MRI

MRI

In October’s issue of Science a study showed a physiological response to a placebo topical analgesia. This article addresses the study design and findings, and concludes with its relation to chiropractic.

The study contained a population of 13 subjects, who were told that they were part of a trial to test the efficacy of a new pain killer cream. First patients were exposed to a painful heat source on their arm, and then researchers applied the ‘control cream’ (which was the same cream as the supposed pain-reducing cream). The patients’ pain ratings were then recorded. Next, researchers repeated the experiment but this time with the pain reducing cream, however, after administering the cream they lowered the temperature of the heat source without informing the patient. Therefore, the patients felt less pain with the pain-reducing cream.

In the second phase of the study, researchers performed functional MRIs at the C5-C6 junction on the patient while exposing the arm to a painful heat stimulus.  One part of the forearm was covered with the ‘control’ and the other with the ‘pain-reducing’ cream; each spot was exposed 25 times and at the same heat. The placebo effect took hold, and patients reported an average of 26% less pain in the analgesic arm.

Of course, proving the placebo effect is nothing new. What is amazing is that the fMRIs revealed that the ipsilateral dorsal horns lit up when the ‘control’ was exposed to the heat, but did not equally activate during the ‘pain-killer’ trials. Continue reading “Placebo Effect Seen on MRI” »