Expectation plays an essential role in placebo analgesia. Modulation of pain perception by placebos depends on expectation, as shown in many studies (Kirsch, 1999; Price et al., 1999, 2008). Montgomery and Kirsch conducted one of the first studies in which expected pain levels were manipulated and directly measured (Montgomery and Kirsch, 1997). They used a …
Experimental research into placebo effects demonstrates that routine biomedical pharmacological and procedural interventions contain significant ritual dimensions. This research also suggests that ritual healing not only represents changes in effect, self-awareness, and self-appraisal of behavioral capacities but involves modulations of symptoms through neurobiological mechanisms. Recent scientific investigations into placebo acupuncture suggest several ways that observations from ritual studies can be verified experimentally. Placebo effects are often described as ‘non-specific’; the analysis presented here suggests that placebo effects are the ‘specific’ effects of healing rituals.
Clinical trials of post-traumatic stress disorder (PTSD) show a high rate of placebo response, ranging from 19% to 62% (Ipser & Stein, 2012; Kelmendi et al., 2016; Sher, 2004). Despite these placebo responses across a number of clinical trials, nothing is known about their underlying mechanisms. In fact, the clinical trial setting does not allow us to differentiate between placebo effects due to psychological factors such as patients’ expectations and other phenomena such as spontaneous remission and regression to the mean. The recent explosion of placebo research and the shift in the conceptualization of the placebo effect in several medical conditions, such as pain and motor disorders, makes us understand that their psychological and neurobiological underpinnings can be investigated in some detail. Indeed, what we have learned over the past few years is that different brain mechanisms are at work during the placebo response (Benedetti, Amanzio, Rosato, & Blanchard, 2011; Benedetti, Carlino, & Piedimonte, 2016; Wager & Atlas, 2015).
In recent years, the placebo effect has been a topic of considerable interest both in the scientific and the clinical community. In this time, the placebo effect has evolved from being considered a nuisance in clinical and pharmacological research to becoming a neurobiological phenomenon worthy of scientific investigation in its own right. Recent research shows that placebo effects are genuine psychobiological events attributable to the overall therapeutic context and that these effects can be robust in both laboratory and clinical settings. These psychosocially induced biochemical changes in a patient's brain and body may, in turn, affect the course of a disease and the response to therapy. Here we summarize and discuss the current insights into placebo mechanisms and discuss the potentially widespread implications for research and clinical practice. Even though a systematic knowledge of placebo effects across the lifespan is lacking, we aim at highlighting specific aspects related to the care of elderly patients and those suffering from neurodegenerative diseases.
Placebos and placebo effects have held an ambivalent place in health care for at least two centuries. On the one hand, placebos are traditionally used as controls in clinical trials to correct for biases. Among other factors, these include regression to the mean, the natural course of the disorder, and effective co-interventions. In this context, the placebo effect is viewed as an effect to be factored out in order to isolate and accurately measure the specific effects of the treatment. On the other hand, there is mounting scientific evidence that placebo responses represent complex psychoneurobiological events involving the contribution of distinct central nervous system as well as peripheral physiological mechanisms that influence pain perception, clinical symptoms, and substantially modulate the response to active analgesics. In this review, we bring together three perspectives of placebo research including psychological mechanisms, neurobiological pathways and molecular substrates of placebo analgesia and their contribution to active pain medications. The emphasis is particularly on recent studies illuminating mechanisms underlying individual differences in placebo responsiveness.
Behavior analysts have shown that a single-subject experimental design (SSED) is a useful tool for identifying the effectiveness of specific therapeutic techniques, whereas researchers outside applied behavior analysis (ABA) maintain that randomized placebo-controlled trials (RPCT) provide the most definitive test of efficacy. In this paper, the possible benefits that could result from supporting SSED studies by placebo control groups are discussed. However, the use of placebo groups in psychotherapy research arouses considerable controversy and many researchers argue against it. The main aim of this paper is to clarify theoretical and methodological problems associated with using placebo groups in psychotherapy research and to demonstrate that these problems can be solved if the assumptions on which they are based are reformulated. The article also discusses ethical issues about the use of placebo groups in research on the effectiveness of psychotherapy.
There is only some literature regarding the influence of verbal suggestions on cognitive performance in healthy volunteers. For example, the performance in a knowledge test was enhanced when participants were told that they had subliminally received the correct answer. However, enhancing cognitive performance only via verbal suggestions without prior conditioning phases has not yet been examined. The goal of our study was therefore to investigate the effects of mental training based on verbal suggestions compared to a control training on cognitive performance in a student population using a balanced-placebo-design.
Placebo effects can be very effective in certain pain conditions, but their use is still highly controversial. Several studies show that patients would accept a placebo treatment under certain circumstances, particularly when they are informed prior to the treatment or when there are no effective treatment alternatives. This study examines the question, which factors influence the degree of acceptability of a hypothetical placebo application.
This “Dodo bird verdict” (DBV) — everybody has won — has been applied to a long-time and never-ending debate about which psychotherapy approach is more effective in treating patients in need of psychotherapy (1), psychodynamic psychotherapy (PDPT), cognitive-behavioral psychotherapy (CBT), or one of the many other therapy modalities that exist in between and beyond and claim to be the best for all and everybody. Psychotherapists of all colors and proveniences have a clear answer to this question: Mine is the best because I believe it in and I am good at it…... The empirical side of this competition tells a different story. Whenever different psychotherapies were tested in clinical trials against another therapy of the same or different kind or against another control condition (see below), the effects of one therapy was not that much different from another therapy. Meta-analyses of today (2) confirm what Rosenzweig described in the classical DBV paper 80 years ago (1): All psychotherapies operate with similar assumptions, implement similar means, and generate similar results, based on what has been called “common factors” that are immanent to all psychotherapy traditions.
But when you look at the distribution of genuine placebo publications in our database (3) (Figure) it was not before the late 1950's when placebo research started to slowly grow, and two milestone papers mark the beginning of it: Henry Beecher’s ever-since-cited paper, “The Powerful Placebo,” of 1955 (4), and Stewart Wolf’s almost completely forgotten, “The Pharmacology of Placebos,” of 1959 (5)