An intriguing new research study links certain personality traits to the ability to obtain pain relief from a placebo.
University of Michigan researchers say the finding may explain why sham medicines work for some and not others. Knowledge of a link between certain personality traits and perception of pain relief could be used to improve tests of new treatments.
Researchers discovered that it’s not just your mind telling you the sham drug is working or not. Your brains own natural painkiller chemicals may actually respond to the pain differently depending on your personality.
Investigators found that those who are good at coping when life gets tough; perceived by others as being a straight shooter; and willing to help others without expecting anything in return – are likely to benefit from placebo treatments.
However, if you are more of the angry, hostile type, then placebos will probably not be of significant benefit.
Researchers found 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 study, published online in the journal Neuropsychopharmacology, was performed by researchers from the University of Michigan and colleagues at the University of North Carolina and University of Maryland.
Investigators determined 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.
For the study, researchers led by Jon-Kar Zubieta, M.D., Ph.D., followed nearly 50 healthy volunteers, both male and female, between the ages of 19 and 38. They gave each person a battery of standard psychological tests that help identify the strongest personality traits an individual has, and then had them lie down in a brain scanner called a positron emission tomography or PET machine.
They told the volunteers that they were going to experience pain from salt water injected into their jaw muscle, and that a painkiller — actually, a placebo — would be injected at certain times.
They asked patients to rate how much relief they expected to get before the experiment began. Then, during the 20-minute period when volunteers received salt water and/or “painkiller”, they asked them repeatedly to say how effective they though the painkiller was.
Meanwhile, the PET scanner made images of volunteers’ brains, allowing the researchers to see how much of the natural painkillers called endogenous opioids, were released in certain areas of each person’s brain under painful or “painkiller” conditions.
They also drew blood from some of the patients during the experiment, and measured levels of a stress-induced chemical called cortisol.
After the tests, the researchers performed sophisticated statistical analysis to determine how personality traits influenced pain ratings, brain chemical response and cortisol levels.
If the findings are confirmed on a larger scale, scientists who study new drugs and other treatments will reap significant benefits as drug effectiveness is difficult to measure because of placebo responses.
Zubieta 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 explains.
“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.”
Zubieta and his team hope to continue the research among people with depression, and to continue to explore how genetics as well as personality influence placebo response.
He notes that the findings may even have implications for the doctor-patient relationship — for instance, patients who have certain personality traits and placebo-response tendencies may also be more likely to partner with their doctors on their care, and discuss frankly any concerns they have about their response to treatment.
Source University of Michigan