Placebos often work, some researchers now think, not because of patients’ imagination but because their bodies actually react as if they had gotten the real medicine.

The placebo effect, which occurs when study subjects experience beneficial effects after receiving fake treatments or medications, may be stronger than previously believed—literally activating pain-reducing chemicals in the brain and other changes to make some patients feel better.

The power of the placebo was highlighted again in a recent review in the Lancet in which more than 100 published studies on placebos were analyzed by an international team of researchers. The team found that just the “expectation” of recovery may actually change a patient’s body and brain to physiologically promote healing—even though placebo treatments—unknown to the patients—contain no “real” medicine.

When patients with Parkinson’s disease got a placebo injection in one study, for example, their brains released dopamine—a chemical important for controlling movement. Other studies have shown positive brain changes in patients with depression who received a placebo.

“The placebo response is a real phenomenon with the potential for promoting therapeutic benefit for patients,” says Franklin Miller of the National Institutes of Health, one of the researchers in the Lancet review. Miller said research should focus on ways to help doctors use the placebo effect to help patients—without deceiving them.

Although doctors have long known of the power of placebos, many were not sure if these sham treatments actually led to physical changes, or just helped some patients who believed it would help.

The term placebo means “I shall please” in Latin and was first used to describe 13th-century hired mourners who chanted it as part of the Vespers for the Dead. As early as the 16th century, Catholics gave those who said they were “possessed” by the devil false holy objects to prove exorcisms as fake. By 1811 a medical dictionary described the placebo as “something given to please the patient.”

Sid Kirchheimer

Bulletin.aarp.org