I have previously discussed in detail the reasons why, despite a fairly large and often positive research literature, I believe the evidence is strong that acupuncture works almost entirely as a placebo. Shortly after posting my most recent discussion of this issue, I ran across a paper which illustrates the phenomenon in an unusual and unexpected way. Steven Novella has already reviewed this paper on his blog, so I won’t go through it in detail, but I did want to call attention to this odd and interesting bit of evidence.
Chae Y, Lee IS, Jung WM, Park K, Park HJ, Wallraven C. Psychophysical and neurophysiological responses to acupuncture stimulation to incorporated rubber hand. Neurosci Lett. 2015 Feb 11;591C:48-52. doi: 10.1016/j.neulet.2015.02.025. [Epub ahead of print]
The researchers in this paper used a process called “incorporation,” a bit of psychological sleight-of-hand (pun intended) that allowed them to create in their subjects the sensation that a rubber model of a hand was actually part of their own body. In brief, then hand subjects sit with one hand hidden from view below a table and with a rubber hand positioned where their own hand would be if it was rested on the table. They then stroked the rubber hand and the subjects’ own hand simultaneously, creating the sensory illusion that the rubber hand belonged to the subject’s body.
This is weird enough, and says some interesting things about how our brains work and how they don’t always interpret the world around us correctly. But in this experiment, the incorporation was just the first step. The investigators then performed acupuncture on the rubber hand and measured responses in a couple of ways. They asked patients about signs of what is called DeQi, a sensation associated with acupuncture that is sometimes used in acupuncture studies as a marker of treatment effects. They also looked at activity in the subjects’ brains using a functional MRI unit.
What they found was that performing acupuncture on a rubber hand that one had been tricked by a visual and tactile illusion into seeing as one’s own hand had the same kinds of effects on the subject as acupuncture practices on their real body.
The findings of the present study clearly demonstrate that acupuncture stimulation to a rubber hand resulted in the expe-rience of the DeQi sensation when the rubber hand was fully incorporated into the body.
The present study also demonstrated that acupuncture stimu-lation to the incorporated rubber hand was associated with brain activations in the DLPFC, insula, SII, and MT visual area. These findings are consistent with those of previous studies which found that acupuncture stimulation leads to common brain activations inthe sensorimotor cortical network, including the insula and SII Although acupuncture stimulation was only applied to the incor-porated rubber hand in the present study, the stimulation clearly produced similar brain activations as does acupuncture to the realhand.
Interestingly, this is not the first study showing that so-called phantom acupuncture can mimic real acupuncture, though what “real” means in this context is unclear.
Though I am certain acupuncturists will disagree, what does seem clear is that if you can induce the sensations and brain activity associated with acupuncture by using needles in places not considered “real” acupuncture points, fake needles that don’t penetrate the skin, toothpicks, and now even needles poked into a fake hand not even connected to a subject’s body, the sensations and brain activity you are invoking come from the mind of the subject, not the acupuncture. What clearer definition of a placebo is there than a treatment that exerts its effects entirely through the beliefs of the subject without ever having to actually be applied to their body?