Predictability of placebo responses and their clinical implications

Abstract The bulk of research on the mechanisms underlying placebo effects has been conducted for painful stimuli in laboratory settings. Such studies identify a long list of learning mechanisms that can explain observed effects, as well as provide evidence that placebo analgesia is associated with reproducible patterns of brain activity. These studies also show that placebo effects are unstable across contexts, and the magnitude of a participant’s response in one setting does not generalize following subtle manipulations of the procedure, suggesting that placebo effects are primarily driven by immediate, context-specific expectations and, thus, remain essentially unpredictable. Recent studies challenge this notion by finding that clinical placebo effects in chronic pain patients can be predicted by genetics, brain properties and language use. If replicated, latter results suggest that placebo effects can be understood and harnessed in clinical treatment of chronic pain conditions and beyond.