Review Acupuncture, psyche and the placebo response Paul Enck a, ⁎, Sibylle Klosterhalfen a,b , Stephan Zipfel a a University Hospital Tübingen, Dept. of Psychosomatic Medicine, Tübingen, Germany b University of Düsseldorf, Institute for Clinical Neurobiology and Medical Psychology, Düsseldorf, Germany abstract article info Article history: Received 23 November 2009 Accepted 8 March 2010 Keywords: Acupuncture Placebo Psyche 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. © 2010 Elsevier B.V. All rights reserved. Contents 1. Efficacy of acupuncture — more than placebo? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 2. Acupuncture trial control procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 2.1. Waiting list and “treatment as usual” as controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 2.2. Minimal acupuncture as control condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 2.3. The “Streitberger” needle and other sham acupuncture needles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 2.4. Other control strategies for acupuncture trials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 3. How valid are sham acupuncture procedures? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 3.1. Blinding strategies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 3.2. Patient/subject selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 3.3. Moderators of response: physician's behaviour . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 4. Are acupuncture effects specific and distinguishable from sham procedures? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 4.1. Central effects of acupuncture versus sham acupuncture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 4.2. Peripheral (autonomic) effects of acupuncture versus sham acupuncture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 5. Are acupuncture analgesia and placebo analgesia the same? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 1. Efficacy of acupuncture — more than placebo? Ever since acupuncture became a widely accepted treatment strategy in various clinical conditions, especially in pain disease, a controversy has arisen as to whether acupuncture in comparison to the respective control conditions (see below, Section 2) is an effective treatment option or whether the accounted acupuncture effects reflect merely a placebo response (Enck et al., 2008). Madsen et al. (2009) metaanalysed 13 pain trials with a total of 3025 patients with tension headache (1 study), migraine (1), osteoarthritis (3), low back pain (3), post-OP pain (2), colonoscopy (1), fibromyalgia (1), and scar pain (1). They summarized that a small but significant effect of acupuncture was noticeable that corresponds Autonomic Neuroscience: Basic and Clinical 157 (2010) 68–73 ⁎ Corresponding author. University Hospital, Department of Internal Medicine VI: Psychosomatic Medicine and Psychotherapy, Frondsbergstr. 23, 72076 Tübingen, Germany. Tel.: +49 7071 2989118; fax: +49 7071 294382. E-mail address: paul.enck@uni-tuebingen.de (P. Enck). 1566-0702/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.autneu.2010.03.005 Contents lists available at ScienceDirect Autonomic Neuroscience: Basic and Clinical journal homepage: www.elsevier.com/locate/autneu