[Paleopsych] Skeptic's Dictionary: Placebo Effect
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Scientists See How Placebo Effect Eases Pain - Scientific American
February 20, 2004
Power of the placebo: Simply expecting relief from pain can help,
study shows, February 19, 2004
"Against Depression, a Sugar Pill Is Hard to Beat Placebos Improve
Mood, Change Brain Chemistry in Majority of Trials of
Antidepressants" by Shankar Vedantam Washington Post
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"The physician's belief in the treatment and the patient's faith in
the physician exert a mutually reinforcing effect; the result is a
powerful remedy that is almost guaranteed to produce an improvement
and sometimes a cure." -- Petr Skrabanek and James McCormick,
Follies and Fallacies in Medicine, p. 13.
The placebo effect is the measurable, observable, or felt improvement
in health not attributable to treatment. This effect is believed by
many people to be due to the placebo itself in some mysterious way. A
placebo (Latin for I shall please) is a medication or treatment
believed by the administrator of the treatment to be inert or
innocuous. Placebos may be sugar pills or starch pills. Even fake
surgery and fake psychotherapy are considered placebos.
Researchers and medical doctors sometimes give placebos to patients.
Anecdotal evidence for the placebo effect is garnered in this way.
Those who believe there is scientific evidence for the placebo effect
point to clinical studies, many of which use a control group
treated with a placebo. Why an inert substance, or a fake surgery or
therapy, would be effective is not known.
the psychological theory: it's all in your mind
Some believe the placebo effect is psychological, due to a belief in
the treatment or to a subjective feeling of improvement. Irving
Kirsch, a psychologist at the University of Connecticut, believes that
the effectiveness of Prozac and similar drugs may be attributed almost
entirely to the placebo effect. He and Guy Sapirstein analyzed 19
clinical trials of antidepressants and concluded that the expectation
of improvement, not adjustments in brain chemistry, accounted for 75
percent of the drugs' effectiveness (Kirsch 1998). "The critical
factor," says Kirsch, "is our beliefs about what's going to happen to
us. You don't have to rely on drugs to see profound transformation."
In an earlier study, Sapirstein analyzed 39 studies, done between 1974
and 1995, of depressed patients treated with drugs, psychotherapy, or
a combination of both. He found that 50 percent of the drug effect is
due to the placebo response.
A person's beliefs and hopes about a treatment, combined with their
suggestibility, may have a significant biochemical effect. Sensory
experience and thoughts can affect neurochemistry. The body's
neurochemical system affects and is affected by other biochemical
systems, including the hormonal and immune systems. Thus, it is
consistent with current knowledge that a person's hopeful attitude and
beliefs may be very important to their physical well-being and
recovery from injury or illness.
However, it may be that much of the placebo effect is not a matter of
mind over molecules, but of mind over behavior. A part of the behavior
of a "sick" person is learned. So is part of the behavior of a person
in pain. In short, there is a certain amount of role-playing by ill or
hurt people. Role-playing is not the same as faking or malingering.
The behavior of sick or injured persons is socially and culturally
based to some extent. The placebo effect may be a measurement of
changed behavior affected by a belief in the treatment. The changed
behavior includes a change in attitude, in what one says about how one
feels, and how one acts. It may also affect one's body chemistry.
The psychological explanation seems to be the one most commonly
believed. Perhaps this is why many people are dismayed when they are
told that the effective drug they are taking is a placebo. This makes
them think that their problem is "all in their mind" and that there is
really nothing wrong with them. Yet, there are too many studies which
have found objective improvements in health from placebos to support
the notion that the placebo effect is entirely psychological.
Doctors in one study successfully eliminated warts by painting them
with a brightly colored, inert dye and promising patients the warts
would be gone when the color wore off. In a study of asthmatics,
researchers found that they could produce dilation of the airways
by simply telling people they were inhaling a bronchiodilator, even
when they weren't. Patients suffering pain after wisdom-tooth
extraction got just as much relief from a fake application of
ultrasound as from a real one, so long as both patient and
therapist thought the machine was on. Fifty-two percent of the
colitis patients treated with placebo in 11 different trials
reported feeling better -- and 50 percent of the inflamed
intestines actually looked better when assessed with a
sigmoidoscope ("The Placebo Prescription" by Margaret Talbot, New
York Times Magazine, January 9, 2000).*
It is unlikely that such effects are purely psychological. But it is
not necessarily the case that the placebo is actually effective in
the nature-taking-its-course theory
Some believe that at least part of the placebo effect is due to an
illness or injury taking its natural course. We often heal
spontaneously if we do nothing at all to treat an illness or injury.
Furthermore, many disorders, pains and illnesses, wax and wane. What
is measured as the placebo effect could be, in many cases, the
measurement of natural regression. In short, the placebo may be
given credit that is due to nature.
However, spontaneous healing and spontaneous remission of disease
cannot explain all the healing or improvement that takes place because
of placebos. People who are given no treatment at all often do not do
as well as those given placebos or real medicine and treatment.
the process-of-treatment theory
Another theory gaining popularity is that a process of treatment that
involves showing attention, care, affection, etc., to the
patient/subject, a process that is encouraging and hopeful, may itself
trigger physical reactions in the body which promote healing.
According to Dr. Walter A. Brown, a psychiatrist at Brown University,
there is certainly data that suggest that just being in the healing
situation accomplishes something. Depressed patients who are merely
put on a waiting list for treatment do not do as well as those
given placebos. And -- this is very telling, I think -- when
placebos are given for pain management, the course of pain relief
follows what you would get with an active drug. The peak relief
comes about an hour after it's administered, as it does with the
real drug, and so on. If placebo analgesia was the equivalent of
giving nothing, you'd expect a more random pattern ("The Placebo
Prescription" by Margaret Talbot, New York Times Magazine, January
Dr. Brown and others believe that the placebo effect is mainly or
purely physical and due to physical changes which promote healing or
feeling better. It is assumed that the physical changes are not caused
by the placebo itself. So, what is the explanatory mechanism for the
placebo effect? Some think it is the process of administering it. It
is thought that the touching, the caring, the attention, and other
interpersonal communication that is part of the controlled study
process (or the therapeutic setting), along with the hopefulness and
encouragement provided by the experimenter/healer, affect the mood of
the subject, which in turn triggers physical changes such as release
of endorphins. The process reduces stress by providing hope or
reducing uncertainty about what treatment to take or what the outcome
will be. The reduction in stress prevents or slows down further
harmful physical changes from occurring.
The process-of-treatment hypothesis would explain how inert
homeopathic remedies and the questionable therapies of many
"alternative" health practitioners are often effective or thought to
be effective. It would also explain why pills or procedures used by
conventional medicine work until they are shown to be worthless.
Forty years ago, a young Seattle cardiologist named Leonard Cobb
conducted a unique trial of a procedure then commonly used for
angina, in which doctors made small incisions in the chest and tied
knots in two arteries to try to increase blood flow to the heart.
It was a popular technique -- 90 percent of patients reported that
it helped -- but when Cobb compared it with placebo surgery in
which he made incisions but did not tie off the arteries, the sham
operations proved just as successful. The procedure, known as
internal mammary ligation, was soon abandoned ("The Placebo
Prescription" by Margaret Talbot, New York Times Magazine, January
Of course, spontaneous healing or regression can also adequately
explain why homeopathic remedies might appear to be effective. Whether
the placebo effect is mainly psychological, misunderstood spontaneous
healing, due to showing care and attention, or due to some combination
of all three may not be known with complete confidence.
the powerful placebo challenged
The powerful effect of the placebo is not in doubt. It should be,
however, according to Danish researchers Asbjørn Hróbjartsson and
Peter C. Götzsche. Their meta-study of 114 studies involving placebos
found "little evidence in general that placebos had powerful clinical
effects...[and]...compared with no treatment, placebo had no
significant effect on binary outcomes, regardless of whether these
outcomes were subjective or objective. For the trials with continuous
outcomes, placebo had a beneficial effect, but the effect decreased
with increasing sample size, indicating a possible bias related to the
effects of small trials ("Is the Placebo Powerless? An Analysis of
Clinical Trials Comparing Placebo with No Treatment," The New England
Journal of Medicine, May 24, 2001 (Vol. 344, No. 21)."
According to Dr. Hróbjartsson, professor of medical philosophy and
research methodology at University of Copenhagen, "The high levels of
placebo effect which have been repeatedly reported in many articles,
in our mind are the result of flawed research methodology."* This
claim flies in the face of more than fifty years of research. At the
very least, we can expect to see more rigorously designed research
projects trying to disprove Hróbjartsson and Götzsche.
the origin of the idea
The idea of the powerful placebo in modern times originated with H. K.
Beecher. He evaluated over two dozen studies and calculated that about
one-third of those in the studies improved due to the placebo effect
("The Powerful Placebo," 1955). Other studies calculate the placebo
effect as being even greater than Beecher claimed. For example,
studies have shown that placebos are effective in 50 or 60 percent of
subjects with certain conditions, e.g., "pain, depression, some heart
ailments, gastric ulcers and other stomach complaints."* And, as
effective as the new psychotropic drugs seem to be in the treatment of
various brain disorders, some researchers maintain that there is
not adequate evidence from studies to prove that the new drugs are
more effective than placebos.
Placebos have even been shown to cause unpleasant side effects.
Dermatitis medicamentosa and angioneurotic edema have resulted from
placebo therapy, according to Dodes. There are even reports of
people becoming addicted to placebos.
the ethical dilemma
The power of the placebo effect has led to an ethical dilemma. One
should not deceive other people, but one should relieve the pain and
suffering of one's patients. Should one use deception to benefit one's
patients? Is it unethical for a doctor to knowingly prescribe a
placebo without informing the patient? If informing the patient
reduces the effectiveness of the placebo, is some sort of deception
warranted in order to benefit the patient? Some doctors think it is
justified to use a placebo in those types of cases where a strong
placebo effect has been shown and where distress is an aggravating
factor.* Others think it is always wrong to deceive the patient
and that informed consent requires that the patient be told that a
treatment is a placebo treatment. Others, especially "alternative"
medicine practitioners, don't even want to know whether a treatment is
a placebo or not. Their attitude is that as long as the treatment is
effective, who cares if it a placebo? Of course, if the placebo effect
is an illusion, then another ethical dilemma arises: should placebos
be given if it is known that deception does not really reduce pain or
aid in the cure of anything?
are placebos dangerous?
While skeptics may reject faith, prayer and "alternative" medical
practices such as bioharmonics, chiropractic and
homeopathy, such practices may not be without their salutary
effects. Clearly, they can't cure cancer or repair a punctured lung,
and they might not even prolong life by giving hope and relieving
distress as is sometimes thought. But administering useless therapies
does involve interacting with the patient in a caring, attentive way,
and this can provide some measure of comfort. However, to those who
say "what difference does it make why something works, as long as it
seems to work" I reply that it is likely that there is something which
works even better, something for the other two-thirds or one-half of
humanity who, for whatever reason, cannot be cured or helped by
placebos or spontaneous healing or natural regression of their pain.
Furthermore, placebos may not always be beneficial or harmless. In
addition to adverse side effects, mentioned above, John Dodes notes
Patients can become dependent on nonscientific practitioners who
employ placebo therapies. Such patients may be led to believe
they're suffering from imagined "reactive" hypoglycemia,
nonexistent allergies and yeast infections, dental filling amalgam
"toxicity," or that they're under the power of Qi or
extraterrestrials. And patients can be led to believe that diseases
are only amenable to a specific type of treatment from a specific
(The Mysterious Placebo by John E. Dodes, Skeptical Inquirer,
In other words, the placebo can be an open door to quackery.
See also confirmation bias, control study, communal
reinforcement, magical thinking, nocebo, Occam's razor,
post hoc fallacy, regressive fallacy, selective thinking,
self-deception, subjective validation, testimonials, and
For examples of beliefs deeply affected by the placebo effect see the
"alternative" health practices
* The Mysterious Placebo by John E. Dodes
* The placebo effect is the healing force of nature by G.
* The Mysterious Placebo Effect by Carol Hart Modern Drug
Discovery July/August 1999
* Kirsch, Irving , Ph.D. and Guy Sapirstein, Ph.D. "Listening to
Prozac but Hearing Placebo: A Meta-Analysis of Antidepressant
Medication" Prevention & Treatment, Volume 1, June 1998.
* The Placebo Prescription - New York Times Magazine 1/09/2000
* Sham Surgery Returns as a Research Tool by Sheryl Gay
Stolberg, New York Times 4/25/1999
* "Placebo Effect Accounts For Fifty Percent Of Improvement In
Depressed Patients Taking Antidepressants" by the American
* "Placebo Effects Prove the Value of Suggestion" by Charles
Henderson, Ph.D. (Interesting experiment on subliminal
* Is Prescribing Placebos Ethical? experts argue the pros and
Engel, Linda W. et al. The Science of the Placebo - Toward an
Interdisciplinary Research Agenda ( BMJ Books, 2002).
Fisher, Seymour and Roger P. Greenberg. eds. From Placebo to
Panacea: Putting Psychiatric Drugs to the Test (John Wiley and Sons,
Hróbjartsson, Asbøjrn and Peter C. Götzsche. "Is the Placebo
Powerless? An Analysis of Clinical Trials Comparing Placebo with No
Treatment," The New England Journal of Medicine, May 24, 2001 (Vol.
344, No. 21).
Harrington, Anne. ed. The Placebo Effect : An Interdisciplinary
Exploration (Harvard University Press, 1999).
Hartwick, Joseph J. Placebo Effects in health and Disease: Index of
new Information with Authors, Subjects, and References (Washington,
D.C.: ABBE Publications Association, 1996).
Jerome, Lawrence E. Crystal Power - The Ultimate Placebo Effect
(Amherst, NY: Prometheus, 1996).
Skrabanek, Petr, Ph.D. and James McCormick, M.D. (1990). Follies &
Fallacies in Medicine. Prometheus.
Ogelsby, Dr. Paul. The Caring Physician : The Life of Dr. Francis
W. Peabody (Harvard University Press, 1991).
Shapiro, Arthur K. and Elaine. The Powerful Placebo: From Ancient
Priest to Modern Physician (Johns Hopkins University Press, 1997).
Stanovich, Keith E. How to Think Straight About Psychology, 3rd
ed., (New York: Harper Collins, 1992).
Sternberg, Esther M. and Philip W. Gold. "The Mind-Body Interaction in
Disease," Scientific American," special issue "Mysteries of the Mind,"
White, Leonard, Bernard Tursky and Gary Schwartz. Placebo: Theory
Research, and Mechanisms, ed. (New York: Guilford Press, 1985).
Robert Todd Carroll
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