There is very little doubt that acupuncture works to relieve pain; in 1999 the U.S. Food and Drug Administration (FDA) removed acupuncture needles from its list of "experimental devices" and reclassified them as approved medical devices. Abundant scientific evidence exists that acupuncture provides pain relief, although some studies in the past have suggested that at least part of this relief may be due to the placebo effect, because in some cases "sham" acupuncture has been perceived by patients to "work" as well as real acupuncture.
But few deny that acupuncture works. They just argue about how it works. Traditional explanations have centered on the Eastern belief that there is a type of life energy called Qi (pronounced "chi" or "chee") which flows through the body, and that by inserting the acupuncture needles one can redirect or channel that energy to remove imbalances or blockages. Until recently, Western scientists have tried to explain the effects of acupuncture needles as stimulating the hypothalamic-pituitary glands at the base of the brain and stimulating an increased production of endorphins, which have natural pain-relieving qualities.
Recent research seems to indicate that neither of these explanations is correct, or at least neither is completely correct. Instead, brain scans taken while patients were receiving acupuncture treatment seem to indicate that it works by increasing cerebral glucose metabolism in regions of the brain that process pain signals. This has the effect of increasing the ability of pain receptors in those areas of the brain to bind with the body's natural painkillers (such as endorphins), and thus weaken the pain signals.
Brain activity shows that it's not all placebo effect
In one study magnetic resonance imaging (MRI) scans taken of patients' brains during treatment showed that pain levels as seen with the MRI definitely decreased, and that the decrease corresponded to the use of real acupuncture points. Because the MRI showed brain activity in these areas when the real acupuncture points were used and not when "sham" points were used, researchers felt that "…there really is something going on here…it was likely the increased tolerance to pain was real and not just an artifact of treatment, known as a placebo effect."
In a more recent study using positron emission tomography-computed tomography (PET-CT) neuroimaging, metabolic changes were also seen in the regions of the brain that process pain signals. In this study, subjects with chronic migraine headaches were placed either in a traditional acupuncture group (TAG), a controlled acupuncture group (CAG) which used different acupuncture points, or a non-intervention group. The TAG subjects experienced more relief from their migraines than the other groups, and also showed in the PET-CT scans the most increased activity in the areas of the brain associated with pain management.
In the third study, recently published in the journal Archives of Internal Medicine, scientists analyzed previous research on nearly 18,000 acupuncture patients, and performed a meta-analysis on it; the process took over six years. It also tested for "sham" acupuncture, in studies in which needles were inserted superficially or used "trick" needles that retracted into the handle when used. They found that people who benefit from acupuncture treatment are receiving real benefits, not just a psychological boost or placebo effect-generated simulation. One of the study authors, Dr. Andrew L. Avins, said that their results show "robust evidence" that acupuncture provides "modest benefits over usual care for patients with diverse sources of chronic pain."
A fourth study, published in the journal NeuroImage, also used PET-CT scans of subjects diagnosed with fibromyalgia, and who had previously reported being in constant pain at least half of the time. During the study they took no new medications for their pain. Scans were taken of their brains before their first acupuncture treatment, and then retaken a month later, after their eighth treatment. Most of the subjects reported a subjective lessening of their pain. In the brain scans, increased activity was detected in the thalamus, cingulate, caudate, insula, and amygdala regions of the brain, increasing the binding ability of mu-opiod receptors there. This allowed these receptors (which receive signals from the body and "translate" them to the sensation of pain) to bind more readily with the brain's naturally-produced opiods. The result was the transmission of fewer or reduced pain signals, thus providing the subjects with reduced sensations of pain.
Researchers in this study felt that the discovery that acupuncture increases the ability of these pain receptors to bind to natural opiods promises new hope in the ongoing study of how to provide relief from chronic pain. For example, if acupuncture improves the pain receptors' ability to bind to natural opiods, would the use of morphine or other opiod drugs after acupuncture treatment provide even greater pain-killing effectiveness? Follow-up research is being done along these lines.
So although there is still no definitive answer as to how inserting a needle into one part of the body produces a change in brain chemistry that reduces pain, there does seem to be an increasing body of evidence showing that it does just that, and is not just the result of the placebo effect. And this is good news. The treatment of chronic pain is one of the most challenging areas of medical practice and research, so anything that actually works to reduce pain is welcome news indeed, both to physicians and their patients.