Behavioural and neural correlates of placebo responses in healthy and clinical populations

Michael Smith Foundation for Health Research/Lotte and John Hecht Memorial Foundation Post-Doctoral Fellowship Award

Placebo effects pose challenges to the conduct of clinical research. Double-blind randomized placebo-controlled trials can demonstrate superiority of an active intervention to a placebo. However, in some cases placebo control / complete blinding is difficult or impossible. For instance, in invasive or surgical interventions, placebo use raises ethical questions.

Susceptibility to placebo effects varies substantially across individuals: some experience pronounced placebo effects, while others show little or no response. Sources of this variation are poorly understood. Recent evidence from basic research has pointed to the role of reward expectancy and neural reactivity to rewards as key mechanisms of placebo response.

We seek to identify predictors of individual placebo responses in a sample of healthy volunteers, focusing on reward expectancy and reactivity. We will also examine individual variation in placebo response in an ongoing randomized controlled trial of an endovascular procedure in multiple sclerosis at UBC.

Understanding individual variation in placebo response could ultimately be used in clinical research:

1. To model placebo-related variance of patients in clinical trials where placebo control is impossible or problematic
2. To guide selection of patients for clinical trials