Lessons Learned From Nocebo Effects in Clinical Trials for Pain Conditions and Neurodegenerative Disorders

Hypothalamic-Pituitary-Adrenal Activity in Adverse Events Reporting after Placebo Administration

Participants of clinical trials who receive a placebo treatment often report a variety of adverse events, sometimes called nocebo effects. The reason why these adverse events occur is not clear, and understanding the underlying mechanisms represents a challenge that is likely to improve the interpretation of clinical trials as well as medical practice. Here, we studied 192 healthy subjects who received placebo oxygen through a mask after reading (READ) or not reading (NO-READ) a list of possible adverse events of oxygen breathing: headache, chest pain, abdominal pain, and cough. The whole hypothalamus-pituitary-adrenal axis was assessed just before and right after placebo breathing by measuring the hypothalamic corticotropin-releasing hormone (CRH), pituitary adrenocorticotropic hormone (ACTH), and adrenal cortisol (COR). In addition, both state and trait anxiety were assessed. We found that 64.5% of the NO-READ group reported no adverse events, 30.2% had one, and only 5.2% had two adverse events. In contrast, only 20.8% of the READ group reported no adverse events, whereas 1, 2, 3, and 4 adverse events were reported with a frequency of 21.8%, 19.8%, 19.8%, and 17.7%, respectively. In addition, when the READ group reported three and four adverse events, CRH, ACTH, and COR were significantly increased compared to the NO-READ group, along with an increase in state anxiety scores. These data indicate that hypothalamic-pituitary-adrenal activity and state anxiety are increased in those subjects who report many adverse events after reading a list of adverse events, thus highlighting a possible neuroendocrine mechanism after placebo administration.

How do nocebo effects in placebo groups of randomized controlled trials provide a possible explicative framework for the COVID-19 pandemic?

Introduction: Randomized clinical trials (RCTs) are useful to study the role of individual and contextual factors in which therapies vs placebos are administered and to provide an important perspective for understanding the phenomenon of nocebo-related risks.Areas covered: The results of nocebo effects in RCT placebo groups, measured in terms of adverse events (AEs) and dropouts, will be presented as an explicative framework for the COVID-19 pandemic. Currently, SARS-CoV-2 vaccines are the only RCTs routinely conducted during the pandemic. Information about efficacy and safety of different vaccines represents a fertile ground for nocebo phenomena. Individual and contextual factors will be emphasized in order to understand the presence of a refusal of immunization associated with a specific vaccine considered less effective and safe. Critical aspects and some guidelines will be presented in order to counteract the nocebo effects and to improve adherence to drug treatments and the vaccination campaign.Expert opinion: The nocebo effect could explain the presence of strong resistance in European countries to immunization with a vaccine perceived as less effective, compared to others. Increased awareness of the nocebo effect would be relevant as it could lead to a greater participation in the vaccination campaign and in protecting individuals against SARS-CoV-2 infection.

How Do Nocebo Phenomena Provide a Theoretical Framework for the COVID-19 Pandemic?

The COVID-19 pandemic is a major health issue, which leads to psychological and behavioural changes. In particular, among various negative feelings, fear seems to be one of the main emotional reactions that can be as contagious as the virus itself. The actual pandemic is likely to function as an important stressor, especially in terms of chronic anxiety and lack of control over the succession of unforeseeable environmental events. In this direction, the psychological impact of previous quarantine measures showed important negative psychological effects, including post-traumatic stress symptoms (PTTS) with long-lasting effects. The presence of psychological discomfort and disturbances due to negative contextual factors can be studied using the nocebo phenomenon as a possible theoretical explanatory framework. Although in the absence of studies linking nocebo to Covid-19 and data-driven evidence, the context of the actual pandemic may be seen as a fertile ground for amplified discomfort and anxiety. The media provide dramatic and negative descriptions and often present conflicting sources of information, which can lead to physical and mental health problems, diminishing response to treatment. This can be worse when supported by conspiracy theories or misinformation. The aim of this perspective review is to propose a new theoretical framework for the COVID-19 pandemic, which should be supported by future empirical studies. In particular, the negative contextual factors, which can predispose individuals to psychological distress and the onset of the nocebo phenomena will be presented here, in order to suggest possible guidelines to mitigate the devastating effects of COVID-19.

Nocebos in rheumatology: emerging concepts and their implications for clinical practice

Nocebo effects are noxious reactions to therapeutic interventions that occur because of negative expectations of the patient. In the past decade, neurobiological data have revealed specific neural pathways induced by nocebos (that is, interventions that cause nocebo effects), as well as the associated mechanisms and predisposing factors of nocebo effects. Epidemiological data suggest that nocebos can have a notable effect on medication adherence, clinical outcomes and health-care policy. Meta-analyses of randomized controlled trials (RCTs) of patients with rheumatic and musculoskeletal diseases (RMDs) indicate that withdrawal of treatment by placebo-arm participants owing to adverse events is common; a proportion of these events could be nocebo effects. Moreover, in large-scale, open-label studies of patients with RMDs who transition from bio-originator to biosimilar therapeutics, biosimilar retention rates were much lower than in previous double-blind switch RCTs. This discrepancy suggests that in addition to the lack of response in some patients because of intrinsic differences between the drugs, nocebos might have an important role in low biosimilar retention, thus increasing the need for awareness and early identification of nocebo effects by rheumatologists and allied health-care professionals.

Are Patients With Schizophrenia Spectrum Disorders More Prone to Manifest Nocebo-Like-Effects? A Meta-Analysis of Adverse Events in Placebo Groups of Double-Blind Antipsychotic Trials

Background: Antipsychotic clinical trials use to present adverse events (AEs) for the drug under evaluation to treat schizophrenia. Interestingly, patients who receive the placebo during antipsychotic trials often report several AEs, but little is known about the essence of these negative effects in patients with schizophrenia spectrum disorders (SCD). In the present meta-analysis, we evaluated the relationship between the level of psychiatric symptomatology expressed as Positive and Negative Syndrome Scale (PANSS) scores and the rates of AEs reported in the placebo arms of double-blind clinical trials, for commonly prescribed atypical antipsychotic medications.

Methods: We selected 58 clinical trials describing AEs in SCD placebo groups, which compared atypical antipsychotic medications with placebo. A total of 6,301 placebo-treated patients were considered. AE profiles of the class were clusterized using MedDRA classification and analysed using a meta-regression approach.

Results: In the placebo arms the proportions of patients with any AE was 66.3% (95% CI: 62.7–69.8%). The proportion of withdrawal of patients treated with placebo because of AEs was 7.2% (95% CI: 5.9–8.4%). Interestingly, the AEs in the placebo arms corresponded to those of the antipsychotic-atypical-medication-class against which the placebo was compared. Namely, using meta-regression analysis we found an association between the level of psychiatric symptomatology measured with PANSS scores and higher AEs reported as nervous system (p = 0.020) and gastrintestinal disorders (p = 0.004). Moreover, the level of a higher psychiatric symptomatology expressed with PANSS scores was also related with higher AEs associated with psychiatric symptoms (p = 0.017).

Conclusion: These findings emphasise that the AEs in placebo arms of clinical trials of antipsychotic medications were substantial. Importantly, a higher level of psychiatric symptomatology makes SCD patients more prone to express AEs, thus contributing to possible drop-outs and to a lower adherence to treatments. These results are consistent with the expectation theory of placebo and nocebo effects.

Effects of acute psychological stress on placebo and nocebo responses in a clinically relevant model of visceroception

There is evidence to suggest a role of emotions in placebo and nocebo effects, but whether acute psychological stress changes the magnitude of placebo or nocebo responses has not been tested. In a clinically relevant model of visceroception, we assessed effects of acute psychological stress on changes in urgency and pain in response to positive or negative treatment suggestions. In 120 healthy volunteers, perceived urge-to-defecate and pain in response to individually calibrated rectal distensions were measured with visual analogue scales during a BASELINE. Participants then underwent the Trier Social Stress Test (N = 60) or a simple cognitive task (control, N = 60) and were randomized to positive (placebo), negative (nocebo), or neutral treatment information regarding intravenous administration of saline. The series of distensions was repeated, and changes in visual analogue scales from BASELINE to TEST were compared between groups using analysis of covariance and planned post hoc tests. Treatment information emerged as a main factor (P <0.001), supporting treatment information effects for both urgency and pain. Effects for urgency were modulated by stress (interaction effect: P <0.05): Positive information reduced urgency (P = 0.025), while negative information increased urgency (P = 0.026) only in stressed groups. For pain, effects of stress emerged for nocebo responses, which were only evident in stressed groups (P = 0.009). This is the first experimental study supporting effects of acute psychological stress on placebo and nocebo responses in visceroception. Results call for mechanistic as well as patient studies to assess how psychological stress shapes patients' treatment expectations and thereby affects health outcomes.

Clinical relevance of contextual factors as triggers of placebo and nocebo effects in musculoskeletal pain

Placebo and nocebo effects are embodied psycho-neurobiological responses capable of modulating pain and producing changes at different neurobiological, body at perceptual and cognitive levels. These modifications are triggered by different contextual factors (CFs) presented in the therapeutic encounter between patient and healthcare providers, such as healing rituals and signs. The CFs directly impact on the quality of the therapeutic outcome: a positive context, that is a context characterized by the presence of positive CFs, can reduce pain by producing placebo effects, while a negative context, characterized by the presence of negative CFs, can aggravate pain by creating nocebo effects. Despite the increasing interest about this topic; the detailed study of CFs as triggers of placebo and nocebo effects is still lacked in the management of musculoskeletal pain.

Increasing evidence suggest a relevant role of CFs in musculoskeletal pain management. CFs are a complex sets of internal, external or relational elements encompassing: patient’s expectation, history, baseline characteristics; clinician’s behavior, belief, verbal suggestions and therapeutic touch; positive therapeutic encounter, patient-centered approach and social learning; overt therapy, posology of intervention, modality of treatment administration; marketing features of treatment and health care setting. Different explanatory models such as classical conditioning and expectancy can explain how CFs trigger placebo and nocebo effects. CFs act through specific neural networks and neurotransmitters that were described as mediators of placebo and nocebo effects.

Available findings suggest a relevant clinical role and impact of CFs. They should be integrated in the clinical reasoning to increase the number of treatment solutions, boosts their efficacy and improve the quality of the decision-making. From a clinical perspective, the mindful manipulation of CFs represents a useful opportunity to enrich a well-established therapy in therapeutic setting within the ethical border. From a translational perspective, there is a strong need of research studies on CFs close to routine and real-world clinical practice in order to underline the uncertainty of therapy action and help clinicians to implement knowledge in daily practice.