During the Korean War, a surgeon developed acute appendicitis. As the wounded needed surgery, he asked a nurse to inject him with morphine. After his appendectomy, the surgeon looked through the records and found that ‘since he appeared distressed’ the nurse injected saline, probably to avoid mental fogging. But the surgeon expected the nurse to follow his instructions, which invoked a placebo response that countered the severe pain of acute appendicitis.1,2
Today, we know that the placebo response accounts for part of every therapeutic benefit, complicates every clinical trial and influences every interaction between nurses and patients. Even worms and flies show placebo-like effects,3 suggesting that the response partly arises from a fundamental biological process.
Certainly, the placebo response makes an important contribution to drug efficacy. In epilepsy, for example, between 10% and 15% of patients taking placebo show at least a 50% reduction in seizure frequency compared to baseline.4 People that show a strong placebo response can improve by up to 50% on the Unified Parkinson’s Disease Rating Scale, which is similar to the benefit produced by drugs.5