-
Annals of Behavioral Medicine : a... Oct 2022Choice has been proposed as a method of enhancing placebo effects. However, there have been no attempts to systematically evaluate the magnitude, reliability, and... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Choice has been proposed as a method of enhancing placebo effects. However, there have been no attempts to systematically evaluate the magnitude, reliability, and moderators of the influence of choice on the placebo effect.
PURPOSE
To estimate the effect size of choice on the placebo effect and identify any moderators of this effect.
METHODS
Web of Science, PsycINFO, EMBASE, and PubMed were systematically searched from inception to May 2021 for studies comparing placebo treatment with any form of choice over its administration (e.g., type, timing) to placebo treatment without choice, on any health-related outcome. Random-effects meta-analysis was then used to estimate the effect size associated with the influence of choice on the placebo effect. Meta-regression was subsequently employed to determine the moderating effect of factors such as type of choice, frequency of choice, and size of the placebo effect without choice.
RESULTS
Fifteen independent studies (N = 1,506) assessing a range of conditions, including pain, discomfort, sleep difficulty, and anxiety, met inclusion criteria. Meta-analysis revealed that choice did significantly enhance the placebo effect (Hedges' g = 0.298). Size of the placebo effect without choice was the only reliable moderator of this effect, whereby a greater effect of choice was associated with smaller placebo effects without choice.
CONCLUSIONS
Treatment choice can effectively facilitate the placebo effect, but this effect appears more pronounced in contexts where the placebo effect without choice is weaker. Because most evidence to date is experimental, translational studies are needed to test whether providing choice in clinical scenarios where placebo effects are weaker may help boost the placebo effect and thereby improve patient outcomes.
Topics: Anxiety Disorders; Humans; Placebo Effect; Reproducibility of Results; Research Design; Sleep Initiation and Maintenance Disorders
PubMed: 35022650
DOI: 10.1093/abm/kaab111 -
Handbook of Clinical Neurology 2021The study of the placebo effect, or response, is related to the investigation of the psychologic component of different therapeutic rituals. The high rate of placebo... (Review)
Review
The study of the placebo effect, or response, is related to the investigation of the psychologic component of different therapeutic rituals. The high rate of placebo responses in Parkinson's disease clinical trials provided the impetus for investigating the underlying mechanisms. Ruling out spontaneous remission and regression to the mean through the appropriate experimental designs, genuine psychologic placebo effects have been identified, in which both patients' expectations of therapeutic benefit and learning processes are involved. Specifically, placebo effects are associated with dopamine release in the striatum and changes in neuronal activity in the subthalamic nucleus, substantia nigra pars reticulata, and motor thalamus in Parkinson's disease, as assessed through positron emission tomography and single-neuron recording during deep brain stimulation, respectively. Conversely, verbal suggestions of clinical worsening or drug dose reduction induce nocebo responses in Parkinson's disease, which have been detected at both behavioral and electrophysiologic level. Important implications and applications emerge from this new knowledge. These include better clinical trial designs, whereby patients' expectations should always be assessed, as well as better drug dosage in order to reduce drug intake.
Topics: Deep Brain Stimulation; Humans; Nocebo Effect; Parkinson Disease; Placebo Effect; Subthalamic Nucleus; Thalamus
PubMed: 34225946
DOI: 10.1016/B978-0-12-820107-7.00027-6 -
The American Journal of Medicine Jun 2014The placebo effect is defined as any improvement of symptoms or signs following a physically inert intervention. Its effects are especially profound in relieving... (Review)
Review
The placebo effect is defined as any improvement of symptoms or signs following a physically inert intervention. Its effects are especially profound in relieving subjective symptoms such as pain, fatigue, and depression. Present to a variable extent in all therapeutic encounters, this effect is intensified by hands-on contact with close verbal communication between caregiver and recipient. Thus, it may be used to benefit patients but provides a ready avenue for unscrupulous "healers" of all types. Conventional medical practitioners often intervene in some way and, without knowing what caused the improvement, may claim credit for the apparent benefit. Physicians must be skeptical about apparent "responses" to treatments, using the information described herein to better understand what we are-or are not-accomplishing to provide the best possible outcomes for our patients. Less well studied, the "nocebo effect" defines negative responses to placebo interventions. This latter effect may be quite profound and likely is causative in many maladies believed to have psychic origins.
Topics: Attitude of Health Personnel; Causality; Humans; Nocebo Effect; Placebo Effect; Professional-Patient Relations; Psychophysiologic Disorders; Psychophysiology
PubMed: 24518105
DOI: 10.1016/j.amjmed.2014.02.002 -
European Journal of Clinical... Jul 2022Randomized controlled trials (RCT) in mental disorders research commonly use active control groups including psychotherapeutic shams or inactive medication. This... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Randomized controlled trials (RCT) in mental disorders research commonly use active control groups including psychotherapeutic shams or inactive medication. This meta-analysis assessed whether placebo conditions (active controls) had an effect compared to no treatment or usual care (passive controls).
METHODS
PubMed, Scopus, PsycINFO, PsycARTICLES, Ovid, the Cochrane Central Register of Controlled Trials and Web of Science were searched from inception to April 2021 and reference lists of relevant articles. Three-arm RCTs, including active and passive control groups, were selected. Where individual standardized mean difference (SMD) was calculable, random effects meta-analyses were performed to estimate an overall effect size with 95% confidence intervals (CI) comparing active vs passive controls. Heterogeneity was assessed using I² statistic and meta-regression. Funnel asymmetry was evaluated using Egger's test (Prospero registration: CRD42021242940).
RESULTS
24 articles with 25 relevant RCTs were included in the review, of which 11 studies were of high risk of bias. There was an improvement in outcomes favouring the placebo conditions, compared to passive controls, overall (25 studies, SMD 0.24, 95% CI 0.06-0.42, I² = 43%) and in subgroups with anxiety (SMD 0.45, 95% CI 0.07-0.84, I² = 59%) or depression (SMD 0.22, 95% CI 0.04-0.39, I² = 0%). Meta-regression did not show a significant explanation for heterogeneity. Egger's test showed no asymmetry (p = .200).
CONCLUSIONS
A small placebo effect was observed in mental disorders research overall, and in patients with anxiety or depression. These findings should be interpreted with caution in the light of heterogeneity and risk of bias.
Topics: Anxiety; Humans; Mental Disorders; Placebo Effect
PubMed: 35224726
DOI: 10.1111/eci.13762 -
Manual Therapy Aug 2016Placebo and nocebo represent complex and distinct psychoneurobiological phenomena in which behavioural and neurophysiological modifications occur together with the... (Review)
Review
INTRODUCTION
Placebo and nocebo represent complex and distinct psychoneurobiological phenomena in which behavioural and neurophysiological modifications occur together with the application of a treatment. Despite a better understanding of this topic in the medical field, little is known about their role in physiotherapy.
PURPOSE
The aim of this review is: a) to elucidate the neurobiology behind placebo and nocebo effects, b) to describe the role of the contextual factors as modulators of the clinical outcomes in rehabilitation and c) to provide clinical and research guidelines on their uses.
IMPLICATIONS
The physiotherapist's features, the patient's features, the patient-physiotherapist relationship, the characteristics of the treatment and the overall healthcare setting are all contextual factors influencing clinical outcomes. Since every physiotherapy treatment determines a specific and a contextual effect, physiotherapists should manage the contextual factors as a boosting element of any manual therapy to improve placebo effects and avoid detrimental nocebo effects.
Topics: Humans; Musculoskeletal Diseases; Musculoskeletal Manipulations; Nocebo Effect; Pain Management; Physical Therapy Modalities; Placebo Effect; Treatment Outcome
PubMed: 27133031
DOI: 10.1016/j.math.2016.04.006 -
The New England Journal of Medicine Feb 2020
Review
Topics: Conditioning, Psychological; Humans; Hyperalgesia; Nervous System Physiological Phenomena; Nocebo Effect; Placebo Effect
PubMed: 32023375
DOI: 10.1056/NEJMra1907805 -
Journal of Clinical Sleep Medicine :... May 2021Hunasikatti M. Real effect vs placebo effect. . 2021;17(5):1141.
Hunasikatti M. Real effect vs placebo effect. . 2021;17(5):1141.
Topics: Double-Blind Method; Humans; Placebo Effect
PubMed: 33560205
DOI: 10.5664/jcsm.9092 -
Neurourology and Urodynamics Jul 2020The proposal "Can we harness the placebo effect to improve care in lower urinary tract dysfunction?" was discussed at the International Consultation on... (Review)
Review
The proposal "Can we harness the placebo effect to improve care in lower urinary tract dysfunction?" was discussed at the International Consultation on Incontinence-Research Society (ICI-RS) 2019 meeting. The placebo effect can change the treatment outcome whether the treatment is an active treatment or placebo. The total active treatment outcome is a combination of the placebo and the active treatment effect which is seen in placebo-controlled trials. The placebo effect plays an important role in the treatment of lower urinary tract dysfunction in overactive bladder, bladder pain syndrome, and stress urinary incontinence. In clinical practice, a number of factors can be employed to use the placebo effect to maximize its effect on patients receiving an active treatment, such as having the same environment for review such as the same appointment time, same room, and same clinician. Clinicians should also be aware of the nocebo effect which is increased with an overemphasis on side effects or negative outcomes.
Topics: Humans; Lower Urinary Tract Symptoms; Placebo Effect; Treatment Outcome
PubMed: 32311166
DOI: 10.1002/nau.24351 -
Scientific Reports Nov 2022The placebo effect is a powerful psychobiological phenomenon whereby a positive outcome follows the administration of an inert treatment thought to be effective. Growing... (Randomized Controlled Trial)
Randomized Controlled Trial
The placebo effect is a powerful psychobiological phenomenon whereby a positive outcome follows the administration of an inert treatment thought to be effective. Growing evidence shows that the placebo effect extends beyond the healing context, affecting also motor performance. Here we explored the placebo effect on the control of goal-directed movement, a fundamental function in many daily activities. Twenty-four healthy volunteers performed upper-limb movements toward a target at different indexes of difficulty in two conditions: in the placebo condition, an electrical device (inert) was applied to the right forearm together with verbal information about its positive effects in improving movement precision; in the control condition, the same device was applied along with verbal information about its neutral effects on performance. Interestingly, we found shorter movement time in the placebo compared to the control condition. Moreover, subjective perception of fatigability was reduced in the placebo compared to the control condition. These findings indicate that the placebo effect can improve the execution of goal-directed movements, thus adding new evidence to the placebo effect in the motor domain. This study could inspire future applications to improve upper-limb movements or in clinical settings for patients with motor deficits.
Topics: Humans; Forearm; Goals; Movement; Placebo Effect; Psychomotor Performance; Upper Extremity
PubMed: 36380087
DOI: 10.1038/s41598-022-23489-y -
British Journal of Clinical Pharmacology Aug 2022The placebo effect and the specific effect are often thought to add up (additive model). Whether additivity holds can dramatically influence the external validity of a... (Review)
Review
AIM
The placebo effect and the specific effect are often thought to add up (additive model). Whether additivity holds can dramatically influence the external validity of a trial. This assumption of additivity was tested by Kleijnen et al in 1994 but the data produced since then have not been synthetized. In this review, we aimed to systematically review the literature to determine whether additivity held.
METHODS
We searched Medline and PsychInfo up to 10 January 2019. Studies using the balanced placebo design (BPD), testing two different strengths of placebos, were included. The presence of interaction was evaluated by comparing each group in the BPD with analysis of variance or covariance.
RESULTS
Thirty studies were included and the overall risk of bias was high: four found evidence of additivity and 16 studies found evidence of interaction (seven had evidence of positive additivity).
CONCLUSION
Evidence of additivity between placebo and specific features of treatments was rare in included studies. We suggest interventions for placebo-sensitive ailments should be tested in trials designed to take interactions seriously once an exploratory RCTs has proven their efficacy with sufficient internal validity.
Topics: Humans; Placebo Effect
PubMed: 35384004
DOI: 10.1111/bcp.15345