Clinical studies suggested that both specific and non-specific factors may play a role in acupuncture therapy. Some studies of acupuncture, with the objective of distinguishing specific from non-specific therapeutic effects, have been reported.
1. Sham acupuncture vs real acupuncture:There have been numerous evidences that real (active) acupuncture is superior than sham acupuncture in cardiovascular function, postoperative pain, headache, neck and low back pain. These studies suggest that the placebo effects (non-specific effects) are minor for acupuncture treatment. In contrast, others reported that there is limited evidence that acupuncture is more effective than no treatment for chronic pain; and inconclusive evidence that acupuncture is more effective than placebo, sham acupuncture or standard care (Sham acupuncture 2007).
In sham acupuncture procedure, needles are generally inserted into the non-meridian points, while needles are inserted into the meridian points in real acupuncture based on the traditional Chinese medicine (TCM). However, the meridian system has not been proved by our modern science. On the other hand, recent anatomical and physiological studies demonstrated an important role of somatosensory pathway to mediate anti-nociceptive effects and autonomic nerve function.
Therefore, it is conceivable that the somatosensory stimulation on the non-meridian points may have similar effects with the somatosensory stimulation on the meridian points. Acupuncture often shows only a small positive trend compared to sham needling, but this may be explained that these studies are simply comparing two forms of somatosensory stimulation.
2. Psychological factors: The psychological factors (often referred to as placebo) become particularly important, because psychological factors rely on the endogenous modulation of various functions. Acupuncture is possibly an uniquely effective method in the activation of positive placebo effects. The analgesic effects of acupuncture and placebo were compared in different painful conditions (migraine, chronic low back pain and osteoarthritis), as were patients’ expectations of the therapeutic results. Patients who believed they were received acupuncture group showed clinical improvements superior to those who believed they were in the placebo group. Patients with high expectations about the effects of acupuncture showed more response than those who did not believe in the treatment, independently of treatment group(Expectancy and belief 2005).
It remains unclear whether acupuncture or simulated method of acupuncture provide physiologically important stimulation or represent placebo or nonspecific effects.
3. Acupuncturists’ behavior:A recent report suggests the importance of acupuncturists’ communication styles. Acupuncturists were trained to interact in 1 of 2 communication styles: high or neutral expectations.
High expectations; acupuncturists conveyed high expectations of improvement, using positive utterances such as “I think this will work for you,” “I’ve had a lot of success with treating knee pain,” and “Most of my patients get better.”
Neutral expectations; Acupuncturists conveyed uncertainty with utterances such as “It may or may not work for you,” “It really depends on the patient,” and “We’re uncertain, and that’s why we are doing the study,” with words like “uncertain.”
Statistically significant differences were observed in pain reduction and satisfaction, favoring the high expectations group. Acupuncturists’ styles had significant effects on pain reduction and satisfaction, suggesting that the analgesic benefits of acupuncture can be partially mediated through placebo effects related to the acupuncturist’s behavior (Patient provider communication 2010).
4. Mental activity of expectation:The insula ipsilateral to the site of needling was activated to a greater extent during real acupuncture than during the placebo intervention. Real acupuncture and placebo (with the same expectation of effect as real acupuncture) cause greater activation than skin pricks (no expectation of a therapeutic effect) in the right dorsolateral prefrontal cortex (PFC), anterior cingulate cortex (ACC) and midbrain . Mental activity of expectation mediates placebo effects.The expectation initially activates PFC, resulting in the alteration of some other brain regions. These suggest that acupuncture has a specific physiological effect and that patients’ expectation and belief regarding a potentially beneficial treatment modulate activity in component areas of the reward system (Expectancy 2012).
It should be emphasized that emotional impact can alter the brain activity, resulting in stimulation of various neurotransmitters and neuropeptides in the CNS. Placebo is as physiological mechanism as any other.Mental activity, conscious or unconscious, may modulate somatic mechanisms as effectively as any peripheral stimulus. The somatic factors stimulated by real or sham acupuncture and psychological factors stimulated by expectation and acupuncturist-patient relationship (so called placebo effects) may act in harmony to utilize endogenous mechanisms most effectively.