The Dummy Pill

Placebo pills can make people feel better...or worse. Placebos may induce improvements in brain function but may also cause side effects—especially among psychiatric patients.

By Dwek Dwek, published on May 01, 2003 - last reviewed on April 02, 2009

Placebos may induce improvements in brain function but may also cause side effects—especially among psychiatric patients.

In one study, Andrew Leuchter, M.D., a professor of psychiatry at the University of California, Los Angeles, found that 38 percent of depressed patients who received placebos showed lasting mood improvement, while some 52 percent of depressed patients who received medication reported feeling better.

The placebo effect is well known, but this study was the first to isolate neurological change. Control subjects who reported improvement showed greater electrical activity and blood flow in the prefrontal cortex, which is associated with mood and anticipation. Leuchter, who published the findings in the American Journal of Psychiatry, theorizes that expectations are largely responsible for the improvement, noting that people pursue treatment when mentally ready.

In a second study, negative expectations were found to be equally powerful: Approximately one-fourth of patients taking placebos are troubled by nonspecific side effects, according to a review in the Journal of the American Medical Association. Patients who are anxious or depressed are more likely to report negative or nonspecific side effects, but as many as 80 percent of healthy patients may experience the nocebo (Latin for "I will harm") effect, as well.

Aesthetic variables demonstrate the crude power of nocebos: Patients given blue pills in one study were more likely to report sedation than patients who received pink meds.

And a reality check can defuse even the most potent placebo. The moods of Leuchter's buoyed subjects deteriorated when they discovered they'd received bogus drugs.