The proteins in your blood could reveal whether or not you will experience the placebo effect. People who show a placebo response appear to have certain blood proteins 鈥� some of which are linked to inflammation, which could explain the healing powers of the placebo effect.
A sugar pill or sham treatment can often make people feel better, but the reasons why have long been a mystery. Research over the past 20 years has focused on how specific brain regions might play a role and how genes could influence the response.
Karin Meissner at the Ludwig Maximilian University of Munich in Germany and her colleagues looked for clues in blood instead, as it is much easier to access and study.
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The team induced nausea in 100 volunteers by asking them to sit in a small booth with moving black and white lines on two separate days. On the second day, 10 of the volunteers were given transcutaneous electrical nerve stimulation (TENS), in which a pressure point on the wrist was stimulated with electrodes placed on the skin. Sixty volunteers were given a sham TENS treatment that provided little or no electrical stimulation. The remaining 30 volunteers had no treatment at all.
All the volunteers gave a blood sample before and after the nausea-inducing experience, and each person was asked to rate their level of nausea. People who had a 50 per cent reduction in their nausea on the second day, after receiving a sham treatment, were considered to have shown the placebo effect.
From the samples, the researchers analysed differences in blood proteins before and after the nausea-producing experience, and whether these changed after a placebo treatment. They found 74 proteins that seem to be linked to the placebo effect. The levels of these proteins could predict who was likely to respond to a placebo, the team says.
This might also help explain how the placebo effect works. Some of these proteins are known to play a role in controlling inflammation in the body, for example, which is involved in a range of disorders, as well as pain. 鈥淲e might be able to impact inflammation with placebo,鈥� says Kathryn Hall at Harvard Medical School.
Some of the other proteins have been linked to social bonding via their actions on neurons. 鈥淧robably here there is a [friendly] interaction between the experimenter and participant that influences the placebo response,鈥� says Luana Colloca at the University of Maryland School of Nursing.
The findings could have implications for drug clinical trials. It might be possible to predict which volunteers are likely to respond to a placebo, and better assess drugs that are designed to target inflammation.
In addition, the research could shape the way disorders are treated. It might be possible to treat people who are more likely to experience a placebo response with milder drugs at lower doses, says Colloca.
鈥淩ather than shying away from it鈥� we need to figure out how to use the placebo response to improve how we treat patients,鈥� agrees Hall.
Both Hall and Colloca stress that the findings will need to be replicated, both for nausea and for other disorders. 鈥淚t鈥檚 really exciting,鈥� says Hall. 鈥淏ut it鈥檚 early days.鈥�
PLoS One
