Are All Placebo Effects Equal? Placebo Pills, Sham Acupuncture, Cue Conditioning and Their Association

• Main Authors: Kong, Jian (Author), Spaeth, Rosa (Author), Cook, Amanda (Author), Kirsch, Irving (Author), Claggett, Brian (Author), Smoller, Jordan W. (Author), Kaptchuk, Ted J. (Author), Vangel, Mark G. (Contributor), Gollub, Randy Lyanne (Contributor)
• Other Authors: Massachusetts Institute of Technology. Institute for Medical Engineering & Science (Contributor), Martinos Imaging Center (McGovern Institute for Brain Research at MIT) (Contributor), Harvard University- (Contributor), McGovern Institute for Brain Research at MIT (Contributor)
• Format: Article
• Language: English
• Published: Public Library of Science, 2013-09-30T12:54:50Z.
• Subjects: Article
• Online Access: Get fulltext

Placebo treatments and healing rituals have been used to treat pain throughout history. The present within-subject crossover study examines the variability in individual responses to placebo treatment with verbal suggestion and visual cue conditioning by investigating whether responses to different types of placebo treatment, as well as conditioning responses, correlate with one another. Secondarily, this study also examines whether responses to sham acupuncture correlate with responses to genuine acupuncture. Healthy subjects were recruited to participate in two sequential experiments. Experiment one is a five-session crossover study. In each session, subjects received one of four treatments: placebo pills (described as Tylenol), sham acupuncture, genuine acupuncture, or no treatment rest control condition. Before and after each treatment, paired with a verbal suggestion of positive effect, each subject's pain threshold, pain tolerance, and pain ratings to calibrated heat pain were measured. At least 14 days after completing experiment one, all subjects were invited to participate in experiment two, during which their analgesic responses to conditioned visual cues were tested. Forty-eight healthy subjects completed experiment one, and 45 completed experiment two. The results showed significantly different effects of genuine acupuncture, placebo pill and rest control on pain threshold. There was no significant association between placebo pills, sham acupuncture and cue conditioning effects, indicating that individuals may respond to unique healing rituals in different ways. This outcome suggests that placebo response may be a complex behavioral phenomenon that has properties that comprise a state, rather than a trait characteristic. This could explain the difficulty of detecting a signature for "placebo responders." However, a significant association was found between the genuine and sham acupuncture treatments, implying that the non-specific effects of acupuncture may contribute to the analgesic effect observed in genuine acupuncture analgesia.
National Center for Complementary and Alternative Medicine (U.S.) (R01AT005280)