Behavioral factors in the placebo response

Given its presence in almost every clinical trial, the placebo is the most frequently studied substance in clinical research. Demonstration of treatment efficacy demands that the target (active) agent must be shown to be statistically significantly superior to an inert substance (placebo) not believed to be a specific therapy for the target condition. In clinical practice, enhancing the non-specific factors that contribute to an enhanced treatment outcome is desirable to maximize the likelihood of therapeutic benefit. Variables affecting the impact of placebo on clinical research and practice remain poorly understood, however, as they have not been systematically studied. The present article will discuss behavioral factors that have been found to be relevant in placebo mechanisms.