August 1, 2013
Placebo Effects Of Different Therapies Not Identical
Conditioning, association affect people's responses to placebos
Not all placebos are equal, and patients who respond to one placebo don't always respond to others, according to research published July 31 in the open access journal PLOS ONE by Jian Kong from Massachusetts General Hospital, Harvard Medical School and colleagues from other institutions.
No significant associations were found between participants' responses to the different treatments, suggesting that none of these individuals could be identified as placebo 'responders' or 'non-responders'. However, participants' expectations that the treatment would help relieve pain correlated with their pain thresholds and tolerance.
According to the authors, these and other parameters in their study suggest that responses to a placebo depend on diverse factors including the route of administration (pills or acupuncture), environmental cues, and learning based on verbal suggestions or conditioning. Kong adds, "It implies that placebo responses may not be dependent on stable individual traits but rather are more a characteristic of the circumstances of individuals or a combination of both trait and state."
In addition, they also found subjects' responses to sham acupuncture correlated significantly with their response to genuine acupuncture. This suggest that people who responded to genuine acupuncture were significantly more likely to experience pain relief from sham acupuncture, but the authors clarify that this does not indicate the two are the same. Instead, they suggest that acupuncture may have non-specific pain-relieving effects that may contribute to this observation.
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