Further evidence for individual differences in placebo responding: An interactionist perspective
ABSTRACT A prior investigation found that individuals low in optimism are more likely to follow a negative placebo (nocebo) expectation. The present study tested the hypothesis that individuals high in optimism are more likely to follow a positive placebo expectation.
Individuals (N=56) varying in their level of optimism were randomly assigned to one of three conditions. In the first condition, participants were given the expectation that a placebo sleep treatment would improve their sleep quality (placebo expectation condition). In the second condition, participants engaged in the same sleep treatment activity but were not given the positive placebo expectation (treatment control condition). Finally, a third group did not receive the positive placebo expectation and also did not engage in the placebo sleep treatment (no-placebo control condition).
Optimism was positively associated with better sleep quality in the placebo expectation condition (r=.48, P<.05). Optimism scores were not associated with better sleep quality in either the treatment control condition (r=-.17, P=.46) or the no-placebo control condition (r=-.24, P=.35).
Dispositional optimism relates to placebo responding. This relationship, however, is not manifested in a simple increase or decrease in all types of placebo responding. Rather, it appears that, as optimism increases, response to the positive placebo expectation increases, whereas response to nocebo expectation decreases. It is recommended that future research on personality and placebo effects consider the interaction between situational and dispositional variables.
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ABSTRACT: Placebo effects are beneficial health outcomes not related to the relatively direct biological effects of an intervention and can be elicited by an agent that, by itself, is inert. Understanding these placebo effects will help to improve clinical trial design, especially for interventions such as surgery, CNS-active drugs and behavioural interventions which are often non-blinded. A literature review was performed to retrieve articles discussing placebo implications of clinical trials, the neurobiology of placebo effects and the implications of placebo effect for several disorders of neurological relevance. Recent research in placebo analgesia and other conditions has demonstrated that several neurotransmitter systems, such as opiate and dopamine, are involved with the placebo effect. Brain regions including anterior cingulate cortex, dorsolateral prefrontal cortex and basal ganglia have been activated following administration of placebo. A patient's expectancy of improvement may influence outcomes as much as some active interventions and this effect may be greater for novel interventions and for procedures. Maximizing this expectancy effect is important for clinicians to optimize the health of their patient. There have been many relatively acute placebo studies that are now being extended into clinically relevant models of placebo effect.Brain 07/2008; 131(Pt 11):2812-23. DOI:10.1093/brain/awn116 · 10.23 Impact Factor
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ABSTRACT: A brief theoretical discussion of the placebo effect and of some methodological issues of the measurement of it are followed by a narrative review based on the results of our earlier metaanlysis of fourteen published research on the investigation of placebo effect in sports and exercise. Various factors (e.g. personality factors, perceptual characteristics of the applied substance or treatment) of placebo-effect effecting performance in sports and relevant research are also addressed. Absztrakt A placebo-hatás rövid elméleti áttekintését, valamint a placebo-hatás mérésének néhány módszertani problematikájának bemutatását korábbi metaanalízisünkön alapuló, különböző sportokban végzett placebo-hatás vizsgálatok narratív összefoglalója követi. A sportban megfigyelhető placebo-hatás különböző, a teljesítményt is befolyásoló összetevőit (pl. személyiség, az alkalmazott szer perceptuális tulajdonságai) vizsgáló kutatásokat is ismertetünk.
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ABSTRACT: Abstract Placebo responses are highly variable across individuals. Explaining this variability is one of the keys to understanding endogenous regulatory processes, and is critical for measuring and controlling placebo effects in all kinds of studies. In this chapter, we review literature on the personality and brain correlates of individual differences in placebo analgesia. An emerging brain literature has used functional magnetic resonance imaging (fMRI), opioid binding, dopamine binding, and structural brain imaging to predict the magnitude of individual placebo responses. Brain predictors in prefrontal cortices and ventral striatum/nucleus accumbens are relatively consistent across studies and methodologies, showing promise for understanding the neural bases of placebo analgesia. However, most studies use voxel-wise correlation maps to relate brain measures and placebo analgesia, which do not provide unbiased measures of predictive accuracy. Thus, the utility of these brain measures remains to be determined by larger-scale studies using appropriate analytic methods. Finally, we address an apparent paradox in the placebo literature: placebo responses appear to be both related to stable person-level variables (e.g. brain structure, genetics, personality) and highly variable across situational contexts. We suggest that a resolution lies in recognizing that placebo responses, like many other psychologic phenomena, arise from person × situation interactions, and that both must be considered jointly in order to understand and predict who will be a placebo ‘responder’ in a given situation.Placebo and Pain, Edited by Luana Colloca and Magne Arve Flaten and Karin MeissnerA2 - Luana Colloca, Magne Arve Flaten and Karin Meissner, 01/2013: pages 89-102; Academic Press., ISBN: 9780123979285