A systematic review of sex differences in the placebo and the nocebo effect

Positive and Negative Verbal Instructions Associated With Sham Ischemic Preconditioning Moderate Improvements of Knee-Extension Resistance Exercise in Trained Men

PURPOSE

To verify the effects of positive and negative verbal instructions regarding sham ischemic preconditioning (sham-IPC) on leg-extension resistance-exercise performance.

METHODS

Thirty-five trained men were randomized to 1 of 3 groups: positive expectation, negative expectation, or control. Participants completed leg-extension strength tests in 4 trials (2 familiarization, 1 baseline, and 1 experimental). Experimental trials consisted of participants' receiving sham-IPC (3 × 5 cycles at only 20 mmHg). In positive- and negative-expectation groups, participants received verbal instructions that would improve or worsen performance, respectively. Controls did not receive any verbal suggestion. Outcomes were maximum number of repetitions, maximal isometric voluntary contraction, and muscle power output.

RESULTS

Expectations about sham-IPC were significantly higher in the positive-expectation than in the negative-expectation and control groups. Participants in the positive group reported a significantly greater number of repetitions than both the negative-expectation (d = 1.11) and control groups (d = 0.77). No differences between groups were shown for maximal isometric voluntary contraction (d range = 0.05-0.67) and power output (d range = -0.08 to 1.02).

CONCLUSIONS

Our results highlight the importance of measuring expectations prior to sham-IPC, which may significantly influence the results of randomized controlled trials.

Nucleus accumbens functional connectivity changes underlying alcohol expectancies in bipolar disorder and prospective alcohol outcomes: a within-subject randomized placebo-controlled alcohol administration fMRI study

Introduction

Alcohol use disorder (AUD) occurs at higher rates in individuals with bipolar disorder compared to the general population. A paucity of data are available on specific mechanisms that may contribute to bipolar and AUD co-occurrence. We recently reported differences in alcohol expectancies and placebo response during alcohol administration in early-stage bipolar disorder, compared to healthy young adults. This current report investigated subjective and neural response following placebo beverage consumption in young adults with bipolar disorder.

Methods

As part of a within-subject placebo-controlled alcohol administration study, 54 young adults (53% with bipolar disorder type I, age mean + SD = 23 + 2 years, 64% female) completed resting state functional MRI (rsfMRI) scans at baseline (pre-beverage) and following placebo and alcohol consumption (counter-balanced). Participants completed subjective response measures during placebo and alcohol beverage conditions. Between-group differences in subjective response and placebo-related changes in functional connectivity of the Nucleus Accumbens (NAc) with other brain regions, compared to a pre-beverage rsfMRI baseline condition, were investigated. Fisher-transformed correlation coefficients between ROIs and seed-to-clusters showing a significant group-by-condition (placebo, pre-beverage rsfMRI) interaction were calculated. Associations with prospective alcohol use and problems were explored in a subgroup with longitudinal data.

Results

Young adults with bipolar disorder reported greater intoxication during the placebo condition, compared to healthy young adults (main effects of group: p < 0.05). Compared to pre-beverage rsfMRI, the placebo condition related to increased connectivity between bilateral NAc and regions within the sensorimotor network in bipolar disorder. Comparison participants showed the opposite pattern of placebo-related changes in connectivity (group-by-condition, p-FDR < 0.05). Greater anxiolytic effects endorsed during placebo and associated increases in NAc functional connectivity related to greater alcohol use and alcohol problems at follow-up in bipolar disorder (p < 0.05).

Discussion

Results suggest differences in placebo response in bipolar disorder, including distinct neural correlates, that may relate to prospective alcohol use/problems. Given the theoretical association between placebo response and self-reported alcohol expectancies, findings could open the door to interventions aimed at changing expectancies.

Sex-related differences in the association between migraine, COVID-19, and long COVID: a population-based cohort

Background

Coronavirus disease 2019 (COVID-19), caused by the SARS-CoV-2 virus, placed unprecedented pressure on public health systems due to its mortality and global panic-and later due to long COVID challenges. One of these long COVID symptoms, headache, often resembles migraine-like features. Migraine shares similarities with COVID-19 and long COVID, yet the influence of sex is understudied. Our primary objective was to study the interrelationship between COVID-19 and migraine prevalence, while considering sex differences. The secondary objective was to examine how long COVID symptoms (headache, anosmia, memory, and concentration problems) affect males and females with and without COVID-19 and migraine.

Methods

All analyses were conducted using Lifelines, a prospective cohort study in the northern Netherlands. Baseline characteristics (2006-2014), self-reported migraine diagnoses (until 2021), and questionnaires on COVID-19 and long COVID symptoms (2020-2022) were collected. Logistic regression analyses were conducted to study the association between lifetime migraine and current SARS-CoV-2 infections while adjusting for age, sex, diet, educational attainment, activity, and smoking. Descriptive and sex-stratified analyses were conducted on long COVID symptoms.

Results

A total of 150,507 individuals were included, of which 29,680 (19.7%) reported migraine and 120,827 (80.3%) not. A total of 1,867 individuals with migraine [6.3% of individuals with migraine, 44.0 years (IQR 36.1-50.3)] and 6,797 individuals without migraine [5.6% of individuals without migraine, 44.4 years (IQR 35.3-52.2)] reported to be SARS-CoV-2 infected. The majority of individuals with migraine consisted of females (77.0% of those with migraine vs. 54.0% of those without migraine). The adjusted odds of having SARS-CoV-2 infections was 6.3% higher among those with (a history of) migraine compared with individuals without migraine in the logistic regression model (OR = 1.06, 95% CI 1.01-1.12). A slightly higher OR was observed in females (OR = 1.08, 95% CI 1.02-1.15), and the association was not apparent in males (OR = 1.00, 95% CI 0.88-1.12). Secondary analyses revealed that individuals with both migraine and COVID-19, and females in particular, were the most frequently bothered by long COVID symptoms headache, anosmia, concentration, and memory problems. Individuals with none of these diseases were the least bothered.

Conclusions

Individuals with migraine, especially females, are slightly more likely to report and/or contract COVID-19. Those with both conditions report long COVID symptoms more frequently, suggesting a shared vulnerability or pathophysiology. This may indicate the need for clinical surveillance of migraine patients recovering from COVID-19.

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.

Top-down control of the descending pain modulatory system drives placebo analgesia

In placebo analgesia, prior experience and expectations lead to pain suppression by the administration of an inert substance, but causal evidence for its neural basis is lacking. To identify the underlying neural circuits, we reverse-translated a conditioned placebo protocol from humans to mice. Surprisingly, the placebo effect suppresses both nociception and unconditioned emotional-motivational pain-related behavior. Descending pain modulatory neurons in the periaqueductal gray (PAG) are critical for both morphine and placebo antinociception. The placebo effect depends on input to the PAG from the medial prefrontal and anterior cingulate cortices, but not anterior insular cortex. Conditioning enhances noxious stimulus-evoked endogenous opioid release in the PAG to produce analgesia. Our results suggest that cortical control of the descending pain modulatory system (DPMS) is gated by rapid endogenous opioid signaling in the PAG during placebo trials. This study bridges clinical and preclinical research, establishing a central role for the DPMS in placebo analgesia.

Gene Expression Correlates with Disability and Pain Intensity in Patients with Chronic Low Back Pain and Modic Changes in a Sex-Specific Manner

Chronic low back pain (cLBP) lacks clear physiological explanations, and the treatment options are of limited effect. We aimed to elucidate the underlying biology of cLBP in a subgroup of patients with Modic changes type I (suggestive of inflammatory vertebral bone marrow lesions) by correlating gene expression in blood with patient-reported outcomes on disability and pain intensity and explore sex differences. Patients were included from the placebo group of a clinical study on patients with cLBP and Modic changes. Blood was collected at the time of inclusion, after three months, and after one year, and gene expression was measured at all time points by high-throughput RNA sequencing. The patients reported disability using the Roland-Morris Disability Questionnaire, and pain intensity was assessed as a mean of three scores on a 0-10 numeric rating scale: current LBP, worst LBP within the last two weeks, and mean LBP within the last two weeks. The gene expression profiles were then correlated to the reported outcomes. Changes in gene expression over time correlated significantly with changes in both disability and pain. The findings showed distinct patterns in men and women, with negligible overlap in correlated genes between the sexes. The genes involved were enriched in immunological pathways, particularly T cell receptor complex and immune responses related to neutrophils. Several of the genes harbour polymorphisms that previously have been found to be associated with chronic pain. Taken together, our results indicate gender differences in the underlying biology of disability and pain intensity in patients with low back pain.

Convergent state-control of endogenous opioid analgesia

Pain is a dynamic and nonlinear experience shaped by injury and contextual factors, including expectations of future pain or relief1. While μ opioid receptors are central to the analgesic effects of opioid drugs, the endogenous opioid neurocircuitry underlying pain and placebo analgesia remains poorly understood. The ventrolateral column of the posterior periaqueductal gray is a critical hub for nociception and endogenous analgesia mediated by opioid signaling2. However, significant gaps remain in understanding the cell-type identities, the sub-second neural dynamics involved in pain modulation, the role of endogenous peptide neuromodulators, and the contextual factors influencing these processes. Using spatial mapping with single-nuclei RNA sequencing of pain-active neurons projecting to distinct long-range brain targets, alongside cell type-specific and activity-dependent genetic tools for in vivo optical recordings and modulation of neural activity and opioid peptide release, we identified a functional dichotomy in the ventrolateral periaqueductal gray. Neurons expressing μ opioid receptors encode active nociceptive states, whereas enkephalin-releasing neurons drive pain relief during recovery from injury, in response to learned fear predictions, and during placebo analgesia. Finally, by leveraging the functional effects of placebo analgesia, we used direct optogenetic activation of vlPAG enkephalin neurons to drive opioid peptide release, resulting in a robust reduction in pain. These findings show that diverse need states converge on a shared midbrain circuit that releases endogenous opioids with high spatiotemporal precision to suppress nociceptive activity and promote analgesia.

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.

Gender differences in the response to antipsychotics or mood stabilizers in patients with acute mania: An individual patient data meta-analysis of placebo-controlled studies

Evidence suggests a worse clinical course in women compared to men with bipolar disorder. However, little research has explored gender differences in the efficacy of anti-manic medication. We sought to determine whether there are gender differences in efficacy of drug treatment in acute manic episodes of bipolar I disorder, and the influence of dichotomized age as a proxy for menopausal status and baseline severity on gender differences. We performed an individual patient data meta-analysis of 10 short term placebo controlled registration trials for treatment of acute mania (N = 2199) performed between 1996 and 2007 using the (Young) Mania Rating Scale ((Y)MRS)) as outcome. We observed a difference in effect size in mean change and responder status between men and women (NNT = 6.3 vs. 5.3), with a small but significant effect of gender on treatment response (β = 0.031). The effect size was larger in women older than 47 compared to women aged 47 and under (NNT = 4.2 vs. 7.5), and to a lesser extent, larger in men over 47 years compared those aged 47 and under (NNT = 3.8 vs. 6). Results were mainly driven by differences in response in the placebo group and independent of baseline severity. These findings suggest that men and premenopausal women might have a clinically modest advantage over their women and postmenopausal counterparts in treatment with anti-manic medication. Our results were limited by our sample not including antimanic agents registered after 2007 and by the absence of direct biological information regarding sex and menopausal state. Future research should aim to replicate current findings utilizing biological confirmation on the menopausal status and test whether findings are generalizable to newer antimanic agents.

Mitigating the Nocebo Effect in Biosimilar Use and Switching: A Systematic Review

BACKGROUND

In the context of biosimilar use and switching, a patient's negative perception of a biosimilar might trigger a nocebo effect, where negative expectations unrelated to its pharmacologic action may lead to worsened symptoms, resulting in less perceived therapeutic benefit or worsened adverse events. Considering the crucial role biosimilars have in reducing health care costs and expanding access to safe biologics globally, it is essential to develop and implement effective strategies to mitigate the possible occurrence of such nocebo effects.

OBJECTIVE

The aim of this systematic literature review was two-fold: (i) to review strategies that have been applied and/or tested for minimising the nocebo effect in clinical practice, within and outside the context of biosimilar switching, and (ii) to propose recommendations on useful mitigation strategies to minimise the occurrence of the nocebo effect in the context of biosimilar switching.

METHODS

Biomedical databases PubMed and Embase were screened up until the end of April 2023 with a search string consisting of the following search terms "nocebo", "biosimilar", "mitigation", "strategy", and "prevention" and related synonyms. The search strategy was supplemented by snowballing of the included studies. The quality of the studies was assessed using the Joanna Briggs Institute Critical Appraisal Checklist for Systematic Reviews and Research Syntheses, the Scale for the Assessment of Narrative Review Articles, and the Mixed Methods Appraisal Tool.

RESULTS

Of the 1617 identified and screened records, 60 met the inclusion criteria. Among these, 10 (17%) were conducted within the context of biosimilar switching, 7 of which specifically tested strategies to mitigate the nocebo effect. Among the remaining 50 studies conducted outside the biosimilar switching context, 46 tested mitigation strategies. Across the included studies, 13 distinct mitigation strategies were identified, which can be employed within the context of biosimilar switching: (i) open non-verbal communication, (ii) positive framing, (iii) empathic communication, (iv) validating communication, (v) shared decision making, (vi) self-affirmation, (vii) education of patients and health care professionals about the nocebo effect, (viii) education of patients and health care professionals about biosimilars, (ix) soft-skills training for health care professionals, (x) personalised information, (xi) supporting information, (xii) multidisciplinary approach, (xiii) organisation of the switch.

CONCLUSION

This review has identified a set of strategies that have been tested to mitigate the nocebo effect, which can be applied by health care professionals in the context of biosimilar switching with the aim of mitigating the occurrence of a nocebo effect. We recommend implementing a combination of mitigation strategies for patients and health care professionals to utilise before, during, and after a switch. It should be noted that given the limited number of studies specifically testing nocebo mitigation strategies within the biosimilar switching context to date, it is not yet possible to draw definite conclusions about the effect size of each mitigation strategy individually or in combination.

Effects of open and hidden administration of treatment-related information; a multi-experiment study

BACKGROUND

Two experiments (E1 and E2; N = 44 and N = 52, respectively) investigated the effect of positive (PI) and neutral information (NI) about a dental procedure, and if the delivery of the information by the treatment team (open administration) or unbeknownst to the treatment team (hidden administration), affected pain.

METHODS

Using a mixed design, patients undergoing drilling in a molar were randomized to the NI or PI groups. Before, during, and after treatment, patients reported their pain and stress levels. In E1 the treatment team delivered the information. In E2, an assistant not engaged in the treatment delivered the information.

RESULTS

In the PI group in E1, pain was reduced by 50 % compared to the NI group, and the effects of stress on pain were mitigated. These effects were abolished in E2. The dentist reported having displayed positive nonverbal behaviours (e.g. smiling and longer eye contact) in the PI group in E1, but not in E2.

DISCUSSION

Positive information reduced pain only when administrated openly. There was no effect of positive information administrated hidden from the treatment team. As information was similar in both experiments, factors other than the information most likely reduced pain in the PI group in E1.

CONCLUSION

Delivering positive information by the treatment team may generate behavioural cues which generate placebo effects.

Sex Differences in the Safety and Subjective Effects of Two Oral Δ9-Tetrahydrocannabinol-Containing Cannabis Products over Multiple Doses Among Healthy Adults

Introduction: A growing number of females report consuming cannabis products. There is a paucity of data on sex differences in safety and subjective effects after repeated use of varying oral doses of Δ9-tetrahydrocannabinol (THC; the primary psychoactive constituent of cannabis). Materials and Methods: Data were from two randomized, double-blind, placebo-controlled, multiple-dose, between-subject trials of two THC-containing oral cannabis products. Healthy adults received placebo, low-dose THC (∼2.5 or ∼5 mg per dose), or high-dose THC (∼7.5 or ∼10 mg per dose) twice daily for 7 days. There were 38 males (8 placebo, 17 low-dose THC, 13 high-dose THC) and 46 females (8 placebo, 17 low-dose THC, 21 high-dose THC). Analyses compared adverse events (AEs) and subjective effects between males and females, by THC dose. Results: In the placebo and low-dose THC groups, there were no sex differences in the relative rate of AEs. In the high-dose THC group, females versus males reported 3.08 (95% confidence interval [CI]=1.31-8.33) times as many AEs. There were no significant interactions of sex×low-dose THC group for any subjective effect. In the high-dose THC group, females versus males reported greater "relaxed" ratings (b=15.14, 95% CI=1.44-28.84, p=0.027), whereas in the placebo group, males versus females reported greater ratings of "liking the effect" (b=-30.01, 95% CI=2.77-57.26, p=0.028). Although analyses were underpowered to assess the sex×THC dose×day interaction, the initial sex disparity in AEs and some subjective effects in the high-dose THC group appeared to shrink after the first day. Conclusions: In this exploratory analysis, sex differences in some responses to oral THC were nuanced. Females appeared more sensitive than males to AEs and some subjective effects at higher but not lower doses. Males reported higher ratings than females on some subjective effects in response to placebo. Initial sex differences in response to higher doses of oral THC tended to diminish over 7 days of dosing. If replicated, findings could help inform sex-specific dosing strategies of medical cannabis products and could help educate medical cannabis patients on any temporality of effects.

The Impact of Cannabidiol Expectancy on Cortisol Responsivity in the Context of Acute Stress: Associations with Biological Sex

Background: Cannabidiol (CBD), a nonpsychoactive cannabinoid found in the cannabis plant, has gained interest for its purported stress- and anxiety-reducing effects. However, the mechanisms underlying these effects remain unclear. Our group previously found that CBD expectancy alone resulted in lower state anxiety (vs. CBD-free expectancy) among those who strongly believed it was helpful for such purposes, in addition to influencing physiological measures (i.e., heart rate variability). Aims: Using data collected as part of this previously published larger study, we aimed to explore the extent to which CBD expectancy alone impacts cortisol in the context of a laboratory stressor. Methods: A sample of 43 healthy adults (23 female) participated in one orientation and two experimental laboratory sessions. They received the same oil (CBD-free) during both experimental sessions but were told they received CBD oil in counterbalanced order in one of their sessions. Participants then engaged in a laboratory stressor (the Maastricht Acute Stress Test; MAST) and salivary cortisol samples were collected throughout [T1: baseline; T2: 90-min postabsorption (PA); T3: poststress (0-PS); T4: 10-min poststress (10-PS); T5: 30-min poststress (30-PS)]. Linear marginal models were used for analyses. Results: Findings indicated that a physiological stress response was elicited in the context of the MAST, which is consistent with what has been reported previously. Interestingly, while cortisol levels were significantly lower in the CBD expectancy condition (vs. CBD-free) immediately following the MAST (0-PS) and 10-min later (10-PS), this effect seems to be largely driven by males, evidenced by a three-way interaction. Cortisol levels did not reliably vary across expectancy conditions at any other time point. Conclusion: Overall, these results suggest that CBD expectancy appears to blunt cortisol in anticipation of a stressor, particularly in males. Findings suggest that it is important to consider the impact of drug-related expectations when assessing CBD-related effects on stress-related processes.

Placebo treatment affects brain systems related to affective and cognitive processes, but not nociceptive pain

Drug treatments for pain often do not outperform placebo, and a better understanding of placebo mechanisms is needed to improve treatment development and clinical practice. In a large-scale fMRI study (N = 392) with pre-registered analyses, we tested whether placebo analgesic treatment modulates nociceptive processes, and whether its effects generalize from conditioned to unconditioned pain modalities. Placebo treatment caused robust analgesia in conditioned thermal pain that generalized to unconditioned mechanical pain. However, placebo did not decrease pain-related fMRI activity in brain measures linked to nociceptive pain, including the Neurologic Pain Signature (NPS) and spinothalamic pathway regions, with strong support for null effects in Bayes Factor analyses. In addition, surprisingly, placebo increased activity in some spinothalamic regions for unconditioned mechanical pain. In contrast, placebo reduced activity in a neuromarker associated with higher-level contributions to pain, the Stimulus Intensity Independent Pain Signature (SIIPS), and affected activity in brain regions related to motivation and value, in both pain modalities. Individual differences in behavioral analgesia were correlated with neural changes in both modalities. Our results indicate that cognitive and affective processes primarily drive placebo analgesia, and show the potential of neuromarkers for separating treatment influences on nociception from influences on evaluative processes.

Risk factors associated with nocebo effects: A review of reviews

Objective

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

Methods

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

Results

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

Conclusions

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

Reducing Emotional Distress with Open-Label Placebos: Assessing the Role of Motor Engagement in Pill Consumption

It has been posited that ingesting a pill constitutes a pivotal action that facilitates the effects of open-label placebos (OLPs: placebos honestly prescribed). In the present OLP experiment, the motor components of a placebo treatment were systematically varied. The participants (n = 183) were randomly allocated to one of four groups that all viewed aversive pictures. The 'active OLP' group took a placebo pill with specific instructions concerning the sequence of motor actions for the intake. The 'usual OLP' group swallowed the pill (without specific motor instructions), while the third group received an 'imaginary OLP' (no pill intake). The fourth group applied cognitive reappraisal (CR; active control group) to reduce emotional distress. The participants rated their affective state as well as the efficacy and plausibility of the treatment approach. Moreover, blood pressure and pulse were recorded as indicators of bodily arousal. The four groups did not differ in their valence ratings and physiological measures. The 'imaginary OLP' received higher ratings for both effectiveness and plausibility than the 'usual OLP'. CR was rated as superior relative to all OLP conditions. In conclusion, reducing emotional distress with OLPs does not necessitate the consumption of a placebo pill. In terms of acceptability and ease of implementation, CR stands as a well-established alternative.

Sex Differences in Cardiovascular Management: A Call for Better Acknowledgment-Part 1 Pharmacological Differences in Women and Men; How Relevant Are They?

BACKGROUND

Sex differences (SDs) in pharmacology of cardiovascular (CV) drugs have been described previously; however, paradoxically, there are scarce recommendations in therapy based on these differences. It is of utmost importance to identify whether these SDs determine a modified clinical response and the potential practical implications for this, to provide a base for personalized medicine.

AREA OF UNCERTAINTY

The aim of this article was to outline the most important pharmacological drivers of cardiovascular drugs that differ between women and men, along with their implications and challenges in clinical practice.

DATA SOURCES

A detailed assessment of English-written resources reflecting SDs impact in CV drug pharmacology was performed using PubMed and Embase databases.

RESULTS

Despite large variations in CV drug pharmacokinetics and pharmacodynamics in individuals, correcting for height, weight, surface area, and body composition compensate for most "sex-dependent" differences. In addition, individual, cultural, and social factors significantly impact disease management in women versus men. Gender-biased prescribing patterns and gender-dependent adherence to therapy also influence outcomes. The development of sex-specific guidelines requires that they should reflect the SDs implications for the management of a disease and that the evidence should be carefully evaluated as to whether there is an adequate representation of both sexes and whether sex-disaggregated data are reported.

CONCLUSIONS

Pharmacological drivers are under the influence of an impressive number of differences between women and men. However, to establish their significance in clinical practice, an adequate representation of women in studies and the reporting of distinct results is mandatory.

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.

The Effect of Singular Nonverbal Behaviours of Experimenters on Pain Reports

Introduction

Studies suggest facial expressions of caregivers may be important in placebo effects; however, this has not been systematically tested. This experiment investigated the effects of caregivers' singular positive nonverbal behaviours (NBs) on pain reports.

Methods

Fifty-one males and 53 females (total of 104) participants were randomized to four groups that were displayed positive facial expressions, tone of voice, body movement, or neutral NBs of videotaped experimenters. Subjective reports of pain, stress, arousal, and cardiac activity were obtained in a pre-test, a conditioning phase, and at a post-test. Four minutes of heat pain was induced in each test, and a placebo cream was administered before the conditioning and post-test in all groups.

Results

There were no differences between the NB groups in the reduced pain. Males had larger reduction in pain in the post-test, and females had lower arousal than the opposite sex. During the conditioning, females had larger reduction in pain ie, unconditioned pain response (UPR). In females, the UPR predicted the reinforced expectation ie, increase in expectations from conditioning to post-test, and fear of minor pain negatively predicted both the UPR and reinforced expectation.

Discussion

Singular NBs of caregiver were weak to enhance placebo effects. Females had lower pain during conditioning, and the UPR amplitude in females was associated with positive expectations. Moreover, for females, fear of minor pain weakened the UPR and expectations of cream.

Conclusion

No NB of caregivers is more effective in reducing pain. Caregivers' NBs are less effective when displayed individually. Males and females may be different in underlying mechanisms of placebo effects.

A developmental framework for understanding the influence of sex and gender on health: Pediatric pain as an exemplar

Sex differences are a robust finding in many areas of adult health, including cardiovascular disease, psychiatric disorders, and chronic pain. However, many sex differences are not consistently observed until after the onset of puberty. This has led to the hypothesis that hormones are primary contributors to sex differences in health outcomes, largely ignoring the relative contributions of early developmental influences, emerging psychosocial factors, gender, and the interaction between these variables. In this paper, we argue that a comprehensive understanding of sex and gender contributions to health outcomes should start as early as conception and take an iterative biopsychosocial-developmental perspective that considers intersecting social positions. We present a conceptual framework, informed by a review of the literature in basic, clinical, and social science that captures how critical developmental stages for both sex and gender can affect children's health and longer-term outcomes. The literature on pediatric chronic pain is used as a worked example of how the framework can be applied to understanding different chronic conditions.

Challenges with embedding an integrated sex and gender perspective into pain research: Recommendations and opportunities

The focus of this article, within this BBI horizons special issue, is on sex, gender, and pain. We summarise what is currently known about sex- and gender-related variations in pain, exploring intersectional biological and psychosocial mechanisms, and highlight gaps in knowledge and understanding. Five key challenges with the exploration of sex and gender in pain research are presented, relating to: conceptual imprecision, research bias, limitations with binary descriptions, integrating sex and gender, and timely adoption/implementation of good research practice. Guidance on how to overcome such challenges is provided. Despite clear evidence for sex and gender differences in pain, there are conceptual and methodological barriers to overcome. Innovation in methods and approach can help develop more effective and tailored treatment approaches for men, women, boys, girls, and gender-diverse people.

The Nocebo Effect

Adverse nocebo responses can cause harm to patients and interfere with treatment adherence and effects in both clinic practice and clinical trials. Nocebo responses refer to negative outcomes to active medical treatments in clinical trials or practice that cannot be explained by the treatment's pharmacologic effects. Negative expectancies and nocebo effects are less known than placebo responses. Nocebo effects can be triggered by verbal suggestions, prior negative experiences, observation of others experiencing negative outcomes, and other contextual and environmental factors. As research advances over the years, mechanistic knowledge is accumulating on the neurobiological mechanisms of nocebo effects. This review summarizes studies on different facets of nocebo effects and responses and discusses clinical implications, ethical considerations, and future directions.

Nocebo-associated treatment discontinuation with subcutaneous anti-osteoporotic drugs. A systematic review and meta-analysis of placebo-arm dropouts in randomized-controlled trials

OBJECTIVE

Nocebo is a concept of therapeutics referring to unpleasant symptoms attributed by a patient to a drug, due to negative anticipation. Patients receiving oral anti-osteoporotic drugs in randomized controlled trials (RCT) can experience adverse events leading to dropout, implying that nocebo contributes to treatment discontinuation for these drugs. In this study we aim to investigate the nocebo effect of subcutaneous anti-osteoporotic drugs with a higher compliance rate than orally administered drugs.

STUDY DESIGN

We searched MEDLINE, EMBASE, SCOPUS, and Cochrane databases for double-blind trials investigating subcutaneous anti-osteoporotic drugs for osteoporosis (namely, denosumab, teriparatide, abaloparatide and romosozumab) published up to May 2023.

MAIN OUTCOME MEASURE

Dropouts due to reported adverse events in the placebo arms ("nocebo dropouts").

RESULTS

Data from 17 trials were extracted. Among 10,529 placebo-treated patients the pooled nocebo-dropout percentage was 3 % for denosumab (average: 0.03; 95 % CI: 0.01-0.05), 1 % for romosozumab (average: 0.01; 95 % CI: 0.00-0.03) and 6 % for teriparatide and abaloparatide (average: 0.06; 95 % CI: 0.05-0.07). Nocebo-dropouts were significantly higher in men than women (6 % vs. 3 %, respectively, p = 0.012), in older (mean age >68 years) than in younger patients (5 % vs. 1 %, respectively, p = 0.017) and in those with more severe osteoporosis (based on the percentage of participants with prior fragility-related fractures in the study cohort) compared with patients with no prior fracture history (4 % vs. 1 %, respectively, p = 0.046).

CONCLUSION

Nocebo responses may contribute to treatment discontinuation with subcutaneous anti-osteoporotic drugs in clinical practice. Higher nocebo-related dropout rates in the higher-risk RCT population (older patients, males, those with prior fractures) show that nocebo mechanisms have the potential to hinder therapeutic efforts to specific populations who would benefit most. Prospero registration number CRD42020212843.

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

OBJECTIVES

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

DESIGN

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

DATA SOURCES

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

OUTCOME MEASURES

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

RESULTS

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

CONCLUSIONS

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

FUNDING

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

PROSPERO REGISTRATION NUMBER

CRD42023392281.

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.

Baseline heart rate variability predicts placebo hypoalgesia in men, but not women

Introduction

Placebo hypoalgesic effects vary greatly across individuals, making them challenging to control for in clinical trials and difficult to use in treatment. We investigated the potential of resting vagally-mediated heart rate variability (vmHRV) to help predict the magnitude of placebo responsiveness.

Methods

In two independent studies (total N = 77), we administered a placebo paradigm after measuring baseline HRV. In Study I, we delivered heat pain to the forearm, on skin patches treated with "real" and "control" cream (identical inactive creams). In Study II, electrical pulses to the forearm were modulated by sham transcutaneous electrical nerve stimulation. We combined data from both studies to evaluate the relationship between vagally-mediated HRV (vmHRV) parameters and the placebo response size, while also assessing sex differences in this relationship.

Results and Discussion

This revealed a positive association between vmHRV and the degree of pain relief, and this effect was driven by men. These results not only reveal new insights into the (sex-specific) mechanisms of placebo hypoalgesia, but also suggest that measuring vmHRV may be helpful in predicting placebo responsiveness. Given that placebo hypoalgesic effects contribute substantially to treatment outcomes, such a non-invasive and easily obtained predictor would be valuable in the context of personalized medicine.

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.

Placebo effects on cutaneous pain and itch: a systematic review and meta-analysis of experimental results and methodology

ABSTRACT

Placebo effects, positive treatment outcomes that go beyond treatment processes, can alter sensations through learning mechanisms. Understanding how methodological factors contribute to the magnitude of placebo effects will help define the mechanisms by which these effects occur. We conducted a systematic review and meta-analysis of experimental placebo studies in cutaneous pain and itch in healthy samples, focused on how differences in methodology contribute to the resulting placebo effect magnitude. We conducted meta-analyses by learning mechanism and sensation, namely, for classical conditioning with verbal suggestion, verbal suggestion alone, and observational learning, separately for pain and itch. We conducted subgroup analyses and meta-regression on the type of sensory stimuli, placebo treatment, number of acquisition and evocation trials, differences in calibrated intensities for placebo and control stimuli during acquisition, age, and sex. We replicated findings showing that a combination of classical conditioning with verbal suggestion induced larger placebo effects on pain ( k = 68, g = 0 . 59) than verbal suggestion alone ( k = 39, g = 0.38) and found a smaller effect for itch with verbal suggestion alone ( k = 7, g = 0.14). Using sham electrodes as placebo treatments corresponded with larger placebo effects on pain than when topical gels were used. Other methodological and demographic factors did not significantly affect placebo magnitudes. Placebo effects on pain and itch reliably occur in experimental settings with varied methods, and conditioning with verbal suggestion produced the strongest effects. Although methods may shape the placebo effect to some extent, these effects appear robust overall, and their underlying learning mechanisms may be harnessed for applications outside the laboratory.

Transcranial direct current stimulation for post-COVID fatigue: a randomized, double-blind, controlled pilot study

Fatigue is one of the most frequent and disabling symptoms of the post-COVID syndrome. In this study, we aimed to assess the effects of transcranial direct current stimulation on fatigue severity in a group of patients with post-COVID syndrome and chronic fatigue. We conducted a double-blind, parallel-group, sham-controlled study to evaluate the short-term effects of anodal transcranial direct current stimulation (2 mA, 20 min/day) on the left dorsolateral prefrontal cortex. The modified fatigue impact scale score was used as the primary endpoint. Secondary endpoints included cognition (Stroop test), depressive symptoms (Beck depression inventory) and quality of life (EuroQol-5D). Patients received eight sessions of transcranial direct current stimulation and were evaluated at baseline, immediately after the last session, and one month later. Forty-seven patients were enrolled (23 in the active treatment group and 24 in the sham treatment group); the mean age was 45.66 ± 9.49 years, and 37 (78.72%) were women. The mean progression time since the acute infection was 20.68 ± 6.34 months. Active transcranial direct current stimulation was associated with a statistically significant improvement in physical fatigue at the end of treatment and 1 month as compared with sham stimulation. No significant effect was detected for cognitive fatigue. In terms of secondary outcomes, active transcranial direct current stimulation was associated with an improvement in depressive symptoms at the end of treatment. The treatment had no effects on the quality of life. All the adverse events reported were mild and transient, with no differences between the active stimulation and sham stimulation groups. In conclusion, our results suggest that transcranial direct current stimulation on the dorsolateral prefrontal cortex may improve physical fatigue. Further studies are needed to confirm these findings and optimize stimulation protocols.

Follow-Up of Side Effects throughout the Entire Course of Coronavirus Vaccination

Vaccines are considered the best protective means against coronavirus infection. There is increasing interest in reporting the side effects of vaccines, especially for individuals younger than 18 years old. Accordingly, this analytical cohort study aims to report on the side effects of adult and young individuals who received vaccination within 24 h, 72 h, 5 days, and 1 week through the entire course of vaccination (ECoV). A validated online survey was used to collect information. In total, 1069 individuals were completely followed. Most individuals received the Pfizer vaccine (59.6%). Most individuals had received two doses (69.4%). Very strong and statistically significant associations with side effects (p < 0.05, Phi (Φ) > 0.25) throughout the ECoV were reported for the type of vaccine and female gender. Non-smokers reported weak statistically significant associations. Fatigue and localized pain were the most commonly reported side effect, with onset within 24 h and duration of less than 72 h. The prevalence of reported side effects was statistically significantly higher among young individuals (<18 years old) than among adults (X2 (1) =7.6, p = 0.006. Phi φ = 0.11).

The Perception among Israeli Gastroenterologists Regarding Treatment of Patients with Biosimilar Medications

Background and Objectives: The ever-expanding entry of biosimilar drugs into the Israeli market requires doctors to decide whether to prescribe these medications. We aimed to assess the prevalence of biosimilar use and Israeli gastroenterologists' knowledge, experience, and perception of biosimilar treatment. Materials and Methods: A cross-sectional survey was conducted among Israeli Gastroenterology Association (IGA) members between March and May 2022 using a structured 20-item questionnaire. Results: The questionnaire was completed by 108 gastroenterologists. Sixty-two percent prescribed biosimilars to their patients in the past year. Most of the patients (81%) were biologically naïve and only 19% were switched to a biosimilar. Most gastroenterologists (75%) answered that the effectiveness is the same. The rates of resistance to switching were 19%, 36%, and 70% for patients in remission for over two years, pregnant women, and difficulty reaching remission, respectively. In cases seeing a lack of response after switching, most physicians chose to change the mechanism of action, with only a small percentage returning to the brand-name drug. Conclusions: Most Israeli gastroenterologists are not concerned about biosimilars' safety and efficacy. Despite this, most physicians will prefer the brand-name drug, especially regarding adalimumab. The populations in which physicians most oppose switching are those who have had difficulty achieving remission and pregnant women.

The Effects of Expectations and Worries on the Experience of COVID-19 Symptoms

Introduction

The COVID-19 pandemic has been shown to have profound effects on both mental and physical health. Distress and widespread uncertainty about global events and personal risk are associated with increased worry and negative expectations that impact physical health. Thus, the current pandemic poses a possibility for the experience of nocebo effects.

Objective

To evaluate the likelihood of nocebo-induced COVID-19 symptoms in a US sample.

Methods

An online study on the mental health impact of COVID-19 asked participants to complete a set of biweekly surveys over a 6-month period between April 2020 and May 2021. We focus on responses from 3,027 individuals who reported never testing positive for COVID-19. We assessed the association between two types of worry and self-reported symptoms of COVID-19. We used multi-level models to examine variations across and within participants over time. We further investigated the effects of pre-existing health conditions and mental health status.

Results

There was a positive association between symptoms and both general (b= 2.56, p<0.01) and personal worry (b=2.77, p<0.01). However, worry reported at one timepoint was not specifically associated with symptoms reported two weeks later (p = 0.63, p=0.56). We also found that a greater number of prior clinical comorbidities and greater mental health burden were significant predictors of symptom reporting.

Conclusions

These results suggest that increased worries during the COVID-19 pandemic were associated with greater symptoms. Further studies investigating worry and symptoms in populations with confirmed negative COVID-19 tests or isolated populations will be needed to isolate the occurrence of true nocebo effects during the pandemic.

Impact of media coverage on side effect reports from the COVID-19 vaccine

OBJECTIVE

Past research shows that media coverage of medicine side effects can produce a nocebo response. New Zealand news media discussed myocarditis following the Pfizer COVID-19 vaccine. This study examined whether side effects mentioned in the media increased compared to control symptoms not mentioned.

METHODS

The study analysed 64,086 vaccine adverse reaction reports, retrieved from the medicine safety authority. Generalised linear regressions compared the side effect rate during three discrete periods of media reporting (August 2021, December 2021, April 2022) with the pre-media baseline rate. The outcomes were weekly reports of chest discomfort, monthly reports of chest, heart and breathing symptoms, and myocarditis, pericarditis, and anxiety. Control symptoms were fever, numbness, and musculoskeletal pain. Logistic regressions investigated factors associated with side effect reporting.

RESULTS

The reporting rate of chest discomfort was 190% greater in the five weeks after the first media item (p < .001). The monthly reporting rates of the symptoms mentioned in the media were significantly greater after the news coverage (ps ≤ 0.001). There was no effect of media on the control side effect fever (p = .06). There was an effect of media on myocarditis, pericarditis and anxiety (ps < 0.001). Anxiety, male gender, and younger age were significantly associated with side effects.

CONCLUSION

The results indicate that a media-induced nocebo response occurred. This is most likely due to increased expectations and awareness of COVID-19 vaccine side effects, elevated symptom experience from anxiety, and consequently greater reporting of the symptoms in line with the media coverage.

The Impact of Sex and Gender in Medicine and Pharmacology

Sex and gender play a pivotal role in health and disease. Differences can be identified in symptoms, biomarkers, lifetime experiences of diseases, incidence, prevalence, therapeutic options, health-related behavior, and resiliency. However, awareness of sex and gender differences in medicine is still limited. Systematic implementation of sex and gender-sensitive research is not yet the norm, resulting in gaps in evidence especially in the diagnosis and treatment of diseases in women. For decades research has predominantly included male persons and animals, leading to a lack of information about symptoms in female individuals or the classification of their symptoms as "atypical". Currently, the inclusion of female participants in clinical marketing access trials is mandatory. However, this does not automatically translate into sex-disaggregated analyses potentially limiting the discovery of sex-specific targeted therapeutic schemes. Consistent consideration of sex and gender in planning, conducting, analyzing, and dissemination of pharmacological research projects is an important prerequisite for closing the gender data gap. Targeted implementation strategies might help to include sex and gender aspects in different parts of the health system and thereby support the improvement of health care for all patients. Health economic aspects could be a further drive for the implementation of sex- and gender-sensitive medicine.The current chapter focuses on the role of sex and gender in biomedical research and, consequently, their potential role in pharmacology. We will explore the commonly used terminology in the field, the historical development of sex and gender-sensitive medicine (SGSM), the relevance of sex and gender to research and clinical practice and conclude with an outlook on future developments in the field.

Dual-site transcranial direct current stimulation to treat tinnitus: a randomized controlled trial

Transcranial direct current stimulation (tDCS) has been proposed as a potential intervention for subjective tinnitus, but supporting evidence remains limited. We aimed to investigate the effect of anodal high-definition tDCS of the left temporal area and right dorsolateral prefrontal cortex on tinnitus severity. This double-blind randomized controlled trial included 77 patients (age range 18-79, 43 male) with chronic subjective tinnitus as their primary complaint. Thirty-eight subjects received six consecutive sessions of dual-site sequential high-definition-tDCS with electrodes positioned over the left temporal area and right dorsolateral prefrontal cortex. Both areas were stimulated for 15 min per session, with total stimulation time amounting to 30 min. Thirty-nine subjects received sham stimulation. The primary outcome measure was the change in tinnitus severity, as evaluated by the Tinnitus Functional Index, from baseline to a follow-up visit at 8 ± 2 weeks after treatment completion. Secondary outcomes included changes in perceived tinnitus loudness, as measured with a visual analogue scale and a tinnitus matching procedure, as well as scores on the Hospital Anxiety and Depression Scale, and the Hyperacusis Questionnaire. No differences in Tinnitus Functional Index change scores were identified between the active treatment and sham control groups (linear regression: P = 0.86). The Tinnitus Functional Index scores decreased significantly over time in both groups (P = 0.0012), indicating the presence of a considerable placebo effect. These change scores were significantly influenced by sex (linear regression: P = 0.037) and baseline symptoms of anxiety (linear regression: P = 0.049) in both groups. In general, Tinnitus Functional Index scores decreased more profoundly in males and in subjects with a higher degree of anxiety at baseline. None of the included secondary measures differed significantly between experimental arms. Our results suggest that dual-site sequential high-definition-tDCS of the left temporal area and right dorsolateral prefrontal cortex does not alleviate tinnitus severity. Interestingly, in our study population, fluctuations in tinnitus severity were influenced by gender and concurrent mental condition. It is therefore important to take these factors into account when conducting or planning randomized controlled trials in tinnitus populations.

Vaccine hesitancy prospectively predicts nocebo side-effects following COVID-19 vaccination

The directionality between vaccine hesitancy and COVID-19 vaccine side-effects has not been hitherto examined. We hypothesized a nocebo effect, whereby vaccine hesitancy towards the second Pfizer vaccination dose predicts subsequent side-effects for a booster dose, beyond other effects. We expected these nocebo effects to be driven by (mis)information in males and prior experience in females. A representative sample of older adults (n = 756, mean age = 68.9 ± 3.43) were questioned in a typical cross-lagged design (wave 1 following a second Pfizer dose, wave 2 after their booster). As hypothesized, earlier vaccine hesitancy predicted subsequent booster side-effects for females (β = 0.10 p = 0.025, f ² = 0.02) and males (β = 0.34, p < 0.001, f ² = 0.16); effects were stronger in males (χ²Δ (1) = 4.34, p = 0.03). The (W1-to-W2) side-effect autoregression was stronger in females (β = .34, p < 0.001; males β = 0.18, p < 0.001), χ²Δ (1) = 26.86, p < 0.001. Results show that a quantifiable and meaningful portion of COVID-19 vaccine side-effects is predicted by vaccine hesitancy, demonstrating that side-effects comprise a psychosomatic nocebo component in vaccinated individuals. The data reveal distinct risk levels for future side-effects, suggesting the need to tailor public health messaging.

Young female participants show blunted placebo effects associated with blunted responses to a cue predicting a safe stimulus in the right dorsolateral prefrontal cortex

Discrimination of cues predicting non-nociceptive/nociceptive stimuli is essential for predicting whether a non-painful or painful stimulus will be administered and for eliciting placebo/nocebo (pain reduction/pain enhancement) effects. Dysfunction of the neural system involved in placebo effects has been implicated in the pathology of chronic pain, while female sex is one of the important risk factors for development of chronic pain in young adults. The dorsolateral prefrontal cortex (dl-PFC) is suggested to be involved in placebo effects and is sensitive to sex and age. In this study, to examine the neural mechanisms by which sex and age alter placebo and nocebo effects, we analyzed cerebral hemodynamic activities in the dl-PFC in different sex and age groups during a differential conditioning task. During the training session, two different sounds were followed by low- and high-intensity electrical shocks. In the following recording session, electrical shocks, the intensity of which was mismatched to the sounds, were occasionally administered to elicit placebo and nocebo effects. In young female participants, both placebo effects and hemodynamic responses to the conditioned sounds in the right dl-PFC were significantly lower than those in elderly female participants, while there were no age differences in male participants. The hemodynamic responses to the sound paired with the safe stimulus in the right dl-PFC were significantly correlated with placebo effects, except in the young female group. These results suggest that blunted placebo effects in the young female participants are ascribed to blunted responses to the sound associated with the safe stimulus in the right dl-PFC, and that sex- and age-related factors may alter the responsiveness of the right dl-PFC to associative cues predicting a safe stimulus.

Differentiating Gender and Sex in Dental Research: A Narrative Review

While in humans the term “sex” refers to the biological attributes that distinguish subjects as male, female, and intersex, the term “gender” refers to psychological, social, and cultural factors that strongly influence attitudes, behaviors, and relationships of individuals. Recently, it has been emphasized how the integration of these two terms in the design of the research can improve the methodology of the research itself. However, in dental research, the influence of gender has not gained enough consideration and it is often used indiscriminately as a synonym for sex. This narrative review discusses the usefulness of considering gender and sex in dental research, whose guidelines have been provided so far on this topic, and whether the top 20 dental scientific journals promote the analysis of sex and gender in their guidelines. Sex and gender analysis in dental research could be important both for analyzing biological differences such as those in the immune or neuro-immune system, cardiovascular physiology, developmental anomalies or deformities, and psychosocial differences such as lifestyle, pain experience and prevalence of chronic pain, eating behavior, and access to healthcare services. As for the specific policies for sex and gender analysis and reporting, only five out of 20 biomedical journals have included them in their editorial policy, which refers mainly to the correct use of the terms “sex” and “gender.” In conclusion, we found that no specific and differentiated sex and gender analysis and reporting are required in dental journals. Their integration, which is still not routinely applied, may be improved in the future by updating editorial guidelines and developing more specific methodological recommendations.

Central correlates of placebo effects in nausea differ between men and women

INTRODUCTION

Despite growing evidence validating placebo effects in nausea, little is known about the underlying cortical mechanisms in women and men. Therefore, the present study examined sex differences and electroencephalography (EEG) characteristics of the placebo effect on nausea.

METHODS

On 2 consecutive days, 90 healthy subjects (45 females) were exposed to a nauseating visual stimulus. Nausea was continuously rated on an 11-point numeric rating scale, and 32 EEG channels were recorded. On day 2, subjects were randomly allocated to either placebo treatment or no treatment: the placebo group received sham acupuncture, whereas the control group did not receive any intervention.

RESULTS

In contrast to the control group, both sexes in the placebo group showed reduced signs for anticipatory nausea in the EEG, indexed by increased frontal lobe and anterior cingulate activity. Among women, the improvement in perceived nausea in the placebo group was accompanied by decreased activation in the parietal, frontal, and temporal lobes. In contrast, the placebo-related improvement of perceived nausea in men was accompanied by increased activation in the limbic and sublobar (insular) lobes.

CONCLUSION

Activation of the parietal lobe in women during the placebo intervention may reflect altered afferent activity from gastric mechanoreceptors during nausea-induced tachyarrhythmia, whereas in men, altered interoceptive signals in the insular cortex might play a role. Thus, the results suggest different cerebral mechanisms underlying the placebo effects in men and women, which could have implications for the treatment of nausea.

Oxytocin and the social facilitation of placebo effects

Significant clinical improvement is often observed in patients who receive placebo treatment in randomized double-blind placebo-controlled trials. While a proportion of this "improvement" reflects experimental design limitations (e.g., reliance on subjective outcomes, unbalanced groups, reporting biases), some of it reflects genuine improvement corroborated by physiological change. Converging evidence across diverse medical conditions suggests that clinically-relevant benefits from placebo treatment are associated with the activation of brain reward circuits. In parallel, evidence has accumulated showing that such benefits are facilitated by clinicians that demonstrate warmth and proficiency during interactions with patients. Here, we integrate research on these neural and social aspects of placebo effects with evidence linking oxytocin and social reward to advance a neurobiological account for the social facilitation of placebo effects. This account frames oxytocin as a key mediator of treatment success across a wide-spectrum of interventions that increase social connectedness, thereby providing a biological basis for assessing this fundamental non-specific element of medical care.

The neglect of sex: A call to action for including sex as a biological variable in placebo and nocebo research

Sex differences exist in the prevalence, progression and treatment efficacy of a wide array of medical conditions. While the placebo and nocebo effects have become increasingly relevant in the clinical arena, little is known about the influence of biological sex on placebo and nocebo effects. This paper discusses the existing, relatively limited and sometimes conflicting evidence about how sex impacts the occurrence and magnitude of the placebo and nocebo effects, mainly focusing on pain studies. We present recent evidence that when compared to men, women suffering from chronic orofacial pain may derive greater benefit from the placebo effect for analgesia. Nonetheless, we broadly argue that the field is not currently positioned to draw definitive conclusions and propose several important factors that may explain the inconsistency in the literature and that should be taken into account in future research. These include the specific target symptom of the placebo or nocebo manipulation and whether or not the target is related to the medical condition, the placebo or nocebo induction method, the sex of the experimenter or physician, and so forth. Future research should intentionally include sex a biological variable to favor translation of placebo and nocebo mechanisms into clinical applications.

Placebo-Related Adverse Events in Rheumatoid Arthritis

Prospective, double-blind, randomized, placebo-controlled studies are considered to provide the highest quality of interventional evidence. This meta-analysis summarizes the frequencies of adverse events according to the Medical Dictionary for Regulatory Activities (MedDRA) in the placebo arms of 101 such studies in rheumatoid arthritis, including a total of 17,150 patients in the placebo arms and 37,819 patients in the verum arms. Placebo-treated patients reported more than one adverse event in a median of 55.0%, 65.5%, and 72.5% (compared to 72.3% in the verum arms), and a serious adverse event in 2.5%, 5.8%, and 8.6% (compared to 5.9% in the verum arms), with stable doses of corticosteroids, conventional synthetic disease-modifying antirheumatic drugs (DMARDs), and biological DMARDs as background therapies, respectively. Odds ratios were comparable between placebo and verum arms for nausea (1.00 with 95% confidence interval (CI) 0.86–1.17), for hepatobiliary disorders (1.08 with CI 0.85–1.36), for abnormal hepatic functions (1.09 with CI 0.83–1.44), and general disorders and administration site conditions (1.39 with CI 0.95–2.03). A publication bias has to be assumed for nausea (p = 0.018; Egger’s test), diarrhoea (p = 0.022), and serious infections and infestations (p = 0.009). In conclusion, patients should be aware that “adverse events” may occur even with placebo medication, independent from an additional verum medication added to the background therapy. Further studies are warranted to respect and overcome the psychological and other issues related to these placebo-related “adverse events”.

The placebo and nocebo effects in functional urology

A placebo is an inert substance normally used in clinical trials for comparison with an active substance. However, a placebo has been shown to have an effect on its own; commonly known as the placebo effect. A placebo is an essential component in the design of conclusive clinical trials but has itself become the focus of intense research. The placebo effect is partly the result of positive expectations of the recipient on the state of health. Conversely, a nocebo effect is when negative expectations from a substance lead to poor treatment outcomes and/or adverse events. Randomized controlled trials in functional urology have demonstrated the importance of the placebo and nocebo effects across different diseases such as overactive bladder, urinary incontinence, lower urinary tract symptoms and interstitial cystitis/painful bladder syndrome, as well as male and female sexual dysfunction. Understanding the true nature of the placebo-nocebo complex and the scope of its effect in functional urology could help urologists to maximize the positive effects of this phenomenon while minimizing its potentially negative effects.

Outcome of Reverse Switching From CT-P13 to Originator Infliximab in Patients With Inflammatory Bowel Disease

BACKGROUND

Patients suffering from inflammatory bowel diseases (IBD) and treated with originator infliximab are increasingly being switched to biosimilars. Some patients, however, are "reverse switched" to treatment with the originator. Here we assess the prevalence of reverse switching, including its indication and outcomes.

METHODS

In this retrospective multicenter cohort study, data on patients with IBD from 9 hospitals in the Netherlands were collected. All adult patients with IBD were included if they previously had been switched from originator infliximab to the biosimilar CT-P13 and had a follow-up time of at least 52 weeks after the initial switch. The reasons for reverse switching were categorized into worsening gastrointestinal symptoms, adverse effects, or loss of response to CT-P13. Drug persistence was analyzed through survival analyses.

RESULTS

A total of 758 patients with IBD were identified. Reverse switching was observed in 75 patients (9.9%). Patients with reverse switching were predominantly female (70.7%). Gastrointestinal symptoms (25.5%) and dermatological symptoms (21.8%) were the most commonly reported reasons for reverse switching. In 9 patients (12.0%), loss of response to CT-P13 was the reason for reverse switching. Improvement of reported symptoms was seen in 73.3% of patients after reverse switching and 7 out of 9 patients (77.8%) with loss of response regained response. Infliximab persistence was equal between patients who were reverse-switched and those who were maintained on CT-P13.

CONCLUSIONS

Reverse switching occurred in 9.9% of patients, predominantly for biosimilar-attributed adverse effects. Switching back to originator infliximab seems effective in patients who experience adverse effects, worsening gastrointestinal symptoms, or loss of response after switching from originator infliximab to CT-P13.

Nocebo-Prone Behavior Associated with SARS-CoV-2 Vaccine Hesitancy in Healthcare Workers

Among healthcare workers (HCWs), SARS-CoV-2 vaccine hesitancy may be linked to a higher susceptibility to nocebo effects, i.e., adverse events (AEs) experienced after medical treatments due to negative expectations. To investigate this hypothesis a cross-sectional survey was performed with a self-completed questionnaire that included a tool (Q-No) for the identification of nocebo-prone individuals. A total of 1309 HCWs (67.2% women; 43.4% physicians; 28.4% nurses; 11.5% administrative staff; 16.6% other personnel) completed the questionnaires, among whom 237 (18.1%) had declined vaccination. Q-No scores were ≥15 in 325 participants (24.8%) suggesting nocebo-prone behavior. In a multivariate logistic regression model with Q-No score, age, gender, and occupation as independent variables, estimated odds ratios (ORs) of vaccination were 0.43 (i.e., less likely, p < 0.001) in participants with Q-No score ≥ 15 vs. Q-No score < 15, 0.58 in females vs. males (p = 0.013), and 4.7 (i.e., more likely) in physicians vs. other HCWs (p < 0.001), independent of age, which was not significantly associated with OR of vaccination. At least one adverse effect (AE) was reported by 67.5% of vaccinees, mostly local pain and flu-like symptoms. In a multivariate logistic regression model, with Q-No score, age, gender, and occupation as independent variables, estimated ORs of AE reporting were 2.0 in females vs. males (p < 0.001) and 1.47 in physicians vs. other HCWs (p = 0.017) independently of age and Q-No score, which were not significantly associated with OR of AE. These findings suggest that nocebo-prone behavior in HCWs is associated with SARS-CoV-2 vaccination hesitancy indicating a potential benefit of a campaign focused on nocebo-prone people.

Sex Differences in the Blood Oxygen Level-Dependent Signal to Placebo Analgesia and Nocebo Hyperalgesia in Experimental Pain: A Functional MRI Study

Objective

Placebo as well as nocebo responses are widely found in scientific research and clinical practice. Growing evidence suggests sex differences in placebo as well as nocebo responses. However, data concerning this question are still insufficient. This study examined whether the BOLD signals of two responses, as measured with functional MRI (fMRI), differ by sex under conditions of equivalent experimental pain perception.

Method

Thirty-one healthy volunteers (14 female) underwent two fMRI scans, once during a placebo intervention and once during a nocebo intervention, pseudorandomly ordered, in an acute lower back pain (ALBP) model. We collected visual analog scale (VAS) data after each scanning. fMRI data from different sex groups were subjected to functional connectivity (FC) analysis and behavioral correlation analysis (BCA).

Results

The results showed statistical differences in VAS scores between male and female participants, in both placebo and nocebo responses. Both groups also showed reduced FC in the pain-associated network of the placebo response and elevated FC in the pain-related network of the nocebo response. However, in the placebo condition, male participants displayed increased FC in the ventromedial prefrontal cortex, parahippocampal gyrus (PHP), and posterior cingulate cortex (PCC), while female participants showed increased FC in the dorsolateral prefrontal cortex, hippocampal gyrus (HP), and insular cortex (IC). In the nocebo condition, male participants showed decreased FC in the PCC and HP, while female participants displayed decreased FC in the mid-cingulate cortex, thalamus (THS), and HP. The BCA results of the two groups were also different.

Conclusion

We found that the endogenous opioid system and reward circuit play a key role in sex differences of placebo response and that anxiety and its secondary reactions may cause the sex differences of nocebo response.

The Nocebo Effect: A Review of Contemporary Experimental Research

BACKGROUND

Nocebo effect, the occurrence of adverse symptoms fallowing an inactive treatment, is much less understood than its opposite, placebo effect. This systematic review of contemporary studies exploring the nocebo effect focuses on (1) the mechanisms underlying the nocebo effect, (2) the characteristics of participants exhibiting a more intensive nocebo response, and (3) the circumstances that might reduce or prevent the nocebo effect.

METHOD

We included experimental nocebo studies published in English that examined the occurrence of nocebo in various domains (i.e., types of sensations and symptoms) and different levels of nocebo response (e.g., performance, self-assessment) and in different populations of participants (healthy and clinical). Using Web of Science, PsycInfo and PubMed, we identified 25 papers (35 studies) that met our criteria with a total of N = 2614 participants, mostly healthy volunteers.

RESULTS

Nocebo was invoked by manipulating expectations, conditioning or both. A narrative content synthesis was conducted. Nocebo was successfully invoked in a range of domains (e.g., pain, nausea, itch, skin dryness) and levels (sensory, affective, psychological, and behavioral). Various characteristics of the conditioning procedure and participants' emotions, expectations, and dispositions are found to be related to the nocebo response, which sheds insight into the possible mechanisms of the nocebo effect. Strategies successful and unsuccessful in diminishing the nocebo response are identified. Limitations of this review include a small sample of studies.

CONCLUSION

These findings point to the universality of nocebo as well as to the importance of participant characteristics and experimental circumstances in invoking the nocebo effect. Further research should examine the nocebo effect in clinical populations.

Sex differences in type and occurrence of adverse reactions to opioid analgesics: a retrospective cohort study

OBJECTIVES

Sex as a biological variable affects response to opioids. However, few reports describe the prevalence of specific adverse reactions to commonly prescribed opioids in men and women separately. A large cohort was used to investigate sex differences in type and occurrence of adverse reactions associated with use of codeine, tramadol, oxycodone and hydrocodone.

DESIGN

Retrospective cohort study.

SETTING

Participants in the Right Drug, Right Dose, Right Time (RIGHT) Study.

PARTICIPANTS

The medical records of 8457 participants in the RIGHT Study who received an opioid prescription between 1 January 2004 and 31 December 2017 were reviewed 61% women, 94% white, median age (Q1-Q3)=58 (47-66).

PRIMARY AND SECONDARY OUTCOME MEASURES

Adverse reactions including gastrointestinal, skin, psychiatric and nervous system issues were collected from the allergy section of each patient's medical record. Sex differences in the risk of adverse reactions due to prescribed opioids were modelled using logistic regression adjusted for age, body mass index, race and ethnicity.

RESULTS

From 8457 participants (of which 449 (5.3%) reported adverse reactions), more women (6.5%) than men (3.4%) reported adverse reactions to at least one opioid (OR (95% CI)=2.3 (1.8 to 2.8), p<0.001). Women were more likely to report adverse reactions to tramadol (OR (95% CI)=2.8 (1.8 to 4.4), p<0.001) and oxycodone (OR (95% CI)=2.2 (1.7 to 2.9), p<0.001). Women were more likely to report gastrointestinal (OR (95% CI)=3.1 (2.3 to 4.3), p<0.001), skin (OR (95% CI)=2.1 (1.4 to 3.3), p=0.001) and nervous system issues (OR (95% CI)=2.3 (1.3 to 4.2), p=0.004).

CONCLUSIONS

These findings support the importance of sex as a biological variable to be factored into pain management studies.