The Role of Attention in Placebo and Nocebo Effects

Background Although some existing models propose that attention may be crucially implicated in placebo/nocebo effects, empirical research on this aspect remains limited and scattered.Purpose This systematic review aims to provide an inclusive overview of studies that have either directly manipulated or assessed attention within the context of placebo and nocebo procedures so to gain a synthetized picture of the role of this variable in placebo/nocebo effects. Importantly, only studies in which attention represented a mechanism or mediator of the placebo/nocebo response, and not a primary outcome, were included.Methods A systematic search was conducted across multiple databases, including PubMed, Scopus, PsycINFO, Web of Science, and Embase, to identify peer-reviewed studies. These studies were subjected to methodological evaluation and eligibility criteria for inclusion.Results We identified and classified 12 studies into three categories based on their focus: (i) those that directly assessed attention, (ii) those that directly manipulated participants' attention, and (iii) those that combined both a direct manipulation and assessment of attention. In all selected studies attention acted as a mechanism or mediator of the placebo/nocebo response, and was not considered a primary outcome of the placebo/nocebo manipulation.Conclusions The synthesis of the included studies reveals that the role of attention in placebo and nocebo effects is still a topic of debate, marked by variations in how attention is conceptualized and measured. Results suggest that attention has significant clinical implications, particularly in optimizing therapeutic efficacy by directing patients' focus toward signs of healing and away from indicators of illness or distress. To advance our understanding, future research should explore these attentional mechanisms, in conjunction with neurophysiological correlates.To date, empirical research on the role of attention in placebo/nocebo effects remains scarce and inconclusive. The aim of this systematic review is to offer an overview of studies that have either directly manipulated or assessed attention as a mechanism or mediator of placebo/nocebo responses. Peer-review studies were subjected to methodological evaluation and eligibility criteria, and 12 studies were selected and classified into 3 categories based on their focus: (i) those that directly assessed attention, (ii) those that directly manipulated participants' attention, and (iii) those that combined both a direct manipulation and assessment of attention. The synthesis of the included studies points to the nuanced methodological approaches to the study of the role of attention in placebo and nocebo effects, marked by variations in how this variable is conceptualized and measured. Overall, results support the idea that placebo/nocebo effects are not always a direct byproduct of expectations, with attention acting as an important factor to consider when exploring this relationship. Particularly, attention plays an important role in optimizing therapeutic efficacy by directing patients' focus toward signs of healing and away from indicators of illness or distress.