The enhanced placebo effect illustrated in this study applied only to subjective reports from patients about their perception of pain and the severity of their condition. More objective measures of grip strength showed no difference in improvements between the two placebos.
The results also provided evidence that what doctors tell patients about side effects directly influences their experience of them. Prior to participating in the study, doctors provided informed consent forms alerting the patients as to the side effects they might experience: temporary soreness for acupuncture and fatigue and dry-mouth for the pills. Of those receiving placebos, 25 percent of sham acupuncture and 31 percent of placebo pill patients reported experiencing the very side effects suggested to them even when nothing was administered to cause them.
This study takes the first step away from examining the placebo effect as a generalized phenomenon to one investigating how it varies in specific clinical environments. Kaptchuk and his colleagues have initiated other National Institute of Health funded studies that will explore the placebo phenomenon in clinical trials for different illnesses and in laboratory experiments that focus on underlying neurobiological, biochemical, genetic and psychological mechanisms.
Though the results of this study add evidence pointing to the existence of a placebo effect in a clinical environment, Kaptchuk does not recommend the use of placebos with patients or deception in the doctor-patient encounter. The aim is to understand how the ritual of healing affects health outcomes.
Contact: John Lacey
Harvard Medical School