce the pulmonary allergic inflammatory response in rats by inducing short-term stress

Purpose

Asthma is characterized by pulmonary cell infiltration and hyper-responsiveness of the airways. Short-term stress reduces airway inflammation. Thus, in the present study, we examined the effects of short-term stress induced by repeated treatment with saline injections on the pulmonary allergic inflammatory response in rats.

Methods

Adult male rats were divided into three groups: Naïve group (non-sensitized, challenged, or treated rats), Control group (rats sensitized with ovalbumin (OVA) to induce lung inflammation), and Saline group (rats treated for five days with saline before OVA sensitization). Inhalation challenges were performed one week after the booster with aerosolized OVA. On day 18, the effect of saline injections on total and differential leukocytes in bronchoalveolar lavage (BAL), femoral marrow lavage (FML), and blood was evaluated. The percentage of mucus, serum corticosterone, collagen, cytokines in lung explants, and norepinephrine levels were also measured.

Results

OVA sensitization increased the circulating leukocytes and their migration to the lung, decreasing the bone marrow leukocytes. The repeated saline injections prevented this migration by decreasing the number of leukocytes in BAL and blood in the control group. Cytokine Interleukin-4 (IL-4) was higher in the control group than in the naive and saline groups; cytokines Interleukin-6 (IL-6), Interleukin-10 (IL-10), and tumor necrosis factor-alpha (TNFα) were higher in the control and saline groups than in the naïve group; Interferon gamma (IFNγ) was higher in the saline group than in the naive and control groups; norepinephrine increased in animals sensitized with OVA and was higher only in the saline group relative to the naïve group.

Conclusions

These results suggest that short-term stress could contribute to the anti-allergic airway inflammation effects of a given treatment.

Dopamine has no direct causal role in the formation of treatment expectations and placebo analgesia in humans

Dopamine-based reward and learning mechanisms have been suggested to contribute to placebo effects. However, the exact role of dopaminergic neurotransmission in their generation and maintenance is still unclear. This study aimed to shed light on the causal role of dopamine in establishing positive treatment expectations, as well as on the magnitude and duration of their effect on pain. To this end, we used an established placebo analgesia paradigm in combination with 2 opposing pharmacological modulations of dopaminergic tone, i.e., the dopamine antagonist sulpiride and the dopamine precursor L-dopa which were both applied in an experimental, double-blind, randomized, placebo-controlled trial with a between-subject design in N = 168 healthy volunteers. The study medication successfully altered dopaminergic tone during the conditioning procedure. Contrary to our hypotheses, the medication did not modulate the formation of positive treatment expectation and placebo analgesia tested 1 day later. Placebo analgesia was no longer detectable on day 8 after conditioning. Using a combined frequentist and Bayesian approach, our data provide strong evidence against a direct dopaminergic influence on the generation and maintenance of placebo effects. Further exploration of the neurochemical mechanisms underlying placebo analgesia remains paramount in the quest to exploit these effects for optimal treatment outcomes. Trial registration: ClinicalTrials.gov German Clinical Trials Register, ID: DRKS00029366, https://drks.de/search/en/trial/DRKS00029366.

Pain, mindfulness, and placebo: a systematic review

Introduction

Pain is a complex phenomenon influenced by psychosocial variables, including the placebo effect. The effectiveness of mindfulness-based interventions (MBIs) for pain has been demonstrated in experimental studies and systematic reviews, but the mechanisms of action are only starting to be established. Whether the expectations of individuals experiencing pain can be manipulated during MBIs remains to be systematically evaluated, and what role placebo effects might play remains to be explored.

Methods

To evaluate the literature analyzing placebo effects in MBIs for pain, we performed a systematic review based on searches conducted in PubMed, Web of Science, and SCOPUS databases. Our search revealed a total of 272 studies, of which only 19 studies were included (10 acute pain and nine chronic pain), considering the inclusion and exclusion criteria related to expectations and placebo effects.

Results

From the 19 included studies, six measured placebo effects only in relation to the pharmacological intervention used in the study and not to an MBI.

Discussion

The results of the few studies that focused on the placebo effects of the MBIs indicate that placebo and expectations play a role in the MBIs' effects on pain. Although expectations and placebo effects are frequently discussed in the context of mindfulness and pain research, these results show that these factors are still not routinely considered in experimental designs. However, the results of the few studies included in this systematic review highlight a clear role for placebo and expectancy effects in the overall effects of MBIs for both acute and chronic pain, suggesting that routine measurement and further consideration in future studies are warranted. Additional research in this fascinating and challenging field is necessary to fully understand the connection between MBIs, placebo/expectations, and their effects on pain relief.

The development of an implicit measure of treatment expectations

In three preregistered studies, we investigated whether implicit treatment expectations, using a relational implicit measure (the MT-PEP), vary between participants provided opposing information about novel medical treatments (Studies 1 and 2) or who responded based on normative beliefs toward common over-the-counter drugs (Study 3). The studies revealed large Cohen's d effect sizes of both novel and well-known treatment information within the implicit measure. The studies also provide evidence of convergent validity, with MT-PEP scores associated with explicit beliefs about medicine and over-the-counter drug familiarity. Implicit treatment expectations can be assessed and offer a novel tool for the intersection of social psychology and medicine.

Optimizing placebo and minimizing nocebo effects through communication: e-learning and virtual reality training development

BACKGROUND

The effects of many treatments in healthcare are determined by factors other than the treatment itself. Patients' expectations and the relationship with their healthcare provider can significantly affect treatment outcomes and thereby play a major role in eliciting placebo and nocebo effects. We aim to develop and evaluate an innovative communication training, consisting of an e-learning and virtual reality (VR) training, for healthcare providers across all disciplines, to optimize placebo and minimize nocebo effects through healthcare provider-patient communication. The current paper describes the development, mid-term evaluation, optimization, and final evaluation of the communication training, conducted in The Netherlands.

METHODS

The development of both the e-learning and the VR training consisted of four phases: 1) content and technical development, 2) mid-term evaluation by healthcare providers and placebo/communication researchers, 3) optimization of the training, and 4) final evaluation by healthcare providers. To ensure the success, applicability, authenticity, and user-friendliness of the communication training, there was ongoing structural collaboration with healthcare providers as future end users, experts in the field of placebo/communication research, and educational experts in all phases.

RESULTS

Placebo/communication researchers and healthcare providers evaluated the e-learning positively (overall 7.9 on 0-10 scale) and the content was perceived as useful, accessible, and interesting. The VR training was assessed with an overall 6.9 (0-10 scale) and was evaluated as user-friendly and a safe method for practicing communication skills. Although there were some concerns regarding the authenticity of the VR training (i.e. to what extent the virtual patient reacts like a real patient), placebo and communication researchers, as well as healthcare providers, recognized the significant potential of the VR training for the future.

CONCLUSIONS

We have developed an innovative and user-friendly communication training, consisting of an e-learning and VR training (2D and 3D), that can be used to teach healthcare providers how to optimize placebo effects and minimize nocebo effects through healthcare provider-patient communication. Future studies can work on improved authenticity, translate the training into other languages and cultures, expand with additional VR cases, and measure the expected effects on providers communication skills and subsequently patient outcomes.

"I Was Almost in Disbelief" - Qualitative Analysis of Experiences and Expectations Among Psoriasis Patients Undergoing Biologic Treatment with Secukinumab

Purpose

Psoriasis is a highly debilitating chronic inflammatory disease. Increased understanding of its pathophysiology has enabled development of targeted treatments such as biologics. Several medical treatments have been shown to be influenced by patients' experiences and expectations. However, only little is known about patients' experiences with and expectations towards biologics. Our objectives were to identify patients' treatment experiences and treatment expectations and assess their trajectories over the course of treatment with the IL-17A inhibitor secukinumab. Moreover, we aimed to document effects of psoriasis, factors that influence symptomatology, and prior treatment experiences.

Patients and Methods

We conducted semi-structured interviews with n = 24 patients with moderate-to-severe plaque psoriasis and employed a qualitative content analysis to derive thematic and evaluative codes. Findings were validated via peer debriefings with experienced dermatologists.

Results

Patients reported burdensome physical and psychological psoriasis symptoms and identified factors that can improve or worsen symptomatology, including stress and self-efficacy. Prior treatment experiences were mostly negative. Past barriers to effective treatment included time constraints or limited access. Concerning secukinumab, patients initially expected complete to partial remission of symptoms and occurrence or absence of side effects. Closer inspection of expectations and experiences revealed three trajectories. For most patients, initial expectations were met and future expectations remained unchanged. For the other patients, however, the experience did not match their initial expectation. One group then adapted their future expectations according to their experience, while the other group did not.

Conclusion

To our knowledge, this is the first qualitative study to assess expectations towards treatment effectiveness and side effects, their trajectories, and interplay with experiences among psoriasis patients. Our findings highlight the value of further research on the subject in order to optimize care for psoriasis patients and to learn more about the trajectories and influence of treatment expectations in general.

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

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

Working with patients' treatment expectations - what we can learn from homeopathy

The usual homeopathic remedy, "globules," does not contain any pharmacologically active ingredient. However, many patients and practitioners report beneficial effects of homeopathic treatment on various health outcomes. Experimental and clinical research of the last two decades analyzing the underlying mechanisms of the placebo effect could explain this phenomenon, with patients' treatment expectations as the predominant mechanism. Treatment expectations can be optimized through various factors, such as prior information, communication, and treatment context. This narrative review analyses how homeopathy successfully utilizes these factors. Subsequently, it is discussed what evidence-based medicine could learn from homeopathic practice to optimize treatment expectations (e.g., using an empathic, patient-centered communication style, deliberately selecting objects in practice rooms, or using clear treatment rituals and salient contextual stimuli) and thereby treatment effectiveness. Homeopathic remedy does not work beyond the placebo effect but is recommended or prescribed as an active treatment by those who believe in it. Thus, practitioners need to understand the manner in which homeopathy (as an example of inert treatment) works and are advised to reintegrate its underlying effective placebo mechanisms into evidence-based medicine. This promises to increase treatment efficacy, tolerability, satisfaction, and compliance with evidence-based treatments, and addresses the desires patients are trying to satisfy in homeopathy in an ethical, fully informed way that is grounded in evidence-based medicine.

Learning by observing: a systematic exploration of modulatory factors and the impact of observationally induced placebo and nocebo effects on treatment outcomes

Introduction

Observational learning (OL) refers to learning through observing other people's behavior. OL has been suggested as an effective and simple tool to evoke treatment expectations and corresponding placebo and nocebo effects. However, the exact mechanisms by which OL shapes treatment outcomes, its moderating factors and possible areas of application remain unclear. We thus reviewed the existing literature with two different literature searches to answer the following questions: Which influencing factors contribute to OL-induced placebo and nocebo effects (in healthy volunteers and patients) and how large are these effects (search 1)? In which medical fields has OL been used so far to modulate treatment expectancy and treatment outcomes in patients, their caregivers, and at-risk groups (search 2)? We also aimed to explore whether and how the assessment of treatment expectations has been incorporated.

Methods

We conducted two independent and comprehensive systematic literature searches, both carried out on September 20, 2022.

Results

We identified 21 studies that investigated OL-mediated placebo and nocebo effects for pain and itch, the (placebo) efficacy of sham treatment on anxiety, and the (nocebo) induction of medication side effects (search 1). Studies showed that OL can efficiently induce placebo and nocebo effects across different presentation modes, with medium effect sizes on average: placebo effects, d = 0.79 (range: d = -0.36-1.58), nocebo effects, d = 0.61 (range: d = 0.04-1.5). Although several moderating factors have been investigated, their contribution to OL-induced effects remains unclear because of inconsistent results. Treatment expectation was assessed in only four studies. Regarding medical applications of OL (search 2), we found 12 studies. They showed that OL was effectively applied in preventive, therapeutic and rehabilitative interventions and that it was mainly used in the field of psychosomatics.

Discussion

OL effects on treatment outcomes can be both positive and negative. Future research should investigate which individuals would benefit most from OL and how OL can be implemented most effectively to induce placebo and avoid nocebo effects in clinical settings.

Systematic review registration

This work was preregistered at the Center for Open Science as open-ended registration (doi: 10.17605/OSF.IO/FVHKE). The protocol can be found here: https://archive.org/details/osf-registrations-fvhke-v1.

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.

Negative expectations (nocebo phenomenon) in clinical interventions: A scoping review

Unpredictable, undesirable, and confusing reactions in the face of psychological or medical interventions make the clinical presentation more complicated and may represent clinically unexplained symptoms and also disturbed the doctor-patients relationship and decrease patients' benefits of treatment. It seems that negative expectations from the treatment (nocebo phenomenon) can explain such reactions. The aim of the current study is a scoping review and investigate different aspects of the nocebo phenomenon (negative expectations) in clinical interventions. This paper follows a scoping review of the existence, importance, and multidimensions of the nocebo phenomenon in medical and psychological interventions. Data sources include literature databases (ProQuest, PubMed, Google Scholar, and Scopus) reviewed from inception dates to 2023, and the terms negative expectations, nocebo effect, placebo effect, negative placebo, and clinical interventions were searched. The review of the available articles showed that negative expectations play an important role in the process and effectiveness of clinical interventions. Negative expectations (here named nocebo effect) can significantly interfere with rapport and treatment processes. Some underlying components of the nocebo effect include negative expectancies, conditioning, social learning, memory, cognitive distortions, meaning, motivation, somatic focus, negative reinforcements, personality, anxiety, and neurophysiological factors such as CCK, dopamine, and cortisol are proposed for development and presence of nocebo phenomenon in clinical practice. Negative expectations with its biopsychosocial aspects play an important and amazing role in disorganizing medical and psychological interventions. Using appropriate methods to reduce nocebo effects in therapeutic interventions may increase treatment compliance and adherence and increase the effectiveness of interventions.

Discontinuation of Fumaric Acid Esters is Affected by Depressive Symptomatology: A Retrospective Analysis

Fumaric acid esters (FAEs) remain a widespread therapy option for moderate-to-severe psoriasis. However, drug survival of FAEs is limited by adverse events (AEs) or inadequate treatment response. Depressive disturbances are highly prevalent in psoriasis patients and are hypothesized to be associated with the reporting of AEs and therapy discontinuation. This study's aim was to analyze whether psoriasis patients with comorbid depressive symptomatology are more likely to discontinue treatment with FAEs due to AEs and/or inadequate treatment response. Data were retrospectively extracted from the records of patients starting therapy with FAEs in the Department of Dermatology, University Hospital Essen, Germany between 2017 and 2022, covering the first 52 weeks of treatment. Psoriasis severity and depressive symptomatology, as well as AEs and therapy discontinuation, were analyzed. Psoriasis patients (N = 95, 47.37% female) with depressive symptomatology (42.11%) were more likely to discontinue therapy due to patient-reported AEs, while the total number of reported AEs was not associated with depression. The results support the hypothesis that among psoriasis patients with depressive symptoms, the associated introspection and somatization may result in increased sensitivity for AEs and thus in quicker therapy discontinuation. In these patients, the occurrence of nocebo effects should be minimized, e.g. by special communication techniques.

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

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

The influence of psychological traits and prior experience on treatment expectations

BACKGROUND

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

METHODS

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

RESULTS

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

DISCUSSION

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

How Can Experimental Endotoxemia Contribute to Our Understanding of Pain? A Narrative Review

The immune system and the central nervous system exchange information continuously. This communication is a prerequisite for adaptive responses to physiological and psychological stressors. While the implicate relationship between inflammation and pain is increasingly recognized in clinical cohorts, the underlying mechanisms and the possibilities for pharmacological and psychological approaches aimed at neuro-immune communication in pain are not fully understood yet. This calls for preclinical models which build a bridge from clinical research to laboratory research. Experimental models of systemic inflammation (experimental endotoxemia) in humans have been increasingly recognized as an approach to study the direct and causal effects of inflammation on pain perception. This narrative review provides an overview of what experimental endotoxemia studies on pain have been able to clarify so far. We report that experimental endotoxemia results in a reproducible increase in pain sensitivity, particularly for pressure and visceral pain (deep pain), which is reflected in responses of brain areas involved in pain processing. Increased levels of blood inflammatory cytokines are required for this effect, but cytokine levels do not always predict pain intensity. We address sex-dependent differences in immunological responses to endotoxin and discuss why these differences do not necessarily translate to differences in behavioral measures. We summarize psychological and cognitive factors that may moderate pain sensitization driven by immune activation. Together, studying the immune-driven changes in pain during endotoxemia offers a deeper mechanistic understanding of the role of inflammation in chronic pain. Experimental endotoxemia models can specifically help to tease out inflammatory mechanisms underlying individual differences, vulnerabilities, and comorbid psychological problems in pain syndromes. The model offers the opportunity to test the efficacy of interventions, increasing their translational applicability for personalized medical approaches.

To respond or not to respond: exploring empathy-related psychological and structural brain differences between placebo analgesia responders and non-responders

Introduction

Placebo responsiveness is highly variable across individuals. In the domain of pain, it may range from pronounced hypoalgesia to no response at all. Which factors predict such variation awaits clarification, as the available literature is characterized by mixed and inconclusive results. Particularly interesting in this case are social factors such as empathy or prosocial behavior, as prior work has stressed the connection between feeling pain yourself and empathizing with pain observed in others.

Methods

In a mixed confirmatory and exploratory approach, this study investigated potential psychological and structural brain differences between placebo responders and non-responders in the domain of pain. We aggregated data of four behavioral and neuroimaging studies that had been designed to investigate the effects of placebo analgesia on empathy.

Results

Analyses comparing groups of placebo responders and non-responders showed significant group differences in trait characteristics, with responders reporting increased helping behavior and lower psychopathic traits compared to non-responders. Uncorrected results further showed higher pain-related empathic concern in responders vs. non-responders. These results were accompaniedby tentative group differences in brain structure: placebo analgesia non-responders exhibited increased gray matter volume in left inferior temporal and parietal supramarginal cortical areas, and an increased cortical surface area in bilateral middle temporal cortex.

Discussion

Together, our findings suggest that modifiability of one's pain perception by means of placebo effects is linked to personality traits characterizing social emotions and behavior. They also hint that these psychological as well as brain structural characteristics might be beneficial for the identification of placebo responders. At the same time, they stress the importance of considering contextual factors such as the study setting or paradigm when investigating the association between individual characteristics and placebo responding.

How familiar are German dermatologists with placebo and nocebo effects and to what extent are these targeted in clinical practice: A survey within the dermatological community

BACKGROUND

Every medical treatment inevitably comprises not only physiological, but also psychological components, reflected by placebo and nocebo effects, which significantly affect treatment outcome. However, the extent of knowledge on the mechanisms steering placebo and nocebo effects in the dermatological community in Germany is currently unclear.

OBJECTIVES

To assess the state of knowledge about placebo and nocebo effects in the German dermatological community, to evaluate whether this knowledge is already being used in clinical practice, and to investigate whether German dermatologists are interested in learning more about the topic.

METHODS

German Dermatologists, the majority working in their own practice, were asked to fill in an online survey addressing the knowledge about placebo and nocebo effects and the feasibility of special techniques to enhance placebo and minimize nocebo effects within the clinical routine.

RESULTS

N = 154 complete (79%) or partial (21%) responses to the survey were recorded in the online database and included in the analysis. All participants reported to know what the placebo effect is and 59.7% (74/124) indicated that they already had experience with prescribing or recommending a treatment without active substances. In contrast, only 62.0% (80/129) stated to know what the nocebo effect is. Participants showed a rather superficial knowledge regarding placebo and nocebo mechanisms. The majority of participants (76.7%, 99/129) expressed their willingness to be further educated about the underlying mechanisms mediating placebo and nocebo effects and the possible application in clinical practice.

CONCLUSIONS

The current survey offers a so far unique insight into the state of knowledge of German dermatologists on placebo and nocebo effects. The results indicate a need for education about this topic. Encouragingly, however, German dermatologists considered communication strategies to maximize placebo and reduce nocebo effects and expressed motivation to be trained to implement these strategies in everyday clinical practice.

Psychological distress, perceived stress and nocebo effect (multifood adverse reaction) in irritable bowel syndrome patients

BACKGROUND

Psychological distress and perceived stress may complicate the clinical presentation, course, and treatment of patients with functional gastrointestinal disorders. The correlation between psychological distress, perceived stress, and the nocebo effect (multifood adverse reaction) in patients with irritable bowel syndrome (IBS) was the main aim of the present study.

MATERIALS AND METHODS

In this cross-sectional correlation study, data on 4,763 Iranian adults, 748 of whom by purposive sampling were patients with IBS (65.1% female), working in 50 different health centers affiliated to the Isfahan University of Medical Sciences across Isfahan province were examined. For assessing dietary intake, a 106-item self-administered Dish-based Semi-Quantitative Food Frequency Questionnaire that was specifically designed and validated for Iranian adults was used. General Heath Questionnaire 12 and Stressful Life event Questionnaire were used to assess psychological distress and perceived stress. By using a modified Persian version of the Rome III questionnaire, IBS was assessed. Based on researcher-made definition of nocebo effect (multiitem food intolerance), 164 people had the nocebo phenomenon in IBS group.

RESULTS

Age, sex, education, marital status, antidepressant use, and specifically chronic underlying disease (odds ratio [OR]: 3.54, 95% confidence interval [CI]: 1.73-7.23) of general characteristics had a significant correlation (P <.05) with presenting nocebo responses in IBS patients. Psychological distress (OR: 1.415; 95% CI: 0.992-2.020; P = 0.056) had a significant correlation with nocebo effect and did not find significant correlation with perceived stress (OR: 0.999; 95% CI: 0.990-1.008; P = 0.865). Data were analyzed by Chi-square test, analysis of variance, and OR.

CONCLUSION

The present study showed that psychological distress with chronic underlying disease and antidepressant use are important elements in presenting multifood adverse reactions that we named here as the nocebo effect in IBS patients. Reducing psychological distress and managing chronic underlying diseases appear to be an effective factor in reducing the nocebo phenomenon in IBS patients. For managing the nocebo responses in IBS patients, these findings may help clinicians to improve their interventions. Further studies are required to confirm these findings.

Hydrocortisone to reduce dexamethasone-induced neurobehavioral side-effects in children with acute lymphoblastic leukaemia-results of a double-blind, randomised controlled trial with cross-over design

BACKGROUND

Dexamethasone is a cornerstone of paediatric acute lymphoblastic leukaemia (ALL) treatment, although it can induce serious side-effects. Our previous study suggests that children who suffer most from neurobehavioural side-effects might benefit from physiological hydrocortisone in addition to dexamethasone treatment. This study aimed to validate this finding.

METHODS

Our phase three, double-blind, randomised controlled trial with cross-over design included ALL patients (3-18 years) during medium-risk maintenance therapy in a national tertiary hospital between 17th May 2018 and 5th August 2020. A baseline measurement before and after a 5-day dexamethasone course was performed, whereafter 52 patients with clinically relevant neurobehavioural problems were randomised to receive an intervention during four subsequent dexamethasone courses. The intervention consisted of two courses hydrocortisone (physiological dose 10 mg/m2/d in circadian rhythm), followed by two courses placebo, or vice versa. Neurobehavioural problems were assessed before and after each course using the parent-reported Strengths and Difficulties Questionnaire (SDQ) as primary end-point. Secondary end-points were sleep problems, health-related quality of life (HRQoL), hunger feeling, and parental stress, measured with questionnaires and actigraphy. A generalised mixed model was estimated to study the intervention effect.

RESULTS

The median age was 5.5 years (range 3.0-18.8) and 61.5% were boys. The SDQ filled in by 51 primary caregivers showed no difference between hydrocortisone and placebo in reducing dexamethasone-induced neurobehavioral problems (estimated effect -2.05 (95% confidence interval (CI) -6.00-1.90). Also, no benefit from hydrocortisone compared to placebo was found for reducing sleep problems, hunger, parental stress or improving HRQoL.

CONCLUSIONS

Hydrocortisone, when compared to placebo, had no additional effect in reducing clinically relevant dexamethasone-induced neurobehavioural problems. Therefore, hydrocortisone is not advised as standard of care for children with ALL who experience dexamethasone-induced neurobehavioural problems.

TRIAL REGISTRATION

Netherlands Trial Register NTR6695/NL6507 (https://trialsearch.who.int/) and EudraCT 2017-002738-22 (https://eudract.ema.europa.eu/).

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

Importance

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

Objective

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

Design, Setting, and Participants

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

Main Outcomes and Measures

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

Results

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

Conclusions and Relevance

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

Association between personality traits and placebo effects: a preregistered systematic review and meta-analysis

ABSTRACT

Placebo effects are ubiquitous yet highly variable between individuals and therefore strongly affect clinical trial outcomes such as pain relief. It is unclear whether dispositional psychological traits influence responsiveness to placebo. This preregistered meta-analysis and systematic review synthesized the literature investigating the association between personality traits and placebo effects. Based on 21 studies with 798 participants, we performed formal meta-analyses for 10 different personality traits, including behavioral inhibition, fun seeking, goal-drive persistence, reward responsiveness, empathic concern, empathic fantasy, perspective-taking, personal distress, optimism, and anxiety. We did not find evidence of associations between any of these traits and magnitude of placebo effects, which was supported by equivalence tests. Furthermore, we did not find evidence for moderating factors such as placebo manipulation type (conditioning or nonconditioning) or condition (pain or nonpain). These findings challenge the notion that personality influences responsiveness to placebos and contradict its utility for identifying placebo "responders" and "nonresponders."

Really just a little prick? A meta-analysis on adverse events in placebo control groups of seasonal influenza vaccination RCTs

BACKGROUND

The Corona pandemic and ongoing mass vaccinations raise the question of the nocebo mechanisms involved. Since immunization is usually administered to healthy people as a preventive health measure, adverse events (AE) following immunization are less accepted and could contribute to vaccine hesitancy. Assuming that vaccinees experience nocebo responses, the aim of this meta-analysis was to investigate the effect sizes of solicited adverse events (or assumed reactogenicity) reported in placebo groups in RCTs on seasonal influenza vaccination.

METHODS

Literature search via PubMed, Web of Science, and CENTRAL was conducted considering gray literature. Only RCTs with placebo groups using pharmacologically inert substances (like saline) were included. Quality was assessed using Cochrane Collaboration's Risk of Bias Tool. Effect sizes were estimated using a random mixed effects model based on k = 31 studies covering 14,326 participants in placebo groups.

RESULTS

Reported solicited AEs in placebo groups showed significant effect sizes of proportions (ES_p). In k = 13 analyzed placebo groups, 35 % of the participants reported at least one solicited systemic AE (p = 0.007). The most common particular solicited systemic AEs were headache (k = 27; 17 %; p = 0.001), malaise (k = 13; 12 %; p = 0.004), and hyperhidrosis (k = 4; 12 %; p < 0.001) within one week after vaccination.

CONCLUSION

The results show significant solicited AEs in placebo groups, indicating substantial nocebo responses after vaccination. Based on the fact that most vaccination programs include similar groups of healthy people, we expect that comparable nocebo effects occur during other campaigns. Health care professionals should be aware of the nocebo response and take action to prevent or decrease the burden of adverse events following immunization. Fear of side effects must be addressed early in order to diminish vaccine hesitancy. Prospero identifier: CRD42020156287, October 2019.

[Placebo effects in analgesia : Influence of expectations on the efficacy and tolerability of analgesic treatment]

Expectations of patients influence the perception and neuronal processing of acute and chronic pain and modulate the effectiveness of analgesic treatment. The expectation of treatment is not only the most important determinant of placebo analgesia. Expectations of treatment also influence the efficacy and tolerability of "active" pharmacological and non-pharmacological treatment of pain. Recent insights into the psychological and neurobiological mechanisms underlying the clinically relevant effects of treatment expectations enable and call for the systematic integration and modulation of treatment expectations into analgesic treatment concepts. Such a strategy promises to optimize analgesic treatment and to prevent or reduce the burden of unwanted side effects and the misuse of analgesics, particularly of opioids. This review highlights the current concepts, recent achievements and also challenges and key open research questions.

Preoperative optimization of cardiac valve patients' expectations: Study protocol of the randomized controlled ValvEx-trial

Introduction

Complete recovery after surgery depends on psychological factors such as preoperative information, expectations, and surgery-associated anxiety. Prior studies have shown that even a short preoperative psychological intervention aiming at optimized expectations (EXPECT) can improve postoperative outcomes in coronary artery bypass patients. However, this intervention may benefit only a small subgroup of heart surgery patients since implementing preoperative psychological interventions into the daily clinical routine is difficult due to the additional time and appointments. It is unclear whether the EXPECT intervention can be shortened and whether heart valve patients would also benefit from interventions that optimize patients' expectations. The multicenter ValvEx trial aims (i) to adapt an effective preoperative psychological intervention (EXPECT) to make it brief enough to be easily integrated into the preoperative routine of heart valve patients and (ii) to examine if the adapted preoperative psychological intervention improves the subjectively perceived illness-related disability (PDI) up to 3 months after surgery.

Materials and analysis

In two German university hospitals, N = 88 heart valve patients who undergo heart surgery are randomized into two groups [standard of care (SOC) vs. standard of care plus interventional expectation manipulation (SOC and EXPECT)] after baseline assessment. Patients in the EXPECT group additionally to standard of care participate in the preoperative psychological intervention (30-40 min), focusing on optimizing expectations and have two booster-telephone calls (4 and 8 weeks after the surgery, approx. 15 min). Both groups have assessments again on the evening before the surgery, 4 to 6 days, and 3 months after the surgery.

Discussion

The trial demonstrates excellent feasibility in the clinical routine and a high interest by the patients.

Ethics and dissemination

The Ethics Committees of the Department of Medicine of the Philipps University of Marburg and the Department of Medicine of the University of Giessen approved the study protocol. Study results will be published in peer-reviewed journals and presented at congresses.

Clinical trial registration

ClinicalTrials.gov, identifier NCT04502121.

Social communication pathways to COVID-19 vaccine side-effect expectations and experience

OBJECTIVE

Negative beliefs about medication and vaccine side-effects can spread rapidly through social communication. This has been recently documented with the potential side-effects from the COVID-19 vaccines. We tested if pre-vaccination social communications about side-effects from personal acquaintances, news reports, and social media predict post-vaccination side-effect experiences. Further, as previous research suggests that side-effects can be exacerbated by negative expectations, we assessed if personal expectations mediate the relationships between social communication and side-effect experience.

METHOD

In a prospective longitudinal survey (N = 551), COVID-19 vaccine side-effect information from three sources-social media posts, news reports, and first-hand accounts from personal acquaintances-as well as side-effect expectations, were self-reported pre-vaccination. Vaccination side-effect experience was assessed post-vaccination.

RESULTS

In multivariate regression analyses, the number of pre-vaccination social media post views (β = 0.17) and impressions of severity conveyed from personal acquaintances (β = 0.42) significantly predicted an increase in pre-vaccination side-effect expectations, and the same variables (βs = 0.11, 0.14, respectively) predicted post-vaccination side-effect experiences. Moreover, pre-vaccination side-effect expectations mediated the relationship between both sources of social communication and experienced side-effects from a COVID-19 vaccination.

CONCLUSIONS

This study identifies links between personal acquaintance and social media communications and vaccine side-effect experiences and provides evidence that pre-vaccination expectations account for these relationships. The results suggest that modifying side-effect expectations through these channels may change the side-effects following a COVID-19 vaccination as well as other publicly discussed vaccinations and medications.

Placebo and nocebo effects: from observation to harnessing and clinical application

Placebo and nocebo effects are salubrious benefits and negative outcomes attributable to non-specific symbolic components. Leveraging advanced experimental and analytical approaches, recent studies have elucidated complicated neural mechanisms that may serve as a solid basis for harnessing the powerful self-healing and self-harming capacities and applying these findings to improve medical practice and minimize the unintended exacerbation of symptoms in medical practice. We review advances in employing psychosocial, pharmacological, and neuromodulation approaches to modulate/harness placebo and nocebo effects. While these approaches show promising potential, translating these research findings into clinical settings still requires careful methodological, technical, and ethical considerations.

A digital application and augmented physician rounds reduce postoperative pain and opioid consumption after primary total knee replacement (TKR): a randomized clinical trial

BACKGROUND

Severe postoperative pain not only is a considerable burden for patients but also leads to overprescription of opioids, resulting in considerable health concerns. The remarkable development of new technologies in the health care system provides novel treatment opportunities in this area and could exploit the additional placebo effect, provide added value for patients, and at the same time support hospital staff. We aimed to test the pain- and opioid intake-reducing effects of enhanced postoperative pain management by boosting pain medication by using a technical application and/or augmented physician rounds.

METHODS

In a four-arm, randomized clinical trial, 96 patients (24 patients per group) scheduled for a total knee replacement (TKR) were randomized into four groups for four postoperative days: an "application" group (APP) with information via an iPad-based application; a "doctor" group (DOC) with augmented physician rounds; a combination group (APP+DOC), which received both interventions; and a "treatment as usual" group (TAU) as a baseline with no additional intervention besides the standard care which consists of standardized medication, regular physician rounds, and physiotherapy. Postoperative pain and opioid requirements pre- and postoperatively until hospital discharge were recorded.

RESULTS

The difference between post- and preoperative pain was significantly different between the groups (P=.02, partial η2=.10). APP+DOC experienced greater postoperative pain relief than DOC (mean: 2.3 vs. 0.7, 95% CI: 0.08-3.09; P=.04) and TAU (mean 2.3 vs. 0.1; 95% CI: 0.69-3.71; P=.005), respectively, the difference compared to APP (mean 2.3 vs. 1.7; 95% CI -1.98-1.76) was not significant. Opioid consumption differed significantly between groups (P=.01, partial η2=.12). APP+DOC (72.9 mg) and DOC (75.4 mg) consumed less oxycodone than APP (83.3 mg) and TAU (87.9 mg; 95% CI: 2.9-22.1; P=.003). APP+DOC consumed significantly less oxycodone than DOC (d=0.2-0.4). There were no significant group differences in NSAID and Morphine sulfate consumption. Patients in APP+DOC were more satisfied with their treatment than patients in TAU (P=.03, partial η2=.09).

CONCLUSIONS

The combination of an innovative digital app, which implements open drug administration and augmented physician rounds that support the doctor-patient relationship can significantly improve postoperative pain management.

TRIAL REGISTRATION

The protocol was approved by the local ethics committee of the ethical commission of the German Psychological Society (Deutsche Gesellschaft für Psychologie; DGPs). The study was registered at DRKS.de (identifier: DRKS00009554).

Complexity theory in the management of patients with musculoskeletal pain

Nonlinear systems are not susceptible to research with a reductionist approach. In this sense, the complexity theory provides an alternative approach to quantify the importance of contextual factors in patients with musculoskeletal pain. The use of positive (placebo) or negative (nocebo) contextual factors in the therapeutic setting could largely account for the non-specific component of treatment efficacy, directly affecting the quality of patients’ health-related outcomes (e.g., pain, disability, or satisfaction). In recent years, there has been a better understanding of the effects of contextual factors. However, the knowledge and awareness of them is limited and heterogeneous among physical therapists, reducing their translational value in the field of physiotherapy. The purpose of this essay is to describe the management of patients with musculoskeletal pain from the complexity theory perspective.

Using expectation violation models to improve the outcome of psychological treatments

Expectations are a central maintaining mechanism in mental disorders and most psychological treatments aim to directly or indirectly modify clinically relevant expectations. Therefore, it is crucial to examine why patients with mental disorders maintain dysfunctional expectations, even in light of disconfirming evidence, and how expectation-violating situations should be created in treatment settings to optimize treatment outcome and reduce the risk of treatment failures. The different psychological subdisciplines offer various approaches for understanding the underlying mechanisms of expectation development, persistence, and change. Here, we convey recommendations on how to improve psychological treatments by considering these different perspectives. Based on our expectation violation model, we argue that the outcome of expectation violation depends on several characteristics: features of the expectation-violating situation; the dynamics between the magnitude of expectation violation and cognitive immunization processes; dealing with uncertainties during and after expectation change; controlled and automatic attention processes; and the costs of expectation changes. Personality factors further add to predict outcomes and may offer a basis for personalized treatment planning. We conclude with a list of recommendations derived from basic psychology that could contribute to improved treatment outcome and to reduced risks of treatment failures.

Pre-surgery optimization of patients' expectations to improve outcome in heart surgery: Study protocol of the randomized controlled multi-center PSY-HEART-II trial

The PSY-HEART-I trial indicated that a brief expectation-focused intervention prior to heart surgery improves disability and quality of life 6 months after coronary artery bypass graft surgery (CABG). However, to investigate the clinical utility of such an intervention, a large multi-center trial is needed to generalize the results and their implications for the health care system. The PSY-HEART-II study aims to examine whether a preoperative psychological intervention targeting patients' expectations (EXPECT) can improve outcomes 6 months after CABG (with or without heart valve replacement). EXPECT will be compared to Standard of Care (SOC) and an intervention providing emotional support without targeting expectations (SUPPORT). In a 3-arm multi-center randomized, controlled, prospective trial (RCT), N = 567 patients scheduled for CABG surgery will be randomized to either SOC alone or SOC and EXPECT or SOC and SUPPORT. Patients will be randomized with a fixed unbalanced ratio of 3:3:1 (EXPECT: SUPPORT: SOC) to compare EXPECT to SOC and EXPECT to SUPPORT. Both psychological interventions consist of 2 in-person sessions (à 50 minute), 2 phone consultations (à 20 minute) during the week prior to surgery, and 1 booster phone consultation post-surgery 6 weeks later. Assessment will occur at baseline approx. 3-10 days before surgery, preoperatively the day before surgery, 4-6 days later, and 6 months after surgery. The study's primary end point will be patients' illness-related disability 6 months after surgery. Secondary outcomes will be patients' expectations, subjective illness beliefs, quality of life, length of hospital stay and blood sample parameters (eg, inflammatory parameters such as IL-6, IL-8, CRP). This large multi-center trial has the potential to corroborate and generalize the promising results of the PSY-HEART-I trial for routine care of cardiac surgery patients, and to stimulate revisions of treatment guidelines in heart surgery.

"Let's see what happens:"-Women's experiences of open-label placebo treatment for menopausal hot flushes in a randomized controlled trial

Open-label (honestly prescribed) placebos are an ethical way to evoke placebo effects in patients. As part of a mixed-methods study, we conducted in-depth interviews with eight menopausal women who underwent and benefitted from open-label placebo treatment in a randomized-controlled trial of hot flushes. Data were analyzed using Interpretative Phenomenological Analysis. We found that the women had low expectations about the placebo treatment yet endorsed what they referred to as “hope” and openness to “see what happens”. Recording hot flushes via the symptom diary was viewed as a valuable opportunity for self-examination and appraising outcomes. Receiving relief from the placebo treatment empowered women and enhanced their sense of control and agency. In summary, participants’ initial openness towards placebos, their hopes to get better, monitoring symptoms closely, and taking the initiative to address symptoms were components of a positive open-label placebo experience.

Taste-immune associative learning amplifies immunopharmacological effects and attenuates disease progression in a rat glioblastoma model

Mechanistic target of rapamycin (mTOR)-signaling is one key driver of glioblastoma (GBM), facilitating tumor growth by promoting the shift to an anti-inflammatory, pro-cancerogenic microenvironment. Even though mTOR inhibitors such as rapamycin (RAPA) have been shown to interfere with GBM disease progression, frequently chaperoned toxic drug side effects urge the need for developing alternative or supportive treatment strategies. Importantly, previous work document that taste-immune associative learning with RAPA may be utilized to induce learned pharmacological placebo responses in the immune system. Against this background, the current study aimed at investigating the potential efficacy of a taste-immune associative learning protocol with RAPA in a syngeneic GBM rat model. Following repeated pairings of a novel gustatory stimulus with injections of RAPA, learned immune-pharmacological effects could be retrieved in GBM-bearing animals when re-exposed to the gustatory stimulus together with administering 10 % amount of the initial drug dose (0.5 mg/kg). These inhibitory effects on tumor growth were accompanied by an up-regulation of central and peripheral pro-inflammatory markers, suggesting that taste-immune associative learning with RAPA promoted the development of a pro-inflammatory anti-tumor microenvironment that attenuated GBM tumor growth to an almost identical outcome as obtained after 100 % (5 mg/kg) RAPA treatment. Together, our results confirm the applicability of taste-immune associative learning with RAPA in animal disease models where mTOR overactivation is one key driver. This proof-of-concept study may also be taken as a role model for implementing learning protocols as alternative or supportive treatment strategy in clinical settings, allowing the reduction of required drug doses and side effects without losing treatment efficacy.

Savor the flavor: A randomized double-blind study assessing taste-enhanced placebo analgesia in healthy volunteers

Placebo effects substantially contribute to analgesic treatment outcomes and might be leveraged to enhance gold-standard treatments. The taste of oral medications has been proposed to boost placebo effects. Here, we aimed at estimating how far the taste of an oral medication enhances placebo analgesia. We conducted a randomized, double-blind, between-group, single-visit study, with pre-treatment baseline. Over the course of three substudies, 318 healthy volunteers (297 included) were tested in a clinical trial setting. Participants were subjected to experimental tonic cold water pain (cold pressor test) before and after receiving taste-neutral (water), or bitter (quinine), or sweet (saccharin), or no placebo drops. Pre- versus post-treatment changes in area under the pain rating curve, the main outcome, indicated that placebo treatment showed a small analgesic effect versus no treatment. Added taste induced placebo enhancement in the very small effect size range, but accounted for a substantial portion of the overall placebo effect. No noteworthy advantage of sweet over bitter placebo was observed. An exploration of heart rate (HR) recordings indicated that placebo treatments were associated with an increase in peak HR-response to cold water, but these were not associated with placebo analgesia at an individual level. Placebo treatments were associated with minimal side effects. These results indicate that added taste may be an easy-to-implement, cost-effective, and safe way to optimize treatment outcomes and that taste-neutral preparations may reduce placebo-related outcome variance in clinical trials. Further studies are needed to test if these findings can be translated into clinical scenarios.