You may have heard this story as it is all over the popular press right now. We are told that scientists have discovered some of the mechanisms underlying acupuncture analgesia. As always with alternative therapy reports the media have enthusiastically bitten off the hand of the press release (see this great account from the blog stuff and nonsense) but there is a bit of a problem and it lies at the heart of the research question. Others have beaten me to it in analysing the study and its conclusions so rather than go over all that ground again (do read the linked blogs – they sum it up brilliantly) I thought I’d just offer my perspective.
Essentially the study, published in Nature Neuroscience, found that inserting and twiddling acupuncture needles in what is described as an acupuncture point in mice with induced injuries (do mice really have their own meridian charts developed over thousands of years?) seemed to reduce pain behaviour and that this effect was closely associated with local tissue adenosine and adenosine receptor levels. No control for acupuncture was used. The authors conclude in the paper that the specific clinical effects of acupuncture for pain are in part mediated by adenosine and in the press release that the results “add to the scientific heft underlying acupuncture”. The media conclude that “scientists find why acupuncture works”.
But here’s the thing: it is not clear that acupuncture clinically has any real specific therapeutic effects to speak of as real acupuncture rarely outperforms sham in trials, even where the sham is non-penetrating. In fact it is becoming clearer that it doesn’t. Even the placebo effect of acupuncture for pain does not seem large. So if needling has an active and specific effect in the tissues it is not strong enough to be distinguished from placebo in controlled clinical trials.
So in the end it’s a bit like looking for the reasons that explain why I am so great at basketball (when everybody knows that I suck at basketball since I am only 5 foot 5inches tall and have a complete lack of talent); or studying the mechanisms by which halibut do so well in cycle races (via a study in mackerel). I have a post coming soon discussing the issues surrounding acupuncture in detail so more to follow….
Original Abstract: Adenosine A1 receptors mediate local anti-nociceptive effects of acupuncture
Acupuncture is an invasive procedure commonly used to relieve pain. Acupuncture is practiced worldwide, despite difficulties in reconciling its principles with evidence-based medicine. We found that adenosine, a neuromodulator with anti-nociceptive properties, was released during acupuncture in mice and that its anti-nociceptive actions required adenosine A1 receptor expression. Direct injection of an adenosine A1 receptor agonist replicated the analgesic effect of acupuncture. Inhibition of enzymes involved in adenosine degradation potentiated the acupuncture-elicited increase in adenosine, as well as its anti-nociceptive effect. These observations indicate that adenosine mediates the effects of acupuncture and that interfering with adenosine metabolism may prolong the clinical benefit of acupuncture.
Goldman N, Chen M, Fujita T, Xu Q, Peng W, Liu W, Jensen TK, Pei Y, Wang F, Han X, Chen JF, Schnermann J, Takano T, Bekar L, Tieu K, & Nedergaard M (2010). Adenosine A1 receptors mediate local anti-nociceptive effects of acupuncture. Nature neuroscience PMID: 20512135
Madsen, M., Gotzsche, P., & Hrobjartsson, A. (2009). Acupuncture treatment for pain: systematic review of randomised clinical trials with acupuncture, placebo acupuncture, and no acupuncture groups BMJ, 338 (jan27 2) DOI: 10.1136/bmj.a3115
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