People with certain personality traits are more likely to get pain relief from a placebo, a finding that could help improve clinical trials.
November 16, 2012|
Marta Pecina/University of Michigan
Individuals who are altruistic, resilient, and straightforward show greater activity in brain regions associated with reward and are more likely to enjoy pain relief when a placebo is administered during a painful experience, according to a study reported this week (November 15) in Neuropsychopharmacology. The findings suggest that simple personality tests could be used to improve the accuracy of clinical trials by identifying people likely to skew results with high placebo responses.
“This is interesting because it’s one of the first studies to look at how personality traits are associated with placebo analgesia not only in terms of subjective reports of pain relief, but also with quite solid objective measures in key parts of the brain,” said Tor Wager, a neuroscientist at the University of Boulder, Colorado, who was not involved in the study.
Placebos are known to have strong analgesic effects. In 2007, neuroscientist Jon-Kar Zubieta of the University of Michigan showed that such effects were associated with activity in the nucleus accumbens, a brain region involved in reward and pleasure. That suggested that placebo analgesia might occur in part because positive expectations of reward (pain relief) spike dopamine levels in the brain and stimulate the release of endogenous painkillers called mu-opioids.
But individuals vary considerably in their responses, and some studies have suggested that personality traits such as optimism and anxiety may predict response levels. Others have found that a composite of personality traits—including novelty seeking, harm avoidance, fun seeking, and reward responsiveness, which are thought to be related to dopamine reward circuits—can predict a substantial portion of placebo analgesic effects. Still, “there was nothing terribly conclusive,” said Zubieta.
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- Resilient People Experience More Relief From Placebos (medicalnewstoday.com)
- Placebo’s Effect May Depend on Your Genes (livescience.com)
- The Placebo Gene? (sciencebasedmedicine.org)