Analysis of the placebo response to the therapeutic environment

Abstract

Placebo is critical for evaluating medical interventions, but it's also clear that the biologyunderpinning the placebo effect in humans could have significant clinical and societal impacts. Placebo effects, real responses to false cues, potentially stand at odds with the view that, for adaptive reasons, organisms respond only to true environmental cues. In placebo effects, phenotypic responses are seen in the absence of a biologically active agent. The reason for the increase in the placebo response is largely unknown, but several attempts have been made to overcome this problem. How placebos work is still not quite understood, but it involves a complex neurobiological reaction that includes everything from increases in feel-good neurotransmitters, like endorphins and dopamine, to greater activity in certain brain regions linked to moods, emotional reactions, and self-awareness. All of it can have therapeutic benefit. Reacting to a placebo is not proof that a certain treatment doesn't work, but rather that another, non-pharmacological mechanism may be present. If placebo responses seen in humans are the result of phenotypic plasticity, then placebo-like effects should be observable in other species - particularly in cases where the environment has been altered to disrupt its reliability. This is the case, and placebo-like effects are seen in a variety of model systems.