Objectives. Our objective was to investigate the time course of the placebo effect of acupuncture on pain and the factors affecting the placebo effect. Methods. Previously we retrieved three-armed randomized acupuncture trials including sham and no-treatment groups which were published until October 2009. We searched electronic databases again to identify additional trials from October 2009 to ...

The authors propose that the placebo effect is mediated by reward-related mechanisms. Recent evidence suggests that it is the expectation of reward (in this case, the expectation of clinical benefit) that triggers the placebo response. In Parkinson's disease, the placebo effect is mediated by the release of dopamine in the striatum. The authors argue that placebo-induced dopamine release in lim...