Placebo effect is strongest for hopeful, research finds

Those who experienced pain relief from the fake analgesic didn't just report it; their brain showed that their body's pain suppression mechanisms — the natural release of opioid-like chemicals in the brain — snapped into high gear. And when researchers looked to see which subjects responded most strongly to the placebos, they saw people who rated highly on measures of altruism and the capacity to withstand and overcome stressors. They also tended to be highly straightforward: more direct and frank in their approach to others, less guarded and not manipulative.

“People with those factors had the greatest ability to take environmental information — the placebo — and convert it to a change in biology,” said University of Michigan psychiatrist Dr. Jon-Kar Zubieta, the paper's senior author and an expert on the placebo effect.