Here is yet another example of the power of the placebo from Hippocrates’ Shadow: Secrets from the House of Medicine (David Newman)

“…Just five months after Dr. Freeds group published their work, a group in Vancouver, Canada, published a study…using a brain imaging technique called positron emission tomography scans, or PET scans, the researchers recorded the production of dopamine from the diseased areas of the brains of Parkinsons patients. While this had been done before, the researchers performed the images on an unusual group: patients from the active treatment and placebo groups of a trial being done to test a new drug for Parkinsons at their medical center. The PET scans showed that patients receiving placebos had visibly and measurably increased dopamine output from the diseased cells. The PET scans had allowed researchers for the first time to see the placebo effect….

Skeptics have argued that these studies dont provide evidence of a true physiologic placebo effect because pain, or even nausea, can be a subjective measurement. But dopamine output in the brain, and endorphins, are not subjective. Physical healing is also not subjective. Just as more pain reduction is seen with two placebo pills than with one, ulcers seen by endoscopy in the lining of the stomach or intestine heal more quickly when a patient is given two placebo pills rather than one. Real medicine reduces high blood pressure, but an inert pill does so as well, albeit somewhat less effectively. Real medications for asthma dilate the lung passages, making it easier to breathe; but if you tell an asthma patient that hes going to receive a medication that will dilate his lung passages, and then give him an inhaled placebo, his lung passages dilate. The patterns of placebo response are virtually identical to the patterns seen when using an effective pill.”