Personality traits might do more than help you win a popularity contest. According to new University of Michigan-led neuroscience research, co-authored by University of Maryland (UM) School of Dentistry Dean Christian S. Stohler, DMD, DrMedDent, such traits also might make you more likely to get pain relief from a placebo - a fake medicine.
"This work fits into the bigger picture regarding the degree to which our individual response to a stress factor is imprinted in our personality. The release of stress-relieving neurotransmitters, such as opiates in our brain, triggered by the application of the stress explain much of the individual variance in the response to treatment," says Stohler.
In short, if you're more of an angry, hostile type, they find, a placebo won't do much for you.
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. 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 work, published online today in the journal Neuropsychopharmacology, was done by a team of researchers at the University of Michigan, the University of North Carolina, and the University of Maryland.
The results build on nearly a decade's worth of work on the placebo effect by the team led by Jon-Kar Zubieta, MD, PhD, the Phil Jenkins Professor of Depression in the University of Michigan Department of Psychiatry. Stohler is a nationally recognized contributor to pain research and often collaborates with colleagues at the University of Michigan, where he served as director of research before coming to the UM School of Dentistry as dean in January 2003.
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.
If confirmed, the findings could help researchers who study new drugs and other treatments - a field where placebo responses can muddy the results and make it unclear whether the real therapy is working. Perhaps someday researchers will be able to adjust their results to account for the individual placebo responses of volunteers in their clinical trials. Zubieta notes that the new findings came from a study involving pain, but that they also may 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 their 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."