Placebo effects: clinical aspects and neurobiology
Barry S. Oken
Brain (2008) 131 (11): 2812-2823.
doi: 10.1093/brain/awn116
+ Author Affiliations
Department of Neurology, Oregon Health & Science University, Portland, OR 97239, USA
Correspondence to: Barry S. Oken, Department of Neurology, CR-120, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA E-mail:
oken@ohsu.edu
Summary
Placebo effects are beneficial health outcomes not related to the relatively direct biological effects of an intervention and can be elicited by an agent that, by itself, is inert. Understanding these
placebo effects will help to improve clinical trial design, especially for interventions such as surgery, CNS-active drugs and behavioural interventions which are often non-blinded. A literature review was performed to retrieve articles discussing
placebo implications of clinical trials, the neurobiology of
placebo effects and the implications of
placebo effect for several disorders of neurological relevance. Recent research in
placebo analgesia and other conditions has demonstrated that several neurotransmitter systems, such as opiate and dopamine, are involved with the
placebo effect. Brain regions including anterior cingulate cortex, dorsolateral prefrontal cortex and basal ganglia have been activated following administration of
placebo.
A patient's expectancy of improvement may influence outcomes as much as some active interventions and this effect may be greater for novel interventions and for procedures. Maximizing this expectancy effect is important for clinicians to optimize the health of their patient. There have been many relatively acute
placebo studies that are now being extended into clinically relevant models of
placebo effect.