Acupuncture, psyche and the placebo response

With growing use of acupuncture treatment in various clinical conditions, the question has been posed whether the reported effects reflect specific mechanisms of acupuncture or whether they represent placebo responses, as they often are similar in effect size and resemble similarities to placebo analgesia and its mechanisms. We reviewed the available literature for different placebos (sham procedures) used to control the acupuncture effects, for moderators and potential biases in respective clinical trials, and for central and peripheral mechanisms involved that would allow differentiation of placebo effects from acupuncture and sham acupuncture effects. While the evidence is still limited, it seems that biological differences exist between a placebo response, e.g. in placebo analgesia, and analgesic response during acupunture that does not occur with sham acupuncture. It seems advisable that clinical trials should include potential biomarkers of acupuncture, e.g. measures of the autonomic nervous system function to verify that acupuncture and sham acupuncture are different despite similar clinical effects.