For the first time, the new findings link specific, established personality traits with an individual's susceptibility to the placebo effect from a sham medicine for pain.
Researchers have shed light on why some people get pain relief from a placebo - a fake medicine, and others do not.
According to the research done by University of Michigan and their colleagues at the University of North Carolina and University of Maryland, it's not just your mind telling you the sham drug is working or not. Your brain's own natural painkiller chemicals may actually respond to the pain differently depending on your personality.
The researchers showed a significant link between certain personality traits and how much relief people said they felt, when given the placebo - as well as the level of a specific chemical that their brains released.
The findings show that about one-quarter of placebo response was explained by the personality traits of resiliency, straightforwardness, altruism or anger/hostility, as measured on standardized tests.
Other personality traits didn't appear to be linked to placebo response. The new results come from a few dozen healthy volunteers, so the experiment must be repeated in larger, more diverse groups to be confirmed.
Jon-Kar Zubieta, M.D., Ph.D., the Phil Jenkins Professor of Depression in the U-M Department of Psychiatry notes that the new findings came from a study involving pain, but that it may also apply to how personality influences a person's response to other stress-inducing circumstances.
"We started this study not just looking at measures that might seem more obviously related to placebo responses, such as maybe impulsivity, or reward-seeking, but explored potential associations broadly without a particular hypothesis," he said.
"We ended up finding that the greatest influence came from a series of factors related to individual resiliency, the capacity to withstand and overcome stressors and difficult situations.
"People with those factors had the greatest ability to take environmental information-the placebo-and convert it to a change in biology," he added.
The work has been published in the journal Neuropsychopharmacology.