An fMRI study on the interaction and dissociation between expectation of pain relief and acupuncture treatment

Abstract

It is well established that expectation can significantly modulate pain perception. In this study, we combined an expectancy manipulation model and fMRI to investigate how expectation can modulate acupuncture treatment. Forty-eight subjects completed the study. The analysis on two verum acupuncture groups with different expectancy levels indicates that expectancy can significantly influence acupuncture analgesia for experimental pain. Conditioning positive expectation can amplify acupuncture analgesia as detected by subjective pain sensory rating changes and objective fMRI signal changes in response to calibrated noxious stimuli. Diminished positive expectation appeared to inhibit acupuncture analgesia. This modulation effect is spatially specific, inducing analgesia exclusively in regions of the body where expectation is focused. Thus, expectation should be used as an important covariate in future studies evaluating acupuncture efficacy. In addition, we also observed dissociation between subjective reported analgesia and objective fMRI signal changes to calibrated pain on the analysis across all four groups. We hypothesize that as a peripheral-central modulation, acupuncture needle stimulation may inhibit incoming noxious stimuli; while as a top-down modulation, expectancy (placebo) may work through the emotional circuit.

Acupuncture for seasonal allergic rhinitis: a randomized controlled trial

“…64 Neuroscience studies have confirmed that sham needling is not physiologically inert. 65,66 Since the first innovative invention of the placebo acupuncture needle was introduced in 1998, 67 attempts at designing a perfect placebo acupuncture device have been ongoing. However, thus far, no optimal placebo for acupuncture research seems to exist.…”

Dry needling — peripheral and central considerations

“…240 Other functional magnetic resonance studies have confirmed that expectancy can significantly influence acupuncture analgesia. [249][250][251] A recent study concluded that patients with a high degree of dispositional optimism and low state anxiety were particularly receptive to placebo responses. 252 It is likely that similar issues must be considered when designing dry needling studies.…”

The power of imagination — How anticipatory mental imagery alters perceptual processing of fearful facial expressions

“…why strong expectations can reverse placebo conditioning (Benedetti et al, 2003) and (3.) why analgesia following acupuncture can be regionally specific (Kong et al, 2009). Future studies therefore have to carefully assess, whether 'imagery proneness' may be an underestimated mediator of placebo effects and other phenomena of biased perception.…”