Understanding and translating the knowledge about placebo effects: the contribution of psychology.

PURPOSE OF REVIEW: Recent articles have summarized the literature on the neurobiological mechanisms involved in placebo effects. In this article, we review and evaluate the status of the psychological mechanisms in theory and research regarding placebo effects. RECENT
FINDINGS: Currently, the placebo effect literature concentrates more on neurobiological mechanisms than on psychological mechanisms. Both theoretical and empirical coverage of the psychological mechanisms are typically limited to two variables: conditioning and verbally induced expectations. Because psychological processes take center stage in mediating the link between the therapeutic context and placebo responding, greater effort is needed to build empirically derived and theoretically complex psychological process models. Such models would include a broader array of psychological constructs and mechanisms.
SUMMARY: Research and theory on placebo effects has illuminated much regarding the neurobiological mechanisms. The psychological mechanisms, however, have received much less attention. Expanding our knowledge regarding the psychological processes involved in placebo responding would open up opportunities for developing nondeceptive intervention techniques that encourage placebo responses. Ultimately, a concerted empirical effort to clarify the psychological model underlying placebo effects could merge with the evolving neurobiological model to fulfill the promise that placebo effects have for improving patient outcomes.