Side effects can enhance treatment response through expectancy effects: an experimental analgesic randomized controlled trial

How side effects can improve treatment efficacy: a randomized trial

While treatment side effects may adversely impact patients, they could also potentially function as indicators for effective treatment. In this study, we investigated whether and how side effects can trigger positive treatment expectations and enhance treatment outcomes. In this pre-registered trial (DRKS00026648), 77 healthy participants were made to believe that they will receive fentanyl nasal sprays before receiving thermal pain in a controlled experimental setting. However, nasal sprays did not contain fentanyl, rather they either contained capsaicin to induce a side effect (mild burning sensation) or saline (inert). After the first session, participants were randomized to two groups and underwent functional MRI. One group continued to believe that the nasal sprays could contain fentanyl while the other group was explicitly informed that no fentanyl was included. This allowed for the independent manipulation of the side effects and the expectation of pain relief. Our results revealed that nasal sprays with a side effect lead to lower pain than inert nasal sprays without side effects. The influence of side effects on pain was dependent on individual beliefs about how side effects are related to treatment outcome, as well as on expectations about received treatment. Functional MRI data indicated an involvement of the descending pain modulatory system including the anterior cingulate cortex and the periaqueductal gray during pain after experiencing a nasal spray with side effects. In summary, our data show that mild side effects can serve as a signal for effective treatment thereby influencing treatment expectations and outcomes, which is mediated by the descending pain modulatory system. Using these mechanisms in clinical practice could provide an efficient way to optimize treatment outcome. In addition, our results indicate an important confound in clinical trials, where a treatment (with potential side effects) is compared to placebo.

Expectancy Effects in Psychedelic Trials

Clinical trials of psychedelic compounds like psilocybin, lysergic acid diethylamide (LSD), and N,N-dimethyltrptamine (DMT) have forced a reconsideration of how nondrug factors, such as participant expectations, are measured and controlled in mental health research. As doses of these profoundly psychoactive substances increase, so does the difficulty in concealing the treatment condition in the classic double-blind, placebo-controlled trial design. As widespread public enthusiasm for the promise of psychedelic therapy grows, so do questions regarding whether and how much trial results are biased by positive expectancy. First, we review the key concepts related to expectancy and its measurement. Then, we review expectancy effects that have been reported in both micro- and macrodose psychedelic trials from the modern era. Finally, we consider expectancy as a discrete physiological process that can be independent of, or even interact with, the drug effect. Expectancy effects can be harnessed to improve treatment outcomes and can also be actively managed in controlled studies to enhance the rigor and generalizability of future psychedelic trials.

Adverse Events as a Cause of Unblinding of Allocated Arms in Anti-Amyloid Therapy Trials: A Meta-Analysis of the Predictive Value

Anti-amyloid drugs for early Alzheimer's disease, including lecanemab, are associated with adverse events (AEs), such as amyloid-related imaging abnormalities (ARIA)-edema/effusion (E), ARIA-hemorrhage, and infusion-related reactions, which can indicate allocated arms in clinical trials. Herein, we evaluated the predictive value of AEs using a meta-analysis to estimate their incidence and simulated positive predictive value (PPV). The PPV for ARIA-E was high (0.915), but that for ARIA hemorrhage was low (0.630). Infusion-related reactions had a high PPV of 0.910, but with a wide confidence interval. Our results suggest the need to ameliorate the unblinding effects of AEs, particularly ARIA-E in trials.

Correlation of effectiveness and tolerability assessments from a pharmacy-based observational study investigating the fixed-dose combination of 400 mg ibuprofen plus 100 mg caffeine for the treatment of acute headache

Introduction

Observational studies are valuable for investigating correlations between patient-reported treatment outcomes. In this study, we report a secondary analysis of a published pharmacy-based observational (patient-centered "real-world" outcomes) study on experiences reported by patients who treated their headache with an over-the-counter analgesic.

Methods

A pharmacy-based exploratory survey was conducted in German community pharmacies. Patients buying a fixed-dose analgesic combination product (400 mg ibuprofen + 100 mg caffeine; IbuCaff) to treat their headache were offered a questionnaire that contained-among others-questions about time to onset of pain relief (OPR), assessment of time to onset of pain relief (AOPR), assessment of efficacy and tolerability, and pain intensity 2 h after intake. A correlation analysis of the data was performed. Moreover, perceived treatment effects compared to other acute headache medications used in the past were collected.

Results

The correlation between OPR and AOPR was high (Spearman rank correlation r = 0.594, p < 0.0001). Headache patients assessed the onset of analgesic action within 15 min as "very fast" and within 30 min as "fast". The other readouts were correlated as well [assessment of efficacy and % pain intensity difference (%PID) at 2 h: r = 0.487; OPR/AOPR and %PID at 2 h: r = 0.295/0.318; OPR/AOPR and assessment of tolerability: r = 0.206/0.397; OPR/AOPR and assessment of efficacy: r = 0.406/0.594; assessment of efficacy and assessment of tolerability: r = 0.608; p < 0.0001 for all correlations]. Compared to previous treatments, most patients (>89%) assessed the speed of analgesic action, efficacy, and tolerability of IbuCaff as equal to or better than for the previous treatment.

Discussion

Headache patients assessed the onset of analgesia within 15 min as "very fast" and within 30 min as "fast". Efficacy assessments for acute headache medication appear to be highly correlated.

Atropine facilitates water-evoked swallows via central muscarinic receptors in anesthetized rats

Anticholinergic medication causes impaired swallowing with hyposalivation. However, the underlying mechanisms by which these drugs modulate the swallowing reflex remain unclear. This study investigated the effects of the muscarinic acetylcholine receptor (mAChR) nonspecific antagonist atropine on the initiation of swallowing. Experiments were performed on 124 urethane-anesthetized rats. A swallow was evoked by either topical laryngeal application of a small amount of distilled water (DW), saline, citric acid, or capsaicin; upper airway distention with a continuous airflow; electrical stimulation of the superior laryngeal nerve (SLN); or focal microinjection of N-methyl-d-aspartate (NMDA) into the lateral region of the nucleus of the solitary tract (L-nTS). Swallows were identified by electromyographic bursts of the digastric and thyrohyoid muscles. Either atropine, the peripheral mAChR antagonist methylatropine, or antagonists of mAChR subtypes M1-M5 were intravenously delivered. Atropine at a dose of 1 mg/kg increased the number of DW-evoked swallows compared with baseline and did not affect the number of swallows evoked by saline, citric acid, capsaicin, or upper airway distention. Methylatropine and M1-M5 antagonists did not significantly change the number of DW-evoked swallows. Bilateral SLN transection completely abolished DW-evoked swallows, and atropine decreased the swallowing threshold of SLN electrical stimulation. Finally, microinjection of NMDA receptor antagonist AP-5 into the L-nTS inhibited DW-evoked swallows, and atropine facilitated the initiation of swallowing evoked by NMDA microinjection into this region. These results suggest that atropine facilitates DW-evoked swallows via central mAChR actions.NEW & NOTEWORTHY Atropine facilitated the distilled water (DW)-evoked swallows in anesthetized rats. Atropine decreased the swallowing threshold evoked by electrical stimulation of the superior laryngeal nerve, which is a primary sensory nerve for the initiation of DW-evoked swallows. Atropine facilitated the swallows evoked by N-methyl-d-aspartate microinjection into the lateral region of the nucleus of the solitary tract, which is involved in the DW-evoked swallows. We speculate that atropine facilitates the DW-evoked swallows via central muscarinic receptor actions.

The Blinded-Dose Purchase Task: assessing hypothetical demand based on cocaine, methamphetamine, and alcohol administration

RATIONALE

Behavioral economic drug purchase tasks quantify the reinforcing value of a drug (i.e., demand). Although widely used to assess demand, drug expectancies are rarely accounted for and may introduce variability across participants given diverse drug experiences.

OBJECTIVES

Three experiments validated and extended previous hypothetical purchase tasks by using blinded drug dose as a reinforcing stimulus, and determined hypothetical demand for experienced effects while controlling for drug expectancies.

METHODS

Across three double-blind, placebo-controlled, within-subject experiments, cocaine (0, 125, 250 mg/70 kg; n=12), methamphetamine (0, 20, 40 mg; n=19), and alcohol (0, 1 g/kg alcohol; n=25) were administered and demand was assessed using the Blinded-Dose Purchase Task. Participants answered questions regarding simulated purchasing of the blinded drug dose across increasing prices. Demand metrics, subjective effects, and self-reported real-world monetary spending on drugs were evaluated.

RESULTS

Data were well modeled by the demand curve function, with significantly higher intensity (purchasing at low prices) for active drug doses compared to placebo for all experiments. Unit-price analyses revealed more persistent consumption across prices (lower α) in the higher compared to lower active dose condition for methamphetamine (a similar non-significant finding emerged for cocaine). Significant associations between demand metrics, peak subjective effects, and real-world spending on drugs also emerged across all experiments.

CONCLUSIONS

Orderly demand curve data revealed differences across drug and placebo conditions, and relations to real-world measures of drug spending, and subjective effects. Unit-price analyses enabled parsimonious comparisons across doses. Results lend credence to the validity of the Blinded-Dose Purchase Task, which allows for control of drug expectancies.

Impact of active placebo controls on estimated drug effects in randomised trials: a systematic review of trials with both active placebo and standard placebo

BACKGROUND

An estimated 60% of pharmacological randomised trials use placebo control interventions to blind (i.e. mask) participants. However, standard placebos do not control for perceptible non-therapeutic effects (i.e. side effects) of the experimental drug, which may unblind participants. Trials rarely use active placebo controls, which contain pharmacological compounds designed to mimic the non-therapeutic experimental drug effects in order to reduce the risk of unblinding. A relevant improvement in the estimated effects of active placebo compared with standard placebo would imply that trials with standard placebo may overestimate experimental drug effects.

OBJECTIVES

We aimed to estimate the difference in drug effects when an experimental drug is compared with an active placebo versus a standard placebo control intervention, and to explore causes for heterogeneity. In the context of a randomised trial, this difference in drug effects can be estimated by directly comparing the effect difference between the active placebo and standard placebo intervention.

SEARCH METHODS

We searched PubMed, CENTRAL, Embase, two other databases, and two trial registries up to October 2020. We also searched reference lists and citations and contacted trial authors.

SELECTION CRITERIA

We included randomised trials that compared an active placebo versus a standard placebo intervention. We considered trials both with and without a matching experimental drug arm.

DATA COLLECTION AND ANALYSIS

We extracted data, assessed risk of bias, scored active placebos for adequacy and risk of unintended therapeutic effect, and categorised active placebos as unpleasant, neutral, or pleasant. We requested individual participant data from the authors of four cross-over trials published after 1990 and one unpublished trial registered after 1990. Our primary inverse-variance, random-effects meta-analysis used standardised mean differences (SMDs) of active versus standard placebo for participant-reported outcomes at earliest post-treatment assessment. A negative SMD favoured the active placebo. We stratified analyses by trial type (clinical or preclinical) and supplemented with sensitivity and subgroup analyses and meta-regression. In secondary analyses, we investigated observer-reported outcomes, harms, attrition, and co-intervention outcomes.

MAIN RESULTS

We included 21 trials (1462 participants). We obtained individual participant data from four trials. Our primary analysis of participant-reported outcomes at earliest post-treatment assessment resulted in a pooled SMD of -0.08 (95% confidence interval (CI) -0.20 to 0.04; I2 = 31%; 14 trials), with no clear difference between clinical and preclinical trials. Individual participant data contributed 43% of the weight of this analysis. Two of seven sensitivity analyses found more pronounced and statistically significant differences; for example, in the five trials with low overall risk of bias, the pooled SMD was -0.24 (95% CI -0.34 to -0.13). The pooled SMD of observer-reported outcomes was similar to the primary analysis. The pooled odds ratio (OR) for harms was 3.08 (95% CI 1.56 to 6.07), and for attrition, 1.22 (95% CI 0.74 to 2.03). Co-intervention data were limited. Meta-regression found no statistically significant association with adequacy of the active placebo or risk of unintended therapeutic effect.

AUTHORS' CONCLUSIONS

We did not find a statistically significant difference between active and standard placebo control interventions in our primary analysis, but the result was imprecise and the CI compatible with a difference ranging from important to irrelevant. Furthermore, the result was not robust, because two sensitivity analyses produced a more pronounced and statistically significant difference. We suggest that trialists and users of information from trials carefully consider the type of placebo control intervention in trials with high risk of unblinding, such as those with pronounced non-therapeutic effects and participant-reported outcomes.

[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.

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.

Avoiding nocebo and other undesirable effects in chiropractic, osteopathy and physiotherapy: An invitation to reflect

INTRODUCTION

While the placebo effect is increasingly recognised as a contributor to treatment effects in clinical practice, the nocebo and other undesirable effects are less well explored and likely underestimated. In the chiropractic, osteopathy and physiotherapy professions, some aspects of historical models of care may arguably increase the risk of nocebo effects.

PURPOSE

In this masterclass article, clinicians, researchers, and educators are invited to reflect on such possibilities, in an attempt to stimulate research and raise awareness for the mitigation of such undesirable effects.

IMPLICATIONS

This masterclass briefly introduces the nocebo effect and its underlying mechanisms. It then traces the historical development of chiropractic, osteopathy, and physiotherapy, arguing that there was and continues to be an excessive focus on the patient's body. Next, aspects of clinical practice, including communication, the therapeutic relationship, clinical rituals, and the wider social and economic context of practice are examined for their potential to generate nocebo and other undesirable effects. To aid reflection, a model to reflect on clinical practice and individual professions through the 'prism' of nocebo and other undesirable effects is introduced and illustrated. Finally, steps are proposed for how researchers, educators, and practitioners can maximise positive and minimise negative clinical context.

Even when you know it is a placebo, you experience less sadness: First evidence from an experimental open-label placebo investigation

BACKGROUND

Recent studies demonstrate substantial effects of deceptive placebo on experimentally induced sadness, even on autonomic activity. Whether deception is necessary, remains to be elucidated. We investigated the effect of an open-label placebo (OLP) treatment, i.e. an openly administered placebo delivered with a convincing rationale for its sadness-protecting effect.

METHODS

Eighty-four healthy females were randomized to an OLP group or a no-treatment control group. All participants received the same detailed information about the OLP effect, only the OLP group received an OLP nasal spray. Before and after the OLP intervention, participants underwent a sad mood induction procedure combining self-deprecating statements (Velten's method) and sad music. Sadness was assessed by the Positive and Negative Affect Schedule (PANAS-X). Autonomic activity was measured continuously.

RESULTS

Participants in the OLP group reported a significantly attenuated increase in sadness upon mood induction and less sadness after induction compared to the control group (d = 0.79). Regardless of intervention, heart rate decreased during mood inductions with a more pronounced deceleration in the second mood induction.

LIMITATIONS

Generalizability is limited due to the selective sample and the reliance on an experimentally controlled mood induction.

CONCLUSION

OLP treatment had a beneficial effect on perceived sadness, at least at the subjective level. Hence, deception may not necessarily be required for placebos to modulate experienced sad mood. Investigating the beneficial effects of OLP in (sub-)clinical samples would seem a promising and required next step towards a clinical use of placebo-associated positive treatment expectations.

HOW DO THEY ADD UP? THE INTERACTION BETWEEN THE PLACEBO AND TREATMENT EFFECT: A SYSTEMATIC REVIEW

Aim

The placebo effect and the specific effect are often thought to add up (additive model). Whether additivity holds can dramatically influence the external validity of a trial. This assumption of additivity was tested by Kleijnen et al in 1994 but the data produced since then have not been synthetized. In this review, we aimed to systematically review the literature to determine whether additivity held.

Methods

We searched Medline and PsychInfo up to 10 January 2019. Studies using the balanced placebo design (BPD), testing two different strengths of placebos, were included. The presence of interaction was evaluated by comparing each group in the BPD with analysis of variance or covariance.

Results

Thirty studies were included and the overall risk of bias was high: four found evidence of additivity and 16 studies found evidence of interaction (seven had evidence of positive additivity).

Conclusion

Evidence of additivity between placebo and specific features of treatments was rare in included studies. We suggest interventions for placebo‐sensitive ailments should be tested in trials designed to take interactions seriously once an exploratory RCTs has proven their efficacy with sufficient internal validity.

Placebo and Side Effects Confound Clinical Trials on New Antitussives

This review discusses how the placebo effect related to treatment side effects may confound clinical trials on antitussives and specifically looks at the implications for trials on ATP antagonists. These new antitussives have distinctive side effects on the sensation of taste, and investigators have expressed concerns that this may unblind the clinical trials. Blinding is an essential component of trial design, but the degree of blinding in trials is rarely assessed. The assumptions of additivity and balance in clinical trials are discussed as important factors that allow assessment of the pharmacological activity of an antitussive. How side effects unbalance a clinical trial by amplifying the placebo effect of active treatments is discussed. The point is made that unblinding of trials invalidates any assessment of efficacy but that there is little interest or discussion about this fundamental aspect of trials. Proposals are discussed which may improve the blinding of trials and control placebo effects by changes to participant information, trial design, patient selection and use of active placebos. The issue of unblinding of clinical trials is not a new issue, but if real progress is to be made in developing new antitussives, then it is an issue that needs to be urgently addressed.

Self-blinding citizen science to explore psychedelic microdosing

Microdosing is the practice of regularly using low doses of psychedelic drugs. Anecdotal reports suggest that microdosing enhances well-being and cognition; however, such accounts are potentially biased by the placebo effect. This study used a 'self-blinding' citizen science initiative, where participants were given online instructions on how to incorporate placebo control into their microdosing routine without clinical supervision. The study was completed by 191 participants, making it the largest placebo-controlled trial on psychedelics to-date. All psychological outcomes improved significantly from baseline to after the 4 weeks long dose period for the microdose group; however, the placebo group also improved and no significant between-groups differences were observed. Acute (emotional state, drug intensity, mood, energy, and creativity) and post-acute (anxiety) scales showed small, but significant microdose vs. placebo differences; however, these results can be explained by participants breaking blind. The findings suggest that anecdotal benefits of microdosing can be explained by the placebo effect.

The placebo phenomenon and the underlying mechanisms

The clinical role of the placebo effect is a topic of increasing interest for the scientific community. Focus is shifting from the inert role of placebos in randomized controlled trials (RCTs) to potential effects in clinical applications, since the phenomenon is thought to be inherent in routine clinical practice, affecting therapy success rates. Mediation of the mind-brain-body relationship involves both psychosocial and neurobiological factors, the interaction of which comprises the placebo mechanisms. Psychosocial factors include environmentally induced expectations, reward expectations, and even conditioned responses to certain stimuli. Expectations also depend on previous experience of the patient with a similar procedure and can affect future responses. Moreover, the supportive bedside behavior of the clinician and the positive framing of information provided to the patient have proven to be of great importance, setting the foundations for reconsideration of standardized practices. Neurobiological mechanisms mediate these effects through neurotransmitter and neuromodulator pathways. The best understood mechanisms are those regulating non-opioid- and opioid-mediated analgesic responses that implicate specific brain regions of pain control and activation of endogenous opioids. Other responses concern, among others, hormonal control, motor performance, and antidepressant responses. Although mechanisms underlying placebo responses are not as yet completely elucidated, there is substantial evidence suggesting that placebo effects are indicative of healthy functioning of intact brain structures and occur through actual functional changes, and are not simply subjective symptom reports. These effects can be utilized in treatment optimization while maintaining an ethical and respectful manner toward the patient and the standardized disclosure procedures.

Effectiveness of topical cycloplegics as anterior segment analgesics: systematic review and meta-analysis

OBJECTIVE

Topical cycloplegic agents often are used in ophthalmology in the context of management of ocular inflammation. Preliminary searches of the literature provided little evidence to support their use in relieving pain or reducing inflammation. The goal of this study was to evaluate the current literature for any evidence regarding the effectiveness of cycloplegics for treatment of pain or inflammation in patients with anterior segment injury or inflammation through a systematic review and meta-analysis.

METHODS

Using multiple keywords relating to cycloplegics and inflammatory and infectious eye conditions, a search was conducted on multiple scientific databases for relevant articles. A 2-level screening approach was used and articles that were relevant to the topic were included in the systematic review. Data from these articles, if applicable, were extracted for meta-analyses. Statistical assessments involved computation of I²statistics, Z-value, and χ² statistics.

RESULTS

We screened 5753 articles for relevance. Seven were included in the systematic review and 5 were included in the meta-analysis. There was considerable heterogeneity between the included studies. Statistical analysis revealed significant reductions in pain using homatropine and cyclopentolate after 2 days. Nonsignificant changes in the anterior chamber cells and flare were seen using cyclopentolate and atropine at different follow-up times.

CONCLUSIONS

Little published evidence exists in the literature to guide the use of cycloplegics on relieving pain and treating inflammation. Therefore, higher-quality randomized controlled trials with longer follow-up times are needed to fully understand the role that cycloplegics play in reducing pain in inflammatory conditions.

Changing mindsets about side effects

Given research showing that the very act of communicating side effects can increase their likelihood, how can providers inform patients about side effects while upholding their oath to do no unnecessary harm? An emerging approach provides a potential solution: truthfully describe certain minor side effects as a sign the treatment is active and working in the body. This approach focuses on instilling adaptive mindsets about the meaning of side effects while still keeping patients informed. This article describes existing research suggesting that this approach can be helpful in improving experience and outcomes in treatments for pain, hypertension and allergy. Compared with control groups given a standard, empathetic message about side effects, patients who were informed that side effects are a sign treatment is working were less anxious about side effects and rated them as less threatening and intense. A longitudinal, randomised controlled trial of this approach in patients receiving oral immunotherapy for food allergies found that describing side effects as a sign treatment was working reduced the rate at which patients contacted providers with concerns about side effects and led to greater increases in a biomarker of allergic tolerance from pretreatment to post-treatment (peanut-specific blood IgG4). In unveiling this approach, this article also raises important issues regarding which treatments and symptoms this approach should be applied to. Finally, we outline questions future research should address to further understand and leverage this approach.

Effects of Patients' Expectation in Dermatology: Evidence from Experimental and Clinical Placebo Studies and Implications for Dermatologic Practice and Research

Patients' expectations towards the benefit of a treatment are key determinants of placebo responses and can affect the development and course of medical conditions and the efficacy and tolerability of active medical treatment. The mechanisms mediating these placebo and nocebo effects have been best described in the field of experimental pain and placebo analgesia. However, also in dermatology experimental and clinical studies demonstrate that various skin diseases such as inflammatory dermatoses and allergic reactions can be modulated by patients' expectations. Dermatologists should consider the important modulatory role of patients' expectations on the efficacy and tolerability of specific treatments and the key role of verbal information, patients' prior treatment experiences (associative learning), and the quality and quantity of doctor-patient communication in shaping treatment expectation. As a consequence, techniques aiming at maximizing patients' expectation effects should be implemented into daily clinical routine. By contrast, in clinical studies expectation effects should be maximally controlled and harmonized to improve the "assay sensitivity" to detect new compounds. Further translational studies, also in dermatoses that have not been investigated yet, are needed to better characterize the mechanisms underlying patients' expectation and to gain further insights into potential clinical implications of these effects in dermatologic conditions. Therefore, in this review, we provide a brief overview on the concept of expectation effects on treatment outcome in general, summarize what is already known about this topic for dermatologic diseases, and finally present the relevance of this topic in clinical dermatology.

Positive expectations predict improved mental-health outcomes linked to psychedelic microdosing

Psychedelic microdosing describes the ingestion of near-threshold perceptible doses of classic psychedelic substances. Anecdotal reports and observational studies suggest that microdosing may promote positive mood and well-being, but recent placebo-controlled studies failed to find compelling evidence for this. The present study collected web-based mental health and related data using a prospective (before, during and after) design. Individuals planning a weekly microdosing regimen completed surveys at strategic timepoints, spanning a core four-week test period. Eighty-one participants completed the primary study endpoint. Results revealed increased self-reported psychological well-being, emotional stability and reductions in state anxiety and depressive symptoms at the four-week primary endpoint, plus increases in psychological resilience, social connectedness, agreeableness, nature relatedness and aspects of psychological flexibility. However, positive expectancy scores at baseline predicted subsequent improvements in well-being, suggestive of a significant placebo response. This study highlights a role for positive expectancy in predicting positive outcomes following psychedelic microdosing and cautions against zealous inferences on its putative therapeutic value.

Historical Controls in Randomized Clinical Trials: Opportunities and Challenges

Randomized control trials (RCTs) with placebo are the gold standard for determining efficacy of novel pharmaceutical treatments. Since their inception, over 75 years ago, researchers have amassed a large body of underutilized data on outcomes in the placebo control arms of these trials. Although rare disease indications have used these historical placebo data as synthetic controls to reduce burden on patients and accelerate drug discovery, broad use of historical controls is in its infancy. Large-scale historical placebo data could be leveraged to benefit both drug developers and patients if warehoused and made more available to guide trial design and analysis. Here, we examine challenges in utilizing historical controls related to heterogeneity in trial design, outcome ascertainment, patient characteristics, and unmeasured pharmacogenomic effects. We then discuss the advantages and disadvantages of current approaches and propose a path forward to broader use of historical controls in RCTs.

Sharing clinical notes, and placebo and nocebo effects: Can documentation affect patient health?

This paper connects findings from the field of placebo studies with research into patients' interactions with their clinician's visit notes, housed in their electronic health records. We propose specific hypotheses about how features of clinicians' written notes might trigger mechanisms of placebo and nocebo effects to elicit positive or adverse health effects among patients. Bridging placebo studies with (a) survey data assaying patient and clinician experiences with portals and (b) randomized controlled trials provides preliminary support for our hypotheses. We conclude with actionable proposals for testing our understanding of the health effects of access to visit notes.

Putting the 'Art' Into the 'Art of Medicine': The Under-Explored Role of Artifacts in Placebo Studies

Research in social psychology demonstrates that physical environmental factors – or “artifacts” such as provider clothing and office décor – can influence health outcomes. However, the role of artifacts in augmenting or diminishing health outcomes is under-explored in the burgeoning discipline of placebo studies. In this paper, we argue that a careful consideration of artifacts may carry significant potential in informing how placebo effects can be maximized, and nocebo effects minimized in clinical settings. We discuss the potential mechanisms, including classical conditioning, response expectancy, and mindsets, by which artifacts might enhance or diminish these effects. Next, we propose testable hypotheses to investigate how placebo and nocebo effects might be elicited by artifacts in care settings, and conclude by providing innovative research designs to advance this novel research agendum.

[The role of placebo and nocebo mechanisms in depressive diseases and their treatment]

BACKGROUND

There is substantial evidence that placebo and nocebo effects occur during treatment with antidepressants. A better understanding of the underlying mechanisms of these effects is necessary to optimize the outcome of treatment and to make clinical studies more sensitive.

METHODS

Placebo and nocebo mechanisms were analyzed based on empirical studies and the results are summarized in a narrative review.

RESULTS

Clinical studies and also experimental mechanism-oriented studies underline the effects of placebo and nocebo mechanisms in the treatment with antidepressants.

CONCLUSION

The success of treatment in the use of antidepressants can be increased and the probability of side effects can be reduced by the effective use of placebo mechanisms and reduction of nocebo effects. The results emphasize the influence of clinician-patient interactions, the role of the treatment context and previous experiences with other treatments of the patient. Simultaneously, the results of this research field stimulate a new understanding of mental disorders, in particular depression and also provide points of reference for optimization of psychotherapeutic treatment.

Optimizing patient expectations to improve therapeutic response to medical treatment: A randomized controlled trial of iron infusion therapy

OBJECTIVES

Patient expectations have the ability to influence health outcomes and have been shown to play an important role as part of the placebo effect to influence the response to medical treatments. Increasing positive expectations have been proposed as an intervention to improve treatment response, although evidence for this to date is limited. We investigated whether a brief 10-min intervention directly targeting patient expectations prior to an iron infusion could enhance expectations and improve treatment response, in terms of patients' reported fatigue.

DESIGN

Randomized controlled trial.

METHODS

Forty-three patients diagnosed with iron deficiency anaemia were randomized to a brief expectation intervention or active control group prior to an intravenous iron infusion. Chalder Fatigue Scale scores were assessed prior to randomization and at one and four weeks.

RESULTS

The expectation intervention significantly improved patients' expectations about the effectiveness of the intravenous iron infusion, t(21) = -3.95, p = .001. While there were no significant differences between groups in fatigue at the one-week follow-up, fatigue was significantly lower in the intervention group at the four-week follow-up compared to the control group, F(1, 25) = 6.25, p = .019. This was largely influenced by a significant reduction in physical, as opposed to mental fatigue scores.

CONCLUSIONS

Boosting patients' positive expectations may be an effective way of enhancing patient response to treatment. In particular, targeting patient expectations with a brief intervention prior to medical treatments may result in a greater and longer therapeutic effect.

Maximizing placebo response in neurological clinical practice

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

Drug-Placebo Additivity in Randomized Clinical Trials

In randomized clinical trials (RCTs), it is assumed that nonspecific effects beyond action of pharmacological agents are roughly equivalent in drug and placebo treatment groups. Hence, since the inception of RCTs, drug efficacy is determined by comparing outcomes in active to those in placebo control arms. However, quantitation of efficacy is based on an unproven assumption, that drug and placebo responses are always additive. Response to treatment in RCTs can be differentially influenced by the perturbing effects of patient expectations, side effects, and pharmacogenomic interactions in both drug and placebo arms. Ability to control for these effects requires understanding of when and where they arise, how to mitigate, analyze, and even leverage their impact. Here, we examine three factors that influence additivity: expectation, side effects, and pharmacogenomics. Furthermore, to provide novel insights into nonadditivity and solutions for managing it, we introduce systems pharmacogenomics, a network approach to integrating and analyzing the effects of the numerous interacting perturbations to which a patient is exposed in RCTs.

The placebo and its effects: A psychoneuroendocrinological perspective

Placebos are usually employed deceptively in clinical trials in order to control for non-specific effects. However, since placebos themselves have been found to cause clinically relevant changes and in some cases are indistinguishable from the verum they are tested against, this theoretically inert, but practically effective intervention has become a scientific discipline in its own right. In this review, it is argued that placebos are generic and genuine biopsychosocial interventions and as such are highly interesting candidates for a psychoneuroendocrinological perspective. Yet, despite a considerable conceptual proximity between explanatory models of placebos and their effects with psychoneuroendocrine models and findings, placebos have thus far not been subject to systematic psychoneuroendocrine examination. Consequently, it would be highly interesting and informative to make placebos the target of psychoneuroendocrine scrutiny.

Decreasing the Burden of Side Effects Through Positive Message Framing: an Experimental Proof-of-Concept Study

PURPOSE

Informing patients about treatment side effects increases the occurrence and intensity of side effects. Since the obligatory informed consent procedure in drug treatments requires transparency and nocebo research suggests that the informed consent of a drug leads to an increased occurrence of the mentioned side effects, the aim of this proof of concept study was to determine the effect of two different framings of informed consent on the occurrence, intensity, and perceived threat of side effects.

METHODS

Healthy male participants (n = 80) were randomized to one of two framing groups. The positive framing group was informed that the common side effect dizziness was a sign that the drug had started to work, while the neutral framing group was told that dizziness is an unpleasant but well-known side effect. Side effects were measured after the administration of metoprolol, an antihypertensive agent. Post hoc moderator analyses investigated the effect of pre-existing negative beliefs about the general harm of medication on the framing manipulation.

RESULTS

Metoprolol-specific drug-attributed side effects were rated significantly less threatening in the positive framing group. The between-group effect size (Cohen's d) was small (d = 0.38, p = 0.049). Exploratory post hoc moderator analyses suggest that participants who believed that medication is a source of harmful effects benefited from positive framing, compared to neutral framing of drug-attributed side effects.

CONCLUSIONS

Positive framing was partially effective in decreasing specific side effect measures, particularly among participants with a tendency to believe that medicine is harmful. Informed consent procedures should therefore be personalized, focusing on patients with negative treatment beliefs.

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

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

A test of positive suggestions about side effects as a way of enhancing the analgesic response to NSAIDs

Side effects are frequent in pharmacological pain management, potentially preceding analgesia and limiting drug tolerability. Discussing side effects is part of informed consent, yet can favor nocebo effects. This study aimed to test whether a positive suggestion regarding side effects, which could act as reminders of the medication having been absorbed, might favor analgesia in a clinical interaction model. Sixty-six healthy males participated in a study "to validate pupillometry as an objective measure of analgesia". Participants were unknowingly randomized double-blind to positive vs control information about side effects embedded in a video regarding the study drugs. Sequences of moderately painful heat stimuli applied before and after treatment with diclofenac and atropine served to evaluate analgesia. Atropine was deceptively presented as a co-analgesic, but used to induce side effects. Adverse events (AE) were collected with the General Assessment of Side Effects (GASE) questionnaire prior to the second induced pain sequence. Debriefing fully informed participants regarding the purpose of the study and showed them the two videos.The combination of medication led to significant analgesia, without a between-group difference. Positive information about side effects increased the attribution of AE to the treatment compared to the control information. The total GASE score was correlated with analgesia, i.e., the more AEs reported, the stronger the analgesia. Interestingly, there was a significant between-groups difference on this correlation: the GASE score and analgesia correlated only in the positive information group. This provides evidence for a selective link between AEs and pain relief in the group who received the suggestion that AEs could be taken as a sign "that help was on the way". During debriefing, 65% of participants said they would prefer to receive the positive message in a clinical context. Although the present results cannot be translated immediately to clinical pain conditions, they do indicate the importance of testing this type of modulation in a clinical context.

Minimizing Drug Adverse Events by Informing About the Nocebo Effect-An Experimental Study

Relevance: Informing patients about potential adverse events as part of the informed consent may facilitate the development of nocebo-driven drug adverse events (nocebo side effects). Objective: To investigate whether informing about the nocebo effect using a short information sheet can reduce nocebo side effects. Methods: A total of N = 44 participants with weekly headaches for at least 6 months were recruited using the cover story of a clinical trial for a headache medicine. In reality, all participants took a placebo pill and were randomized to the nocebo information group or the standard leaflet group. Participants were instructed to read the bogus medication leaflet entailing side effects information shortly before pill intake. The nocebo group additionally received an explanation about the nocebo effect as part of the leaflet. Questionnaires were completed at baseline, 2 min, and 4 days after the pill intake. We conducted general linear models with bootstrap sampling. Baseline symptoms were included as a covariate. Results: Most participants (70.5%) reported nocebo side effects at 2 min. Participants who received the nocebo information (n = 24) reported less nocebo symptoms than the control group (n = 20) (estimated difference: 3.3, BCa 95% CI [1.14; 5.15], p = 0.01, Cohen's d = 0.59). Baseline symptoms, perceived sensitivity to medicine, and side effect expectations each moderated the group effect (estimated difference in slope: 0.47, BCa 95% CI [0.19; 0.73], p = 0.001, d = 0.75; 1.07 [0.27; 1.61], p = 0.006, d = 0.73; 1.57 [0.38; 2.76], p = 0.02, d = 0.58). No group differences were found at 4-day follow-up. After revealing the actual aim of the study, 86% of the participants evaluated the nocebo information to be helpful in general. Conclusions: Results provide the first evidence that informing about the nocebo effect can reduce nocebo side effects.

Placebo Effects in Psychotherapy: A Framework

The issue of placebo response and the extent of its effect on psychotherapy is complex for two specific reasons: i) Current standards for drug trials, e.g., true placebo interventions, double-blinding, cannot be applied to most psychotherapy techniques, and ii) some of the "nonspecific effects" in drug therapy have very specific effects in psychotherapy, such as the frequency and intensity of patient-therapist interaction. In addition, different psychotherapy approaches share many such specific effects (the "dodo bird verdict") and lack specificity with respect to therapy outcome. Here, we discuss the placebo effect in psychotherapy under four aspects: a) nonspecific factors shared with drug therapy (context factors); b) nonspecific factors shared among all psychotherapy traditions (common factors); c) specific placebo-controlled options with different psychotherapy modalities; and d) nonspecific control options for the specific placebo effect in psychotherapy. The resulting framework proposes that the exploration and enumeration of context factors, common factors, and specific factors contributes to the placebo effects in psychotherapy.

The conundrum of depression clinical trials: one size does not fit all

In this paper we review the history of antidepressant (AD) development, since the discovery of imipramine in 1957 to the present day. Through this exploration we will show that the increasing placebo response is likely a red herring and that a higher magnitude of placebo response is not an adequate explanation for AD trials' high failure rates. As a better explanation for their lack of success, we will examine some of the fundamental flaws of AD clinical trials and their origins in historical forces. We focus on underpowering, which occurs as a consequence of unrealistic expectations for AD performance. In addition, we describe the lack of precision in the depression outcome measurements for the past 40 years and show how these measures contrast with those used in clinical trials of other chronic diseases, which use simpler outcome measures. Finally, we describe the role of regulatory agencies in influencing clinical trial design and how the assumption that 'one size fits all' for the past 60 years has led to flawed design of AD clinical trials.

Are Blue Pills Better Than Green? How Treatment Features Modulate Placebo Effects

Treatment-related expectations are important predictors for placebo effects in various medical conditions. They are formed by verbal and nonverbal cues during the administration of treatments, such as verbal suggestions, conscious and unconscious associations with previous treatments, characteristics of patients and health-care providers as well as perceptual characteristics of the treatment. This review provides an overview of studies that aimed to elucidate the impact of treatment characteristics on expectations and placebo effects. Results show that high price, brand label, the use of invasive placebos and high placebo dose increase the expectations toward the beneficial effect of a placebo treatment, which in turn boost the placebo effect. Neuroimaging studies provide first insights into the neurobiological mechanisms underlying these differential placebo effects.

Placebo and Active Treatment Additivity in Placebo Analgesia: Research to Date and Future Directions

Placebo analgesia is a robust experimental and clinical phenomenon. While our understanding of the mechanisms of placebo analgesia has developed rapidly, some central questions remain unanswered. Among the important questions is how placebo analgesia interacts with active analgesic effects. It is an assumption underlying double-blind randomized placebo-controlled trials (RCTs) that the true effect of a treatment can be determined by examining the effect of the active treatment arm and subtracting the response in the placebo group ("the assumption of additivity"). However, despite the importance of this assumption for the interpretation of RCTs, it has rarely been formally examined. This article reviews the assumption of additivity in placebo analgesia by examining studies employing factorial designs manipulating both the receipt of an active analgesic and instructions about the treatment being delivered. In reviewing the literature, we identified seven studies that allowed a test of additivity. Of these, four found evidence against additivity, while the remaining three studies found results consistent with additivity. While the limited available data are somewhat mixed, the evidence suggests that at least under some conditions the assumption of additivity does not hold in placebo analgesia. The concordance between mechanisms of the active analgesic and placebo analgesia may influence whether additivity occurs or not. However, more research using factorial designs is needed to disentangle the relationship between placebo analgesia and the active effect of analgesic treatments.

Expectations about the effectiveness of pain- and itch-relieving medication administered via different routes

BACKGROUND

Placebo effects on pain have been found to vary in size for different routes of medication administration (e.g. oral vs. injection). This has important implications for both clinical research and practice. To enhance our understanding of these differential placebo effects, research on the underlying expectations about multiple routes and symptoms other than pain is vital.

METHODS

A cross-sectional, Internet-based survey was conducted in a representative sample of the Dutch population (n = 508). Respondents rated the expected effectiveness of pain- and itch-relieving medication in six forms, representing oral, injection and topical routes of administration.

RESULTS

Injected medication was expected to be most effective for relieving pain, and topical medication for relieving itch. Furthermore, exploratory analyses showed that injections were expected to have the most rapid onset and long-lasting effects, and to be most frightening and expensive, while topical medication was expected to be the safest and the easiest to use, and oral medication was expected to have the most side effects. Higher expected effectiveness was moderately associated with expectations of more rapid onset and long-lasting effects, and better safety and ease of use. Associations of expected effectiveness with respondent characteristics (e.g. medication use and personality characteristics) were statistically small or nonsignificant.

CONCLUSIONS

Expected effectiveness of medication differed depending on route of administration and targeted symptom. These findings have important implications for the design and interpretation of clinical trials and suggest that medication effects might be enhanced by prescribing medicine via the route that patients expect to be most effective for their complaint.

SIGNIFICANCE

Differences in the expected effectiveness of medication depend on the route of administration (oral, injection, topical) and targeted symptom (pain, itch). These findings have important implications for clinical practice and the design and interpretation of clinical trials.

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

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

A Question of Control? Examining the Role of Control Conditions in Experimental Psychopathology using the Example of Cognitive Bias Modification Research

While control conditions are vitally important in research, selecting the optimal control condition can be challenging. Problems are likely to arise when the choice of control condition is not tightly guided by the specific question that a given study aims to address. Such problems have become increasingly apparent in experimental psychopathology research investigating the experimental modification of cognitive biases, particularly as the focus of this research has shifted from theoretical questions concerning mechanistic aspects of the association between cognitive bias and emotional vulnerability, to questions that instead concern the clinical efficacy of ‘cognitive bias modification’ (CBM) procedures. We discuss the kinds of control conditions that have typically been employed in CBM research, illustrating how difficulties can arise when changes in the types of research questions asked are not accompanied by changes in the control conditions employed. Crucially, claims made on the basis of comparing active and control conditions within CBM studies should be restricted to those conclusions allowed by the specific control condition employed. CBM studies aiming to establish clinical utility are likely to require quite different control conditions from CBM studies aiming to illuminate mechanisms. Further, conclusions concerning the clinical utility of CBM interventions cannot necessarily be drawn from studies in which the control condition has been chosen to answer questions concerning mechanisms. Appreciating the need to appropriately alter control conditions in the transition from basic mechanisms-focussed investigations to applied clinical research could greatly facilitate the translational process.