Affect and emotions in placebo and nocebo effects: What do we know so far?

Assessing the longevity of attribute framing in attenuating the nocebo effect to brand and generic medication

The perception of taking a generic, relative to brand, medication has been demonstrated to exacerbate the nocebo effect. Conversely, positive attribute framing has been shown to attenuate the nocebo effect. However, little is known about the longevity of positive attribute framing nor how it interacts with generic versus brand treatment cues. Healthy participants (N = 205) were randomised to receive either sham-modafinil capsules with a brand or generic appearance, in conjunction with standard negative side effect framing (brand-negative: N = 42; generic-negative: N = 41) or positive side effect framing (brand-positive: N = 40; generic-positive: N = 40). The remainder were randomised to a no-treatment control (N = 42). Participants were informed that modafinil could enhance alertness and cognitive performance and reduce fatigue. Critically, modafinil was described as having several potential side effects. Treatment-related side effects, alertness, fatigue and cognitive performance were measured at baseline, 30-min post-treatment and 24 h later. Nocebo and placebo effects were observed across modafinil-treated participants relative to control. Positive framing significantly reduced warned side effects for 24 h. Perceived side effect likelihood, severity, and worry mediated the nocebo, but not framing, effect. Results have important implications for the presentation of side effect information, providing a potential route to reduce unwanted negative effects of generic medication.

Heal Me!-Investigating the "Red Potion" Concept and Its Influence on Gamers' Cardiovascular Endurance

The "red potion," inspired by video games, emulates the health point replenishment mechanism for injured game characters. Conversely, red ginger, known for its potential tonic properties in enhancing cardiovascular endurance, poses challenges in acquisition within specific regions. Several previous studies have highlighted the existence of an inseparable link when gamers are engaged in real-world activities, even without actively playing the game in the virtual world. This suggests the potential for the "red potion" concept to enhance the well-being of gamers in reality. A statistical ANOVA experiment involved 90 participants, all avid gamers, categorized into three groups: basic, placebo, and experimental. The basic group (BG) received a red-colored beverage without red ginger infusion or the 'red potion' concept. In contrast, the placebo group (PG) received a similar beverage described as a "red potion" but without red ginger. Lastly, the experimental group (EG) received a red ginger-infused beverage without the "red potion" concept. Despite receiving different treatments, all beverages were presented in the same red color. Participants underwent the "beep test" to assess their baseline stamina. The results revealed that both PG and EG exhibited comparable cardiovascular endurance, affirming the potential of the "red potion" concept to positively influence gamers.

Practitioner warmth and empathy attenuates the nocebo effect and enhances the placebo effect

Augmented patient-practitioner interactions that enhance therapeutic alliance can increase the placebo effect to sham treatment. Little is known, however, about the effect of these interactions on maladaptive health outcomes (i.e., the nocebo effect). Healthy participants (N = 84) were randomised to a 3-day course of Oxytocin nasal drops (actually, sham treatment) in conjunction with a high-warmth interaction (Oxy-HW: N = 28), a low-warmth interaction (Oxy-LW: N = 28) or to a no treatment control group (NT: N = 28). All participants were informed that the Oxytocin treatment could increase psychological well-being but was associated with several potential side effects. Treatment-related side effects, unwarned symptoms, and psychological well-being were measured at baseline and all post-treatment days. Side effect reporting was increased in the Oxy-LW condition compared to the other groups across all days. Conversely, increased psychological well-being was observed in the Oxy-HW condition, relative to the other conditions, but only on Day 1. Among those receiving treatment, positive and negative expectations, and treatment-related worry, did not vary by interaction-style, while psychological well-being and side effect reporting were inversely associated at the level of the individual. Results have important implications for practice, suggesting poorer quality interactions may not only reduce beneficial health outcomes but also exacerbate those that are maladaptive.

Placebo Effects Are Small on Average in the 7.5% CO2 Inhalational Model of Generalized Anxiety

BACKGROUND

Anxiety disorders are highly prevalent and socio-economically costly. Novel pharmacological treatments for these disorders are needed because many patients do not respond to current agents or experience unwanted side effects. However, a barrier to treatment development is the variable and large placebo response rate seen in trials of novel anxiolytics. Despite this, the mechanisms that drive placebo responses in anxiety disorders have been little investigated, possibly due to low availability of convenient experimental paradigms. We aimed to develop and test a novel protocol for inducing placebo anxiolysis in the 7.5% CO2 inhalational model of generalized anxiety in healthy volunteers.

METHODS

Following a baseline 20-minute CO2 challenge, 32 healthy volunteers were administered a placebo intranasal spray labelled as either the anxiolytic "lorazepam" or "saline." Following this, participants surreptitiously underwent a 20-minute inhalation of normal air. Post-conditioning, a second dose of the placebo was administered, after which participants completed another CO2 challenge.

RESULTS

Participants administered sham "lorazepam" reported significant positive expectations of reduced anxiety (P = .001), but there was no group-level placebo effect on anxiety following CO2 challenge post-conditioning (Ps > .350). Surprisingly, we found many participants exhibited unexpected worsening of anxiety, despite positive expectations.

CONCLUSIONS

Contrary to our hypothesis, our novel paradigm did not induce a placebo response, on average. It is possible that effects of 7.5% CO2 inhalation on prefrontal cortex function or behavior in line with a Bayesian predictive coding framework attenuated the effect of expectations on subsequent placebo response. Future studies are needed to explore these possibilities.

The relationship between expectancy, anxiety, and the nocebo effect: a systematic review and meta-analysis with recommendations for future research

Despite the theoretical prominence of expectancy and anxiety as potential mechanisms of the nocebo effect, not all studies measure expectancy and/or anxiety, and there are inconsistent findings among those that do. The present study sought to systematically review and meta-analyse available data to evaluate the relationship between expectancy, anxiety and the nocebo effect. The two key questions were: (1) whether nocebo manipulations influence expectancy and anxiety; and (2) whether expectancy and anxiety are associated with the subsequent nocebo effect. Fifty-nine independent studies (n = 3129) were identified via database searches to 1st August 2021. Nocebo manipulations reliably increased negative expectancy with a large effect (g = .837) and state anxiety with a small effect (g = .312). Changes in expectancy and state anxiety due to the nocebo manipulation were associated with larger nocebo effects (r = .376 and .234, respectively). However, there was no significant association between dispositional anxiety and the nocebo effect. These findings support theories that rely on situationally-induced expectancy and anxiety, but not dispositional anxiety, to explain nocebo effects. Importantly, being malleable, these findings suggest that interventions that target maladaptive negative expectancies and state anxiety could be beneficial for reducing the harm nocebo effects cause across health settings. Recommendations for future research are discussed.

Socially Acquired Nocebo Effects Generalize but Are Not Attenuated by Choice

BACKGROUND

Socially observing a negative treatment-related experience has been shown to modulate our own experience with the same intervention, leading to worsened health outcomes. However, whether this social learning generalizes to similar but distinct interventions has not been explored nor what manipulations can reduce these effects.

PURPOSE

To determine whether socially acquired nocebo effects can be generated by observing a negative experience with a similar, but distinct intervention, and whether choice can reduce these effects.

METHODS

Across three experiments, a community sample of healthy adults (N = 336) either watched a confederate report cybersickness to the same Virtual Reality (VR) activity they were assigned to (Social Modeling: Consistent); a similar, but different VR activity (Social Modeling: Inconsistent); or did not view the confederate (No Social Modeling). Participants were either given choice over the VR (Choice) or assigned by the experimenter (No Choice).

RESULTS

Across the experiments, there was significantly greater cybersickness in both Social Modeling groups relative to No Social Modeling, while the two Social Modeling groups did not differ. There was no significant effect of Choice or a Choice by Social Modeling interaction. Social Modeling elicited greater anxiety and expectancies for cybersickness. Furthermore, these mechanisms mediated the association between social modeling and cybersickness.

CONCLUSIONS

Socially acquired side-effects were demonstrated to generalize to similar, but distinct interventions, highlighting the diffuse and robust effect social modeling can have on our experiences. However, choice did not attenuate the experience of cybersickness, highlighting the need for alternative methods to counteract the effect of social modeling.

The role of positive information provision in open-label placebo effects

Open label placebos (OLPs) appear generally efficacious among clinical samples, but the empirical evidence regarding their use in non-clinical and sub-clinical samples, as well as when administered independent of a convincing rationale, is mixed. Healthy participants (N = 102) were randomised to either a 6-day course of OLP pills with information provision (OLP-plus: N = 35), without information provision (OLP-only: N = 35), or no-treatment control group (N = 32). OLP pills were described as enhancing physical (symptoms and sleep) and psychological (positive and negative emotional) well-being. Well-being was assessed at baseline and on Day 6. Expectancies and adherence were measured. OLP administration interacted with baseline well-being. The OLP-plus group demonstrated increased well-being on all outcomes other than positive emotions, but only when they reported decreased baseline well-being. OLP-only and control groups did not differ. The OLP-plus group demonstrated elevated expectancies, that mediated the OLP effect on physical symptoms relative to control, but only when well-being was lower than average at baseline (i.e. moderated-mediation). Results demonstrate the importance of information provided with OLPs. The moderating effect of baseline outcomes may reconcile inconsistent results regarding clinical and non-clinical samples. Accounting for baseline symptoms in non-clinical and sub-clinical samples is likely to enhance our understanding of when OLPs are effective.

The impact of pharmaceutical form and simulated side effects in an open-label-placebo RCT for improving psychological distress in highly stressed students

Open-label placebo (OLP) may be utilized to reduce psychological distress. Yet, potential contextual effects have not been explored. We investigated the impact of pharmaceutical form and the simulation of side effects in a parallel group RCT (DRKS00030987). A sample of 177 highly stressed university students at risk of depression were randomly assigned by computer generated tables to a 1-week intervention with active or passive OLP nasal spray or passive OLP capsule or a no-treatment control group. After the intervention, groups differed significantly in depressive symptoms but not regarding other outcomes of psychological distress (stress, anxiety, sleep quality, somatization), well-being or treatment expectation. OLP groups benefitted significantly more compared to the no-treatment control group (d = .40), OLP nasal spray groups significantly more than the OLP capsule group (d = .40) and the active OLP group significantly more than the passive OLP groups (d = .42). Interestingly, before intervention, most participants, regardless of group assignment, believed that the OLP capsule would be most beneficial. The effectiveness of OLP treatments seems to be highly influenced by the symptom focus conveyed by the OLP rationale. Moreover, pharmaceutical form and simulation of side effects may modulate efficacy, while explicit treatment expectation seems to play a minor role.

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.

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.

Open-Label Placebo Administration Decreases Pain in Elderly Patients With Symptomatic Knee Osteoarthritis - A Randomized Controlled Trial

Background

Recent studies indicate that the administration of open-label placebos (OLP) can improve symptoms in various medical conditions. The primary aim of this 3-week randomized controlled trial was to examine the effects of OLP treatments on pain, functional disability, and mobility in patients with arthritic knee pain.

Methods

Sixty patients (55% females; mean age, 66.9 ± 9.7 SD years) were randomized to one of two OLP treatments (n = 41) or no treatment (NT; n = 19). OLP treatments were accompanied by the verbal suggestion "to decrease pain" (OLP-pain, n = 20) or "to improve mood" (OLP-mood, n = 21). Pain and mood levels were monitored on 11-point Numeric Rating Scales (NRSs) in a patient diary, and global clinical improvement (CGI-I) was assessed at the end of the study. At baseline and after 21 days, patients filled in validated questionnaires to assess symptoms and functional disability of the knee (WOMAC), mental and physical quality of life (SF-36), state anxiety (STAI-state), perceived stress (PSQ-20), and self-efficacy (GSE). In addition, knee mobility (neutral zero-method), heart rate variability (HRV), and diurnal cortisol levels were evaluated before and after treatment.

Results

Evaluation of daily pain ratings indicated significant pain decrease in the OLP groups compared to NT (p = 0.013, d = 0.64), with no difference between the OLP-pain and the OLP-mood groups (p = 0.856, d = 0.05). OLP treatment also improved WOMAC pain (p = 0.036, d = 0.55), again with no difference between the two OLP groups (p = 0.65, d = 0.17). WOMAC function and stiffness, knee mobility, stress, state anxiety, quality of life, and self-efficacy did not change differently between groups.

Conclusion

OLP treatment improved knee pain in elderly patients with symptomatic knee osteoarthritis (OA), while functional disability and mobility of the knee did not change. The content of the verbal suggestion was of minor importance. OLP administration may be considered as supportive analgesic treatment in elderly patients with symptomatic knee OA.

Trial Registration

German Clinical Trials Register (https://www.drks.de/), DRKS00015191 (retrospectively registered).

The association of affective state with the assimilation of daily pain expectancy and pain experience

ABSTRACT

Expectancies for pain and pain relief are central to experimental models of placebo analgesia and nocebo hyperalgesia, and are a promising target for clinical intervention in patients with chronic pain. Affective states may play an important role in modulating the degree to which expectancies influence pain, broadening the opportunities for intervention targets. However, findings to date have been mixed and mostly limited to laboratory designs. Few studies have examined the interplay of naturally occurring affective states, pain expectancies, and pain experiences in the course of daily life with chronic pain. In the present study, patients with temporomandibular disorder reported their daily pain expectancies and affective states each morning, and their daily pain experience each evening, over a two-week period. Multilevel modeling analyses revealed the association of morning pain expectancies with subsequent pain experiences was moderated by morning positive affective state (B=.04, SE=.02, t=2.00, p=.046), such that the congruent assimilation of a low pain expectancy with a low pain experience was starkest when morning positive affect was higher than usual. Relatedly, higher morning positive affect predicted greater odds of experiencing a match between pain expectancies and pain experience when the expectation was for low, but not high, pain levels (OR: 1.19, CI: 1.01-1.41, p=.03). Negative affect, in contrast, did not significantly influence the assimilation of high pain expectancies with high pain experiences. These findings extend prior experimental studies by showing that the association of daily pain expectancies with pain experience varies as a function of affective state.

Do individual psychological characteristics predict induction and generalization of nocebo and placebo effects on pain and itch?

BACKGROUND

Nocebo and placebo effects, i.e., adverse or beneficial treatment effects, respectively, putatively due to expectancies can modulate pain and itch. These effects can generalize within the pain or itch modality. Predicting the induction and generalization of these effects can be helpful in clinical practice. This study aims to investigate whether psychological characteristics related to the fear-avoidance model predict the induction and generalization of nocebo and placebo effects on pain and itch in young healthy participants.

METHODS

Data from two previous experiments were analyzed. In Experiment 1, we induced nocebo and placebo effects on heat pain and tested generalization to pressure pain and to cowhage-evoked itch (n = 33 in a nocebo group, n = 32 in a placebo group). In Experiment 2, we induced nocebo effects on cowhage-evoked itch and tested generalization to mechanical itch and to mechanical touch (n = 44). Potential predictors were anxiety- and stress symptoms, attention to pain/itch, and pain/itch catastrophizing. Multiple regression analyses were performed.

RESULTS

For nocebo effects, none of the individual psychological characteristics significantly predicted induction of nocebo effects nor their generalization. For placebo effects, only less stress symptoms, lower attention to pain, and higher pain catastrophizing weakly predicted a stronger generalization of placebo effects from heat pain to pressure pain.

CONCLUSION

The tested psychological characteristics may not play an important role in the induction and generalization of nocebo and placebo effects in healthy individuals. However, firm conclusions cannot be drawn with the current sample. Future studies should validate findings in larger and more diverse samples.

A social affective neuroscience lens on placebo analgesia

Pain is a fundamental experience that promotes survival. In humans, pain stands at the intersection of multiple health crises: chronic pain, the opioid epidemic, and health disparities. The study of placebo analgesia highlights how social, cognitive, and affective processes can directly shape pain, and identifies potential paths for mitigating these crises. This review examines recent progress in the study of placebo analgesia through affective science. It focuses on how placebo effects are shaped by expectations, affect, and the social context surrounding treatment, and discusses neurobiological mechanisms of placebo, highlighting unanswered questions and implications for health. Collaborations between clinicians and social and affective scientists can address outstanding questions and leverage placebo to reduce pain and improve human health.

Cutoff criteria for the placebo response: a cluster and machine learning analysis of placebo analgesia

Computations of placebo effects are essential in randomized controlled trials (RCTs) for separating the specific effects of treatments from unspecific effects associated with the therapeutic intervention. Thus, the identification of placebo responders is important for testing the efficacy of treatments and drugs. The present study uses data from an experimental study on placebo analgesia to suggest a statistical procedure to separate placebo responders from nonresponders and suggests cutoff values for when responses to placebo treatment are large enough to be separated from reported symptom changes in a no-treatment condition. Unsupervised cluster analysis was used to classify responders and nonresponders, and logistic regression implemented in machine learning was used to obtain cutoff values for placebo analgesic responses. The results showed that placebo responders can be statistically separated from nonresponders by cluster analysis and machine learning classification, and this procedure is potentially useful in other fields for the identification of responders to a treatment.

Pre-Exposure, But Not Overshadowing, Inhibits Nocebo Hyperalgesia

Nocebo hyperalgesia is a pervasive problem that significantly adds to the burden of pain. Conditioning is a key mechanism of nocebo hyperalgesia and recent evidence indicates that, once established, nocebo hyperalgesia is resistant to extinction. This means that preventive strategies are critical. We therefore tested whether two novel strategies - overshadowing (Experiment 1) and pre-exposure (Experiment 2) - could inhibit conditioned nocebo hyperalgesia. Overshadowing involves introducing additional cues during conditioning that should compete with and overshadow learning about the target nocebo cue. Pre-exposure involves pre-exposing the target nocebo cue in the absence of pain, which should diminish its ability to become associated with pain later. In both studies, healthy volunteers (N = 141) received exposure to a series of electrocutaneous pain stimuli with and without a sham electrode 'activated', which they were led to believe was a genuine hyperalgesic treatment. Nocebo conditioning was achieved by pairing sham activation with high pain prior to testing at equivalent pain intensity. In both studies, standard nocebo conditioning led to clear nocebo hyperalgesia relative to natural history controls. In Experiment 1, there was no evidence that overshadowing attenuated nocebo hyperalgesia. Importantly, however, Experiment 2 found that pre-exposure successfully attenuated nocebo hyperalgesia with post hoc analysis suggesting that this effect was dose-dependent. These findings provide novel evidence that pre-exposure, but not overshadowing, could be a cheap and effective way for mitigating the substantial harm caused by conditioned nocebo hyperalgesia in clinical settings. PERSPECTIVE: Nocebo hyperalgesia causes substantial patient burden with few preventive options available. Our study found novel evidence that pre-exposing treatment cues without pain, but not overshadowing them with other cues, has the capacity to inhibit conditioned nocebo hyperalgesia. Pre-exposure may therefore be an effective preventive strategy to combat nocebo hyperalgesia.