mollwollfumble said:
From before starting this topic, I’ve reasoned that the best way to test analgesia with sugar (and related substances) is with rats. Rats wouldn’t be so influenced by purely psychological factors. I’d test pain by looking for “glottal stops” in the breathing pattern, using a belt around the chest, a non-invasive technique. The more stress a rat is under, the more irregular its breathing would be.
No time to read it yet, doesn’t mention sugar. About the relative strength of different types of placebos. Full article publically available.
http://media.virbcdn.com/files/7c/FileItem-112506-KaptchukJCEdevises2000.pdf
On the linked article. In one study, oral placebo failed to lower blood pressure whereas injected placebo did. The oral drug also failed to reduce blood pressure. In another study: “88 highly refractory patients
with rheumatoid arthritis had previously “been exposed to an almost unbelievable number of nostrums, cultists, chemicals and physical agents, all of which had failed. When these patients received placebo pills for up to 4 weeks, 50% of them improved. If patients did not respond to the oral placebo, or had only a transient response, their treatment was changed by the investigators to injections of normal saline. Sixty-four percent of those resistant to placebo tablets responded to injections. 82% of all placebo-treated patients had some benefit, which lasted for 2 to 20 months.” (which placebo pills? I ask myself).
Also from linked article, sham acupuncture was compared to placebo pills. “a vexing problem in the study of
acupuncture, and other devices, is to select a placebo that mimics the verum and yet is a bona fide placebo!”. I would argue that the same problem exists with placebo pills. “In a study of 51 dental operative patients who received either real or sham acupuncture, blinding of patients was accomplished by hiding both the real and sham needles in a tube. The sham needle, however, never touched the skin because it became embedded in plastic on the undersurface of the holder. The result was that both real and sham acupuncture produced “100% success and high levels of patient acceptance”.
Other placebos compared included transcutaneous electrical nerve stimulation (TENS), sham surgery for
such diverse conditions as angina pectoris, asthma, osteoarthritis of the knee, and Parkinson’s disease.
A Google scholar search for the main author, Kaptchuk, also produces a wide range of papers about other placebos, including acupuncture, homeopathy, medical devices, complementary and alternative medicine, traditional Chinese medicine, “healing ritual”, nocebos, bias present even within double-blind randomised control trials, chiropractors, massage therapists, naturopathic physicians, effect of spoken words, interpersonal healing, ginseng, Navajo, biomedicine, ethics of using placebos in medical trials, the effect of informing patient up front that they are going to receive a placebo, supportive patient-physician relationship, yin-yang, “I made up the whole thing” patient response, “a taxonomy of unconventional healing practices”, holistic thinking, qigong, Gua Sha treatment.
Good stuff, I had no idea that there were so many different types of placebo.
One problem with the belt around the chest. Rats have hair. Hair flexes and has hysteresis. The more hair an animal has, the less accurate a belt around the chest (fitted with a strain gauge) would be at measuring breathing irregularities. Perhaps it should be nude mice.
So I’ve now narrowed the original question down. Given that a placebo effect is caused by a rise in endogenous endorphins, can this rise be triggered by sugar and similar chemicals purely by chemical means independent of psychological expectations, and if so is it triggered by taste or by ingestion?