Optimists are no longer alone in promoting “mind over matter.” A compelling study claims there is chemical credence for the placebo effect, at least in masking pain.

University of Michigan at Ann Arbor neuroscientist Jon-Kar Zubieta, who led the work, says that people produce a natural painkilling chemical in the brain when they expect to experience relief. Researchers gave test subjects a slow, long, harmless injection of a pain-inducing salt solution into the jaw. When the injection began, the subjects were asked to rate their level of pain. As it continued, the researchers said, falsely, that they had just added pain-relieving serum into the solution. Subjects were asked again to rank their discomfort.

Throughout the episode, subjects’ brains were scanned using positron-emission tomography. It showed that in people who said they felt less uncomfortable, particular regions of the brain produced painkilling endorphins right after the placebo was promised. The people who expected to get relief actually produced it.

The results “open a new avenue for understanding pain as a complex experience that is moderated by a type of emotional mechanism,” Zubieta says. If the mind can induce chemical changes in the brain, psychologists and physicians could possibly devise ways to prompt natural medication through the power of suggestion. If fruitful, the approach could be tried for a variety of conditions. “The idea is to harness these mechanisms,” Zubieta explains. “Ultimately you want people to be more resilient, to have more capacity to suppress a negative experience.”