We’ve all heard of the power of the placebo effect – the benefit from receiving an inactive medication or a phony simulated treatment. But how do placebos work? Do they improve objective measures of disease? Do they improve the patient’s subjective symptoms? Do they do both? A cleverly designed study in last week’s New England Journal of Medicine (link 1 below) answers that question. The investigators chose asthma as the disease in which to study the effect of placebo because asthma can cause u...