Provided by David Satcher, M.D., Ph.D.
Surgeon General of the United States of America
Chapter 2
Overview of Treatment
Placebo Response
Recognized since antiquity, the placebo effect refers to the
powerful role of patients’ attitudes and perceptions that help them improve and
recover from health problems. Hippocrates established the therapeutic principle
of physicians laying their hands in a reassuring manner to draw on the inner
resources of the patient to fight disease. Technically speaking, the placebo
effect refers to treatment responses in the placebo group, responses that cannot
be explained on the basis of active treatment (Friedman et al., 1996a). A
placebo is an inactive treatment, either in the form of an inert pill for
studying a new drug treatment or an inactive procedure for studying a
psychological therapy. The effects of active treatment are often compared with a
control group that receives a pharmacological or psychological placebo.
It is not unusual for a placebo effect to be found in up to 50 percent of
patients in any study of a medical treatment (Schatzberg & Nemeroff, 1998). For
example, about 30 percent of patients typically respond to a placebo in a
clinical trial of a new antidepressant (see Chapter 4). The rate is even higher
for an antianxiety agent (an anxiolytic) (Schweizer & Rickels, 1997). The
placebo effect is of such import that a placebo group or other control group15
is mandated by the Food and Drug Administration in clinical trials of a new
pharmacotherapy to establish its efficacy prior to marketing (Friedman et al.,
1996a). If the pharmacotherapy is not statistically superior to the control,
efficacy cannot be established. It is somewhat more difficult to fashion an
analog of an inert pill in the testing of new and experimental psychological
therapies. Psychological studies can employ a “psychological” placebo in the
form of a treatment known to be ineffectual. Or they can employ a comparison
group, which receives an alternative psychological therapy. Some treatment
studies employ both a “psychological” placebo, as well as a comparison group.16
The basis of the placebo response is not fully known, but there are thought to
be many possible reasons. These reasons, which relate to attributes of the
disorder or the disease, the patient, and the treatment setting, include
spontaneous remission, personality variables (e.g., social acquiescence),
patient expectations, attitudes of and compassion by clinicians, and receiving
treatment in a specialized setting (Schweizer & Rickels, 1997). In studies of
postoperative pain, the placebo response is mediated by patients’ production of
endogenous pain-killing substances known as endorphins (Levine et al., 1978).
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