Acupuncture - Theories and Evidence

Acupuncture is widely practised in the 21st century in scientifically developed countries for a wide range of ailments ranging from chronic pain, giddiness and high blood pressure to gastrointestinal disorders and sexual dysfunction. Yet the reasons for its vaunted efficacy remain a matter of controversy. In traditional Chinese medical theory, the mechanism of action in acupuncture was understood in terms of the flow of qi and the balance of yin and yang through the body's meridians, a complex network painstaking charted but never found. Modern medical researchers have examined old and new needling points, and some view them as “trigger points” that stimulate physiological responses in the body. There is also clear evidence of strong placebo effects, although it has not been conclusively established that that this is either the main or the only significant effect.

This volume contains twelve articles covering the latest scientific explanations of the mechanism of acupuncture and critical reviews of clinical trials on its efficacy by leading scholars, including Edzard Ernst at Exeter, Lixing Lao at the University of Maryland, PC Leung at the Chinese University of Hong Kong and Thomas Lundeberg at Karolinska Institute.

In this text Hai Hong, a senior fellow and adjunct professor at the Nanyang Technology University in Singapore, has collated scientific explanations for acupuncture (part one) and acupuncture clinical research modalities (part two). The contributors in part one include Thomas Lundeberg, Stephen Birch, Ching-Liang Hsieh, Konstantina Theodoratou and the editor himself, whilst the second part of the book has contributions from a further 19 authors (including Edzard Ernst).

Thomas Lundeberg writes on the mechanisms of acupuncture in pain. He describes some of the associated biochemical changes that can be measured, including the release of neuropeptides, the release of vasodilatory mediators resulting in increased blood flow, the increase of skeletal muscle glucose uptake and the regulation of homeostasis. He explains that deqi results in the activation of socalled 'Ergo receptors' (pressure receptors commonly activated by strong muscle contractions), which results in the release of endogenous opioids (-endorphins and enkephalins), monoamines (serotonin and norephinephrin), GABA (-aminobutyric acid) and glycine which modulates nociceptive transmission and sympathetic tone. Lundeberg also reports that low (two hertz) and high (100 hertz) frequency electroacupuncture result in different biochemical reactions. The former stimulates -endorphin release (via increased serotonin release in spinal cord), whereas the latter reduces aspartate and glutamate release in the spinal cord. Overall Lundeberg stresses that acupuncture is a complex treatment involving empathy, touch, intention, attention and expectation, and thus any measured biochemical changes only constitute part of the whole picture.

The rest of the chapters in part one deal with scientific approaches to the traditional aspects of acupuncture. Stephen Birch argues that the direct 'cause and effect' approach used in Western scientific research is not applicable to traditionallybased systems of acupuncture, and thus calls for a different approach. Hai Hong adds to this the fact that the acupuncture channel system remains unexplained from a scientific viewpoint, concluding that the channel system has been found useful as an explanatory model because during acupuncture treatment the body behaves as if these pathways existed.

Ching-Liang Hsieh reports on studies where acupuncture has been shown to have yin or yang specific effects (e.g. warming of the palm versus the dorsal aspect of the hand), and documents the physiological effects relating to defined acupuncture points, as well as the effects related to different types of needle manipulation (such as high or low frequency electroacupuncture and manual manipulation).

Konstantina Theodoratou describes ways of visualising acupuncture effects using modern techniques such as PET (positron emission tomography), functional MRI (magnetic resonance imaging) and SPECT (single-proton emission computer tomography). She stresses that although the short-term analgesic effects can be explained by these visualisations (involving, for example, signals detected in the hypothalamus and limbic system), the long-term effects of acupuncture remain unexplained. She hypothesises that the prolonged analgesic effect of acupuncture may be due to induction of a reorganisation of functional connectivity across different brain subsystems. Theodoratou introduces the reader to the possible mechanisms involved in the acupuncture treatment of pain. She emphasises that it has been shown that pain is not the same as tissue damage, nor is it produced at the tissue in question; rather, pain is a function of the brain. She refers to studies which have shown that acupuncture provokes changes in brain chemistry sensation and involuntary body functions. In addition she describes recent neuroimaging studies which revealed that acupuncture stimulation can actuate widespread brain regions largely overlapping with the neural networks for both pain transmission and perception.

In the second half of the book Edzard Ernst complains that acupuncture researchers tend to be enthusiastic amateurs [sic] who use science to prove that their prior beliefs are correct rather than to rigorously test hypotheses. He particularly criticises the lack of 'proper' placebo-controlled RCTs. Ernst's view is opposed robustly in three other chapters
0 by Lao et al., Lee & Zheng and Evan - who approach the placebo problem in acupuncture research from various angles. All agree that a valid acupuncture placebo treatment can only be designed if the mechanism of the true (verum) treatment is known. However, all also agree that the mechanism of how acupuncture works is still poorly understood, which means that all placebo/sham treatments used in published trials are flawed by definition. Moreover this has been experimentally confirmed in numerous studies recently reviewed by a Cochrane report (2010), which showed that 'physical placebos' (including sham acupuncture) were associated with larger effects in control groups compared to 'pharmacological placebos'. Even more surprising is that despite this failure of sham acupuncture as a placebo, verum acupuncture shows superiority to placebo in a significant number of trials. The authors argue that the true effectiveness of acupuncture is demonstrated by studies that show that animals can be effectively treated with acupuncture (and expectation and beliefs are unlikely to play a role). In addition, studies of brain chemistry show that acupuncture induces biochemical modifications in the human brain. The authors suggest therefore that the model of the randomised placebo controlled trial is inappropriate for acupuncture and for other therapies involving healing touch.

The book makes a fascinating read of the diverse angles involved in acupuncture research, particularly in terms of the problem with placebo/sham acupuncture. As the subject matter suggests, it is not an easy read, but the effort is rewarded by providing the acupuncture community with a collection of strong arguments for the validity of acupuncture. In addition the authors offer real gems by providing suggestions for important aspects of future research, such as exploring why acupuncture requires repeated treatments to be effective, and why practitioners should pay attention to dose and needling techniques. Acupuncture researchers need to insist that modern clinical research settings such as pragmatic trials (without placebo arm) should be employed to assess acupuncture and other touch healing therapies. Such an approach will benefit medical research in general as it will steer all health practitioners towards a more ethical and clinically valuable approach to helping patients.

Pia AJ Huber

• Scientific Explanations for Acupuncture:
  • Mechanisms of Acupuncture in Pain: A Physiological Perspective in a Clinical Context (Thomas Lundeberg)
  • Explanatory Nature, Models, Needs and Requirements for Testing Them (Stephen Birch)
  • The Ontological Status of Meridians (Hong Hai)
  • Modern Scientific Explanation of Traditional Acupuncture Theory (Ching-Liang Hsieh)
  • Cognitive Neuroscience, Acupuncture and Pain Treatment. Does a Sting Always Hurt? (K Theodoratou)
• Clinical Trials and Placebo Effects:
  • Frequent Weaknesses in Acupuncture Trials (Edzard Ernst)
  • The Complexities Inherent in Placebo-Controlled Acupuncture Studies (Lixing Lao, Lizhen Wang and Ruixin Zhang)
  • Research Methodology in Acupuncture (Tat-Leang Lee and Zhen Zheng)
  • The Use of Placebos in Acupuncture Trials (Dylan Evans)
  • Improving the Quality of Randomized Controlled Trials (RCTs) in Acupuncture (Zhaoxiang Bian, Chungwah Cheng, Linda Chan, Mandy Cheung, Min Li and Zhixiu Lin)
  • Acupuncture Treatment for Addiction (Ping-Chung Leung, Ellie S Y Pang, Lang Zhang and Eliza L Y Wong)
  • Dense Cranial Electroacupuncture Stimulation for Neuropsychiatric Disorders: Rationale and Clinical Application (Zhang-Jin Zhang and Sui-Cheung Man)