The placebo effect

Passage

The placebo effect describes a genuine improvement in a patient's condition after receiving a treatment that has no active ingredient. Far from being imaginary, the effect can produce measurable physiological changes, such as the release of natural pain-relieving chemicals. Its strength depends partly on expectation: patients who believe a treatment will work tend to experience greater benefit. For researchers, this poses a challenge, because any new drug must outperform not just no treatment at all, but the powerful influence of belief itself.