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Canadian Journal of Psychiatry. Revue... Jul 2023Obsessive-compulsive disorder (OCD) is a major mental health condition with a lifetime prevalence rate of 1.3% among adults. While placebo effects are well described for... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Obsessive-compulsive disorder (OCD) is a major mental health condition with a lifetime prevalence rate of 1.3% among adults. While placebo effects are well described for conditions such as depressive and anxiety disorders, they have not been systematically characterized in OCD.
OBJECTIVES
We aimed to determine the impact of placebos in improving different symptom domains in patients with OCD.
METHODS
We systematically searched PubMed, EMBASE, Scopus, Web of Science, Ovid, the Cochrane Library, and Google Scholar databases/search engine from inception to January 2021 for randomized controlled trials of treatments for OCD with a placebo arm. A modified Cohen's effect size (ES) was calculated using change in baseline to endpoint scores for different measurement scales within placebo arms to estimate placebo effects and to investigate their correlates by random-effects model meta-analyses.
RESULTS
Forty-nine clinical trials (placebo group = 1993), reporting 80 OCD specific (153 measures in general) were included in the analysis. Overall placebo ES (95% confidence interval [CI]) was 0.32 (0.22-0.41) on OCD symptoms, with substantial heterogeneity (I-square = 96.1%). Among secondary outcomes, general scales, ES: 0.27 (95%CI: 0.14-0.41), demonstrated higher ES than anxiety and depression scales, ES: 0.14 (95%CI: -0.4 to 0.32) and 0.05 (95%CI: -0.05 to 0.14), respectively. Clinician-rated scales, ES: 0.27(95%CI: 0.20-0.34), had a higher ES than self-reported scales, ES: 0.07 (95%CI: -0.08 to 0.22). More recent publication year, larger placebo group sample size, shorter follow-up duration, and younger age of participants were all associated with larger placebo ES. Egger's test reflected possible small-study effect publication bias ( = 0.029).
CONCLUSION
Placebo effects are modest in OCD trials and are larger in clinician ratings, for younger patients, and early in the treatment course. These findings underscore the need for clinicians and scientists to be mindful of placebo effects when formulating treatments or research trials for OCD.
SYSTEMATIC REVIEW REGISTRATION NUMBER
PROSPERO CRD42019125979.
Topics: Adult; Humans; Placebo Effect; Obsessive-Compulsive Disorder; Anxiety Disorders
PubMed: 35876317
DOI: 10.1177/07067437221115029 -
Handbook of Clinical Neurology 2016Placebos have long been considered a nuisance in clinical research, for they have always been used as comparators for the validation of new treatments. By contrast,... (Review)
Review
Placebos have long been considered a nuisance in clinical research, for they have always been used as comparators for the validation of new treatments. By contrast, today they represent an active field of research, and, due to the involvement of many mechanisms, the study of the placebo effect can actually be viewed as a melting pot of concepts and ideas for neuroscience. There is not a single placebo effect, but many, with different mechanisms across different medical conditions and therapeutic interventions. Expectation, anxiety, and reward are all involved, as well as a variety of learning phenomena and genetic variants. The most productive models to better understand the neurobiology of the placebo effect are pain and Parkinson's disease. In these medical conditions, several neurotransmitters have been identified, such as endogenous opioids, cholecystokinin, dopamine, as well as lipidic mediators, for example, endocannabinoids and prostaglandins. Since the placebo effect is basically a psychosocial context effect, these data indicate that different social stimuli, such as words and therapeutic rituals, may change the chemistry of the patient's brain, and these effects are similar to those induced by drugs.
Topics: Humans; Nervous System Diseases; Nocebo Effect; Placebo Effect; Psychophysiologic Disorders
PubMed: 27719874
DOI: 10.1016/B978-0-12-801772-2.00048-5 -
Inflammatory Bowel Diseases Sep 2023
Topics: Humans; Crohn Disease; Remission Induction; Placebo Effect
PubMed: 36426807
DOI: 10.1093/ibd/izac240 -
Nature Reviews. Neurology Oct 2022Functional neurological disorder (FND) is characterized by neurological symptoms that cannot be explained by a structural neurological cause. Among the different... (Review)
Review
Functional neurological disorder (FND) is characterized by neurological symptoms that cannot be explained by a structural neurological cause. Among the different aetiological models that have been proposed for FND, of note is the Bayesian predictive coding model, which posits that perception relies on top-down cortical predictions (priors) to infer the source of incoming sensory information. This model can also apply to non-pathological experiences, such as placebo and nocebo effects, wherein sensory information is shaped by prior expectations and learning. To date, most studies of the relationship between placebo and nocebo effects and FND have focused on the use of placebos for diagnosis and treatment of FND. Here, we propose that this relationship might go beyond diagnosis and therapy. We develop a framework in which shared cognitive, personality and neuroanatomical factors justify the consideration of a deeper link between FND and placebo and nocebo effects. This new perspective might offer guidance for clarification of the pathogenesis of FND and for the identification of potential biomarkers and therapeutic targets.
Topics: Bayes Theorem; Conversion Disorder; Humans; Nocebo Effect; Placebo Effect
PubMed: 36075980
DOI: 10.1038/s41582-022-00711-z -
International Review of Neurobiology 2020The placebo effect is a widely recognized phenomenon in clinical research, with a negative perception that it could hide the "true" drug effect. In clinical care its... (Review)
Review
The placebo effect is a widely recognized phenomenon in clinical research, with a negative perception that it could hide the "true" drug effect. In clinical care its positive potential to increase known drug effects has been neglected for too long. The placebo and nocebo responses have been described in many neurologic disorders such as Parkinson's, Huntington's and Alzheimer's diseases, restless leg syndrome, tics, essential tremor, dystonia, functional movement disorders, neuropathic pain, headaches, migraine, amyotrophic lateral sclerosis, myasthenia gravis, chronic inflammatory demyelinating polyneuropathy, multiple sclerosis and epilepsy. Knowledge regarding placebo mechanisms and their consequences on clinical outcome have greatly improved over the last two decades. This evolution has led to reconsiderations of the importance of placebo response in the clinic and has given several clues on how to improve it in daily practice. In this chapter, we first illustrate "why," e.g. the reasons (relevance to clinical practice, help in differential diagnosis/treatment of psychogenic movements, clinical impact, proven neurobiological grounds, health economic potential), and "how," e.g. the means (increase patients' knowledge, increase learning, improve patient-doctor relationship, increase Hawthorne effect, increase positive/decrease negative expectations (the Rosenthal effect), personalize placebo response), the placebo should be maximized (and nocebo avoided) in neurological clinical practice. Future studies regarding more specific neurobiological mechanisms will allow a finer tuning of placebo response in clinical practice. The use of placebo in clinical practice raises ethical issues, and a recent expert consensus regarding placebo use in the clinic is a first step to future guidelines necessary to this field.
Topics: Humans; Nervous System Diseases; Personality; Placebo Effect; Placebos
PubMed: 32563294
DOI: 10.1016/bs.irn.2020.04.003 -
Translational Psychiatry Dec 2022Placebo and nocebo effects are salubrious benefits and negative outcomes attributable to non-specific symbolic components. Leveraging advanced experimental and... (Review)
Review
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.
Topics: Nocebo Effect; Placebo Effect
PubMed: 36564374
DOI: 10.1038/s41398-022-02293-2 -
Perspectives in Biology and Medicine 2018The placebo effect can be defined as a bodily change due to the symbolic effects of a treatment or treatment situation. It is further explained by the meaning model: a...
The placebo effect can be defined as a bodily change due to the symbolic effects of a treatment or treatment situation. It is further explained by the meaning model: a positive placebo response is most likely to occur when the meaning of the illness is altered for the patient in a positive direction. Moerman's suggestion that "placebo effect" be replaced by "meaning response" is based in part on dissatisfaction with the characterization of placebo, which is avoided when one focuses instead more comprehensively on placebo effect. The placebo effect can then be explained by the mental processes of expectancy or conditioning and their effect on specific neuro-chemical processes that bring about end-organ changes.
Topics: Conditioning, Psychological; Humans; Mental Processes; Models, Psychological; Placebo Effect
PubMed: 30293974
DOI: 10.1353/pbm.2018.0048 -
European Journal of Pain (London,... Jan 2016Placebo and nocebo effects have been extensively studied in the field of pain and more recently also on itch. In accordance with placebo research on pain, expectancy... (Review)
Review
Placebo and nocebo effects have been extensively studied in the field of pain and more recently also on itch. In accordance with placebo research on pain, expectancy learning via verbal suggestion or conditioning has shown to induce placebo and nocebo effects on itch, in which the combination of both procedures seems most promising. Moreover, itch can also be transferred 'contagiously' in which suggestion and social behavioural learning seem to play a role. With regard to predictors of placebo and nocebo responding on itch and contagious itch, preliminary evidence suggests a role for individual psychological characteristics and personality traits regarding negative outcome expectancies. Although findings on placebo and nocebo effects on itch seem comparable to pain, we have only just begun to understand the underlying mechanisms and predictors of placebo and nocebo effects on itch.
Topics: Humans; Placebo Effect; Pruritus
PubMed: 26417885
DOI: 10.1002/ejp.750 -
Pain Jun 2020Classical conditioning and expectations are well-known underlying mechanisms of placebo hypoalgesia. Only little is known about their differential effect in adults,...
Classical conditioning and expectations are well-known underlying mechanisms of placebo hypoalgesia. Only little is known about their differential effect in adults, however, and even less in children. Previous studies in children evoked placebo hypoalgesia either with expectations alone or in combination with classical conditioning and revealed conflicting results. Furthermore, these studies investigated children of different ages making it even more difficult to draw conclusions. This study tried to disentangle classical conditioning and expectations by investigating them separately. To examine age effects, n = 172 children (6-9, 10-13, and 14-17 years) as well as n = 32 adults (> = 18 years) were tested using a heat pain paradigm investigating the effectiveness of creams some of which were bogusly introduced as analgesic. In addition to subjective pain intensity ratings, peripheral physiological measures were recorded. Results showed a successful induction of placebo hypoalgesia by both mechanisms for pain ratings and heart rate acceleration. Placebo hypoalgesia was particularly pronounced in children younger than 14 years. Furthermore, placebo hypoalgesia was more marked in children whose mothers raised the expectations. It was also stronger in participants who noticed a strong pain reduction during learning trials. These results encourage the use of placebo effect in clinical practice, particularly for younger children. They underline the relevance of an initial pain reduction and encourage the inclusion of parents in treatment.
Topics: Adolescent; Adult; Child; Humans; Motivation; Pain; Pain Measurement; Pain Perception; Placebo Effect
PubMed: 31977929
DOI: 10.1097/j.pain.0000000000001811 -
Expert Review of Neurotherapeutics Jan 2022The widespread use of the word 'placebo' in the medical literature emphasizes the importance of this phenomenon in modern biomedical sciences. Neuroscientific research...
INTRODUCTION
The widespread use of the word 'placebo' in the medical literature emphasizes the importance of this phenomenon in modern biomedical sciences. Neuroscientific research over the past thirty years shows that placebo effects are genuine psychobiological events attributable to the overall therapeutic context, and can be robust in both laboratory and clinical settings.
AREAS COVERED
Here the authors describe the biological mechanisms and the clinical implications of placebo effects with particular emphasis on neurology and psychiatry, for example in pain, movement disorders, depression. In these conditions, a number of endogenous systems have been identified, such as endogenous opioids, endocannabinoids, and dopamine, which contribute to the placebo-induced benefit.
EXPERT OPINION
Every effort should be made to maximize the placebo effect and reduce its evil twin, the nocebo effect, in medical practice. This does not require the administration of a placebo, but rather the enhancement of the effects of pharmacological and nonpharmacological treatments through a good doctor-patient interaction.
Topics: Humans; Nocebo Effect; Pain; Placebo Effect
PubMed: 34845956
DOI: 10.1080/14737175.2022.2012156