Personality and The Placebo Effect

This week, a study in Neuropsychopharmacology reported that people that show personality traits of altruism, resiliency, and straightforwardness are more likely to have a positive result from a placebo. This means that these kinds of people show greater brain activity in the regions associated with reward and are more likely to enjoy pain relief from a placebo. From this study, personality tests could provide a new to improve the accuracy of clinical trials by identifying these kinds of people whom are likely to skew results with high placebo responses.

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In 2007, neuroscientist Jon-Kar Zubieta from the University of Michigan showed that a strong inability to feel pain due to the consumption of a placebo was associated with brain activity in the nucleus accumbens, which is the region of the brain involved with reward and pleasure. This finding suggested that the inability to feel pain due to a placebo may occur because positive expectations of pain relief (or reward) cause a spike in dopamine levels in the brain as well as the release of painkillers called mu-opiods. By conducting experiments through PET scans, Zubieta found that positive expectations alone are not enough for a placebo-induced pain relief response. He also found similiar results, in that people with certain personality traits including altruism, resiliency, and straightforwardness that also have low measures of angry hostility were more likely to experience a placebo-induced pain relief response.

Colored areas show regions of greater mu-opioid
release during placebo administration.
Image from The Scientist

Zubieta noted that, "One big difficulty is trying to control for people with very high placebo response. Many trials fail not because the compound doesn't work, but because placebos are also effective, which creates noise." The continuation of these kinds of studies is important because they will hopefully make clinical trials more accurate and successful by being able to identify which kinds of people will likely show a positive response to a placebo. This way, researchers will be able to more effectively identify a drug's true effect.

I found this article interesting because I had never thought about how a person's personality could determine the effects that a drug has on you. I wonder if personality tests could be given to patients that, for example, are recovering from surgery and are given strong medication such as oxycotin and hydrocone. I know someone that was a fantastic athlete but tore her ACL playing soccer, ended up getting addicted to the pain medication she was taking while recovering from surgery and tragically ended up committing suicide because of it. Perhaps having a personality test given whenever giving out medication is a smart thing for doctors to do because knowing certain personality types could alter the types of medication given out to certain people, which would most likely be way more effective and safer for the patient.

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Article: Personality Predicts Placebo Effects
Written by: Dan Cossins
http://www.the-scientist.com/?articles.view/articleNo/33300/title/Personality-Predicts-Placebo-Effect/