Pre-Exposure, But Not Overshadowing, Inhibits Nocebo Hyperalgesia

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.

Pain Rating is Worth a Thousand Words: Nocebo Hyperalgesia Induced by Verbal Modeling Prevails Over the Effects of Symbolic Modeling and Verbal Suggestion

This study compares the effectiveness of verbal modeling, symbolic modeling, and verbal suggestion in inducing nocebo hyperalgesia. It is the first study to examine the contribution of stress to observationally induced nocebo hyperalgesia. This study's experimental groups represented various sources of social information: a group of people participating in the study (verbal modeling), a single participant (symbolic modeling), and an experimenter (verbal suggestion). During the experiment, participants received electrocutaneous stimuli at the same intensity, some of which were applied with a nocebo (sham device). Participants in the verbal modeling group were acquainted with pain ratings that had allegedly been provided by other participants. The ratings suggested that other participants experienced more pain in the nocebo trials than in the control trials. In the symbolic modeling group, participants observed a videotaped model experiencing more pain in the nocebo than in the control trials. In the verbal suggestion group, participants received a verbal suggestion of hyperalgesia in the nocebo trials and no suggestion in the control trials. No manipulations were used in the control group. To investigate whether nocebo hyperalgesia is stable over time, an additional extinction phase was conducted. Nocebo hyperalgesia was induced by verbal modeling only and was partially mediated by expectancy. Stress was a significant moderator of the induced effect. Nocebo hyperalgesia was extinguished during the extinction phase. The obtained results provide potential implications for minimizing nocebo hyperalgesia in clinical practice by, for instance, controlling patients' expectancies and stress levels. PERSPECTIVE: The study shows the role of pain-related information derived from other people in shaping negative treatment experiences in the individual. Because information from others has a particular impact on individuals experiencing stress, both this information and the stress level of patients should be monitored in the treatment process.

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.

A study protocol testing pre-exposure dose and compound pre-exposure on the mechanisms of latent inhibition of dental fear

BACKGROUND

Dental stimuli can evoke fear after being paired - or conditioned - with aversive outcomes (e.g., pain). Pre-exposing the stimuli before conditioning can impair dental fear learning via a phenomenon known as latent inhibition. Theory suggests changes in expected relevance and attention are two mechanisms responsible for latent inhibition. In the proposed research, we test whether pre-exposure dose and degree of pre-exposure novelty potentiate changes in expected relevance and attention to a pre-exposed stimulus. We also assess if the manipulations alter latent inhibition and explore the possible moderating role of individual differences in pain sensitivity.

METHODS

Participants will be healthy individuals across a wide range of ages (6 to 35 years), from two study sites. Participants will undergo pre-exposure and conditioning followed by both a short-term and long-term test of learning, all in a novel virtual reality environment. The unconditioned stimulus will be a brief pressurized puff of air to a maxillary anterior tooth. Pre-exposure dose (low vs. high) and pre-exposure novelty (element stimulus vs. compound stimuli) will be between-subject factors, with stimulus type (pre-exposed to-be conditioned stimulus, a non-pre-exposed conditioned stimulus, and an unpaired control stimulus) and trial as within-subject factors. Pain sensitivity will be measured through self-report and a cold pressor test. It is hypothesized that a larger dose of pre-exposure and compound pre-exposure will potentiate the engagement of the target mechanisms and thereby result in greater latent inhibition in the form of reduced fear learning. Further, it is hypothesized that larger effects will be observed in participants with greater baseline pain sensitivity.

DISCUSSION

The proposed study will test whether pre-exposure dose and compound stimulus presentation change expected relevance and attention to the pre-exposed stimulus, and thereby enhance latent inhibition of dental fear. If found, the results will add to our theoretical understanding of the latent inhibition of dental fear and inform future interventions for dental phobia prevention.

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.

Susceptibility to Nocebo Hyperalgesia, Dispositional Optimism, and Trait Anxiety as Predictors of Nocebo Hyperalgesia Reduction

OBJECTIVES

The current paper explores the psychological predictors of nocebo hyperalgesia and whether the reduction of nocebo hyperalgesia can be predicted by susceptibility to nocebo hyperalgesia and psychological characteristics.

METHODS

Nocebo effects on pressure pain were first experimentally induced in 83 healthy female participants through conditioning with open-label instructions about the pain-worsening function of a sham TENS device to assess susceptibility to nocebo hyperalgesia. Participants were then randomized to 1 out of 2 nocebo-reduction conditions (counterconditioning/extinction) or to continued nocebo-conditioning (control), each combined with open-label instructions about the new sham device function. Dispositional optimism, trait and state anxiety, pain catastrophizing, fear of pain, and body vigilance were assessed at baseline.

RESULTS

The results showed that lower optimism and higher trait anxiety were related to a stronger induction of nocebo hyperalgesia. Moreover, a stronger induction of nocebo hyperalgesia and higher trait anxiety predicted a larger nocebo reduction across interventions. Also, nocebo hyperalgesia and optimism moderated the effects of the nocebo-reduction interventions, whereby larger nocebo hyperalgesia and lower optimism were associated with a larger nocebo reduction after counterconditioning, compared with control, and also extinction for larger nocebo hyperalgesia.

DISCUSSION

Our findings suggest that open-label conditioning leads to stronger nocebo hyperalgesia when trait anxiety is high and dispositional optimism is low, while these psychological characteristics, along with larger nocebo hyperalgesia, also predict open-label counterconditioning to be an effective nocebo-reduction strategy. Susceptibility to nocebo hyperalgesia, trait anxiety, and dispositional optimism might be indicators of a flexible pain regulatory system.

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.

Beliefs About Medicines Predict Side-Effects of Placebo Modafinil

BACKGROUND

Patients receiving placebo in clinical trials often report side-effects (nocebo effects), but contributing factors are still poorly understood.

PURPOSE

Using a sham trial of the cognition-enhancing "smart pill" Modafinil we tested whether medication beliefs and other psychological factors predicted detection and attribution of symptoms as side-effects to placebo.

METHODS

Healthy students (n = 201) completed measures assessing beliefs about medication, perceived sensitivity to medicines, negative affectivity, somatization, and body awareness; 66 were then randomized to receive Deceptive Placebo (told Modafinil-given placebo, 67 to Open Placebo (told placebo-given placebo, and 68 to No Placebo. Memory and attention tasks assessed cognitive enhancement. Nocebo effects were assessed by symptom checklist.

RESULTS

More symptoms were reported in the Deceptive Placebo condition (M = 2.65; SD = 2.27) than Open Placebo (M = 1.92; SD = 2.24; Mann-Whitney U = 1,654, z = 2.30, p = .022) or No Placebo (M = 1.68; SD = 1.75, Mann-Whitney U = 1,640, z = 2.74, p = .006). Participants were more likely to attribute symptoms to Modafinil side-effects if they believed pharmaceuticals to be generally harmful (incidence rate ratio [IRR] = 1.70, p = .019), had higher perceived sensitivity to medicines (IRR = 1.68, p = .011), stronger concerns about Modafinil (IRR = 2.10, p < .001), and higher negative affectivity (IRR = 2.37, p < .001).

CONCLUSIONS

Beliefs about medication are potentially modifiable predictors of the nocebo effect. These findings provide insight into side-effect reports to placebo and, potentially, active treatment.