THE PLACEBO EFFECT IS MAINLY SUBJECTIVE…
On May 20th of 2009 The Skeptic: Extraordinary Claims, Revolutionary Ideas, and the Promotion of Science, featured an article on the Placebo Effect written by Harriet Hall, MD.
The article was easy to read and had some incredibly interesting things to say. Click Here for the full article, or skim some notable quotes below.
We not only know placebos “work,” we know there is a hierarchy of effectiveness:
- Placebo surgery works better than placebo injections
- Placebo injections work better than placebo pills
- Sham acupuncture treatment works better than a placebo pill
- Capsules work better than tablets
- Big pills work better than small
- The more doses a day, the better
- The more expensive, the better
- The color of the pill makes a difference
- Telling the patient, “This will relieve your pain” works better than saying “This might help.”
If the placebo effect is real, what might the mechanism be? We can’t just write it off as delusions of hyper-suggestible patients. There’s evidence that several things might be going on. The main hypotheses are: expectancy, motivation, conditioning, and endogenous opiates.
In a study of pain after dental surgery, patients were given either intravenous morphine or a saline placebo. If they were told that the saline was a powerful new painkiller, they got just as much relief as the patients who received morphine. In another study, all patients were given morphine for post-op pain, but only half were told they were getting it. The patients who didn’t know they were getting it only experienced half as much pain relief.
The placebo effect is mainly subjective…They work for more elusive complaints…symptoms that require us to accept the patient’s self-report of what he is experiencing.
Harvard University medical researcher Herbert Benson believes that the placebo effect yields clinical improvement for 60–90% of diseases, including angina, asthma, herpes simplex, and ulcers. Studies that have not been replicated have suggested that the placebo effect can influence things like swelling, movement disorders, temperature, pulse, blood pressure, cholesterol, blood sugar, and exercise tolerance.
Dopamine levels increased in the brains of Parkinson’s patients after taking a placebo; and patients who said they felt better released higher levels of dopamine. In another brain imaging study, researchers had patients play a game and estimate their chances of winning. The same reward areas in the brain lit up in subjects who thought they would win as in patients who were most convinced that the placebo painkiller would work.
“‘the placebo can be an open door to quackery'”