Placebo Effect

A measurable improvement in a patient's condition attributable to the therapeutic context (expectation, conditioning, patient-provider interaction) rather than the specific pharmacological action of a treatment. Placebo effects involve real neurobiological mechanisms including endogenous opioid release, dopaminergic activation, and immune modulation. Accounting for the placebo response is essential in clinical trial design through randomization and blinding.

例

• Placebo analgesia: 30-40% pain reduction mediated by endogenous endorphin release, reversible by naloxone
• Parkinson's disease: placebo induces dopamine release in the striatum measurable by PET imaging
• Antidepressant trials: 30-40% placebo response rate complicates efficacy signal detection